Diagnostic Procedures | Physiology | Medical Specialties| Medical & Surgical Procedures | Miscellaneous Terms


DISORDERS

ATYPICAL HEMIFACIAL SPASM

Onset of spasm starting in/around mouth/lip area rather than in eye area. (see Hemifacial Spasm)


BILATERAL HEMIFACIAL SPASM

When there is Bilateral Hemifacial Spasm, spasms occur on both sides of face. If Microvascular Decompression (MVD) surgery is an option, it must be done by two separate operations. (see Hemifacial Spasm)


BELL'S PALSY

Bell's Palsy (BP), also called facial nerve palsy, is usually a one-sided facial paralysis that occurs suddenly and worsens over a period of hours to days. The disorder involves the seventh cranial (facial) nerve -- the nerve that controls movement of the muscles of the face. Facial nerve dysfunction can occur because there is reduced blood supply to the nerve, inflammation and edema within the nerve, or an immune reaction or viral infection. In some cases, the disorder is presumed to be associated with inflammation of the facial nerve where it travels through the bones of the base of the skull. It may also be caused by head injury, tumor, hypertension or infarction.

Symptoms of BP are weakness of facial muscles, impairment of taste, sensitivity to sound on the affected side, headache, face pulled to one side, difficulty with eating and drinking, change in facial appearance (facial droop), difficulty with facial expressions (grimacing), facial paralysis of one side of the face (difficulty closing one eye, making fine facial movements and drooling). Symptoms begin suddenly and peak usually within 48 hours. Seventy-five percent of cases are preceded by upper respiratory infection. It is important to seek medical evaluation so that medically treatable forms of facial paralysis can be identified, even though most cases of BP resolve spontaneously. The goal of treatment is to relieve the symptoms. The goals of therapy are to prevent or minimize significant and long-term paralysis, disfigurement and disability. Treatment may include medications and rarely, surgery.

(Source - Medifocus Guide & Jeffrey A. Brown, MD, Department of Neurological Surgery, Wayne State University School of Medicine)

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BLEPHAROSPASM

Blepharospasm is a common term for conditions that are medically known as Benign Essential Blepharospasm and Essential Blepharospasm. Blepharospasm is defined as, "a chronic, unremitting, bilateral, variably progressive dysfunction of the nerve that controls the muscles around the eye." It manifests itself as an uncontrollable, forcible closure of the eyelids. It often affects both eyes at once, but it can also affect only one eye. In some cases, other muscles in the face can twitch as well, especially around the cheek and brow. Severe blepharospasm can cause the eyelids to be forcibly closed for a duration longer than the typical blink reflex causing a variable interruption in the ability to see. Benign Essential Blepharospasm and Essential Blepharospasm are caused by abnormal nerve impulses to the eyelid muscles.

(Source - Steen-Hall Eye Institute)

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DYSTONIA

Abnormal muscle rigidity, causing painful muscle spasms, unusually fixed postures or strange movement patterns. Dystonia may affect a localized area of the body, or it may be more generalized. The most common types of localized dystonia are torticollis (painful neck spasm) and scoliosis (abnormal curvature of the spine) caused by an injury to the back that produces muscle spasm. Most generalized dystonia occurs as a result of various neurological disorders, including Parkinson's Disease and stroke, and may also be a feature of schizophrenia. Dystonia may be a side effect of antipsychotic drugs.

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HEMIFACIAL SPASM (HFS)

Hemifacial Spasm (HFS), or tic convulsif, is a neuromuscular disorder characterized by frequent involuntary contractions (tics) of the muscles on one side of the face. The disorder occurs in both men and women, although it more frequently affects middle-aged or elderly women. These tics are seldom painful and usually affects one side of the face. Although there is a sensory component to the facial nerve that can produce pain behind the ear, hearing changes are seldom noted.

HFS is caused by compression of the seventh cranial nerve, i.e., the facial nerve. A small vessel (usually an artery, but occasionally a vein) is found to be compressing the root entry zone (REZ) of the facial nerve at the brainstem. This vessel is usually too small to be observed by imaging studies such as magnetic resonance imaging (MRI), computed tomography (CAT scan), or even angiography (arteriography).

Symptoms

The first symptom of HFS is usually an intermittent twitching of the eyelid muscle which results in forced closure of the eye. The spasm may then gradually spread to involve the muscles of the lower face, which may cause the mouth to be pulled to one side. Eventually the spasms involve all of the muscles on the affected side of the face almost continuously.

Treatment

Neurological Approach: In mild cases, doctors may prescribe medications or recommend biofeedback training. The medical approach to treatment has been limited primarily to drug therapy. Limited success has generally been seen and it is not unusual for drug treatment to be unsuccessful in controlling Hemifacial spasms.

Botox® Injections (see Botulinum Toxin - BOTOX®)

Surgery (see Microvascular Decompression - MVD)

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HYPERACUSIS

An exceptionally developed sense of hearing. It may cause the sensation of pain or discomfort in the ears on exposure to loud noises. One of the branches of the facial nerve is the nerve to an ear muscle--the stapedius muscle. Some patients with hemifacial spasm complain of clicks or buzzing in the ear on the side of the spasm before surgery. Surgery itself can change the sensitivity of the muscle to impulses from the nerve so that they develop "hyperacusis," the sensation that sounds that normally would not bother anyone are too loud. This usually resolves over time, but it can take months to years.

(Source - The American Medical Association Encyclopedia of Medicine)

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TRIGEMINAL NEURALGIA - TN

Also known as tic douloureux, is a painful condition that involves a malfunction of the trigeminal nerve (the fifth cranial nerve), that is characterized by intermittent electric shock-like stabbing, usually confined to one side of the face, often triggered by touching the face, chewing, talking or by a cool breeze. In classical (TN) there is a pain-free interval between shocks, but when the disease is more advanced there may be constant, burning component to the pain. The condition is more common in older patients, but it may occur at any age. Most often the cause is compression of the trigeminal nerve by a small vessel at the brainstem entrance of the nerve. Other associated conditions include multiple sclerosis, tumors or blood-vessel malformations of the brain. The condition is often treatable at first by anti-convulsant medications. When these cease to be effective there are several operative procedures available including microvascular decompression, balloon compression, thermal rhizotomy, radiosurgery or glycerol injection. Adults of any age can be affected by trigeminal neuralgia, but the disorder is more common in the elderly.

Symptoms

The pain can occur spontaneously but is often set off by touching a particular spot (trigger point) or by an activity such as brushing the teeth or chewing. Repeated bursts of closely separated lightning-like flashes of excruciating pain can be felt in any part of the lower portion of the face. Most often the pain is felt in the cheek adjacent to the nose or in the jaw area. Recurring as often as 100 times a day, the pain can be totally incapacitating.

Diagnosis

Although no specific test exists for identifying trigeminal neuralgia, its characteristic pain makes it easy for a doctor to diagnose. Doctors also evaluate other possible causes of facial pain, such as diseases of the jaw, teeth, or sinuses or compression of the trigeminal nerve by a tumor or aneurysm.

Treatment

Since the bouts of pain are brief and recurrent, typical pain medications aren't usually helpful, but other drugs, especially certain antiseizure drugs (which stabilize nerve membranes), may be helpful. Carbamazepine is usually tried first, but phenytoin may be prescribed if carbamazepine doesn't work or produces severe side effects. Baclofen, a muscle relaxant, is also helpful. Spontaneous remissions are common, but bouts of the disease often recur at wide intervals.

Trigeminal neuralgia sometimes results when an artery compresses the nerve adjacent to the brain. In such cases an operation can separate the artery from the nerve and relieve the pain for at least a few years. For people with pain that can't be relieved by drugs and who may not be good candidates for surgery, a test can be done in which a local anesthetic is injected into the nerve, temporarily blocking its function. If this relieves the pain, the peripheral branch of the nerve can be cut or injured by injecting a drug into it. Such approaches often produce discomfort in the face and are not considered procedures of choice.

(Source - The Merck Manual - Home Edition & Jeffrey A. Brown, MD, Department of Neurological Surgery, Wayne State University School of Medicine)

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VERTIGO

Each of us has a gyroscope, called the semicircular canals, in the ear. These small but complex organs relay messages to the brain, telling us the positions of our heads. Head movement causes stimulation of the semicircular canals, and we perceive motion. Violent, repetitive movement leads to overstimulation of the canals, with resulting dizziness, nausea and feeling unwell - the syndrome of motion sickness.

On occasion, normal people will experience a sensation of spinning (vertigo) in the absence of motion. This is due to poorly understood irritation of the semicircular canals, caused by a variety of factors, including tiny calcium chips in the canals, virus infections, diminished circulation and certain tumors. This vertigo often occurs when the head is in specific positions; hence, positional vertigo. Because it is relieved when the head is placed in different positions, one can conclude part of the balance mechanism, but not all of it, is malfunctioning. The vertigo is ordinarily benign, lasting for a few hours or days, and then disappears as quickly as it came. Treatment with a formal schedule of head movements, coupled with medication, helps the condition, but most people simply avoid head positions that cause symptoms. Benign positional vertigo is common. If it is severe, recurrent or tends to last, examination by an ear-nose-and-throat specialist is advisable in order to rule out more serious causes, such as tumors.

(Source - Newspaper Enterprise Association)

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DIAGNOSTIC PROCEDURES

AUDITORY BRAINSTEM RESPONSE - ABR

A test for hearing and brain (neurological) functioning. ABR may be used in the evaluation of:

The auditory brainstem response (ABR) test involves attaching electrodes to the head to record electrical activity from the auditory nerve (the hearing nerve) and other parts of the brain. Also known as brainstem auditory evoked potentials (BAEP).

(Source - MedicineNet.com)

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CEREBRAL ANGIOGRAPHY

X-rays taken after contrast dye is injected show arterial and venous circulation in the brain. With digital processing of data (cerebral digital subtraction angiography), small amounts of dye can produce high-resolution images. Cerebral angiography supplements CT and MRI in delineating the site and vascularity of intracranial lesions and is the gold standard for diagnosing stenotic or occluded arteries, congenitally absent vessels, aneurysms, and arterial venous malformations.

After the patient is mildly sedated and given a local anesthetic, a flexible catheter is introduced, usually via the femoral artery, and threaded into the aortic arch. Injection of a contrast dye outlines the arch and origin of the major vessels (during which the patient feels hot discomfort). Individual carotid and vertebral arteries can be cannulated to assess patency, anatomy, and flow through the neck and into the cranium. Vessels as small as 0.1 mm can be visualized. In some centers, the neuroradiologist is also an interventionalist, who may follow angiography with angioplasty, stent placement, intra-arterial thrombolysis, or aneurysm obliteration, depending on the disease process.

(Source - The Merck Manual - Home Edition)

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COMPUTERIZED TOMOGRAPHY - CT or CAT SCAN

A diagnostic technique in which the combined use of a computer and X-rays passed through the body at different angles produces clear, cross-sectional images ("slices") of the tissue being examined. CT (computerized tomography) scanning --also known as CAT (computerized axial tomography) scanning or whole body scanning -- provides clearer and more detailed information than X-rays used by themselves. In addition, CT scanning tends to minimize the amount of radiation exposure.

Why It Is Done

The first CT scanner, which came into operation in 1972, was developed to study the brain. Since then, CT brain scanning has marked a major advance in the diagnosis and treatment of tumors, abscesses, and hemorrhages in the brain, as well as strokes and head injuries. These once required tests, such as angiography and ventriculography (an outmoded technique for imaging the ventricles of the brain), that not only were difficult to perform, lengthy, and not always clear-cut in their findings, but also entailed some risk for the patient. CT scanning, on the other hand, is simple, quick, accurate, and carries a modest exposure to radiation. As well as being essential for the stud of the brain, CT scanning is invaluable in investigating disease of any part of the trunk. It is particularly useful for locating and imaging tumors, and for guiding the operator who is performing a needle biopsy.

Results

Using the information produced by the scanner, a computer constructs cross-sectional images of the tissue under examination. These images, displayed on a TV screen, reveal soft tissues (including tumors) more clearly than normal X-ray pictures. The images are particularly valuable in brain scans due to their sharp definition of ventricles (fluid-filled spaces). The images can be manipulated electronically to provide the best view of the area of interest, and adjacent two-dimensional "slices" can be reconstructed to produce three-dimensional representations as well as images in different planes.

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ELECTROENCEPHALOGRAPHY - EEG

Electroencephalography (EEG) is a simple, painless procedure in which 20 wires (leads) are pasted on the scalp to trace and record the brain's electrical activity. Recordings in the form of wave patterns help identify epilepsy and sometimes certain rare metabolic brain diseases. In some cases, such as epilepsy that is difficult to detect, a recording is made over a 24-hour period. Otherwise the test provides little specific information.

(Source - The Merck Manual - Home Edition)

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ELECTROMYOGRAPHY - EMG

Electromyography (EMG) tests analyze nerve and muscle electrical activity. Some types of electrical activity are normal, whereas some patterns of electrical activity suggest a disease of nerves or muscles. "Nerve conduction velocity" studies (NCV) are tests that are often used in combination with the EMG evaluation. For nerve conduction studies, the muscles and nerves are stimulated with small bursts of electricity to see whether the nerves and muscles respond in a normal way.

What happens when the test is performed?

For the EMG, thin needles are inserted one by one into the muscles being tested. These needles are not hollow and they are thinner than the type of needle used to draw blood. Each needle is attached to a wire that gives signals to a machine. The needle acts like an antenna to detect electrical patterns inside the muscle and the nerves that are attached to that muscle. Most patients find this test mildly uncomfortable.

If you have nerve conduction studies done, small pads will be taped to the skin on your hands or feet. These pads can both deliver mild electric shocks and can detect electric signals coming through the skin. The shocks that are used are too small to be harmful. They feel similar to the kind of shock you might feel if you rubbed your feet on the carpet and then touched a doorknob. You might feel one of your muscles twitch when the electricity is delivered.

The testing takes a variable length of time, depending on how many muscles are being tested. It may require as long as one hour. EMG testing requires 20 to 30 minutes.

What risks are there from the test?

There are no risks from having this test done. The needles used in the EMG are too small to put you at significant risk for bleeding or infection. The shocks do not shock your whole body and are too mild to cause any damage.

How long is it before the result of the test is known?

A neurologist will interpret the electrical signals measured in your muscles and will send a report to your doctor within a few days.

(Source - The Harvard Medical School Family Health Guide)

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EVOKED RESPONSES

Evoked responses are indications of the brain's response to certain stimuli. Sight, sound, and touch each stimulate specific areas of the brain. For example, a flashing light stimulates the back part of the brain where vision is perceived. Normally, the brain's response to a stimulus is too slight to be picked up on an EEG, but responses to a series of stimuli can be averaged by a computer to show that the stimuli were received by the brain. Evoked responses are particularly useful if the person being tested can't talk. For example, a doctor can test an infant's hearing by checking for a brain response after a noise.

Evoked responses may reveal slight damage to the optic nerve (the nerve to the eyes) in a person with multiple sclerosis. In a person with epilepsy, they may also reveal abnormal electrical discharges triggered by deep and rapid breathing or by watching a flashing light.

(Source - The Merck Manual - Home Edition)

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INTRAOPERATIVE MONITORING (IOM)

During the performance of Microvascular Decompression (MVD), monitoring (Intraoperative Monitoring) of two different bodily functions is performed, but not by all neurosurgeons. This is monitoring of the facial or VII cranial nerve and the auditory or VIII cranial nerve.

Facial (VII) Nerve Monitoring

Purpose - During the MVD operation, the entry zone of the cranial nerve is closely examined so as to locate the site of nerve compression (i.e., the offending site). To alert the attending neurosurgeon, as to when the offending site has been located, continuous monitoring of the facial nerve function during the operation is performed.

How Monitored - A continuous drip of a muscle relaxant is administered to the facial nerve so its function can be assessed. The twitches of the nerve are elicited with nerve stimulation. Continued facial nerve function is monitored by continuous recording of electromyographic activity with two recording electrodes. These are the orbicularis oculi and the orbicularis oculus muscles. The muscle contractions are recorded from a motion sensor placed on the cheek. Monopolar stimulation is used to locate the VII nerve.

Auditory (VIII) Nerve Monitoring

Background - The VII and VIII cranial nerves are located very close to each other. Therefore, it is difficult, if not impossible, to decompress the VII nerve without touching or moving the VIII nerve. The auditory nerve is notoriously fragile. Stretching it during retraction of the cerebellum generally means loss of hearing on the effected side. If the auditory (VIII) nerve is traumatized, irreversible deafness is usually the result. The auditory nerve is so fragile that it cannot bear more than the gentlest manipulation under any circumstances.

Purpose - The purpose in monitoring the VIII nerve during MVD is to alert the attending neurosurgeon that the continued hearing function of the patient is being impaired.

How Monitored - An electrode is placed for electro-cochleography, scalp electrodes are inserted for brainstem auditory evoked potential monitoring, and a microphone (a ticker) is placed in the external ear canal to provide the sound stimulus.

(Sources - Massachusetts General Hospital - Microvascular Compression Syndromes, and Working in a Very Small Place)

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MAGNETIC RESONANCE ANGIOGRAPHY - MRA

An MRI study of the blood vessels. It utilizes MR technology to detect, diagnose and aid the treatment of heart disorders, stroke and blood vessel diseases. MRA provides detailed images of blood vessels without using any contrast material, although today a special form of contrast usually is given to make the MR images even clearer. MRA tends to exaggerate the severity of arterial narrowing and therefore does not usually miss occlusive disease of large arteries. The procedure is painless, and the magnetic field is not known to cause tissue damage of any kind.

(Source - The Radiological Society of North America (RSNA) and the American College of Radiology (ACR)

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MAGNETIC RESONANCE IMAGING - MRI

MRI is a diagnostic technique that provides high-quality, cross-sectional images of organs and structures within the body without X-rays or other radiation.

How It Works

During the imaging, the patient lies inside a hollow, cylindrical magnet and is exposed to short bursts of a powerful magnetic field. The nuclei (protons) of the body's hydrogen atoms normally point randomly in different directions, but, in a magnetic field, they line up parallel to each other, like rows of tiny magnets. If the hydrogen nuclei are then knocked out of alignment by a strong pulse of radio waves, they produce a detectable radio signal as they fall back into alignment. Magnetic coils in the machine detect these signals, and a computer changes them into an image based on the strength of signal produced by different types of tissue. Tissues that contain a lot of hydrogen (such as fat) produce a bright image; those that contain little or no hydrogen (such as bone) appear black.

Why It Is Done

MRI allows images to be constructed in any plane; it is particularly valuable in studying the brain and spinal cord. This technique reveals tumors vividly, indicating their precise extent, and produces impressive images of the internal structure of the eye and ear.MRI also produces detailed images of the heart and major blood vessels, provides images of blood flow, and is useful for examining Joints and soft tissues, particularly in the knee. The role of MRI in imaging the abdominal organs is becoming established. Images from MRI are similar in many ways to those produced by CT scanning, but MRI generally gives much greater contrast between normal and abnormal tissues.

How It Is Done

MRI is usually an outpatient procedure. During the examination the patient must lie still; children may be given a general anesthetic. A scan usually takes about half an hour.

Risks

There are no known risks or side effects to MRI. The technique does not use radiation and can, therefore, be performed repeatedly with no known adverse effects. However, any person fitted with a pacemaker, hearing aid, or other electrical device should tell his or her physician before undergoing MRI, since the scanner may interfere with these devices.

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NERVE CONDUCTION STUDIES

Nerve conduction studies are tests that are often used in combination with the EMG evaluation. For nerve conduction studies, the muscles and nerves are stimulated with small bursts of electricity to see whether the nerves and muscles respond in a normal way.

Small pads will be taped to the skin on your hands or feet. These pads can both deliver mild electric shocks and can detect electric signals coming through the skin. The shocks that are used are too small to be harmful. They feel similar to the kind of shock you might feel if you rubbed your feet on the carpet and then touched a doorknob. You might feel one of your muscles twitch when the electricity is delivered. The testing takes a variable length of time, depending on how many muscles are being tested.

(Source - The Harvard Medical SchoolFamily Health Guide)

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NEUROLOGIC EXAMINATION

The neurologic examination begins with careful observation of the patient during history taking. The speed, symmetry, and coordination needed for moving from a chair to the examining table, along with posture and gait, are noted. The patient's demeanor, dress, and responses yield information about mood and social adaptation. The patient's reliance on others to answer questions may indicate failing memory. Errors in language, speech, or praxis; neglect of space; unusual posturing; and other disorders of movement may be apparent before formal testing begins.

Guided by an initial formulation of the anatomy and pathophysiology of the lesion, the examiner expands some components of the examination and deletes others. For a less skilled observer, a full neurologic screening may help detect an unsuspected abnormality or confirm normal status.

Mental status examination

A patient's ability to attend must be assessed first; an inattentive patient cannot be accurately assessed further. Any hint of cognitive decline should lead to administration of the complete Mini-Mental Status Examination, which tests multiple aspects of cognitive function. They include orientation to time, place, and person; memory; verbal and mathematical abilities; judgment; and reasoning. Loss of orientation to person occurs only in severely obtunded, delirious, or demented persons; as an isolated symptom, it suggests malingering. Insight into illness and fund of knowledge are also assessed, although some responses may be influenced by education. Affect and mood are evaluated.

Normally, a person should be able to follow a complex command that involves three body parts and discriminates between right and left (eg, "Put your right thumb on your left ear, and stick out your tongue"). Naming of simple objects and body parts, reading, writing, and repetition are assessed; if function is disturbed, other tests of aphasia are performed. Spatial perception can be tested by asking the patient to imitate simple and complex finger constructions and to draw a clock, cube, house, or interlocking pentagons. The effort expended is often as informative as the final product and may identify impersistence, perseveration, micrographia, and hemispatial neglect. Praxis can be checked by asking the patient to use a toothbrush or comb or to take a match out of a box and strike it.

Cranial nerve examination

The extent of the cranial nerve examination depends on the site of the suspected lesion. Smell (1st [olfactory] cranial nerve) is generally not tested in patients with muscle disease but should always be tested in those with suspected lesions of the anterior fossa or after head trauma. The patient is asked to identify odors (eg, soap, coffee, cloves) presented to each nostril. Alcohol, ammonia, and other irritants test the nociceptive receptors of the 5th (trigeminal) cranial nerve, so they are not used except to detect a malingerer.

The 2nd (optic), 3rd (oculomotor), 4th (trochlear), and 6th (abducens) cranial nerves are tested as part of the visual system. Visual acuity (corrected for refractive error) is tested, visual fields are examined, and funduscopy is performed. The shape, size, reactivity to light, and accommodation of the pupils and extraocular eye movements are noted.

To test the 5th (trigeminal) nerve's three sensory divisions (ophthalmic, maxillary, and mandibular), an examiner uses a pin to evaluate facial sensation and brushes a wisp of cotton against the lower limbus of the cornea to evaluate the corneal reflex. If sensation in the face is lost, the angle of the jaw should be examined. This area, innervated by spinal root C-2, should be spared when the problem is an isolated trigeminal deficit. A weak blink due to facial weakness (eg, 7th cranial nerve paralysis) should be distinguished from a depressed corneal response. Patients who wear contact lenses often have reduced or absent corneal reflexes. Supranuclear corneal hyposensitivity associated with hypalgesia of body as well as face must be distinguished from peripheral lesions. Trigeminal motor function is tested by palpating the masseter muscles while the patient clenches his teeth and by asking him to open his jaw against resistance. The jaw will deviate to the side of a weakened pterygoid muscle.

The 7th (facial) cranial nerve is tested by looking for hemifacial weakness. Asymmetry of facial movements is often more obvious during spontaneous conversation, especially when the patient smiles or, if obtunded, grimaces at a noxious stimulus. The examiner looks for a depressed nasolabial fold and widened palpebral fissure on the side of weakness. If furrowing of the forehead and eye closure are preserved, the cause of lower facial weakness is probably central rather than peripheral. Taste in the anterior 2/3 of the tongue can be tested with sweet, sour, salty, and bitter solutions placed on both sides of the tongue. Hyperacusis may be detected with a vibrating tuning fork held next to the ear.

The 8th (vestibulocochlear, acoustic) cranial nerve carries auditory and vestibular input, so hearing and balance must be evaluated.

The 9th (glossopharyngeal) and 10th (vagus) cranial nerves are usually examined together. The palate should elevate symmetrically, and gag is elicited by touching each side of the posterior pharynx with a tongue blade. However, bilateral absence of the gag reflex is common and may not be significant. In an unresponsive, intubated patient, suctioning the endotracheal tube should trigger coughing. The vocal cords are inspected if hoarseness is evident. Isolated hoarseness (with normal gag and palatal elevation) should prompt a search for lesions compressing the recurrent laryngeal nerve (eg, mediastinal lymphoma, aortic aneurysm).

The 11th (spinal accessory) cranial nerve supplies the sternocleidomastoid and upper trapezius. The former is tested by having a patient turn his head against resistance supplied by the examiner's hand while the examiner palpates the active muscle (opposite the turned head). The trapezius is tested by elevating the shoulders against resistance supplied by the examiner.

The 12th (hypoglossal) cranial nerve innervates the tongue, which is inspected for atrophy, fasciculations, and weakness (deviation toward the side of the lesion).

An abnormality of one cranial nerve requires meticulous scrutiny of adjacent nerves. Such distinctions can be urgent, for example, when brain stem ischemia must be distinguished from a rapidly expanding aneurysm producing cranial nerve paralysis.

Examination of the motor system

The limbs and shoulder girdle should be fully exposed, then inspected and palpated for atrophy, hypertrophy, fasciculations, other involuntary movements (eg, chorea, athetosis, myoclonus, tremor), and asymmetric development. Passive flexion and extension of the limbs in a relaxed patient provide information about muscle tone. Decreased muscle bulk indicates atrophy, but bilateral atrophy or atrophy in large or concealed muscles (unless advanced) may not be obvious. In older persons, loss of some muscle is common (sarcopenia). Hypertrophy occurs when one muscle works harder, substituting for another; pseudohypertrophy occurs when muscle tissue is replaced by excessive fibrous tissue or a storage material.

Fasciculations, the most common abnormal movement, are brief, fine, irregular twitches of the muscle visible under the skin. They usually indicate lesions of the lower motor neuron (eg, nerve degeneration or injury and regeneration) but sometimes occur in normal muscle, particularly in the calf muscles of older persons. Myotonia, the decreased relaxation of muscle after a sustained contraction or direct percussion of the muscle, occurs in myotonic dystrophy and may cause disability (eg, inability to relax and quickly open the closed hand). Increased resistance followed by relaxation (clasp-knife rigidity or phenomenon) occurs with upper motor neuron lesions. Basal ganglia disorders usually produce cogwheel rigidity.

Assessment of muscle strength

For patients, weakness has various meanings, such as fatigue, clumsiness, or numbness. A complaint of muscle weakness should be characterized precisely by describing the exact location, time of occurrence, precipitating and ameliorating factors, and associated symptoms and signs. The patient extends his arms, then legs, to be inspected for weakness (a weak limb soon begins to drift downward), tremor, and other involuntary movements. Strength of specific muscle groups may be tested against resistance. Pain in a muscle or affected joint may preclude an active contraction. With hysterical weakness, resistance to movement may be normal, followed by a sudden giving way.

Subtle weakness may produce a depressed arm swing while walking, a pronator drift of the outstretched arm, decreased spontaneous use of a limb, or an externally rotated leg. Rapid alternating movements may be slowed, and fine dexterity (eg, ability to close a button, open a safety pin, remove a match from its box) impaired.

Grading muscle strength is often difficult when weakness is partial. One scale assigns 0 to no movement, 1 to trace movement, 2 to movement with the aid of gravity, 3 to movement against gravity but not resistance, 4 to movement against resistance supplied by the examiner, and 5 to normal strength. The difficulty with such scales is the large range in strength between grades 4 and 5. Distal strength can be semiquantitatively measured with a handgrip ergometer or by having the patient squeeze an inflated BP cuff.

Functional testing often provides a better picture of disability. As the patient performs various maneuvers, deficiencies are noted and quantitated as much as possible (eg, the number of squats performed or steps climbed). Arising from a squatting position or stepping onto a chair tests proximal leg strength; walking on the heels and on tiptoe tests distal strength. A patient with quadriceps weakness has to push with the arms to get out of a chair. A patient with shoulder girdle weakness may swing his body to move the arms. A patient with pelvic girdle weakness characteristically arises from the supine position by turning prone, kneeling, and slowly pushing erect by using his hands to climb up his thighs (Gowers' sign).

Examination of coordination, stance, and gait

Normal coordination, stance, and gait require the integrity of the motor, vestibular, and proprioceptive pathways. A lesion in any one of the pathways produces characteristic deficits: cerebellar ataxia requires a wide gait for stability; dropfoot causes a steppage gait (in which the leg is elevated higher than normal to avoid catching the foot on surface irregularities); pelvic muscle weakness causes waddling; and spastic leg causes circumduction. A patient with impaired proprioception must constantly observe the placement of his feet to avoid tripping or falling. Coordination can be tested with finger-to-nose or knee-to-shin maneuvers, which help detect ataxic movements.

Sensory testing

A complete sensory examination may be unnecessary, especially when the leading symptoms of pain, paresthesias, and numbness are absent. A quick screening test uses a pinprick (with a clean safety pin) on the face, torso, and four limbs; the patient is asked if the pinprick feels the same on both sides and if it feels dull or sharp. Cortical sensory function is tested by asking the patient to identify a coin, a key, or another object in the palm of the hand (stereognosis) and numbers written on the palm (graphesthesia) and to distinguish two points from one on the palm and on the fingers. Temperature sense can be tested with a cold tuning fork that has one prong rubbed warm with the palm or with test tubes containing hot or cold water. Joint position is tested by moving the terminal phalanges of the fingers, then the toes, up or down. If the patient cannot identify these movements with his eyes closed, the next most proximal joints are tested (eg, ankles if toe movement is not perceived). Dense proprioceptive loss often produces pseudoathetosis of the resting limb and an inability to locate a limb in space when the eyes are closed. If postural position sense is affected, the patient cannot stand with his feet together and eyes closed (Romberg test). To test the patient's sense of vibration, the examiner places his finger under the patient's distal interphalangeal joint and presses a lightly tapped 128-cycle tuning fork over the joint. The examiner feels the vibration through the patient's joint and should note the end of vibration about the same time as the patient. Light touch can be tested with a cotton wisp.

If sensation is disturbed, the anatomic pattern should be localized to peripheral nerves (stocking-glove), particular nerves (mononeuritis multiplex), nerve roots (radiculopathy), spinal cord (a level below which sensation is reduced), brain stem (crossed face-body), or brain (hemisensory loss). The location of the lesion is confirmed by determining whether motor weakness and reflex change follow a similar pattern. Lesions of the brachial and pelvic plexus (eg, neoplasm) often produce patchy sensory, motor, and reflex deficits.

Reflex testing

Deep tendon (muscle stretch) reflex testing evaluates the afferent nerve, synaptic connections within the spinal cord, motor nerves, and descending motor pathways. The biceps reflex is innervated predominantly by C-5; the radial, by C-6; the triceps, by C-7; the quadriceps knee jerk, by L-4; and the ankle jerk, by S-1. Asymmetric increase or depression is noted. Hypoactive reflexes can be augmented by Jendrassik's maneuver, in which the patient locks his hands and vigorously pulls apart as the tendon in the lower extremity is tapped.

Lower motor neuron lesions (eg, affecting the anterior horn cell, spinal root, peripheral nerve, neuromuscular junction, or muscle) depress the reflexes, whereas upper motor neuron lesions (ie, non-basal ganglia disorders anywhere above the anterior horn cell) increase the reflexes. The superficial abdominal reflex is elicited by lightly stroking the four quadrants of the abdomen with a pin. Most central lesions, obesity, and lax skeletal muscles (eg, after pregnancy) depress this reflex. Its absence may indicate spinal cord injury.

The plantar response has several forms: Quick voluntary withdrawal must be distinguished from Babinski's sign (extension of the great toe with fanning of the other toes, often with flexion of the knee and hip), which is slower. Only the latter is of spinal reflex origin and indicates an upper motor neuron lesion. The lateral aspect of the sole must be stroked, because a medial stimulus may inadvertently induce a primitive grasp reflex.

Clonus is the rhythmic, rapid alternation of muscle contraction and relaxation caused by sudden, passive tendon stretching. It is most often tested by rapid dorsiflexion of the foot at the ankle. Sustained clonus suggests damage to the upper motor neuron. Diffuse cortical disease may produce a snout, sucking, or grasp reflex. Sphincteric reflexes may be tested during the rectal examination, or the perianal region may be touched lightly to induce an anal wink.

Autonomic system testing

The examiner checks for postural hypotension, lack of bradycardia-tachycardia in response to the Valsalva maneuver, decrease or absence of sweating, and Horner's syndrome. Disturbances of bowel, bladder, sexual, and hypothalamic function should be noted (each is discussed elsewhere in The Manual).

Cerebrovascular examination

Risk of stroke is increased in a patient who is elderly or who has hypertension, diabetes, hypercholesterolemia, peripheral vascular disease, or heart disease. Blood pressure should be measured in both arms to test for painless aortic dissection as a cause of stroke. The skin, sclerae, fundi, oral mucosae, and nail beds are inspected for hemorrhages and evidence of cholesterol or septic emboli, and the heart is auscultated for new or evolving murmurs and dysrhythmias. Bruits over the cranium may indicate an arteriovenous malformation, fistula, or, occasionally, redirected blood flow across the circle of Willis after carotid occlusion. The carotid arteries are auscultated for bruits in the region of bifurcation; vigorous palpation is avoided. By running the bell of the stethoscope down the neck toward the heart, the examiner can distinguish a bruit from a cardiac systolic murmur, which may change in character. The vigor of the carotid upstroke can provide additional data about a possible stenotic lesion. Peripheral pulses should be palpated to check for peripheral vascular disease and aortic dissection. The temporal arteries are palpated for enlargement or tenderness to exclude temporal arteritis.

(Source - The Merck Manual - Home Edition - [selected link references omitted])

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PHYSIOLOGY

CRANIAL NERVES

Twelve pairs of nerves that emerge directly from the brain -- as opposed to the spinal nerves, which connect with the spinal cord. All but two of the cranial nerve pairs connect with nuclei in the brain stem (the lowest section of the brain). The other two (the olfactory and optic nerves) link directly with parts of the cerebrum (the main mass of the brain). All the nerves emerge through various openings in the cranium (skull); many then soon divide into several major branches. (Note: Fifth Cranial Nerve: Sensory; Seventh Cranial Nerve: Facial; Eighth Cranial Nerve: Auditory.)

(Sources: National Institute of Health; Massachusetts General Hospital; The American Medical Association Encyclopedia of Medicine.)

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THE FIFTH (TRIGEMINAL) CRANIAL NERVE

It arises in the pons, is composed of sensory and motor fibers, and has three divisions: ophthalmic, maxillary, and mandibular. The ophthalmic division supplies sensory fibers to the skin of the upper eyelid, side of the nose, forehead, and anterior half of the scalp. The maxillary division carries sensory impulses from the mucous membranes of the nose, the skin of the cheek and side of the forehead, and the upper lip and upper teeth. The mandibular division carries sensory impulses from the side of the head, chin, mucous membrane of the mouth, lower teeth, and anterior two-thirds of the tongue. (This nerve is sometimes called the great sensory nerve of the head.) The motor fibers are part of the mandibular branch and supply several of the muscles of chewing. Neuralgia of this nerve is the condition known as "tic douloureux".

(Source - Miller-Keane Medical Dictionary, 2000)

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THE SEVENTH (FACIAL) CRANIAL NERVE

Its motor fibers supply the muscles of facial expression, a complex group of cutaneous muscles that move the eyebrows, skin of the forehead, corners of the mouth, and other parts of the face concerned with frowning, smiling, or any of the many other expressions of emotion. The sensory fibers of the facial nerve provide a sense of taste in the anterior two thirds of the tongue, and also supply the submaxillary, sublingual, and lacrimal glands for secretion. Irritation of the facial nerve can produce a paralysis known as "bell's palsy, " BELL'S PALSY, which usually involves only one side of the face with a resulting distortion of facial expression such as inability to close the eye or part of the mouth on the affected side.

The facial nerve is a specific motor nerve (a nerve which tells certain muscles to contract) which controls the muscles on the same side of the face. It allows us to show expression, smile, cry, and wink. Injury to the facial nerve causes a socially and psychological devastating physical defect that may require multiple rehabilitative procedures.

The facial nerve is the seventh of the twelve cranial nerves which have been named as such because they all exit the brainstem through the base of the skull. Everyone has two facial nerves, one for each side of the face. The facial nerve travels with the hearing nerve (cranial nerve eight) as it travels in and around the structures of the middle ear. It exits the front of the ear at the stylomastoid foramen (a hole in the skull base), where it then travels through the parotid gland. In the parotid gland it divides into many branches which provide motor function for the various muscles and glands of the head and neck.

A disorder of the facial nerve may result in facial muscle paralysis, weakness, or twitching of the face; dryness of the eye or the mouth; or alteration of taste on the affected side. However, the finding of one of these symptoms does not necessarily imply a specific facial nerve problem, it is only after a careful investigation that one is able to make a precise diagnosis. (The ability to open the mouth and show the teeth and to close the eyes tightly is tested).

(Source - MedicineNet.com)

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THE EIGHTH (VESTIBULOCOCHLEAR) CRANIAL NERVE

The eighth (ves-tib´´u-lo-kok´le-ar) cranial nerve, which emerges from the brain between the pons and medulla oblongata, behind the facial nerve. The vestibular division serves the vestibule of the ear and the semicircular canals, carrying impulses for the sense of equilibrium. The cochlear division serves the cochlea and carries impulses for the sense of hearing. Called also acoustic nerve and auditory nerve.

(Source - Miller-Keane Medical Dictionary, 2000)

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MEDICAL SPECIALTIES

ANESTHESIOLOGY

A specialty concerned with the study of anesthetics and anesthesia.

The anesthesiologist's principal task is providing pain relief and maintenance of a stable condition during an operation. The anesthesiologist assesses the risk of the patient undergoing surgery and optimizes the patient's condition prior to, during and after surgery.

Anesthesiologists also diagnose and treat acute and long-standing pain problems. They direct resuscitation in the care of patients with cardiac or respiratory emergencies, including the provision of artificial ventilation. Anesthesiologists supervise and teach others involved in anesthesia, respiratory and intensive care.

(Source - The Philadelphia Medical Mall)

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CARDIOLOGY

The medical study of the diagnosis and treatment of diseases affecting the heart and blood vessels.

Cardiologists sub-specialize in diseases of the heart, lungs and blood vessels and manage conditions such as heart attacks. They often perform complicated diagnostic procedures such as cardiac catheterization.

(Source - The Philadelphia Medical Mall)

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NEUROLOGY

The branch of science which treats of the nervous system.

A neurologist is a medical doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system. Pediatric neurologists are doctors with specialized training in children's neurological disorders.

A neurologist's educational background and medical training includes an undergraduate degree, four years of medical school, a one-year internship and three years of specialized training. Many neurologists also have additional training in one area of neurology such as stroke, epilepsy or movement disorders.

(Source - The Philadelphia Medical Mall)

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NEUROPHYSIOLOGY

The study or examination of the nervous system. Clinical Neurophysiologists may be members of a surgical healthcare team that treat the nervous system and disorders that affect it. They are the acknowledged experts on the care team when it comes to electrophysiological function of the nervous system, and as such, they are frequently consulted in highly acute and critical matters that can have a dramatic effect on patient outcome.

Clinical Neurophysiologists work with surgeons to protect the patient from neurological damage during surgery. There work place is the operating room (OR) as a member of the surgical team.

Before surgery, they may review the patient's medical record, confirm the surgical procedure planned, set up the monitoring equipment, and connect the patient using thin needle electrodes to the monitoring system. They may coordinate with the Anesthesiologist to balance the need to anesthetize the patient with required level of medication to insure accurate readings for monitoring.

The Clinical Neurophysiologist's primary responsibility is to warn the surgeon when some aspect of the procedure begins to affect a sensory or motor pathway.

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NEURORADIOLOGY

This medical specialty deals with:

(Source - The Philadelphia Medical Mall)

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NEUROSURGERY

A surgical specialty concerned with the treatment of diseases and disorders of the brain, spinal cord, and peripheral and sympathetic nervous system.

A Neurosurgeon is a medically qualified specialist in surgery who has subspecialised in the surgery of the brain, spinal cord and other nervous tissue. A neurological surgeon may provide either surgical or non-surgical care, depending on the nature of the injury or illness. Some neurosurgeons also practise neurology because specialists in that field are rare.

Neurological surgery is the medical specialty concerned with the diagnosis and treatment of patients with injury to, or diseases of, the brain, spine or peripheral nerves.

(Source - The Philadelphia Medical Mall)

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OPHTHALMOLOGY

Ophthalmology is the diagnosis, medical and surgical treatment of diseases and defects of the eye.

An Ophthalmologist is a physician specialist expert in the treatment of diseases of the eyeball and retina.

(Source - The Philadelphia Medical Mall)

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RADIOLOGY

The study of X-rays in the diagnosis of a disease.

A radiologist is a physician with special training in the use of x-rays, radioactive materials and other imaging procedures to diagnose and treat disease.

(Source - The Philadelphia Medical Mall)

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SURGERY

Surgery is the branch of medicine that treats disease and injury through an operative or manual method.

A surgeon is a physician specializing in surgery; one whose profession or occupation is to cure diseases or injuries of the body by manual operation; one whose occupation is to cure local injuries or disorders (such as wounds, dislocations, tumors, etc.), whether by manual operation, or by medication and constitutional treatment.

(Source - The Philadelphia Medical Mall)

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MEDICAL & SURGICAL PROCEDURES

BOTULINUM TOXIN - BOTOX®

Botulinum toxin is a complex protein produced by the anaerobic bacterium Clostridium Botulinum. Previously known only as a cause of a serious and often fatal paralysis acquired through ingestion of contaminated food, the toxin causes paralysis by blocking the presynaptic release of acetylcholine at the neuromuscular junction. In laymen's terms, Botulinum toxin is produced from the same bacteria responsible for a type of food poisoning called Botulism. Advantage can be taken of this neuromuscular blocking effect to alleviate muscle spasm due to excessive neural activity of central origin or to weaken a muscle for therapeutic purposes.

Treatment for HFS involves the injecting of Botulinum toxin (Botox®) into one or more areas of the affected side of the face: the muscles in the eyelid, the muscles in the cheek bone area and the muscles in the area just below the cheek bone. In extreme cases, the forehead and neck may also be injected. However, very small amounts are injected. Unfortunately, the effectiveness of this treatment is temporary; therefore, periodic injections are required approximately every three to six months. The effectiveness also diminishes over the course of several years of use due to the buildup of antibodies.

There are several immediate side effects that are possible such as a drooping eyelid, dryness of the eye, and the loss of muscle function by the corner of the mouth causing a lopsided smile. A possible long-term side effect is damage to the facial nerve which occurs, in some cases, due to prolonged use of these injections. It should be noted that Botulinum is not curative in chronic neurological disorders.

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MICROVASCULAR DECOMPRESSION - MVD

This highly technical surgery involves a neurosurgeon surgically separating one or more blood vessels/arteries that are impinging upon the seventh (facial) cranial nerve. MVD requires a general anesthetic. A small incision is made behind the ear on the affected side, and a small opening is made in the bone about the size of a quarter. Small implants made of shredded Teflon felt (which looks like wisps of absorbent cotton) are used to maintain the separation of the offending blood vessel/artery on the nerve. The offending blood vessel/artery rests on the felt instead of the nerve. (The felt is held in place by the pressure exerted by the artery/vein on the nerve.)

To preserve the patient's hearing, Intraoperative Monitoring (IOM) is highly recommended. The operation takes approximately two to three hours, and the average length of stay in the hospital is 72 hours. Over 90% of patients are back to work enjoying their former level of physical activity within three months. Unfortunately, like all surgeries, this approach involves some risk which should be discussed at length with your neurosurgeon.

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SPINAL TAP

Also known as a lumbar puncture or "LP", a spinal tap is a procedure whereby spinal fluid is removed from the spinal canal for the purpose of diagnostic testing. It is particularly helpful in the diagnosis of inflammatory diseases of the central nervous system, especially infections, such as meningitis. It can also provide clues to the diagnosis of stroke, spinal cord tumor and cancer in the central nervous system.

A lumbar puncture is so-called because the needle goes into the lumbar portion (the "small") of the back. Other names for a lumbar puncture (an LP) include spinal puncture, thecal puncture, and rachiocentesis.

An LP is most commonly done for diagnostic purposes, namely to obtain a sample of the fluid in the spinal canal (the cerebrospinal fluid) for examination.

An LP can also be done for therapeutic purposes, namely as a way of administering antibiotics, cancer drugs, or anesthetic agents into the spinal canal. Spinal fluid is sometimes removed by LP for the purpose of decreasing spinal fluid pressure in patients with uncommon conditions (such as, for examples, normal-pressure hydrocephalus and benign intracranial hypertension).

The patient is typically lying down sideways for the procedure. Less often, the procedure is performed while the patient is sitting up. LPs in infants are often done upright.

After local anesthesia is injected into the small of the back (the lumbar area), a needle is inserted in between the nearby bony building blocks (vertebrae) into the spinal canal. (The needle is usually placed between the 3rd and 4th lumbar vertebrae). Spinal fluid pressure can then be measured and cerebrospinal fluid (CSF) removed for testing.

The CSF circulates around the brain and spinal cord (the central nervous system). This "water bath" acts as a support of buoyancy for the brain and spinal cord. The support of the CSF helps to protect the brain from injury.

These normal values can be altered by injury or disease of the brain, spinal cord or adjacent tissues. The values are routinely evaluated during examination of the spinal fluid obtained from the lumbar puncture. Additionally, spinal fluid is tested for infection in the microbiology laboratory.

Spinal fluid obtained from the lumbar puncture can be used to diagnose many important diseases such as bleeding around the brain; increased pressure from hydrocephalus; inflammation of the brain, spinal cord, or adjacent tissues (encephalitis, meningitis); tumors of brain or spinal cord, etc. Sometimes spinal fluid can indicate diseases of the immune system, such as multiple sclerosis.

When spinal fluid is removed during an LP, the risks include headache, brain herniation, bleeding, and infection. Each of these complications are uncommon with the exception of headache, which can appear from hours to up to a day after LP. Headaches occur less frequently when the patient remains lying flat 1-3 hours after the procedure. The benefits of the LP depend upon the exact situation but an LP can provide lifesaving information.

(Source - MedicineNet.com)

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MISCELLANEOUS TERMS

CSF LEAK

The leak of cerebrospinal (CSF) fluid from between the cavities within the brain or the central canal in the spinal cord. Cerebrospinal fluid is a watery fluid, continuously produced and absorbed, which flows in the ventricles (cavities) within the brain and around the surface of the brain and spinal cord. The CSF is produced by the choroid plexus, a series of infolded blood vessels projecting into the cerebral ventricles, and it is absorbed into the venous system

(Source - Medicine Net.com Medical Dictionary & MedicineNet.com)

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ENDOSCOPE

Any instrument used to look inside the body. Usually consisting of a fiber-optic tube attached to a viewing device. Endoscopes employing miniature television cameras and tiny surgical implements now allow exploration and endoscopic surgery through small incisions; such surgery is much less traumatic to the patient than traditional open surgery. Laparoscopic surgery, in which the endoscope is inserted through a small incision in the abdomen or chest, is used to correct abnormalities of the ovaries and as an alternative to traditional gall bladder and chest surgery. Arthroscopic surgery is endoscopic surgery performed on joints such as the knee or shoulder.

(Source - encyclopedia.com)

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ROOT ENTRY ZONE/ROOT EXIT ZONE (REZ)

The root exit zone (REZ) is an area of each cranial nerve where the roots of the nerve emerge or exit from the brain stem. The significance of the root exit zone, in the context of such abnormalities as Hemifacial Spasm (HFS), is that while blood vessel compression of a cranial nerve can occur in a number of places along its length, compression is problematic only when it occurs in an area of the nerve called the root exit zone. A review of medical material reveals that the performance of Microvascular Decompression (MVD) is long lasting only when decompression takes place in the root exit zone.

Evidence observed over a long period of time suggests that a number of neurologic syndromes such as Hemifacial Spasm and Trigeminal Neuralgia may be caused by compression of the cranial nerves at the root entry or exit zone of the brain stem.

(Sources - Working in a Very Small Place, and Massachusetts General Hospital - Microvascular Compression Syndromes)

 

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