Appendix B: The Neurological Examination of the Patient

• Mental Status

  • Alertness and Attentiveness

  • Behavior, Mood, and Thought

  • Orientation and Memory

  • Cognitive Abilities

  • Language Disorders

• Cranial Nerve Function

  • Olfactory Nerve (Cranial N. I)

  • Optic Nerve (Cranial N. II)

  • Oculomotor, Trochlear, and Abducens Nerves (Cranial N. III, IV, VI)

  • Trigeminal Nerve (Cranial N. V)

  • Facial Nerve (Cranial N. VII)

  • Vestibulocochlear Nerve (Cranial N. VIII)

  • Glossopharyngeal and Vagus Nerves (Cranial N. IX, X)

  • Spinal Accessory Nerve

  • Hypoglossal Nerve (Cranial N. XII)

• Musculoskeletal System

• Sensory Systems

• Motor Coordination

• Gait and Stance

• Balance

• Deep Tendon Reflexes

The key to the analysis of signs and symptoms referable to the nervous system is a rigorous neurological examination of the patient. This examination begins with an assessment of the patient's mental functioning.

Alertness and Attentiveness

A patient's level of consciousness is defined in terms of responses to stimuli. Rather than simply using terms such as lethargy, obtundation, stupor, and coma, the examiner needs to note the minimal stimulus that elicits a response (eg, voice, shaking the patient, applying pain) and the response (eg, sustained alertness vs. fleeting eye opening with mumbling).

An impaired attention span is usually apparent during history taking. It can be tested more formally by having the patient repeat a series of numbers or count backward from 20. Sequential digit testing is sensitive, but the test is not specific; difficulty may connote impairment of immediate (working) memory.

Inattentiveness so severe that meaningful interaction with the environment is impossible is characteristic of delirium. Such patients are often agitated.

Behavior, Mood, and Thought

Neuropsychiatric abnormalities can be identified in this part of the mental status examination. Affect, the outward expression of mood, may be manifested in clothing, facial expression, amount and type of activity, and stream of conversation. If depression is suspected, the patient should be specifically queried; mood may be more disturbed than affect suggests.

Schizophrenic patients may demonstrate indifference, flattening of affect, or inappropriate mood. They may appear hostile and paranoid. Behavior sometimes suggests hallucinations even when they are denied. Schizophrenic speech may reveal loosening of associations, incoherence, blocking, stereotypy, or distractibility.

Slowing of speech and activity is a manifestation of medial frontal lobe damage (abulia). Lesions of the frontal lobe also produce social disinhibition, inappropriate jocularity, and difficulty sustaining goal-directed behavior.

Orientation and Memory

People aware of their own identity as well as of the basic facts of their surroundings (hospital, home address, city, state; time of day, day of week, month, year) are said to be "oriented to person, place, and time." Memory impairment secondary to brain injury or a dementing illness is usually greater for recent than remote events; such patients are disoriented to place and time but not to person. Disorientation is neither a sensitive nor a specific marker of amnesia, however.

Memory is clinically categorized as immediate (working), recent, and remote. A sensitive test for recent memory is to have the patient repeat three unrelated words (eg, Chicago, orange, thirty-three) and then repeat them after 5 minutes. If unable to recall the words, the patient is asked to select the words from a list. Amnestic disorders tend to affect recall more than recognition. Long-term memory can be tested by having the patient recall people or events from the past and then verifying the answers.

Conventional testing identifies disturbances of explicit memory (see Chapter 67). Amnestic or dementing illnesses are less likely to affect implicit memory systems such as procedural memory (remembering how to perform a skilled motor act).

Cognitive Abilities

Intellectual skills are assessed in standardized IQ tests, which are subject to educational and cultural bias. Tests include calculation, word similarities, word opposites, and proverb interpretation.

Language Disorders

Aphasia is a disturbance of language unexplained by an impairment of the neural machinery for hearing, vision, or vocalizing (see Chapter 60). Clinical subtypes of aphasia can be identified by assessing six basic components of language: spontaneous speech, speech comprehension, naming, repetition, writing, and reading (Figure B–1).

Spontaneous Speech

The patient's speech may be abnormal in a number of ways. Fluency, the amount of speech produced over time, may be reduced. Prosody, the musical qualities of speech (pitch, accent, rhythm), can also be impaired. In paraphasias incorrect words are substituted for correct ones. Patients with literal (or phonemic) paraphasia use words that phonetically resemble the intended word but contain one or more substituted syllables (eg, "hosicle" instead of "hospital"). Those with verbal (or semantic) paraphasia use real but unintended words (eg, "hotel" instead of "hospital"). In some patients paraphasic errors are simply occasional contaminants of speech; in others, they almost entirely replace it.

Even in the absence of paraphasias the content of aphasic speech may be difficult to grasp. Severely restricted vocabulary may be reflected by logorrheic but empty speech as well as by hesitation before certain words. Paragrammatic speech preserves some semblance of syntax despite such profoundly restricted semantic content. By contrast, agrammatic (or telegrammatic) speech omits relational words (such as prepositions or conjunctions).

Speech Comprehension

Casual conversation with the patient may not reveal abnormalities of speech comprehension, which can be mild, moderate, or severe. Specific testing is required. Assessment of speech comprehension should not depend on the patient's verbal responses to commands or questions. A wrong answer to a question could signify a paraphasic error rather than failure of comprehension. If a simple or complex command is followed, it can be presumed that the command was understood. However, failure to follow a command could have explanations other than impaired comprehension, for example, paralysis, apraxia, pain, or negativism.

A more reliable method of testing speech comprehension is to ask yes-or-no questions. Even patients with severely restricted speech output can usually indicate affirmative or negative. Both the patient and the examiner must of course know the correct answers. Still another way of testing speech comprehension is to ask the patient to point to objects or body parts.

As with abnormal speech output, semantic and syntactic (relational) comprehension can be dissociated. Syntactic comprehension can be assessed by asking the patient to handle objects. For example, after identifying a comb, a pen, and a key, ask the patient to put the key on top of the comb or the comb between the key and the pen.

Naming

Patients with adequate vision can be shown objects, body parts, colors, or pictures of actions (confrontation naming). A variety of abnormal responses indicate anomia, the loss of the ability to recall or recognize the names of things. Some patients exhibit paraphasias. Some hesitate and grope for the correct word (tip-of-the-tongue phenomenon). Some patients describe rather than name an object. For example, instead of saying "necktie," the patient says, "It's what you wear around your neck."

Repetition

The patient is asked to repeat sentences such as "In the winter the President lives in Washington." Syntactically complex sentences may be particularly difficult (for example, "If he were to come, I would go out"). Errors most often consist of paraphasic substitutions.

Writing

Testing of writing begins by having patients sign their names. More specific tests of writing include dictated sentences, words, or letters, as well as spontaneous writing; for example, describing what is seen in a room.

Reading

Reading ability is tested by having the patient read aloud simple sentences, words, or letters. Reading comprehension can be tested by having the patient follow written commands that were previously successfully executed as oral commands or by having the patient answer written yes-or-no questions.

Praxis

Praxis refers to performance of a learned motor act. In its broadest sense apraxia refers to impaired motor activity not explained by weakness, incoordination, abnormal tone, bradykinesia, movement disorder, dementia, aphasia, or poor cooperation. Failure to perform an act is not evidence of apraxia. To be apractic the act must be performed incorrectly, or components of the act must be performed imprecisely. Parts of the act might be omitted, sequenced abnormally, or incorrectly oriented in space. There are three types of testing: (1) gesture ("Show me how you would throw a ball"); (2) imitation ("Watch how I point upward, then you do it"); and (3) use of an actual object ("Here is a spoon. Show me how you would use it").

Apraxias are traditionally classified as limb-kinetic, ideational, and ideomotor. With limb-kinetic apraxia the act is understood but motor execution is faulty. With ideational apraxia the idea of the act—the neural representation of the act, or engram—is disrupted. With ideomotor apraxia the idea of the act and the motor components of its execution are functionally disconnected. Such patients might be unable to imitate using a hammer but able to accurately describe its use and, if given a hammer, use it correctly.

Gnosia and Spatial Manipulation

Agnosia is a failure of recognition not explained by impaired primary sensation (tactile, visual, auditory) or cognitive impairment. It has been described as "perception stripped of its meaning." Agnosia differs from anomia in that the patient not only fails to name an object but also cannot select it from a group or match it to a picture. With tactile agnosia (astereognosis), touch threshold is normal yet patients cannot identify what they are touching.

Comparable agnosias exist in the visual and auditory spheres. However, because the responsible lesions are likely to be bilateral, visual and auditory agnosias are rare. Simultanagnosia is the inability to recognize the meaning of a whole scene or object, even though its individual components are correctly recognized.

The left hemisphere usually processes language and the right hemisphere processes spatial information. Right hemispheric (particularly parietal) lesions impair spatial perception and manipulation; patients have difficulty reading maps or finding their way about (topographagnosia), or difficulty copying simple pictures or shapes or drawing simple objects such as a flower or a clock face (constructional apraxia or apractagnosia).

Even more striking is spatial hemineglect syndrome. Patients with damage to the right hemisphere may ignore objects to the left of midline, including the left side of the body (personal neglect syndrome). They may fail to recognize severe hemiplegia (anosognosia) or even to acknowledge left body parts as their own (asomatognosia). Asked to bisect a line, such patients indicate a point to the right of midline. A copied picture might be missing the left half, and a drawn clock face might have all the numbers neatly arranged on the right.

A subtle manifestation of spatial neglect is extinction. Patients are able to recognize a stimulus (visual, auditory, or tactile) on either side when it is presented alone but unable to recognize the stimulus when it is presented on one side while the opposite side is also stimulated.

Several of the cranial nerves are multifunctional; their motor, sensory, and autonomic functions must be assessed separately. The optic nerve is actually a central nervous system tract, and the accessory nerve is anatomically an aberrant spinal nerve (the motor neurons reside in the upper spinal cord).

Olfactory Nerve (Cranial N. I)

When patients complain that foods no longer taste right, the first step is to look into the nose for possible obstruction of airflow. Each nostril is then tested separately, using non-noxious odorants such as coffee or soap. (Pungent substances such as ammonia will stimulate trigeminal nociceptors.) Failure to smell anything is termed anosmia. Unpleasant distortion of an innocuous odorant is termed parosmia.

There are several cerebral representations for olfaction in the brain. As a result anosmia is most often secondary to local nasal disease, or to lesions affecting olfactory fibers as they pass through the cribriform plate (see Figure 32–1).

Optic Nerve (Cranial N. II)

Visual Acuity

Visual acuity is tested with Snellen's chart (at 20 feet) or a hand-held card (at 14 inches). The eyes are tested separately; if acuity is severely reduced, finger counting, detection of hand movement, or light perception should be assessed. Refractive errors are identified by having patients wear their glasses or look through a pinhole. Inspection of the eyes and funduscopic examination will often identify ocular lesions impairing acuity, such as corneal scarring, cataracts, glaucoma, diabetic retinopathy, or macular degeneration.

Visual Fields

The eyes are tested separately. The examiner faces the patient and holds an object equidistant between the patient's and the examiner's eyes to compare his or her own experience with that of the patient. A test object is moved slowly inward from the periphery, and the patient is asked to indicate when it is first seen; or the patient can be told to count fingers in different visual quadrants. Stimuli are presented simultaneously to the right and left fields to identify spatial neglect (extinction).

Visual field testing provides very accurate localization of structural lesions (see Figure 25–5). Monocular visual impairment, including either field defect or scotoma (an area of visual loss surrounded by preserved vision), localizes a lesion to the optic nerve, the retina, or other ocular structures. Bitemporal hemianopia, if caused by a single lesion, places that lesion at the optic chiasm. Homonymous hemianopia, quadrantanopia, or bilateral congruent scotomas indicate a lesion behind the chiasm in the contralateral optic tract, lateral geniculate nucleus of the thalamus, optic radiation, or primary visual cortex.

Funduscopy

Using an ophthalmoscope, the examiner focuses successively on the cornea, anterior chamber, lens, and vitreous body, and then surveys the optic disk, retinal vessels, and the retina itself. Optic atrophy refers to disk pallor; its many causes include glaucoma, optic nerve compression, infarction, and multiple sclerosis.

In papilledema (optic disk swelling) the disk margins become blurred and elevated. Papilledema can be the result of local pathology, for example the inflammatory demyelination of optic neuritis, in which case visual acuity is acutely impaired by swelling of the optic nerve head. When papilledema is the result of increased intracranial pressure, the normal blind spot becomes enlarged but visual acuity is not initially affected; over time, however, the visual fields become constricted and visual acuity is impaired. In addition, the ratio of the diameter of retinal veins to arteries (normally approximately 3:2) increases, and there may be retinal hemorrhages and whitish exudates.

Other abnormalities identified by funduscopy include arterial narrowing (hypertension), exudates (diabetes mellitus, blood dyscrasias), microaneurysms (diabetes mellitus), subhyaloid hemorrhages (located between the retina and the vitreous membrane and associated with subarachnoid hemorrhage), tubercles and other granulomas, phakomas (glial collections, associated with the hereditary diseases neurofibromatosis and tuberous sclerosis), pigmentary changes (retinitis pigmentosa), and emboli (seen within arteriolar branches of the central retinal artery).

Oculomotor, Trochlear, and Abducens Nerves (Cranial N. III, IV, VI)

Pupils

The pupillary light reflex is tested by directing a bright light into each eye and observing the bilateral response. Both pupils should constrict to bright light in either eye. The accommodation reflex and pupillary near response are tested by having the patient converge onto an object held close to the eyes; the pupils should constrict.

Anisocoria (unequal pupils) signifies either a parasympathetic lesion affecting the larger pupil or a sympathetic lesion affecting the smaller pupil. A parasympathetic lesion is indicated by marked pupillary dilatation, loss of the light reflex, or both, as well as involvement of extraocular muscles innervated by the oculomotor nerve. A sympathetic lesion is indicated by pupillary constriction, preservation of the light reflex, and signs of Horner syndrome (ptosis and, in some cases, loss of sweating over the ipsilateral face). A pupil with both parasympathetic and sympathetic denervation will be mid-position and unreactive to light.

A unilateral lesion involving the optic nerve or retina is indicated when neither pupil constricts in response to light directed into the affected eye, but both pupils constrict when light is directed into the unaffected eye (afferent pupillary defect). The pupils react equally because the pupillary light reflex is consensual (Figure B–2A; and see Figure 45–7).

The afferent end of the accommodation reflex pathway is in visual areas of the occipital lobe, which communicate with the parasympathetic component (the Edinger-Westphal nucleus) of the oculomotor nucleus by a route separate from the light reflex pathway. Lesions that selectively interrupt the light reflex pathway (for example, Argyll-Robertson pupils, seen most often with neurosyphilis) destroy the light reflex but do not impair the accommodation reflex.

Extraocular Eye Movement

The examiner looks for (1) paresis producing conjugate limitation of gaze in a particular direction (both eyes are equally affected so there is no diplopia); (2) paresis affecting one or more extraocular muscles (producing disconjugate eye movements with diplopia); and (3) spontaneous involuntary eye movements (eg, nystagmus).

The patient is asked to look to the right, to the left, and up and down in each horizontal direction. When the eyes follow a moving target they move more slowly (pursuit velocity) than when shifting from one static object to another (saccadic velocity). The two types of movement are controlled by separate anatomical and physiological mechanisms that can be selectively affected by lesions of the cerebrum, brain stem, or cerebellum (see Figures 39–2, 39–9, and 39–14).

Horizontal gaze palsy usually indicates a lesion of the frontal eye field (FEF) or the pontine paramedian reticular formation (PPRF) (see Figures 39–6, 39–9, and 39–10). If the FEF is affected the eyes will be deviated toward the side of the lesion. If the PPRF is affected the eyes will be deviated away from the side of the lesion.

Vertical gaze paresis—limitation of conjugate upward and downward gaze—indicates damage to the midbrain, either the rostral interstitial nucleus of the median longitudinal fasciculus or the posterior commissure.

Monocular limitation of adduction with preserved convergence (internuclear ophthalmoplegia) indicates damage to the ipsilateral median longitudinal fasciculus. There is often horizontal nystagmus in the contra-lateral abducting eye (see Figure B–2).

Disconjugate eye movements indicate impairment of particular cranial nerves or extraocular muscles (see Figures 39–4, 39–5, 39–6, and 39–7). If the eye cannot move outward there is a lesion involving either the abducens nerve (N. VI) or the lateral rectus muscle. If the eye cannot move downward when deviated inward there is a lesion of the trochlear nerve (N. IV) or the superior oblique muscle. Any other monocular limitations in movement are caused by a lesion of the oculomotor nerve (N. III) or one of its muscles of innervation (an exception is internuclear ophthalmoplegia).

The oculomotor nerve controls the levator palpebrae muscle, and ptosis is a common sign of lesions of this nerve. Unlike the mild Horner syndrome, oculomotor denervation can result in total eye closure.

The oblique muscles mediate intorsion and extorsion when the eye is either in mid-position or abducted. A compensatory head tilt (away from the side of the lesion) is therefore a feature of trochlear nerve palsy.

Nystagmus

Involuntary repetitive eye movements, or nystagmus, can be either unilateral or bilateral. Pendular nystagmus, with roughly equal velocity in either direction, is most often the result of severe visual impairment during early childhood. Rhythmical nystagmus, a slow drift in one direction followed by a rapid corrective movement in the other, can be present with the eyes at rest and the gaze fixed; it tends to be accentuated by ocular deviation, with the fast component in the direction of gaze.

Horizontal or rotatory nystagmus on primary gaze is most often associated with vestibular lesions, peripheral or central. Vertical nystagmus (the fast component directed upward or downward) suggests a brain stem lesion. Horizontally directed nystagmus on lateral gaze is often a benign side effect of certain drugs, particularly sedatives and anticonvulsants.

Trigeminal Nerve (Cranial N. V)

The three divisions of the trigeminal nerve carry sensation from the face, anterior scalp, eye, and much of the nasal and oral cavities. Fibers in the mandibular division innervate the muscles of mastication (see Figures 45–2 and 45–3).

The examiner initially checks sensations at the forehead, the malar region, and the chin, defining the outer borders of any deficit found. Decreased sensation confined to the entire trigeminal area indicates a peripheral lesion involving the nerve root or the trigeminal ganglion. Decreased sensation confined to one division suggests a more distal lesion. If pain and temperature are decreased, but touch is preserved, the lesion involves the spinal trigeminal tract and nucleus in the lower brain stem or upper cervical cord. If touch is also impaired, the lesion involves the principal trigeminal nucleus in the pons. If impaired sensation extends beyond the borders of the trigeminal area, the lesion is suprasegmental in the upper brain stem, thalamus, or parietal lobe.

Because the corneal reflex is consensual (the efferent end of the reflex pathway is in the facial nerve), a purely trigeminal lesion results in a decreased response in both eyes when the affected side is stimulated and a normal response in both eyes when the unaffected side is stimulated. Unilateral weakness of eye closure occurs in the affected eye when either cornea is stimulated.

Unilateral lesions of the trigeminal nerve or its third division cause the opened jaw to deviate toward the ipsilateral side because of ipsilateral pterygoid muscle weakness. Unilateral suprasegmental lesions are unlikely to cause jaw deviation because motor neurons of the trigeminal motor nucleus receive bilateral innervation from the primary motor cortex.

The jaw jerk is produced by tapping downward on the chin when the jaw is slightly open. Like other tendon reflexes it is decreased or absent with lesions of the nuclear or peripheral nerve (lower motor neurons) and brisk with lesions of the corticobulbar tract or motor cortex (upper motor neurons).

Facial Nerve (Cranial N. VII)

The facial nerve supplies facial muscles, including the frontalis ("wrinkle your forehead"), orbicularis oculi ("close your eyes tightly"), orbicularis oris ("close your lips tightly"), levator anguli oris ("show your teeth"), and platysma ("show your teeth and grimace"). With mild lesions there may not be frank weakness but rather a wider opening between the upper and lower eyelids and a flattening of the nasolabial fold ipsilaterally.

More proximal lesions can involve (1) a branch to the stapedius muscle of the middle ear (resulting in an increased sensitivity to loud sounds, or hyperacusis), (2) the chorda tympani branch to the sublingual and submandibular salivary glands and the tongue (resulting in decreased taste over the tongue's anterior two-thirds, usually tested with sugar or salt), or (3) the greater petrosal branch to the lacrimal gland and nasal mucosa (resulting in decreased lacrimation).

In most people motor neurons innervating the upper facial muscles, particularly the frontal muscle, receive projections from the motor cortex of both hemispheres, whereas those innervating the lower facial muscles receive only contralateral projections. Thus suprasegmental lesions tend to spare the frontal muscle and sometimes eye closure (upper-motor-neuron facial weakness), whereas lower brain stem or nerve damage tends to involve all the facial muscles (lower-motor-neuron facial weakness).

Following peripheral nerve injury such as Bell's palsy or trauma, aberrant reinnervation may produce synkinesis of the eye and mouth. Eye closure results in involuntary elevation of the angle of the mouth on the affected side, whereas baring the teeth results in involuntary closure of the ipsilateral eye.

Vestibulocochlear Nerve (Cranial N. VIII)

The auditory and vestibular nerves run together as the eighth cranial nerve. Both carry information from the labyrinths of the inner ear. The auditory (cochlear) nerve conveys sound information from the cochlea, whereas the vestibular nerve conveys equilibrium information from the utricle, saccule, and semicircular canals (see Figure 40–1).

Auditory Function

Neurons in the cochlear nucleus project both ipsilaterally and contralaterally. Thus unilateral deafness signifies a lesion of the cochlear nucleus, the auditory nerve, or the ear. Deafness from peripheral lesions is of two types. Conduction deafness is the result of obstruction or disease of the external auditory canal, the tympanic membrane, or the middle ear. Sensorineural deafness is the result of damage to the cochlea, the cochlear nerve, or the cochlear nuclei. Conduction deafness preferentially affects low tones; sensorineural deafness preferentially affects high tones. Patients with cochlear nerve or cochlear nucleus lesions may have only mildly impaired hearing for pure tones yet severe difficulty in discriminating speech because of its tonal complexity. Both peripheral and central lesions cause tinnitus.

The auditory examination begins with a simple screening test in which the ability of each ear to detect a watch ticking or two fingers rubbed together is compared. The Weber and Rinne tests help to distinguish conduction from sensorineural deafness. In the Weber test a 512 Hz tuning fork is placed midline on the forehead. With conduction deafness the sound will be heard best on the hearing-impaired side, whereas with sensorineural deafness the sound will be heard best on the normal side. In the Rinne test the tuning fork is placed over the mastoid; when the patient reports that the sound is no longer heard, it is held close to the external auditory meatus. In normal subjects and in those with nerve deafness air conduction will outlast bone conduction. With conduction deafness bone conduction will outlast air conduction. The Weber test is most useful when deafness is unilateral and the Rinne test when deafness is bilateral.

Vestibular Function

The vestibular nerve carries impulses from hair cells in the semicircular canals to the vestibular nuclei in the brain stem. Widespread projections from the vestibular nuclei communicate with the spinal cord, the cerebellum, eye movement control centers, and the forebrain.

Tests of vestibular function involve labyrinthine stimulation, either by head movement, head positioning, or temperature. In some patients vertigo, nystagmus, and sometimes nausea and vomiting are precipitated by any rapid movement of the head. In others, particularly those with benign positional vertigo, vertigo is triggered (after a latency of up to half a minute) by lying on the affected ear.

In the caloric test the ear is irrigated alternately with water several degrees centigrade above and below body temperature. With the head elevated 30 degrees the normal response consists of nystagmus (and vertigo), with the fast component directed away from the cold stimulus but toward the warm stimulus. There are two main patterns of abnormal response. Nystagmus may be absent or briefer in response to a cold or warm stimulus in the same ear; this canal paresis is associated with peripheral vestibular lesions. Conversely, a reduced response may occur when cold water is instilled into one ear or warm water is instilled into the other ear; this directional preponderance is associated with lesions of central vestibular pathways.

When pointing to objects, vertiginous patients whose eyes are closed tend to deviate toward the side of the lesion (past-pointing). Similarly, when walking in place with closed eyes, they tend to rotate toward the affected side.

Glossopharyngeal and Vagus Nerves (Cranial N. IX, X)

Assessment of the ninth and tenth cranial nerves is usually limited to examination of the palate and pharynx. Nasal speech suggests palatal weakness. Hoarseness or a reduced cough suggests laryngeal weakness.

Choking on saliva while talking suggests pharyngeal weakness. Difficulty swallowing (dysphagia) solid food suggests mechanical obstruction such as esophageal carcinoma; dysphagia for liquids as well as solids or for only liquids suggests neurological dysfunction. Dysphagia can be checked by asking the patient to swallow a small amount of water.

When the patient says, "ah" with the mouth open and the tongue relaxed, the palate should rise symmetrically, the uvula should remain in the midline, and the pharyngeal walls should contract symmetrically. With unilateral palatal or pharyngeal weakness, phonation causes the uvula to deviate toward the normal side. The gag reflex is tested by gently touching each side of the pharynx with a cotton-tipped applicator. As with the pupillary and corneal reflexes, the response is bilateral. The response of the palatal and pharyngeal muscles to phonation and tactile stimulation therefore reveals whether a lesion is unilateral or bilateral, and whether the damaged nerves are efferent, afferent, or both.

With unilateral laryngeal lesions the abnormal vocal cord may be positioned in adduction, in which case there may be no symptoms; if it is positioned in abduction there will be hoarseness or aphonia but normal breathing. With bilateral lesions the vocal cords may be positioned in abduction, in which case there will be hoarseness or aphonia but normal breathing; if they are positioned in adduction there will be inspiratory phonation (stridor) and life-threatening respiratory obstruction.

Spinal Accessory Nerve

The sternocleidomastoid is the only major striated muscle with ipsilateral cortical representation. Following destructive cerebral lesions weakness in the sternocleidomastoid is unusual but may occur ipsilaterally; contralateral trapezius weakness may also occur. The sternocleidomastoid is tested by having patients press their chin against resistance in the direction of the contralateral shoulder. Bilateral damage causes weakness of forward head flexion. Trapezius weakness is demonstrated by assessing shoulder elevation or shrugging or by observing winging of the upper scapula.

Hypoglossal Nerve (Cranial N. XII)

The hypoglossal nerve innervates the muscles of the tongue. It arises near the midline of the medulla oblongata and exits the posterior fossa through the hypoglossal foramen. Each hypoglossal nucleus receives bilateral projections from the motor cortex.

Inspection of the tongue may reveal atrophy or fasciculations, either of which indicates damage to lower motor neurons, either peripherally or in the medulla. Tongue atrophy, if unilateral, causes reduction in size on one side with excessive ridging and wrinkling of the affected side. Fasciculations in the tongue can be difficult to tell from normal tongue movements or tremor. These small local contractions are nonrhythmic and make the tongue resemble a bag of worms. They should be present when the tongue is completely at rest.

With unilateral weakness because of lesions of upper or lower motor neurons the tongue deviates toward the weak side. If there is no deviation, weakness is assessed by having the patient push the tongue into each cheek while the examiner pushes against the cheek. With unilateral lesions of upper motor neurons there may be no deviation and little evident weakness, yet patients may experience dysarthria (imperfect articulation), particularly with the lingual consonants (tay for anterior tongue, kay for the posterior tongue). Bilateral tongue weakness causes dysarthria, dysphagia, and sometimes even difficulty breathing.

Bilateral lesions of the lower brain stem can result in bulbar palsy. The tongue is paralyzed, atrophic, and fasciculating. There is no movement of the palate or pharynx with phonation, and the gag reflex is absent. With unilateral supranuclear lesions these muscles are often spared or only mildly impaired because of the bilateral cortical projections to lower brain stem motor neurons.

Bilateral lesions of the cerebrum or upper brain stem, however, can result in severe dysarthria and dysphagia because of effects on the corticobulbar pathway. The tongue is paralyzed but neither atrophic nor fasciculating. The palate and pharynx do not move with phonation, but the gag reflex is hyperactive. Such a patient is said to have pseudobulbar palsy. An interesting and unexplained feature of this syndrome is lability or hyperreflexia of emotional response. A remark that would normally produce a mild chuckle precipitates embarrassed peals of laughter, and asking a question such as "How are you feeling?" may result in explosive weeping.

Observations of spontaneous and commanded movements can reveal patterns of weakness that localize a lesion. Weakness of extensor muscle groups of the arm and flexors of the leg on the same side suggests a lesion of the corticospinal tract on the contralateral side. If the weakness is acute, the limbs may be flaccid; if chronic, there may be increased tone and brisk tendon reflexes (spasticity) (see Figure B–1).

Weakness of both legs (paraparesis) or of both legs and both arms (quadriparesis) may be the result of a lesion of the spinal cord or of widespread dysfunction of the peripheral nervous system or muscles. Lesions of the spinal cord may be associated with a sensory level (see section on Sensory Systems) or bladder dysfunction, and lesions above the spinal cord may be accompanied by signs of brain stem or cortical dysfunction. Peripheral neuropathies tend to produce a generally symmetrical pattern of limb weakness. As a rule, weakness that begins or is greater in the distal arms or legs suggests peripheral neuropathy, whereas weakness of the proximal limb muscles (shoulder and girdle) suggests myopathy (Figure B–3).

Weakness confined to a single limb may reflect plexopathy or mononeuropathy. Examining the strength of individual muscle groups innervated by specific nerves is key, and a chart of muscle innervation by nerve, trunk, and root can be a great aid in localization.

Observing Spontaneous Movement

The motor examination begins with observations of spontaneous movement, which may reveal patterns of weakness but may also reveal spontaneous uncontrolled movements such as tremor, athetosis, chorea, myoclonus, or dystonia. Fasciculations of individual muscle groups can sometimes be enhanced by directly tapping the muscle with a reflex hammer. If unilateral atrophy of limb musculature is suspected, the circumference of the limb should be measured and compared to the same region of the opposite limb.

Detecting a Lesion in the Corticospinal Tract

The patient's arms are held outstretched with palms upward and eyes closed. Mild corticospinal lesions may cause one arm to drift below the level of the other, with pronation of the upturned palm. A subtle sign of corticospinal pathology is clumsiness of fine finger movements, brought out by asking the patient to rapidly and steadily tap the forefinger against the thumb (finger-repetitive test), and then to tap each finger against the thumb in rapid succession (finger-successive test). One should compare the facility with which this is performed by each hand, bearing in mind that most people will be slightly more adept with their dominant side (see Figure B–1).

Testing Muscle Tone

With the patient relaxed, the arms are passively flexed and extended around the elbow and wrist joints. Muscle tone may be flaccid, which is usual following acute paralysis, lower motor neuron lesions, or myopathy; or it may be increased, often with a characteristic give-way relaxation after initial resistance (clasp-knife effect), reflecting spasticity and an upper motor neuron lesion. Tone in the lower limbs may be tested in the supine patient by abruptly lifting the thigh. If the heel lifts briefly off the bed, tone is normal; if the leg rises rigidly off the bed, tone is increased; if the heel drags along the sheets, tone is decreased. Resistance to movement in all directions and throughout range of movement (lead-pipe rigidity) is characteristic of Parkinson disease; it may be accompanied by cogwheeling, a stepwise ratcheting that reflects the tremor of Parkinson disease superimposed on increased tone (Figure B–4).

Testing Muscle Strength

Muscle power is graded on a scale of 0 to 5 (0 = no contraction, 1 = contraction but no movement, 2 = contraction but not against gravity, 3 = movement against gravity but not against even minimal resistance, 4 = movement against minimal to moderate resistance, 5 = normal). Testing includes flexion and extension of the head; abduction, adduction, and rotation of the shoulders; flexion and extension of the elbows, wrists, and fingers; intrinsic hand muscle movements; and flexion and extension of the hip, knee, ankle, and toes. Comparison is made between right versus left, proximal versus distal, and arms versus legs.

Establishing Boundaries and Comparing Sides Are Crucial to the Sensory Examination

As in the motor examination, patterns and symmetry are key. Distal symmetrical sensory loss is characteristic of peripheral neuropathies. Brain stem lesions, for example of the lateral medulla, produce pain and temperature loss ipsilaterally on the face and contralaterally on the body. Bilateral loss of all sensation below a trunk level is characteristic of spinal cord lesions; the sensory level, the upper border of the area of sensory loss, is usually one or two segments higher on the back than on the chest. Preservation of sensation in the sacrum (sacral sparing) indicates an intraparenchymal lesion while loss of sensation indicates an extraparenchymal compressive lesion. Sacral sensory loss (saddle anesthesia) suggests a lesion of the cauda equina or conus medullaris.

Ipsilateral hyperalgesia, an increased sensitivity to pain, may be a result of nerve root irritation at the level of the lesion. Sensory loss develops throughout the root distribution as the lesion expands, and pain and temperature loss occurs in the contralateral leg when a spinal cord lesion produces spinothalamic tract dysfunction. There may also be ipsilateral loss of proprioception because of dorsal column dysfunction. Spinal cord lesions arising within the cord, as in syringomyelia, can damage crossing spinothalamic fibers, causing segmental pain and temperature loss (for example, in a cape-like distribution throughout the shoulders and upper back if damage is in the upper cervical cord, or in the hands if damage is in the lower cervical cord) (Figure B–5).

Testing Pain Sensation

Pain is tested with a safety pin or the sharp end of a broken applicator stick, which should be disposed of after use. Pressing a pin against the bony part of a limb will be felt more sharply than a similar stimulus applied to a fleshy part. A single application of the pin should suffice; repetitive stimulation will increase the stimulus strength through temporal summation in receptor neurons.

Testing proceeds from head to toe in an orderly pattern, comparing locations on each side. Test spots should include proximal and distal upper and lower limbs, both front and back. Bearing in mind the sensory dermatomes (see Figure 22–9), a reasonable strategy is to test over the deltoid (C5), dorsal forearm (C6), thenar eminence (C6, but also median nerve), tip of the little finger (C8, ulnar nerve), medial forearm (T1), and axilla (T2). On the chest one should probe on either side of the midline and test along the back if a sensory level is detected on the chest or abdomen. Because C5 to T1 roots innervate the arms and hands, there is a C4/T2 boundary above the nipple line, and lower cervical cord lesions may produce a sensory level in this region. The lower limbs are tested over the thigh (L2), medial calf (L4), dorsum of the foot (L5), and lateral malleolus or sole of the foot (S1).

If areas of decreased sensation are detected, finer testing is necessary to map the borders and determine whether the lesion involves nerves, roots, or the central nervous system. In addition to anesthesia, patients may report either a dull sensation (hypalgesia), which may be as significant as anesthesia and just as useful in mapping patterns of deficit, or possibly hyperalgesia, which sometimes indicates the upper level of a spinal cord lesion.

Temperature Testing

Pain and temperature are both carried centrally in the spinothalamic tract, so areas lacking hot or cold sensation will most often lack pain sensation as well. If pinprick testing has uncovered a deficit, testing temperature sensation by applying a cold tuning fork to the skin for several seconds can be a very useful procedure to confirm involvement of spinothalamic modalities.

Touch Testing

Testing light touch sensation is not helpful in localizing central lesions because touch sensation is carried by several spinal tracts, but it is very helpful in localizing peripheral lesions of nerves or roots. Testing should follow the procedure for testing pain by stroking lightly with a finger or a cotton wisp. Deficits may include a simple decrease in sensation (hypesthesia), a distorted or abnormal sensation (dysesthesia), or even a painful sensation (allodynia).

Testing Proprioception

With eyes closed one can still sense the position of one's arms and legs because of proprioceptive nerve endings in the joints that convey sensory information by way of the dorsal columns of the spinal cord. To test position sense in the elbow and shoulder, ask the patient to extend the arms with eyes closed and to touch the forefinger to the tip of the nose.

Position sense in the fingers (or wrist) is tested by asking the patient with eyes closed to identify whether the finger (or wrist) has been moved up or down by the examiner. Grasp the patient's finger at the sides rather than the dorsal and palmar surfaces to ensure that the patient does not use pressure sense to judge direction of movement. Position sense is very sensitive; only 1 to 2 millimeters of displacement is required. In rare instances of loss of pro- prioception the arms may drift into odd dystonic postures (pseudoathetosis) when the eyes are closed.

To test the hip and knee joints, ask the supine patient with eyes closed to identify when the leg has been moved to a new position, or to point to the big toe as the leg is moved to a series of positions. Proprioception of the big toe is tested as for the fingers.

The Romberg test for balance is performed by asking the patient to stand unassisted with feet together and eyes closed. The test is considered positive if the patient loses balance. Although dorsal column lesions produce a positive test, so will a variety of other conditions, including inner ear dysfunction and cerebellar lesions. Sensory ataxia, a gait disorder resulting from uncertainty concerning limb position, indicates posterior column lesions.

Testing Vibration Sensation

Vibration is tested with a 128 Hz tuning fork held against the bony wrist and the lateral malleolus of the ankle. Place the stem firmly against the patient's wrist or ankle and instruct the patient to signal when the vibration has stopped. To ensure that sensation has not ceased because of habituation, promptly remove and replace the fork to test whether the patient can still feel vibration; when the patient declares the vibration has stopped, place the fork against your own wrist to confirm that it is no longer vibrating. Vibration sensation can also be tested at the toes, knees, and elbows. Decreased vibratory sensation at the toes and ankles is a sensitive measure of sensory peripheral neuropathy (see Figure B–3).

Complete spinal cord transection will produce bilateral hyperesthesia at the level of the lesion and loss of sensation in all modalities beginning several segments below. Hemisection of the spinal cord (Brown-Séquard syndrome) produces ipsilateral loss of vibration and position sense and contralateral loss of pain and temperature a few levels below the lesion (see Figure B–5). Central cord lesions, such as syringomyelia, injure the spinothalamic fibers as they cross just anterior to the spinal canal, producing bilateral loss of pain and temperature at the level of the lesion while sparing other modalities such as light touch and proprioception.

Testing Cortical Processing of Touch

Sensory information originating in the pathways tested above is processed in the cerebral cortex. But findings from tests of perception will only be significant once the elementary sensory pathways for touch have been found to be intact.

The patient, with arms outstretched and eyes closed, is asked to state which hand has been touched. The examiner lightly touches first one hand, then the other, and then both simultaneously. Patients suffering from spatial neglect may correctly identify single touches on both sides but consistently fail to report a touch on one side when both sides are touched simultaneously (double simultaneous stimulation). This deficit, termed sensory extinction, implicates a lesion of the contralateral parietal lobe.

Graphesthesia is tested by having the patient with eyes closed identify numbers from 1 to 10 traced on the palm of each hand using a pointed but blunt instrument. The traced numbers should be right side up with respect to the patient.

The patient's ability to identify objects by touch (stereognosis) is tested by asking the patient with eyes closed to identify a common object such as a key, comb, or coin that is placed in the palm. The patient is permitted to manipulate the object with his fingers. As always, performance on the right is compared to the left.

Two-point discrimination is tested by first applying a single stimulus, then two stimuli simultaneously and asking the patient with eyes averted to identify these correctly. The separation that can be discriminated will vary with the density of sensory innervation over different skin regions; thus the fingertips can detect the smallest separations. The same areas on both sides should be compared.

Testing coordination and involuntary movement assesses cerebellar and basal ganglia function. Involuntary movements include tremors (repetitive, oscillatory motions), myoclonus (sudden twitching of muscle groups), asterixis (periodic lapse of muscle tone), chorea (rapid, chaotic twitching), athetosis ("wormian" writhing motions), dystonia (athetotic-like movements with held postures), and ballism (proximal flinging movements of the arms).

These movements are best observed with the patient at rest with arms outstretched. Asterixis is brought out by having the patient hold hands dorsiflexed at the wrist in the position used by traffic policeman to command "stop." Periodic lapse of posture (the "wave good-bye" sign) is positive for asterixis. Tremors are classified as resting, postural, and action. Postural tremors can be assessed by having the patient hold the arms in the outstretched posture, whereas action tremors can be assessed by having the patient touch first the examiner's finger and then his own nose. Resting tremors are best assessed by observing the patient seated, lying down, or walking with arms hanging down.

The term ataxia (literally, disorder) refers to a variety of impairments of coordination as well as unsteady gait most often following a cerebellar lesion. Cerebellar lesions cause ipsilateral rebound, dysmetria, and dysdiadochokinesia. Rebound is tested by applying downward pressure against the patient's outstretched arms and releasing abruptly. If rebound is present, the arms will fly up rather than return to the neutral position. Dysmetria consists of overshooting or undershooting the target. In the arms dysmetria is detected with the same finger-to-finger and finger-to-nose test used to detect action tremor, which often coexists. In the legs dysmetria (and action tremor) can be detected by having the patient place a heel on the opposite knee and run it down the shin.

Dysdiadochokinesia, the inability to maintain a steady rhythmic movement, is identified by having the patient perform rapid successive movements (for example, tapping the thumb and index finger together, or one hand against the other, or tapping a foot on the floor) and rapid alternating movements (for example, alternately pronating and supinating the hands or alternately tapping the toe and heel of one foot on the floor).

The patient is asked to stand and walk normally 5 to 10 paces, then turn around and walk back. Observations should be made of posture, arm swing, foot position, step size, and dexterity of motion, especially during turning. During walking the insteps of both feet normally line up along an imaginary line; when there is an increase in the distance between the two feet, the gait is broad-based and suggestive of cerebellar disease or proprioceptive loss.

With flaccid hemiparesis the affected arm has diminished swing and the affected leg may drag (footdrop). When footdrop occurs in isolation, as for example with peroneal nerve injury, the patient may have a "steppage" gait, lifting the leg higher than normal to compensate for foot dragging. With spastic hemiparesis the affected side shows hemiparetic posture, with the arm flexed at the elbow and wrist and leg extended and inverted (see Figure B–1). Gait therefore has a circular form (circumduction) as the patient swings the affected leg off the ground by throwing his body to the opposite side. The foot describes a circular motion with each step. With spastic paraparesis or quadriparesis, as occurs with cerebral palsy, bilateral extensor tone may produce toe-walking or scissoring as a result of bilateral circumduction. Parkinsonian gait is characterized by a forward stoop, loss of arm swing, shuffling, and festination (acceleration, as if the patient were trying to catch up with his center of gravity) (see Figure B–4).

Myopathic gait is characterized by waddling, the result of bilateral hip abductor weakness. Antalgic gait refers to gait in which compensatory maneuvers (eg, favoring one leg) are adopted to minimize pain. Subtle signs of hemiparesis can be detected with the use of stressed gaits, such as walking on toes, heels, or the outside edges of the feet. Note the position of the arms during these gaits for evidence of synkinesia.

Synkinesia or overflow movement is said to occur when the ipsilateral arm and hand posture mimics the position of the foot. Such associated movements are normal in very young children and tend to be prominent in cases of cerebral palsy, but are not normal in adults. Unilateral hand-foot overflow movements can be seen in mild cases of hemiparesis.

Patients are asked to walk a straight line as though on a tight rope, one foot in front of the other. Any deviation from a straight path is noted. This test is sensitive for cerebellar ataxia of gait, as occurs with alcohol intoxication, and is thus the basis of the field sobriety test. However, patients with lesions of the cerebellum for any cause will demonstrate a drunken gait, as can patients with labyrinthine dysfunction, dizziness, weakness, balance trouble, or proprioceptive problems.

Patients with severe cerebellar ataxia or vertigo may not be able to stand with feet together. After examining and establishing the stability of the patient's stance, the patient is told to close his eyes. The Romberg test may identify more subtly impaired stance.

Examining tendon reflexes can confirm whether weakness is due to damage of lower or upper motor neurons. Increased reflexes indicate damage in upper motor neurons; diminished reflexes indicate damage to lower motor neurons (see Figure B–1). Rating is on a scale of 0 to 5, where 0 = absent, 1 = reduced, 2 = normal, 3 = brisk without clonus, 4 = transient clonus, and 5 = sustained clonus. Reflexes of 4 or 5 are usually pathological, but hypoactive reflexes are often normal.

Both sides are compared and reproducible asymmetry is always significant. Tendon reflexes are elicited by tapping a stretched tendon to activate the muscle spindle. The muscle to be tested should be relaxed and not under active contraction. If a tendon response appears to be absent, the response may be enhanced by having the patient perform some task, for example interlocking the fingers of both hands and attempting to pull them apart as the examiner elicits the reflex.

Tendon Reflexes in the Arms

To elicit a biceps reflex the arm is flexed 90 degrees at the elbow; pressure is applied to the biceps tendon using an extended forefinger and then a phasic stretch is elicited by striking the forefinger with the reflex hammer. To elicit the triceps reflex the elbow is also held at 90 degrees and the tendon is struck directly with the hammer. The brachioradial muscle is tested by holding the patient's hand with the elbow flexed and striking the radius just above the wrist.

Finger flexors are tested by having the patient gently flex the fingers against the examiner's outstretched forefinger and then striking the forefinger with the hammer to apply a sudden extension. Brisk reflexes may be associated with reflex spread. For example, stretching the finger flexors may cause the thumb to flex as well, and flicking the nail of the patient's forefinger may similarly trigger finger and thumb flexion (Hoffmann reflex).

Tendon Reflexes in the Legs

The patellar reflex is best elicited with the patient either sitting with legs crossed or supine. The leg is lifted from behind the knee and the patellar tendon is struck below the knee. If the patella reflex is very brisk, clonus may be elicited by extending the leg and, while holding the patella between thumb and forefinger, applying a sharp downward stretch. Reflex spread may include a crossed adductor response, elicited in the supine patient by pressing on the medial knee to slightly spread (abduct) the leg and then striking the hand with the hammer. Adduction of both legs suggests pathological briskness.

The ankle reflex is best elicited with the leg triple-flexed (at the hip, knee, and ankle). The ankle is then dorsiflexed by applying pressure to the ball of the foot with the hand. Striking either this hand or the Achilles tendon with the reflex hammer will produce a sudden stretch of the gastrocnemius tendon and trigger the reflex. In this position it is easy to observe clonus, if present. Ankle clonus usually accompanies spasticity.

Asymmetrical Superficial Reflexes

The plantar response is conveniently tested following the ankle reflex. A blunt instrument (a key or wooden applicator stick) is used to stroke up along the lateral edge of the sole and across the plantar surface. The big toe should be observed for extension and the remaining toes for possible fanning, an extensor plantar response (Babinski reflex). A flexor motion or no toe motion at all can be normal, but a neutral response on one side may be significant in the presence of a clear flexor response on the other side. Babinski reflex indicates a corticospinal lesion (see Figure B–1).

Abdominal reflexes are elicited by drawing a blunt instrument across the abdomen several inches to one side of the umbilicus and then repeating the maneuver on the other side. A normal response is movement of the umbilicus toward the side of stimulation. Symmetrically absent responses are not significant, but an asymmetrically absent response can be associated with upper motor neuron lesions.

Frontal Lobe Reflexes

Several so-called frontal release signs or primitive reflexes have been described. These include the snout reflex, elicited by tapping the mouth gently with the reflex hammer and observing whether the lips purse; the palmomental reflex, elicited by scratching the palm and observing contraction of the mentalis muscle; and the grasp reflex, triggered by stroking the palm and triggering an involuntary grasp. These responses are often associated with frontal lobe lesions, but, with the exception of the grasp reflex, they are also present in many normal adults.