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The detailed neurologic examination in adults

The detailed neurologic examination in adults
Literature review current through: Sep 2023.
This topic last updated: Jul 01, 2022.

INTRODUCTION — Most of the information necessary to localize a lesion in patients with neurologic complaints can be obtained by taking a careful history. Even features that are usually considered to be examination findings can be deduced if the right questions are asked. As an example, to investigate temperature sensation, patients can be asked whether they have any problems detecting water temperature. With regard to fine touch discrimination, patients can be asked whether they have problems pulling the correct coin or other objects out of their pockets. Position sense can be explored by asking whether patients have problems knowing where their feet are on the car accelerator and brake pedals.

Nevertheless, some important information can be learned only by examining the patient. Furthermore, the information obtained from a history depends upon the reliability of the informant. It is essential to have an independent source of information when the informant is a poor observer, has trouble communicating, or for some reason provides misleading information; the neurological examination serves this purpose.

There is no clear consensus among experts regarding the optimal order of performing or presenting the neurologic examination or its components (eg, the motor examination). The order used in this topic is my preferred order for presenting the results of the patient's neurologic examination. It is important that clinicians have a sequence of their choosing that they use consistently.

Components of the standard neurologic examination are found in Table 1 and discussed in detail in this review (table 1). The text is adapted, with permission, from Reference 1 [1].

The examination of comatose patients is discussed separately. (See "Stupor and coma in adults", section on 'General examination'.)

A SCREENING NEUROLOGIC EXAMINATION — Practicing physicians usually do not have the time to perform complete neurologic examinations on all patients. They must be able to perform a rapid examination that screens for most common abnormalities. The results of this screening examination can be used together with the history to decide whether certain components of the examination must be conducted in more detail.

For screening purposes in patients without neurologic complaints, the following neurologic examination is generally adequate and can be completed in five minutes or less.

Mental status — Test patients for orientation to person, place, and time. Make sure they can follow at least one complicated command, taking care not to give them any nonverbal cues. If their responses are appropriate and they are able to relate a detailed and coherent medical history, no further mental status testing is necessary (unless they have cognitive complaints). (See 'Mental status examination' below.)

Cranial nerves — Test visual fields in one eye, both pupillary responses to light, eye movements in all directions, facial strength, and hearing to finger rub. (See 'Cranial nerve examination' below.)

Motor system — Test strength in the following muscles bilaterally: deltoids, triceps, wrist extensors, hand interossei, iliopsoas, hamstrings, ankle dorsiflexors. Test for a pronator drift. Test finger tapping, finger-to-nose, and heel-knee-shin performance. Test tandem gait and walking on the heels. (See 'Motor examination' below.)

Reflexes — Test plantar responses and biceps, triceps, patellar, and ankle reflexes bilaterally. (See 'Reflex examination' below.)

Sensation — Test light touch sensation in all four distal limbs, including double simultaneous stimulation. Test vibration sense at the great toes. (See 'Sensory examination' below.)

This examination must be expanded when an asymmetry or other abnormality is found. As an example, if the triceps muscle is weak in one arm, other muscles innervated by the radial nerve must be tested, as well as other muscles in the distribution of the C7 nerve root. The examination must also be expanded to focus upon patients' specific complaints. Patients complaining of memory loss, for example, need thorough mental status testing even if their performance on the screening examination is perfectly normal.

MENTAL STATUS EXAMINATION — An assessment of mental status should specifically note deficits in the following spheres:

Level of consciousness (arousal)

Attention and concentration

Memory (immediate, recent, and remote)

Language

Visual spatial perception

Executive functioning

Mood and thought content

Praxis

Calculations

Details of this evaluation are discussed separately. (See "The mental status examination in adults" and "Approach to the patient with aphasia".)

The portion of the neurologic examination for which presentation in a consistent sequence is most important is the mental status examination. Certain findings on the mental status examination can only be interpreted by knowing a patient's ability to perform other more fundamental tasks. As an example, difficulty with simple calculations may have some localizing significance in a patient who is otherwise cognitively intact, but not in a patient who is unable to answer any questions because of impaired language function or a depressed level of consciousness. This ambiguity is avoided by reporting the level of alertness first, then language function, and then memory. The remainder of the mental status examination can be presented in any order.

When reporting the results of mental status testing, it is most informative to convey patients' actual responses, rather than interpretations such as "mildly abnormal" or "slightly concrete." A confusing array of terminology is often used to report the findings on mental status testing; some are defined in Table 2 (table 2).

CRANIAL NERVE EXAMINATION

Olfaction (CN I) — I almost never test the sense of smell. It is difficult to know whether patients who cannot identify a particular scent have a disturbance of olfaction or whether they are just not familiar with that scent. I take patients at their word when they give a history of olfactory problems. When formal testing is desired, olfaction is examined by having the patient occlude one nostril and identify a common scent (eg, coffee, peppermint, cinnamon) placed under the other nostril.

Vision (CN II)

Visual fields — Have the patient cover his or her left eye. Stand facing the patient from two arm's lengths away, close your right eye, and stretch your arms forward and to the sides so that your hands are at about "1:30" and "10:30" and just barely visible in your peripheral vision. They should be the same distance from you and the patient. Hold the index finger on each hand extended. Quickly flick the finger on either the left, right, or both hands, and ask the patient to identify where the movement occurs while looking directly at your nose. Move your hands down to roughly "4:30" and "7:30" and test again. Then test analogous portions of the visual field of the patient's left eye (using your right eye as a control).

There are many alternatives to the technique described here for testing visual fields [2]:

Ask patients to tell you when they first see a test stimulus as you slowly move it in from the periphery at various orientations.

Ask patients to count the number of fingers you hold up at various spots in the field.

Ask patients to tell you when they can detect that a small stimulus is red as you move it in from the periphery of the field (the "kinetic red target" method). A pin with a 5 mm red top is typically used.

Ask patients to describe examiner's face (ask if any part of face is missing or appears distorted).

Ask patients to compare visual clarity of fingers presented simultaneously in the two upper (then the two lower) visual quadrants.

Ask patients to count one or two fingers presented in each of the four quadrants as described above.

Ask patients to compare the color of two identical red objects presented simultaneously in the two upper (then the two lower) visual quadrants (object "less red" or duller is abnormal).

Regardless of the technique used, each eye must be tested separately. Otherwise, if there is a defect in a portion of the visual field of only one eye, the other eye will be able to compensate and the defect will not be detected. One example of this situation is the bitemporal hemianopia that can occur with a lesion in the optic chiasm; the defective hemifield of each eye corresponds to the intact hemifield of the other eye, so the patient may be completely unaware of the deficit.

Each technique has advantages and disadvantages, and some neurologists have very strong opinions about which is best. In one study, the kinetic red target technique was more sensitive than other methods, and combinations of two techniques (especially the combination of the kinetic red target technique with the quick finger flick method described first) improved sensitivity further [2]. The reason I prefer the first method described is that the visual stimulus can be presented very briefly, minimizing the opportunity for the patient to shift fixation and maximizing the likelihood that the stimulus is actually in the intended region of the visual field. Also, patients with cognitive or mental status abnormalities can often participate more effectively in this test but have difficulty with the other approaches. A baseline level of attention and cognitive ability is also required for automated visual perimetry. (See "Homonymous hemianopia", section on 'Evaluation and diagnosis'.)

Homonymous hemianopia is a visual field defect involving either the two right or the two left halves of the visual fields of both eyes. Specific examples of these visual field defects and their neuroanatomic correlation are discussed separately. (See "Homonymous hemianopia".)

Acuity — Place a hand-held visual acuity card 14 inches in front of the patient's right eye while the left eye is covered. The patient should wear his or her usual corrective lenses. Ask the patient to read the lowest line on the chart (20/20). If the patient cannot do so, move up a line, and continue doing so until you reach a line where the majority of items are read correctly. Note which line this is and how many errors the patient makes on this line. Repeat the process for the left eye.

Funduscopic examination — Reduce the room illumination as much as possible. Turn on the ophthalmoscope light, adjust the output to the small round beam of white light, and adjust the lens to zero diopters. Examine the patient's right eye by holding the ophthalmoscope to your right eye in your right hand, and examine the patient's left eye by holding the instrument to your left eye in your left hand. Hold the thumb of the opposite hand on the patient's eyebrow above the eye you are examining.

Ask the patient to look straight ahead, and shine the beam of light on the pupil and look for the red reflex - an orange glow reflected from the retina. Move in closer towards the patient's pupil, staying focused on the red reflex. Look for the optic disc, and bring it into focus by adjusting the ophthalmoscope lens. Red lens numbers indicate minus diopters, used with myopic (nearsighted) eyes, while black numbers indicate plus diopters, used for focusing on hyperopic (farsighted) eyes or eyes that have undergone surgical lens removal.

Once the optic disc is clearly identified and sharply focused, the funduscopic examination should proceed to inspect the clarity of the disc outline, and observe for the presence or absence of venous pulsations. The retinal vessels should be followed peripherally in all directions, and the retina should be searched at the same time. Abnormalities of retinal vessels or retinal lesions should be noted.

Pupillary light reflex (CN II and III) — Reduce the room illumination as much as possible. Shine a penlight on the bridge of the patient's nose so that you can see both pupils without directing light at either of them. Check that they are the same size.

Now move the penlight so that it is directly shining on the right pupil, and check to see that both pupils have constricted to the same size. Next, move the penlight back to the bridge of the nose so that both pupils dilate, and then shine the light directly on the left pupil, again checking for equal constriction of the two eyes. Finally, move the penlight rapidly from the left pupil to the right; the pupil size should not change. Swing the light back to the left pupil; again, the pupil size should remain constant. Repeat this "swinging flashlight" maneuver several times to be sure there is no consistent tendency for the pupils to be larger when the light is directed at one eye than when it is directed at the other one. If this relative afferent pupillary defect is found, it suggests an abnormality in the anterior visual pathways. (See 'Afferent pupillary defect' below.)

Eye movements (CN III, IV, and VI) — First observe the patient's eyelids for ptosis. (See "Overview of ptosis".)

Have the patient fixate on your finger held about two feet away, in the vertical and horizontal midline. Observe for nystagmus. Jerk nystagmus is a repetitive, quick movement of the eyes in one direction, alternating with a slower movement of the eyes in the opposite direction, several times in a row. Pendular nystagmus is a slow sinusoidal oscillation of the eyes that may occur in any direction, without fast phases. (See "Overview of nystagmus".)

Ask the patient to avoid any movement of the head but to continue watching your finger as you slowly move it to the patient's right. Observe the smoothness and range of the patient's eye movements. Keep your finger at the far right of the patient's gaze for several seconds while observing for nystagmus. Move your finger slowly to the patient's left and repeat the observations. Return your finger to the vertical and horizontal midline, then move it slowly up, repeating the observations. Then move your finger slowly down and repeat the observations. As the patient looks down, the examiner should hold the patient's upper eyelid to prevent the eye from being covered and nystagmus obscured. Finally, return to the midline position, and move your finger diagonally down and to the left; then return to the midline and move your finger down and to the right.

Eye movement abnormalities may be masked by convergence if the target is too close to the patient. On the other hand, if you stand too far away, it may be difficult for you to see subtle abnormalities. I often position my head close to the patient and move the target (my finger) back and forth behind me.

Facial sensation (CN V) — Lightly touch the patient's right forehead once, and then repeat on the opposite side. Ask the patient if the two stimuli felt the same. Repeat this procedure on the cheek and on the chin. This is usually adequate testing. In some circumstances, the testing should be repeated applying light pressure with a pin. Recall that the angle of the jaw and neighboring cheek is not supplied by the trigeminal nerve, but rather by the great auricular nerve and the C2 - C3 nerve roots (figure 1). Above the ear, the posterior boundary of the trigeminal nerve territory abuts the territory of the lesser occipital nerve and, superiorly, the greater occipital nerve.

Testing of the corneal reflex is not routinely necessary, but it is useful in uncooperative patients or when the rest of the examination suggests that there may be a problem with facial sensation or strength. It is tested by having the patient look to the far left, then touching the patient's right cornea with a fine wisp of cotton (introduced from the patient's right, outside the field of vision) and observing the reflexive blink that occurs in each eye. The process is then repeated with the left eye.

Facial strength

Muscles of mastication (CN V) — Have the patient open the jaw against resistance, then close the jaw against resistance. Have the patient move the chin from side to side.

Muscles of facial expression (CN VII) — Have the patient close his or her eyes tightly. Observe whether the lashes are buried equally on the two sides and whether you can open either eye manually. Then have the patient look up and wrinkle the forehead; note whether the two sides are equally wrinkled. Have the patient smile, and observe whether one side of the face is activated more quickly or more completely than the other.

Hearing (CN VIII) — For a bedside examination, it usually suffices to perform a quick hearing assessment by holding your fingers a few inches away from the patient's ear and rubbing them together softly. Alternatively, you can hold your hand up as a sound screen and ask the patient to repeat a few numbers that you whisper behind your hand, while rhythmically tapping the opposite ear to keep it from contributing. Each ear should be tested separately. Other similar methods can be used to occlude hearing in one ear while testing the other ear; a systematic review of one technique reported good sensitivity and specificity for hearing impairment (90 to 100 percent and 70 to 87 percent, respectively, in adults) [3].

Most textbooks advocate the Weber and Rinne tests for distinguishing conductive hearing loss from sensorineural deafness. I do not; I find that patients have difficulty understanding what is being asked and they give inconsistent responses (especially on the Weber test). Even if these tests gave consistently reliable results, they would still not be as sensitive or as informative as an audiogram. These tests are described and evaluation of hearing is discussed separately. (See "Evaluation of hearing loss in adults".)

Vestibular function (CN VIII) — Peripheral vestibular function can be assessed through the observation of gait and balance as well as the appearance of spontaneous and/or elicited nystagmus (if present). These and other bedside tests of vestibular function are discussed in detail separately. (See "Evaluation of the patient with vertigo".)

Palatal movement (CN IX and X) — Ask the patient to say "aaah" or yawn, and observe whether the two sides of the palate move fully and symmetrically. The palate is most readily visualized if the patient is sitting or standing, rather than supine.

There is generally no need to test the gag reflex in a screening neurologic examination. When there is reason to suspect reduced palatal sensation or strength, the reflex can be checked by observing the response when you touch the posterior pharynx on one side with a cotton swab and then comparing it to the response elicited by touching the other side. About 20 percent of normal individuals do not have a gag reflex; the test is most informative when the responses are asymmetric.

Dysarthria (CN IX, X and XII) — Dysarthria is an impairment of the motor functions necessary for speech production; it is not a language disorder. When the patient speaks, listen for articulation errors, abnormalities of voice quality, and irregularities of rate or rhythm.

Head rotation/shoulder elevation (CN XI) — Have the patient turn the head all the way to the left. Place your hand on the left side of the chin and ask the patient to resist you as you try turning the head back to the right. Palpate the right sternocleidomastoid muscle with your other hand at the same time. Repeat this maneuver in the other direction to test the left sternocleidomastoid. To test shoulder elevation, ask the patient to shrug the shoulders while you resist the movement with your hands.

Tongue movement (CN XII) — Have the patient protrude the tongue and move it rapidly from side to side. Ask the patient to push the tongue against the left cheek from inside the mouth while you push against it from outside, then do the same on the right side of the mouth.

Specific ocular signs

Asymmetric pupils (anisocoria) — Localizing the lesion in a patient with anisocoria requires first determining whether the larger or smaller pupil is abnormal. The smaller pupil is abnormal when the degree of anisocoria is greatest in darkened settings, while the larger pupil is abnormal when the degree of anisocoria is greatest in bright light. Other ocular and neurologic signs further aid in the diagnosis. (See "Approach to the patient with anisocoria".)

Afferent pupillary defect — Anisocoria indicates a lesion in the efferent fibers supplying the pupillary sphincter muscles. A lesion in the afferent limb of the pupillary reflex (ie, in the retina or optic nerve) does not produce anisocoria. Such a lesion is best appreciated on the "swinging flashlight test." To understand this test, one must recognize two facts. First, pupillary size is determined by an average of the illumination detected by each eye. For a simple demonstration of this, observe a normal subject's right pupil while covering the left eye: the pupil enlarges because the average illumination has been effectively halved. Second, the efferent limb of the pupillary reflex is bilateral, so that both pupils receive the same command and they are always the same size. They are only unequal when the efferent pathways are not working properly.

Now consider what happens when a patient has an optic nerve lesion that, for purposes of illustration, is in the left optic nerve and reduces perceived illumination in that eye by 50 percent (figure 2). A bright light directed at the left eye will still increase perceived illumination in that eye compared to ambient room light. The average of the perceived illumination in the two eyes will thus also increase, and both pupils will constrict. Assume that this produces a change in pupil size from 5 to 3 mm. A bright light directed at the right eye will produce a similar response; in this case, the change in perceived illumination from ambient room light will be even greater, producing a change in pupil size from 5 to 2.5 mm, for example. It is difficult for an examiner to appreciate this subtle distinction in the magnitude of the pupillary response. But now consider what happens when the bright light is swung back and forth between the two eyes. When it is directed at the left eye, both pupils are 3 mm. When swung to the right eye, both pupils constrict to 2.5 mm. When swung back to the left eye, both pupils dilate back to 3 mm. Because the examiner usually can observe the pupil under bright light more readily than the other pupil, the examiner notes the left pupil dilating each time the light is directed at it. In effect, by swinging the bright light back and forth, the examiner is simply varying the intensity of the light perceived by the brain, and the pupils are constricting and dilating appropriately in response. This finding is termed a left afferent pupillary defect, or a left Marcus-Gunn pupil.

Gaze palsy — An eye movement abnormality in which the two eyes move conjugately but have limited movement in one direction is called a gaze palsy. It is due to malfunction of one of the "gaze centers" (cortical and brainstem regions responsible for conjugate gaze) or to interruption of the pathways leading from them. When the lesion is in a brainstem gaze center, the neurons there cannot be activated either voluntarily or by reflex (such as the oculocephalic reflex or "doll's eyes response"). This is called a nuclear gaze palsy. When the lesion is in a cortical gaze center, only voluntary gaze is impaired; reflexes can still activate the brainstem neurons responsible for gaze. This is called a supranuclear gaze palsy.

Internuclear ophthalmoplegia — An internuclear ophthalmoplegia or INO is produced by a lesion in the medial longitudinal fasciculus (MLF). This pathway connects the sixth nerve nucleus on one side up to the third nerve nucleus on the other, allowing for conjugate horizontal gaze. A lesion in the MLF is manifest by impaired adduction on the affected side accompanied by nystagmus in the other, abducting eye. (See "Internuclear ophthalmoparesis".)

Localization issues

Facial weakness — The pattern of facial weakness can help differentiate between central and peripheral lesions. When one entire side of the face is weak, the lesion is usually peripheral. With a central lesion (such as a stroke in one cerebral hemisphere), the forehead muscles are often spared because the portion of the facial nerve nucleus supplying innervation to the forehead typically gets input from the motor strips of both cerebral hemispheres. The portion of the facial nerve nucleus innervating the lower face does not have the same bilateral input; its input is predominantly from the contralateral cortex.

Hearing loss — A central lesion affects hearing in both ears almost equally. The only way to produce hearing loss restricted to one ear is with a peripheral lesion.

Palate, pharynx, or larynx weakness — Unilateral weakness of muscles of the palate, pharynx, or larynx indicates a peripheral lesion (ie, at the level of lower motor neuron, neuromuscular junction, or muscle). These muscles are innervated by fibers that originate in the nucleus ambiguus in the medulla and that travel in the glossopharyngeal and vagus nerves (cranial nerves IX and X, respectively). The nucleus ambiguus receives descending input from both cerebral hemispheres. A unilateral central lesion does not produce focal palatal, pharyngeal, or laryngeal weakness because input to the nucleus ambiguus from the other hemisphere remains intact.

Dysarthria — Dysarthria can result from any condition that damages motor control of the structures necessary for speech production, including cerebellar or basal ganglia disorders, and the specific characteristics of the dysarthria may be useful in localization and differential diagnosis. Dysarthria and dysphagia are prominent symptoms of lower motor neuron lesions of cranial nerves IX and X. These symptoms tend to be less prominent after unilateral central lesions because of bilateral cortical input to the nucleus ambiguus.

Bilateral central lesions often produce dramatic speech and swallowing problems, however. This is known as pseudobulbar palsy because the interruption of descending input to the brainstem simulates a lesion in the brainstem itself (a "bulbar" lesion). The character of the dysarthria is different in patients with upper and lower motor neuron lesions. There is classically a strained, strangled character to the speech of the former, while the latter sound breathy, hoarse, and hypernasal.

Neck weakness — The motor nerves of cranial nerve XI that innervate the sternocleidomastoid and trapezius muscles originate in the cervical spinal cord (at the C1-2 level for the sternocleidomastoid and the C3-4 level for the trapezius). They ascend alongside the spinal cord and enter the skull through the foramen magnum, and exit the skull through the jugular foramen. The descending cortical input to the nuclei controlling the trapezius originates almost exclusively in the contralateral cerebral hemisphere. The cortical input to the nucleus for the sternocleidomastoid muscle comes from both hemispheres, but predominantly the ipsilateral one. An additional confounding feature is that the left sternocleidomastoid rotates the head to the right (and vice versa).

As a result, peripheral lesions produce weakness of the ipsilateral sternocleidomastoid and trapezius muscles, resulting in weakness of shoulder elevation on that side but impaired head rotation to the opposite side. Central lesions produce weakness of the ipsilateral sternocleidomastoid but the contralateral trapezius. When a central lesion is large enough to cause more extensive weakness (ie, hemiparesis) there is weakness of shoulder elevation on the side of the hemiparesis and weakness of head rotation toward the side of the hemiparesis.

Tongue weakness — The hypoglossal nerve (CN XII) receives descending cortical input from both hemispheres equally, except for fibers destined for the genioglossus muscle that receive their cortical input only from the contralateral hemisphere. There appears to be variability in this pattern; unilateral central lesions sometimes produce ipsilateral tongue weakness, more often produce contralateral tongue weakness, and most often produce no significant tongue weakness. Unilateral peripheral lesions produce weakness of the ipsilateral tongue muscles resulting in difficulty protruding the tongue to the opposite side. Atrophy and fasciculations are often prominent with peripheral lesions.

MOTOR EXAMINATION

Gait — Observe the patient's casual gait, preferably with the patient unaware of being observed. Have the patient walk toward you while walking on the heels, then walk away from you on tiptoes. Finally, have the patient walk in tandem, placing one foot directly in front of the other as if walking on a tightrope. Note if the patient is unsteady with any of these maneuvers or if there is any asymmetry of movement. Also look for festination, an involuntary tendency for steps to accelerate and become smaller.

Coordination — Coordination testing is often referred to as cerebellar testing, but this is a misnomer. Although the cerebellum is very important in the production of coordinated movements and particular abnormal findings on coordination testing may suggest cerebellar disease, other systems also play critical roles. As an example, severe arm weakness will prevent a patient from performing finger-to-nose testing even though the cerebellum and its pathways may be intact.

Finger tapping — Ask the patient to make a fist with the right hand, and then to extend the thumb and index finger and tap the tip of the index finger on the tip of the thumb as quickly as possible. Repeat with the left hand. Observe for speed, accuracy, and regularity of rhythm.

Rapid alternating movements — Have the patient alternately pronate and supinate the right hand against a stable surface (eg, a table, the patient's own thigh or left hand) as rapidly as possible; repeat for the left hand. Observe speed, accuracy, and rhythm. Impaired ability to perform this task is referred to as dysdiadochokinesis.

Finger-to-nose testing — Ask the patient to use the tip of his or her right index finger to touch the tip of your index finger, then the tip of his or her nose, then your finger again, and so forth. Hold your finger so that it is near the extreme of the patient's reach, and move it to several different positions during the testing. Repeat the test using the patient's left arm. Observe for accuracy and tremor.

Heel-to-shin testing — Have the patient lie supine, place the right heel on the left knee, and then move the heel smoothly down the shin to the ankle. Repeat using the left heel on the right shin. Again, observe for accuracy and tremor.

Involuntary movements — Observe the patient throughout the history and physical examination for the following:

Tremor

Myoclonus — rapid, shock-like muscle jerks

Chorea — rapid, jerky twitches, similar to myoclonus but more random in location and more likely to blend into one another

Athetosis — slow, writhing movements of the limbs

Ballismus — large amplitude flinging limb movements

Tics — abrupt, stereotyped, coordinated movements or vocalizations

Dystonia — maintenance of an abnormal posture or repetitive twisting movements

Other involuntary motor activity

Pronator drift — Have the patient stretch out the arms so that they are level and fully extended with the palms facing straight up, and then close the eyes. Watch for 5 to 10 seconds to see if either arm tends to pronate (so that the palm turns inward) and drift downward. A unilateral pronator drift in one arm suggests an upper motor neuron lesion affecting that arm.

Strength testing — In the upper extremities, test shoulder abduction, elbow extension, elbow flexion, wrist extension, wrist flexion, finger extension, finger flexion, and finger abduction. In the lower extremities, test hip flexion, hip extension, knee flexion, knee extension, ankle dorsiflexion, and ankle plantar flexion. Additional testing may be necessary if some of these muscles are weak or if the patient complains of focal weakness to determine if the weakness is in the distribution of a specific nerve or nerve root.

For each movement, place the limb near the middle of its range, and then ask the patient to resist you as you try to move the limb from that position. As an example, in testing shoulder abduction, the patient's arms should be horizontal, forming a letter T with the body, and the patient should try to maintain that position while you press down on both arms at a point between the shoulders and the elbows. When possible, place one hand above the joint being examined to stabilize the joint, and exert pressure with your other hand just below the joint, to isolate the specific movement you are trying to test.

Grading strength — The most common convention for grading muscle strength is the 0 to 5 Medical Research Council scale:

0 = no contraction

1 = visible muscle twitch but no movement of the joint

2 = weak contraction insufficient to overcome gravity

3 = weak contraction able to overcome gravity but no additional resistance

4 = weak contraction able to overcome some resistance but not full resistance

5 = normal; able to overcome full resistance

The most compelling feature of this scale is its reproducibility; an examiner is unlikely to assign a score of 1 to a muscle that another examiner graded 3 or stronger. A major limitation of the scale is that it is insensitive to subtle differences in strength. In particular, grade 4 covers a wide range, so that in most clinical situations the scale does not allow precise differentiation of the severity of weakness from one muscle to the next. Similarly, it is not a sensitive tool for documenting moderate changes in strength over time. Many clinicians try to compensate for this by using intermediate grades, such as 3+ or 5-, but this results in less reproducibility because there is no consensus on how these intermediate grades should be defined.

Terminology of weakness — Monoparesis refers to weakness of a single limb. Hemiparesis is weakness of one side of the body. Paraparesis is weakness of both lower extremities. Quadriparesis is weakness of all four limbs. Monoplegia, hemiplegia, paraplegia, and quadriplegia are analogous terms that refer to complete or nearly complete paralysis of the involved limbs. Diplegia is a term that is best avoided because it is used differently by different authors.

Muscle bulk — The muscles active in each movement should be inspected and palpated for evidence of atrophy while testing strength. Fasciculations (random, involuntary muscle twitches) should also be noted.

Muscle tone — Muscle tone is the slight residual tension present in voluntarily relaxed muscle. Tone is qualitatively assessed by asking the patient to relax and let you manipulate the limbs passively. This is harder for most patients than you might imagine, and you may need to try to distract them by engaging them in unrelated conversation, or ask them to let their limbs go limp, "like a wet noodle."

Several forms of increased tone (hypertonia) are distinguished, including spasticity, rigidity, and paratonia. Decreased tone (hypotonia) also occurs.

Spasticity — Spasticity depends upon the limb position and on how quickly the limb is moved, classically resulting in a "clasp-knife phenomenon" when the limb is moved rapidly. The limb moves freely for a short distance, but then there is a "catch" and you must use progressively more force to move the limb until at a certain point there is a sudden release and you can move the limb freely again. Spasticity is generally greatest in the flexors of the upper extremity and the extensors of the lower extremity.

Rigidity — Rigidity, in contrast to spasticity, is characterized by increased resistance throughout the movement. Lead-pipe rigidity applies to resistance that is uniform throughout the movement. Cogwheel rigidity is characterized by rhythmic interruption of the resistance, producing a ratchet-like effect. Rigidity is usually accentuated by distracting the patient.

Paratonia — Paratonia (also called gegenhalten) is increased resistance that becomes less prominent when the patient is distracted; without such distraction, the patient seems unable to relax the muscle. This is particularly common in patients who are anxious or demented. When it is prominent, other abnormalities of tone are difficult to assess.

Upper versus lower motor neuron lesions — Several examination findings help to distinguish central from peripheral lesions in the motor system. Deep tendon reflexes (see 'Tendon reflexes' below) provide one clue; reflexes are typically hyperactive with a central lesion and hypoactive with a peripheral one. The Babinski sign (see 'Plantar response' below) is a reliable indicator of a central lesion. Atrophy and fasciculations are common with lower motor neuron disease and unusual with upper motor neuron disease.

The pattern of muscle involvement is also helpful. A central lesion usually results in weakness that is more pronounced in the flexors of the lower extremities than in the extensors, but in the upper extremities the extensors are weaker than the flexors. This is often called pyramidal weakness, but it does not occur with pure lesions of the pyramidal tracts. Instead, it is the net result of disrupting all the descending motor tracts and is probably most appropriately called an upper motor neuron (UMN) pattern of weakness. The UMN pattern of weakness also causes supination of the upper extremity to be weaker than pronation; this accounts for the finding of a pronator drift, in which the arm pronates and drifts downward when the patient is asked to hold it extended with palms up (supinated). This is a fairly sensitive indicator of subtle UMN weakness. It is also useful as a test for internal consistency because patients with nonorganic weakness will often allow their arm to drift downward but fail to pronate it.

Another feature distinguishing a central lesion from a peripheral one is muscle tone (see 'Muscle tone' above). A central lesion is characterized by spasticity, whereas tone is normal or reduced with a peripheral lesion.

Patterns of lower motor neuron weakness — For patients with weakness due to diffuse disease of the peripheral nervous system, the specific pattern of muscle involvement often provides useful localizing information. As an example, predominantly distal weakness usually suggests a disease of peripheral nerves, but predominantly proximal weakness typically occurs in muscle disorders and neuromuscular junction diseases.

For patients with weakness due to focal lesions in the peripheral nervous system, adequate localization can be achieved in most cases by remembering a few simple patterns. In each extremity, consider three principal joints: the hip, knee, and ankle in the lower extremities, and the elbow, wrist, and metacarpophalangeal joint in the upper extremities. At each joint, consider flexion and extension separately. This gives six principal movements in each limb. Most localization problems can be solved by remembering the innervation patterns for these six principal movements (plus shoulder abduction and finger abduction in the upper extremities).

In the upper extremities, the pattern can be remembered by ordering the movements in a kind of spiral that proceeds down the arm (figure 3): shoulder abduction (A), elbow flexion (B), elbow extension (C), wrist extension (D), wrist flexion (E), finger flexion (F), finger extension (G), and finger abduction (H). The corresponding roots then proceed in order: C5 (A), C5-6 (B), C6-7 (C), C6-7 (D), C7-8 (E), C8 (F), C8 (G), and T1 (H). All the extension movements (C, D, and G) are innervated by the radial nerve. The two distal flexion movements (E and F) are supplied by the median nerve, and the proximal one (B) by the musculocutaneous nerve. The axillary nerve supplies the deltoid muscle, which is the main shoulder abductor (A), and the interosseous muscles (H) are innervated by the ulnar nerve.

In the lower extremities, the pattern is simpler (figure 4). The movements can be ordered in sequence down the front first and then the back: hip flexion (A), knee extension (B), ankle dorsiflexion (C), hip extension (D), knee flexion (E), and ankle plantar flexion (F). The corresponding roots are: L2-3 (A), L3-4 (B), L4-5 (C), L4-5 (D), L5-S1 (E), and S1-2 (F). The sciatic nerve innervates the muscles responsible for knee flexion (E); its peroneal branch supplies ankle dorsiflexion (C), while its tibial branch supplies ankle plantar flexion (F). Knee extensor muscles are innervated by the femoral nerve. The innervation of the iliopsoas muscle, which flexes the hip, arises very proximally from the L2 and L3 nerve roots; some consider this to be part of the femoral nerve, and others simply call it the "nerve to iliopsoas." The gluteus muscles, responsible for hip extension (D), are innervated by the gluteal nerves.

REFLEX EXAMINATION — Relaxation is critical during the reflex examination. Tendon reflexes are difficult to elicit when patients tense the muscles being tested. It is helpful to distract patients by engaging them in conversation while testing their reflexes.

Tendon reflexes — The biceps, triceps, brachioradialis, knee (patellar), and ankle (Achilles) reflexes are the ones commonly tested. The joint under consideration should be at about 90 degrees and fully relaxed. It is often helpful to cradle the joint in your own arm to support it. With your other arm, hold the end of the hammer and let the head of the hammer drop like a pendulum so that it strikes the tendon:

Biceps — just anterior to the elbow

Triceps — just posterior to the elbow

Brachioradialis — about 10 cm above the wrist on the radial aspect of the forearm

Knee — just below the patella

Ankle — just behind the ankle

When a patient has reflexes that are difficult to elicit, you can amplify them by using reinforcement procedures: Ask the patient to clench his or her teeth or (when testing lower extremity reflexes) to hook together the flexed fingers of both hands and pull. This is also known as the Jendrassik maneuver.

Clonus is a rhythmic series of muscle contractions induced by stretching the tendon. It most commonly occurs at the ankle, where it is typically elicited by suddenly dorsiflexing the patient's foot and maintaining light upward pressure on the sole.

When reflexes are brisk, it is difficult to detect slight asymmetry. For the most sensitive comparison, it is best to reduce the stimulus until it is just barely above threshold for eliciting the reflex. I typically set aside my reflex hammer and use my fingertips for this purpose. I look for two manifestations of asymmetry:

Is the threshold stimulus the same on each side, or do I consistently need to hit harder on one side than the other?

If the threshold stimulus is the same on each side, does it elicit the same magnitude of response on each side?

Such subtle distinctions are most readily made by testing the reflex on one side immediately after testing the corresponding reflex on the other side, rather than testing all reflexes in one limb before testing the contralateral limb.

Another technique I use to heighten sensitivity to subtle reflex asymmetry is to place my finger on the patient's tendon and strike my finger rather than striking the tendon directly. This helps me aim more accurately and allows me to feel the tendon contraction.

Grading reflexes — The most common convention for grading deep tendon reflexes is simple but imprecise:

0 = absent

1 = reduced (hypoactive)

2 = normal

3 = increased (hyperactive)

4 = clonus

Some examiners use a grade of 5 to designate sustained clonus, reserving 4 for unsustained clonus that eventually fades after 2 to 10 beats. Some examiners also include a reflex grade of 1/2 to indicate a reflex that can only be obtained using reinforcement.

The obvious limitation of this scheme is that it provides no guidelines for determining when reflexes are reduced, normal, or increased. This is left up to individual judgment, based upon the examiner's sense of the range of reflexes present in the normal population.

Interpreting reflexes — Comparison between reflexes in one part of the body and another is much more important than the absolute reflex grade. The most important comparison is between corresponding reflexes on the right and left, where even subtle asymmetry may be significant. As an example, patients with an S1 radiculopathy may have an ankle jerk that would be considered normal, yet it is clearly less brisk than the ankle jerk on the other side. This is another limitation of the reflex grading scale; it does not express subtle distinctions that may be clinically important. For this reason, many examiners augment the scale by using + or - to designate intermediate grades. These grades have very little reproducibility from one examiner to another (or even for a single examiner from one examination to the next). They are only useful for indicating that asymmetry exists, not for quantifying it in any meaningful way.

Affected nerves — The nerve root corresponding to each commonly tested deep tendon reflex is as follows: the biceps and brachioradialis reflexes are mediated by the C5-6 roots, the triceps reflex by the C6-7 roots (mainly C7), the knee jerk by the L3-4 roots (mainly L4), and the ankle jerk by the S1 root. The internal hamstring reflex is less often tested, but it is mediated by the L5 nerve root.

Plantar response — Using a blunt, narrow surface (eg, a wooden Q tip, key, or handle of a reflex hammer), stroke the sole of the patient's foot on the lateral edge, starting near the heel and proceeding along the lateral edge almost to the base of the little toe, then curve the path medially just proximal to the base of the other toes. This should take the form of a smooth J stroke. Always start by applying minimal pressure. This is usually adequate but, if no response occurs, repeat the maneuver with greater pressure.

The normal response is for all the toes to flex (a "flexor plantar response"). When there is damage to the central nervous system motor pathways, an abnormal reflex occurs: the great toe extends (dorsiflexes) and the other toes fan out. This is called an extensor plantar response; it is also known as a Babinski sign.

Superficial reflexes — The abdominal reflexes, cremasteric reflexes, and other superficial reflexes are not usually relevant to standard neurologic examinations.

Primitive reflexes — The grasp, root, snout, and palmomental reflexes are known as primitive reflexes or frontal release signs. These tests do not fit easily into any examination category. They are reflex responses, but their pathways are far more complicated than the monosynaptic arcs of the deep tendon reflexes. I do not test these reflexes. They have very little localizing value, and there is no convincing evidence that they reflect frontal lobe pathology. They are not reliable indicators of abnormal function and, except for the grasp, all are seen in a substantial proportion of normal individuals.

SENSORY EXAMINATION — Sensory examination involves testing first the primary sensory modalities (ie, light touch, pain and temperature, vibration, joint position sense) and then the discriminative sensory functions (ie, stereognosis, graphesthesia, point localization, two point discrimination, and extinction). The former test the integrity of the afferent sensory pathways, whereas the latter test the ability of sensory and association cortices to analyze and interpret sensory input.

The sensory examination is frequently the most frustrating part of the neurologic examination. The instructions often must be repeated several times or more before patients understand what they are being asked to do. This part of the examination is also tiresome and somewhat uncomfortable for patients. For these reasons, the sensory examination is usually one of the last things I test.

Light touch — To test for light touch sensation, have the patient close his or her eyes and tell you whether you are touching the left hand, right hand, or both simultaneously. Repeat this several times, using a single light touch applied sometimes to the medial aspect of the hand and sometimes to the lateral aspect. Note whether the patient consistently fails to detect stimulation in one location. Also note whether the patient consistently "extinguishes" the stimulus on one side of the body when both sides are stimulated simultaneously. Next, touch the patient once lightly on the medial aspect of each hand simultaneously, and ask if they feel the same. Ask the same question for the lateral aspect of each hand. If any abnormalities are detected, extend your region of testing proximally in the limb to map out the precise area of abnormality. Perform analogous testing on the feet.

Pain/temperature — When preparing to test pain and temperature sensation, explain to the patient that you will be touching each finger with either the sharp or the dull end of a safety pin, and demonstrate each. Then with the patient's eyes closed, lightly touch the palmar aspect of the thumb with the sharp point of the pin and ask the patient to say "sharp" or "dull." Repeat this for each finger of each hand, usually using the sharp point but including one dull stimulus on each hand to be sure the patient is paying attention. Next, touch the patient with the pin once lightly on the medial aspect of each hand, and ask if they feel equally sharp. Ask the same question for the lateral aspect of each hand. If any abnormalities are detected, extend your region of testing proximally in the limb to map out the precise area of abnormality. Perform analogous testing on the feet. Discard the pin in a container for contaminated "sharps."

It is not usually necessary to test both pain and temperature; either will suffice. You can test temperature in a fashion analogous to pain; a reasonable stimulus is the flat portion of a tuning fork after it has been immersed in cold water and dried.

Joint position sense — With the finger and thumb of one hand, stabilize the distal interphalangeal joint of the patient's left thumb by holding it on the medial and lateral aspects. With the finger and thumb of your other hand, hold the medial and lateral aspects of the tip of the thumb and move it slightly up or down. Have the patient close his or her eyes and identify the direction of movement. Repeat several times. Most normal patients can identify movements of a few degrees or less. Perform analogous testing of the patient's right thumb and both great toes. If abnormalities are detected, proceed to more proximal joints in the same limb until a joint is found where position sense is intact.

The Romberg test also helps to assess position sense. Have the patient stand with both feet together, and then note whether the patient can maintain balance after closing his or her eyes.

Vibration — Vibration sense can be tested by tapping a 128-Hz tuning fork lightly against a solid surface to produce a slight (silent) vibration. With the patient's eyes closed, hold the nonvibrating end of the tuning fork firmly on the distal interphalangeal joint of the patient's left thumb and ask the patient if the vibration is detectable. Let the vibration fade until the patient no longer detects it, then apply the tuning fork to your own thumb to see if you can still feel any vibration. Repeat this testing on the patient's right thumb and both great toes.

For one of the limbs, stop the vibration before applying the tuning fork to the limb to be sure that the patient is paying attention. If not, clarify to the patient that you are only interested in actual vibration, not just pressure. If any abnormalities are detected, apply the tuning fork to progressively more proximal joints until one is found where the vibration is detected normally.

Graphesthesia — To test for graphesthesia, ask the patient to close the eyes and identify a number from 0 to 9 that you draw on his or her index finger using a ballpoint pen. Repeat with several other numbers and compare to the other hand. There is rarely any need to test graphesthesia in the feet.

Stereognosis — To test for stereognosis, ask the patient to close the eyes and identify a small object (eg, nickel, dime, quarter, penny, key, paper clip) you place in his or her right hand. Test the left hand in the same way.

Two-point discrimination — Two point discrimination is the ability to recognize two points applied simultaneously to the skin as distinct from a single point.

To test this, patients (with eyes closed) are asked to discriminate between the touch of one versus two simultaneously applied stimuli (eg, points of a caliper) to the skin, usually on a digit. The initial distance between the two applied points is gradually decreased from an initial test at about 2 cm until the patient can no longer distinguish between two points, determining the shortest distance at which two points can be distinguished.

Normative values vary by age and location of the region tested. Children and young adults (up to 39 years) can distinguish two points at 4 mm separation, while adults over the age of 80 years may not be able to distinguish two points closer than 8.5 mm [4,5]. The normal threshold for two-point discrimination is several centimeters on the back.

Localization of sensory deficits — The pathways for different sensory modalities cross at different levels in the nervous system, making them very useful for localizing lesions. Unlike the distinction between UMN and lower motor neuron lesions in the motor pathways, there are not really any examination findings that help to confine a lesion to a specific portion of a sensory pathway.

For most localization problems, precise knowledge of the sensory fields of specific peripheral nerves and nerve roots is unnecessary. It is usually sufficient to remember the following:

Sensation travels from the thumb and index finger via the C6 nerve root, from the middle finger via the C7 root, and from the fourth and fifth fingers via the C8 root.

For the remainder of the upper extremity, the root innervation "fans out" from the hand (figure 3).

These innervation patterns cover both the anterior and posterior aspects of the upper extremity. The upper extremity dermatomes are detailed (figure 5).

The L5 dermatome includes the large toe and the lateral lower leg; the S1 dermatome includes the small toe and sole. Roots L4, L3, and L2 cover the region fanning out medially and proximally from the L5 dermatome. The S2 dermatome extends from the S1 dermatome up the back of the leg. The lower extremity dermatomes are detailed (figure 6).

The median nerve carries sensation from all fingers except the fifth finger and half of the fourth, which are served by the ulnar nerve. These nerve territories extend proximally up to the wrist on the palmar aspect of the hand. On the dorsal aspect, the ulnar nerve territory still extends to the wrist, but the median nerve territory fades into radial nerve territory at the metacarpal phalangeal joints. (figure 7).

The common peroneal nerve innervates the lateral leg and the dorsum of the foot; the tibial nerve innervates the sole. (figure 7).

SUMMARY

Essential role of the neurologic examination – While most of the information necessary to localize a lesion in patients with neurologic complaints can be obtained by taking a careful history, some important information can be learned only by examining the patient. (See 'Introduction' above.)

Elements of the examination – The major elements of the neurologic examination include mental status, cranial nerves, motor, reflex, and sensory examinations.

The features of a complete neurologic examination are outlined in the table (table 1).

The screening neurologic examination – A screening neurologic examination assesses general aspects of these five spheres and can be performed in five minutes or less. (See 'A screening neurologic examination' above.)

When to expand the neurologic examination – Depending on abnormalities elicited in the history or during the initial portion of the examination, the clinician chooses to examine certain spheres in greater or lesser detail as described above in order to "localize" the lesion and develop a differential diagnosis. (See individual topic headings above.)

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