180 THE NEUROLOGIC EXAMINATION
Harrison’s Manual of Medicine
THE NEUROLOGIC EXAMINATION
Mental Status Exam
Cranial Nerve (CN) Exam
Coordination and Gait
MENTAL STATUS EXAM
The goal of the mental status exam is to evaluate attention, orientation, memory, insight, judgment, and grasp of general information. Attention is tested by asking the pt to respond every time a specific item recurs in a list. Orientation is evaluated by asking about the day, date, and location. Memory can be tested by asking the pt to immediately recall a sequence of numbers and by testing recall of a series of objects after defined times (e.g., 5 and 15 min). More remote memory is evaluated by assessing pt’s ability to provide a cogent chronologic history of his or her illness or personal life events. Recall of major historic events or dates of major current events can be used to assess knowledge. Evaluation of language function should include assessment of spontaneous speech, naming, repetition, reading, writing, and comprehension. Additional tests such as ability to draw and copy, perform calculations, interpret proverbs or logic problems, identify right vs. left, name and identify body parts, etc. are also important.
CRANIAL NERVE (CN) EXAM
CN I Occlude each nostril sequentially and ask pt to gently sniff and correctly identify a mild test stimulus, such as soap, toothpaste, coffee, or lemon oil.
CN II Check visual acuity with and without correction using a Snellen chart (distance) and Jaeger’s test type (near). Map visual fields (VFs) by confrontation testing in each quadrant of visual field for each eye individually. The best method is to sit facing pt (2–3 ft apart), have pt cover one eye gently, and fix uncovered eye on examiner’s nose. A small white object (e.g., a cotton- tipped applicator) is then moved slowly from periphery of field toward center until seen. Pt’s VF should be mapped against examiner’s for comparison. Formal perimetry and tangent screen exam are essential to identify and delineate small defects. Optic fundi should be examined with an ophthalmoscope, and the color, size, and degree of swelling or elevation of the optic disc recorded. The retinal vessels should be checked for size, regularity, AV nicking at crossing points, hemorrhage, exudates, aneurysms. The retina, including the macula, should be examined for abnormal pigmentation and other lesions.
CNs III, IV, VI Describe size, regularity, and shape of pupils, reaction (direct and consensual) to light and convergence (pt follows an object as it moves closer). Check for lid drooping, lag, or retraction. Ask pt to follow your finger as you move it horizontally to left and right and vertically with each eye first fully adducted then fully abducted. Check for failure to move fully in particular directions and for presence of regular, rhythmic, involuntary oscillations of eyes (nystagmus). Test quick voluntary eye movements (saccades) as well as pursuit (e.g., follow the finger).
CN V Feel the masseter and temporalis muscles as pt bites down and test jaw opening, protrusion, and lateral motion against resistance. Examine sensation over entire face as well as response to touching each cornea lightly with a small wisp of cotton.
CN VII Look for asymmetry of face at rest and with spontaneous as well as emotion-induced (e.g., laughing) movements. Test eyebrow elevation, forehead wrinkling, eye closure, smiling, frowning; check puff, whistle, lip pursing, and chin muscle contraction. Observe for differences in strength of lower and upper facial muscles. Taste on the anterior two-thirds of tongue can be affected by lesions of the seventh CN proximal to the chorda tympani. Test taste for sweet (sugar), salt, sour (lemon), and bitter (quinine) using a cotton-tipped applicator moistened in appropriate solution and placed on lateral margin of protruded tongue halfway back from tip.
CN VIII Check ability to hear tuning fork, finger rub, watch tick, and whispered voice at specified distances with each ear. Check for air vs. mastoid bone conduction (Rinne) and lateralization of a tuning fork placed on center of forehead (Weber). Accurate, quantitative testing of hearing requires formal audiometry. Remember to examine tympanic membranes.
CNs IX, X Check for symmetric elevation of palate-uvula with phonation (“ahh”), as well as position of uvula and palatal arch at rest. Sensation in region of tonsils, posterior pharynx, and tongue may also require testing. Pharyngeal (“gag”) reflex is evaluated by stimulating posterior pharyngeal wall on each side with a blunt object (e.g., tongue blade). Direct examination of vocal cords by laryngoscopy is necessary in some situations.
CN XI Check shoulder shrug (trapezius muscle) and head rotation to each side (sternocleidomastoid muscle) against resistance.
CN XII Examine bulk and power of tongue. Look for atrophy, deviation from midline with protrusion, tremor, and small flickering or twitching movements (fibrillations, fasciculations).
Power should be systematically tested for major movements at each joint (Table 180-1). Strength should be recorded using a reproducible scale (e.g., 0 = no movement, 1 = flicker or trace of contraction with no associated movement at a joint, 2 = movement present but cannot be sustained against gravity, 3 = movement against gravity but not against applied resistance, 4 = movement against some degree of resistance, and 5 = full power; values can be supplemented with the addition of + and – signs to provide additional gradations). The speed of movement, the ability to promptly relax contractions, and fatigue with repetition should all be noted. Loss in bulk and size of muscle (atrophy) should be noted, as well as the presence of irregular involuntary contraction (twitching) of groups of muscle fibers (fasciculations). Any involuntary movements should be noted at rest, during maintained posture, and with voluntary action (Chap. 11).
Table 180-1 Muscles That Move Joints
Important muscle-stretch reflexes to test routinely and the spinal cord segments involved in their reflex arcs include biceps (C5, 6); brachioradialis (C5, 6); triceps (C7, 8); patellar (L3, 4); and Achilles (S1, 2). A common grading scale is 0 = absent, 1 = present but diminished, 2 = normal, 3 = hyperactive, and 4 = hyperactive with clonus (repetitive rhythmic contractions with maintained stretch). The plantar reflex should be tested by using a blunt-ended object such as the point of a key to stroke the outer border of the sole of the foot from the heel toward the base of the great toe. An abnormal response (Babinski sign) is extension (dorsiflexion) of the great toe at the metatarsophalangeal joint. In some cases this may be associated with abduction (fanning) of other toes and variable degrees of flexion at ankle, knee, and hip. Normal response is plantar flexion of the toes. Abdominal, anal, and sphincteric reflexes are important in certain situations, as are additional muscle-stretch reflexes.
For most purposes it is sufficient to test sensation to pinprick, touch, position, and vibration in each of the four extremities (Fig. 180-1 and Fig. 180-2). Specific problems often require more thorough evaluation. Patients with cerebral lesions may have abnormalities in “discriminative sensation” such as the ability to perceive double simultaneous stimuli, to localize stimuli accurately, to identify closely approximated stimuli as separate (two-point discrimination), to identify objects by touch alone (stereognosis), or to judge weights, evaluate texture, or identify letters or numbers written on the skin surface (graphesthesia).
FIGURE 180-1. Anterior view of dermatomes (left) and cutaneous areas supplied by individual peripheral nerves (right). (From HPIM-15, p. 130.)
FIGURE 180-2. Posterior view of dermatomes (left) and cutaneous areas supplied by individual nerves (right). (From HPIM-15, p. 131.)
COORDINATION AND GAIT
The ability to move the index finger accurately from the nose to the examiner’s outstretched finger and the ability to slide the heel of each foot from the knee down the shin are tests of coordination. Additional tests (drawing objects in the air, following a moving finger, tapping with index finger against thumb or alternately against each individual finger) may also be useful. The ability to stand with feet together and eyes closed (Romberg test), to walk a straight line (tandem walk), and to turn should all be observed.
For a more detailed discussion, see Martin JB, Hauser SL: Approach to the Patient with Neurologic Disease, Chap. 356, p. 2326, in HPIM-15.