The Neurologic System

Generalities

In times of magnetic resonance imaging (MRI) and computed tomography (CT), the neurologic exam may seem almost anachronistic. Yet, as the leading British neurologist McDonald Critchley (1900–1997) once said during one of his United States visits, “CT scanning will take away the shadows of neurology, but the music will still remain.” Indeed, the neurologic exam remains the most sophisticated part of physical diagnosis, still able to pinpoint the location of a lesion (“history tells you what it is, but the exam tells you where it is”). Of course, good skills, plus mastering of neuroanatomy and neurophysiology, are a prerequisite. This chapter will highlight the essentials.

• 1.

  What is the purpose of the neurologic exam?

  To localize lesions – that is, to identify the precise site of damage. This is rooted in the eloquence of the nervous system (i.e., the unique property that the brain, spinal cord, and peripheral nerves have of “talking to us”) insofar as each section performs such a discrete function that any loss can be easily traced back to its level. Hence, neuro signs (and symptoms) accurately localize lesions. And this also is why the neuro exam is the bedside tool with the highest sensitivity, specificity, and likelihood ratios. Yet, in contrast to other parts of the exam where inspection or palpation are key, the neurologic exam relies on deductive skills and specific maneuvers. Hence, it is difficult to perform but rewarding. It also is long – at least 1 solid hour.

• 2.

  What are the most important components of the neurologic exam?

  • Mental status

  • Cranial nerves

  • Motor system

  • Sensory system

  • Cerebellum

  • Gait

A

Mental Status Examination

• 3.

  What is dementia ?

  An acquired and persistent cognitive impairment that compromises multiple domains of intellectual function (such as memory, language, etc. – basically, awareness [i.e., the content of consciousness]) while preserving instead perception and arousal (i.e., the level of consciousness). Hence dementia is not coma. Dementia is not delirium either, since this is instead an acute and often reversible confusional state seen in 20% of elderly patients hospitalized for intercurrent illnesses. Dementia is painfully common, affecting 3%–11% of adults older than 65, and its prevalence does increase with aging, so that one-third of subjects older than 80 (and one-half of those older than 90) will eventually suffer from it (something to look forward to). It can be toxic, metabolic, degenerative, inflammatory, infective, or vascular. The earliest signs are often subtle, usually involving short-term memory but otherwise sparing the bulk of the exam. As the disease progresses, frontal release signs appear.

• 4.

  What are frontal release signs ?

  They are the reemergence of primitive reflexes (i.e., signs that are normally present in infants, but resurface in adults only as a result of diffuse frontal lobe disease). Release signs/reflexes include snouting, rooting, sucking , and grasping . Of these, the most sensitive is grasping . To elicit it, place your index and middle fingers in the patient’s palm, apply some pressure, and then slowly withdraw them between the patient’s thumb and index finger. An abnormal response (involuntary squeezing of the examiner’s fingers – with no habituation after three successive strokes) strongly argues for a lesion in the frontal lobes or the deep nuclei and subcortical white matter. Though not too sensitive (13%), it has specificity close to 100%. Contrary to other primitive reflexes (such as palmomental or glabellar ), grasp is never seen in normal subjects.

• 5.

  What are the snouting, rooting, and sucking reflexes?

  • Snouting is the labial pouting/pursing elicited by pressing a tongue blade on the patient’s lips.

  • Rooting is the shift of the mouth toward a tactile stimulus. It can be elicited by gently stroking the lateral upper lip – or, in newborns, by touching the junction of the lips. This causes head-turning and mouth-opening, as if “rooting” toward the stroke (mom’s breast or the bottle).

  • Sucking is pouting or sucking following gentle touching of the patient’s lip. Normal in infants until weaning, it is absent in adults – except in diffuse frontal lobe injury.

• 6.

  What is the palmomental reflex?

  A brief and involuntary contraction of the ipsilateral mentalis muscle , wrinkles and pushes up the chin boss, while at the same time curving the lower lip upward in an inverted “U.” This is elicited by stroking the patient’s palm (thenar eminence) with a blunt object, from proximal to distal. As a release sign , it is often seen in Parkinson’s disease (PD) (where it correlates with degree of akinesia), but also in 3%–70% of older normal individuals. Note that the muscle is called “mentalis,” because its voluntary contraction is often associated with thinking or concentration. Its nerve supply is provided by the facialis (CN VII).

• 7.

  What is the glabellar reflex?

  Another primitive (or “release”) reflex, very much like the grasp and palmomental . It involves V and VII, and is elicited by repetitively tapping on the patient’s glabella (between the eyebrows). The normal response is a brief contraction of the orbicularis, producing a few blinks after the initial taps that stop after subsequent taps – usually fewer than five. In cases of frontal release, there is instead no habituation . Hence, blinking persists as long as tapping continues. This occurs in late extrapyramidal disorders (PD), but also in 3%–33% of older normal subjects.

• 8.

  How do you separate “normal” primitive reflexes from the pathologic ones?

  By judging them like people: by the company they keep. Hence, a “normal” palmomental or glabellar reflex will occur in subjects with an otherwise normal neurologic exam . Thus, they will be isolated. In fact, only fewer than 12% of normal individuals have two primitive reflexes, and fewer than 2% have three . Moreover, normal primitive reflexes tend to fade with repetition (i.e., they are fatigable ). Only 1% of “normal” subjects will continue to exhibit a palmomental reflex after five stimulations. In contrast, patients with real pathology have no habituation.

• 9.

  How long does it take to do a complete mental status examination?

  It can take hours and even days. Yet, for clinical purposes the crucial components can be tested rather quickly. These include (1) level of consciousness, (2) orientation, (3) registration, (4) memory (recall), (5) attention and calculation, (7) intelligence, and (6) language.

• 10.

  What are the most important levels of consciousness ? How do they deteriorate?

  There are four levels of consciousness. In increasing degree of deterioration they are:

  • Alertness: an awake person with normal level of consciousness (alert patient).

  • Lethargy: a sleepy patient who needs continuous stimulation to remain awake.

  • Stupor: an unarousable patient who can still moan, withdraw, or roll around during exam.

  • Coma: a patient who offers no purposeful response to stimulations of any kind.

• 11.

  What is orientation ? How do you assess it?

  Orientation is the patients’ cognizance of their status in time, place, and person. To assess it, ask them to state the year/date/day/month of interview, their location, and their name (state/county/city/hospital/floor). In organic diseases, the sense of time is the first to be lost, while the sense of person is the last one. Hence, patients who are oriented to time and place but do not know who they are, tend to be more psychologic than organic.

• 12.

  What is memory ? How do you assess it?

  Memory is the ability to register and recall prior sensory input. For testing purposes:

  • Registration: ask patients to name three objects and repeat them until fully learned.

  • Recall: distract patients for 3–5 minutes (by doing other parts of the exam, like testing attention and calculation). Then ask them to name the three objects previously learned.

  • Most normal subjects can remember three objects after a brief distraction (recent memory). Acute encephalopathies impair all aspects of memory (both recent and remote). Dementia disrupts instead recent memory and attention span, while preserving remote memory.

• 13.

  How do you assess attention and calculation ?

  By spelling “world” backward or doing serial 7s (i.e., counting backward from 100, in installments of 7, and ending after five subtractions – that is, at 65).

• 14.

  How can one efficiently examine all aspects of mental status?

  Through a battery of carefully analyzed and validated questions, such as the Folstein Mini Mental Status Examination (MMSE) . This consists of 11 items that can be easily administered in 5–10 minutes and are either sensitive for dementia (but not specific), or specific but not sensitive. They evaluate the most important mental status domains ( orientation, registration, attention/calculation, recall , and language ), with a final score of 0–30 (<23 being abnormal).

• 15.

  How reliable is the MMSE in assessing cognitive function?

  Quite reliable. In fact, it has strong likelihood ratios for identifying dementia impairments. It is also valuable for follow-up , even though only significant for large changes (>4 points).

• 16.

  What is the clock-drawing test?

  Another mental status test. It provides patients with a preprinted circle (4 inches in diameter), asking them to “draw a clock.” No further instruction and unlimited time are given. Normal subjects will draw all 12 numbers, even though not necessarily with proper hands or symmetric spaces between them. Missing one number is still acceptable, but absent figures, irrelevant figures, or unusual arrangements/counterclockwise orientation of figures are not . An abnormal clock-drawing test has high specificity for dementia, but low sensitivity (being positive in only 50% of patients).

• 17.

  How do you test for delirium ?

  By looking for (1) acute and fluctuating change in mental status; (2) difficulty in staying focused or keeping track of what is being said; (3) altered level of consciousness (both in defect and in excess); and (4) disorganized thinking, with flights of ideas, often irrelevant and illogical. Hence, delirious patients exhibit a change in both mental status and the ability to stay focused. They also may have disorganized thinking or altered level of consciousness.

• 18.

  What is intelligence ? How do you test it?

  Intelligence is the ability to problem-solve by applying previous knowledge to a new situation and then using reason . It can be tested through calculations (serial 7 calculations), vocabulary, fund of knowledge, abstraction (use of proverbs), and judgment (like what to do with a found wallet).

B

Cranial Nerves Examination

• 34.

  What is the role of cranial nerve examination?

  An important one, since all cranial nerves have discrete functions that permit accurate localization of lesions based only on exam. Yet detailed testing of all cranial nerves is time consuming. Hence, it is unnecessary unless symptoms point toward a specific nerve problem.

• 35.

  How do you test CN I (olfactory nerve)?

  By asking patients to close their eyes, occlude one nostril, and then smell through the open naris a distinctive scent – like cinnamon, cloves, or peppermint. Transient anosmia is common, usually resulting from simple colds or intercurrent sinus infection. Chronic anosmia (especially if congenital) is instead quite important (see Chapter 6 , Question 32). Note that anosmia can also be seen in frontal lobe masses, Alzheimer’s, or PD.

• 36.

  How do you test CN II ( optic nerve)?

  By fundoscopy and color recognition (through Ishihara chart or a common and colorful object), but also by two bedside maneuvers, each testing a separate function of the optic nerve:

  • Visual acuity: ask the patient to read an eye chart from a distance of 20 feet. Glasses or contacts are allowed, since the test measures the best corrected vision. A normal person reads at 20 feet letters that others also can read at 20 feet (20/20 vision). A person who reads at 20 feet letters that others can read at 40 is said to have an acuity of 20/40 (see Chapter 4 , Questions 1–15).

  • Visual fields: their assessment can localize damage anywhere from the retina to the occipital lobes, resulting in loss of vision of only a discrete area (or field). The best way to detect visual cuts is by confrontation: place yourself head-to-head and eye-to-eye with the patient, while both of you occlude the opposite eye (because while looking into each other’s eyes, both you and the patient have the same peripheral vision). To determine whether the patient can see what you see, move objects into his/her peripheral vision, starting from above, then below, then left and right. Patients should be able to see the objects at the same time you do. If they cannot, they probably have a visual cut corresponding to a particular region of peripheral vision (see Chapter 4 , Questions 20–35).

• 37.

  How do you test CN III, IV, and VI?

  Together, since oculomotor (III), trochlear (IV), and abducens (VI) work in concert to produce the various eye movements. To test them, ask patients to hold the head stationary while following your finger as it moves through the main directions of gaze: left-up, left-middle, left-down , and right-up, right-middle, and right-down . Normal eyes move symmetrically and smoothly. Any restriction or double vision (from inability of the eyes to move together) suggests damage to III, IV, or VI (see Chapter 4 , Questions 84–90).

• 38.

  What abnormal eye movements result from damage to CN III, IV, or VI?

  • The oculomotor supplies medial, superior, and inferior rectus; inferior oblique; and levator palpebrae (which raises the eyelid). It also contains parasympathetic fibers that constrict the pupil. Hence, its lesions result in a partially abducted eye that is difficult to adduct, raise, or lower. In fact, it is frequently turned out (exotropia). There also is a drooping eyelid (ptosis) and a pupil that may be larger (mydriatic) and difficult to constrict. In more subtle cases, there may only be diplopia or blurred vision. A CN III palsy that spares the pupils (i.e., ptosis, and external rotation of the globe, but symmetric and equally reactive pupils) suggests diabetes , but also vasculitis and multiple sclerosis, as these conditions primarily affect the more centrally located nerve fibers, while the parasympathetics that constrict the pupil are peripherally located.

  • The trochlear supplies the superior oblique muscle by extending over a trochlea , or pulley. Since this nerve allows us to view the tip of our nose, its lesion will result in an eye that cannot be depressed when adducted . Hence, whenever patients pull their eyes inward (toward the nose), they will be unable to move them downward . This is often subtle. An isolated right superior oblique paralysis results in (1) exotropia to the right (R); (2) double vision that worsens when looking to the left (L); and (3) head tilt to the right (R). The mnemonic is R, L, R ( the marching rule —conversely, the rule for left superior oblique paralysis is L, R, L). This rule and the lack of ptosis and/or mydriasis differentiate the exotropia of CN IV palsy from that of CN III.

  • The abducens supplies the lateral rectus. Hence, its damage prevents eye abduction to the side of the lesion. This results in double vision on horizontal gaze only (horizontal homonymous diplopia). It is often injured in patients with increased intracranial pressure.

• 39.

  How do you test CN V ( trigeminal nerve)?

  It depends on whether you are testing a motor or sensory component. The divisions of the trigeminal nerve are shown in Fig. 17.1 .

  • The sensory component is predominant, providing pain, tactile, and thermic sensations to the face. Note that sensation to the tragus, most of the external ear, and angle of the jaw is not trigeminal and thus is preserved in diseases of the V (it is supplied instead by cervical sensory roots).

  • The motor component is smaller and primarily involved in chewing . It travels along the mandibular branch of the V and controls the masseters and lateral pterygoids. If damaged, it causes deviation of the jaw to the paralyzed side when attempting to open the mouth.

  

• 40.

  Where are the sensory and motor nuclei of the trigeminal nerve?

  They are both in the pons . Yet the sensory also extends into the cervical cord.

• 41.

  How do you test the sensory function of CN V?

  By pinprick or light touch over the areas of distribution of the trigeminal branches: upper (supplied by V1, or ophthalmic; forehead), mid (V2, or maxillary; cheek), and lower (V3, or mandibular; jaw). Sensory function of the ophthalmic branch is also tested by the corneal reflex (see Question 58).

• 42.

  How do you test the motor function of CN V?

  By feeling the masseters during teeth clinching. Contraction must be strong and symmetric.

• 43.

  What are the manifestations of trigeminal motor deficit?

  • Difficulty clenching the teeth (due to weak masseters , at times visibly atrophic).

  • Difficulty deviating the jaw contralaterally (due to weak lateral pterygoids ).

• 44.

  What is the significance of unilateral trigeminal motor deficit?

  It indicates nerve compression (bony metastases) or an ipsilateral pontine lesion. Since trigeminal motor nuclei receive bilateral cortical innervation, hemispheric strokes will not affect them. Hence, bilateral masseter weakness suggests bilateral hemispheric disease (pseudobulbar palsy).

• 45.

  What is the significance of a sensory deficit of the trigeminal nerve?

  It depends on whether it involves both the face and body, or only the face:

  • Isolated facial anesthesia suggests disease of the temporal bone or metastatic spread to the ipsilateral mandible and skull base. This presents with numbness to the chin and lower lip (“numb/chin syndrome”).

  • Combined facial and body anesthesia suggests hemispheric and thalamic involvement, typically cerebrovascular. This presents with numbness to the same side of the face and body (and contralateral to the ischemic area), plus hemiparesis and aphasia. Conversely, patients with facial numbness to one side and body numbness on the opposite have a brain stem lesion, as the sensory nerves from the face haven’t yet crossed the midline.

• 46.

  What is Hutchinson’s sign?

  It is the presence of herpetic vesicles on the nasal tip of patients with ophthalmic zoster – an ominous sign, since it suggests higher risk of ocular complications (uveitis and keratitis). This is because the nasal tip, the cornea, and the iris all share the nasociliary branch of V1. Patients with nasal tip involvement have a 75% chance of ocular involvement (tearing, irritation, photophobia). Still, Hutchinson’s is a rather specific (82%), but poorly sensitive (57%), sign.

• 47.

  What is the jaw-jerk reflex?

  A reflex that tests the integrity of sensory (afferent) and motor (efferent) components of CN V. To test for it, place your index finger (or tongue depressor) over the patient’s chin, while asking them to keep their mouth slightly open. Then, gently tap the index finger with your reflex hammer. Abnormal responses include jaw deviation or brisk closure. Exaggerated masseteric contraction, often with clonus, suggests upper motor neuron pathology (i.e., above the trigeminal nucleus in the mid-pons). This occurs in 70% of pseudobulbar palsy patients (see Question 65).

• 48.

  How do you test CN VII ( facial nerve)?

  Through the muscles of facial expression . Damage to CN VII causes inability to wrinkle the forehead, tightly close the eye ( Fig. 17.2 ), or smile. It also causes facial asymmetry (i.e., ipsilateral widening of the palpebral fissure and sagging of the nasolabial fold).

  

• 49.

  What determines the difference between central and peripheral lesions of CN VII?

  It’s the difference in control of upper versus lower facial muscles: the upper being supplied by brain stem motor neurons (controlled by both sides of the cortex), whereas the lower are supplied by lower motor neurons (controlled by only one side of the cortex).

• 50.

  What are the signs of central lesions of the facial nerve?

  Central lesions (i.e., involving either the cortical/upper motor neuron or its pyramidal tracts) result in contralateral weakness of only the lower half of the face . Thus, patients cannot smile (the face draws to the opposite side as they try to do so) or fully open the mouth, but can still wrinkle the forehead and close the eyes. This lower facial weakness only relates to intentional movements (i.e., those originating in the motor cortex). Emotional movements are typically spared, since they originate in the thalamus and frontal lobe.

• 51.

  What are the signs of peripheral lesions of the facial nerve?

  Peripheral lesions (i.e., involving either the brain stem/lower motor neuron or the nerve itself) result instead in ipsilateral weakness of the entire hemiface. Thus, patients can neither smile, nor open the mouth, nor wrinkle the forehead. Eye closure also is impaired, and the ipsilateral palpebral fissure is wider. Bell’s phenomenon is present too. Weakness affects both volitional and emotional movements. Separating “central” from “peripheral” facial weakness is clinically very important.

• 52.

  Are there any other functions of CN VII that can be affected?

  Yes. CN VII also controls taste to the anterior two-thirds of the tongue, the stapedius muscle, and the lacrimal gland. Hence, its lesions may impair taste, hearing , and tearing .

• 53.

  What about ptosis ?

  This is actually due to lesions of either CN III (which controls the levator palpebrae) or the sympathetic nerves (which control the Mueller muscle). Do not confuse the levator palpebrae, which opens the eyelid, with the orbicularis oculi , which closes the eyelid, and is instead supplied by the VII. Hence, lesions of VII will compromise corneal or glabellar reflexes, but not ptosis.

• 54.

  What is Bell’s palsy ?

  A peripheral mononeuropathy of CN VII. Since it involves the nerve directly (i.e., peripheral damage), Bell’s causes paralysis of both lower and upper facial muscles. Hence, there is ipsilateral inability to smile, open the mouth wide, or wrinkle the forehead. Bell’s also causes dysfunction in (1) taste (reduced in one-half of the cases); (2) hearing (hyperacusis in 20%–30%); and (3) tearing (usually increased, due to weakness of the orbicularis, but sometimes reduced as a result of lacrimal gland dysfunction). In 20% of cases, Bell’s also may present with facial hyperesthesia due to concomitant trigeminal involvement.

• 55.

  What are the causes of Bell’s palsy?

  Peripheral paralysis of CN VII has been described in infectious mononucleosis, herpes zoster, Guillain-Barré syndrome, parotid neoplasms, sarcoidosis, diabetes, or, occasionally, a cerebellopontine tumor. Yet, by definition Bell’s is idiopathic , in fact probably viral. This is not an uncommon condition, which even affected heartthrob George Clooney while still in high school.

• 56.

  What is Bell’s phenomenon ?

  It is the upward rotation of the eyeball, triggered by contraction of the ipsilateral orbicularis . This is usually invisible , since contraction of the orbicularis shuts the eye. Note that Bell’s phenomenon is a completely normal event, occurring in anyone as a result of synkinesis (from the Greek syn , together, and kinesis , motion), a fancy term for an involuntary motion that accompanies a voluntary one. Examples of synkinesis include the movement of a closed eye that accompanies that of the contralateral open eye or the movement of the arms as a result of leg motion during walking. What makes Bell’s phenomenon so unusual is that in patients with peripheral facial paralysis , the eyelid on the affected side is unable to close as a result of weakness of the orbicularis. Hence, the physiologic upward rotation of the eyeball becomes suddenly visible.

• 57.

  Who was Bell?

  Sir Charles Bell (1774–1842) was a Scottish neurophysiologist and surgeon. He was not the same Dr. Bell who taught medicine in Edinburgh and made a big impression on young Conan Doyle (thus becoming the accidental model for Sherlock Holmes). That was Joseph Bell, a mesmerizing teacher who even tried his analytical powers on the mystery of Jack the Ripper, the Whitechapel killer of 1888. Charles Bell was instead the soft-spoken son of an Episcopal minister, who, after being denied a position in Edinburgh, left for London in 1801. There, he made a name for himself as an artist, thanks to his Essays on the Anatomy of Painting . He also attended the military hospital of Haslar, where he had plenty of opportunities to treat the casualties of Wellington’s peninsular campaign. This triggered a lifelong fascination with war , and what it can do to human body and psyche. In 1815, while operating on Waterloo’s wounded, he made sketches and drawings that can still be viewed at the Royal College of Surgeons in Edinburgh. He eventually moved back to his native Scotland, but only after founding the Middlesex Hospital and Medical School. He is remembered not only for his palsy and phenomenon but also for Bell’s law , which states that the anterior spinal roots carry motor fibers, whereas the posterior carry sensory fibers, including proprioception. He also named the “sense of position” as the “sixth sense” – eventually renamed proprioception by Sherrington.

• 58.

  What is the corneal reflex?

  A bedside test of CN V and VII. To elicit it, ask patients to look away (so that they cannot see what the examiner is doing), and then use a cotton wisp to gently touch the edge of their cornea. The normal response is a protective reflexive blinking, which is bilateral (i.e., both eyes blink after stimulation of one) and requires the integrity of both CN V and VII: the ipsilateral V must be intact to receive sensation from the cornea, whereas both facial nerves must be intact to convey the motor response (hence the blinking of both eyes). This is a risky reflex since it can cause corneal damage.

• 59.

  What is the significance of an abnormal corneal reflex?

  It depends on the response. If the ipsilateral eye does not blink after corneal stimulation (while the contralateral does), the most likely explanation is unilateral facial nerve dysfunction . Conversely, if both eyes fail to blink, the explanation is unilateral trigeminal nerve dysfunction , typically in the ipsilateral brain stem. An absent corneal reflex is especially helpful in cases of unilateral sensorineural hearing loss, since it suggests a lesion of the cerebellopontine angle—like an acoustic neuroma. Yet, an abnormal corneal reflex is poorly sensitive, since it requires a tumor >2 cm. It is not specific either, being absent in 10% of normal elderly subjects.

• 60.

  How do you test CN VIII ( acoustic/vestibular nerve)?

  It depends on the function you want to test, vestibular or auditory:

  • Vestibular function should be assessed by the Romberg, positional vertigo, and caloric irrigation tests only in cases of vertigo and dizziness.

  • Auditory function may instead be compromised in very subtle ways. Hence, the need for routine testing. This can be simply done by asking patients if they can hear whispered words, the soft noise of a ticking watch, or fingers rubbing against each other near the ear. Conductive and sensorineural hearing loss can be separated by Rinne and Weber tests (see Chapter 5 , Questions 57–61).

• 61.

  How do we maintain balance?

  Through a complex circuitry that requires intact positional sense input (vision, vestibular, and proprioceptive receptors/pathways), intact sensorimotor integration (cerebellum), and intact motor output (basal ganglia/corticospinal/pyramidal tract). If there is vestibular or proprioceptive damage, the patient will be able to compensate by relying on vision. Yet, darkness (or closed eyes) will remove this compensatory input and thus cause the patient to sway and possibly fall. Conversely, if there is intrinsic cerebellar disease, the patient will be unable to compensate even with open eyes . Hence, Romberg is not a cerebellar test since patients with cerebellar ataxia will not maintain balance even when they can see . It is instead a test for proprioceptive receptors and pathways. Thus, it will be positive in conditions of sensory ataxia (i.e., affecting [1] the sensory nerves (peripheral neuropathy) and/or [2] the dorsal columns of the spinal cord ).

• 62.

  How do you perform the Romberg test?

  Ask patients to first stand up with the heels together, eyes open, and arms by the side. Note any swaying. Then ask them to close their eyes. Observe for a full minute . Normal patients may sway a little more with the eyes closed, but will not fall. Vestibular patients will sway a lot more with the eyes closed but will not fall. Sensory ataxia patients will instead sway and fall with the eyes closed.

• 63.

  Who was Romberg?

  Moritz Heinrich Romberg (1795–1873) was a well-respected Jewish physician who studied and practiced in Berlin, where he distinguished himself as “officer to the indigent” during the cholera epidemics of 1831 and 1837. A popular and beloved teacher, Romberg translated into German the works of Sir Charles Bell, and then wrote a three-volume textbook of neurologic diseases centered on the relation between altered structure and symptoms and signs. He reported his homonymous maneuver in an 1846 description of tabes dorsalis:

  ... the feet feel numbed in standing, walking or lying down ... as if they were covered in fur ... the gait begins to be insecure ... [the patient] puts down his feet with greater force ... keeps his eyes on his feet to prevent his movements from becoming still more unsteady. If he is ordered to close the eyes while in the erect posture, he at once commences to totter and swing from side to side; the insecurity of his gait also exhibits itself more in the dark.

• 64.

  What is the anatomy of CN IX ( glossopharyngeal ) and CN X ( vagus )? How do you test them?

  Axons from several brain stem nuclei mingle together to emerge from the neuraxis through two separate nerves, named by early neuroanatomists as glossopharyngeal (IX) and vagal (X) (the vagus was so termed because, as a vagabond, it wanders long distances in the body). In reality, the origin of the two nerves is essentially identical. Function also is similar: motor control of the palate and pharynx (plus, for CN IX, sensory supply to the pharynx and posterior third of the tongue). Hence, their clinical testing is not entirely separable. Since the brain stem nuclei of these two nerves receive bilateral innervation from the cortex, their dysfunction results from one of three possibilities: (1) bilateral damage to the cortex or pyramidal tracts (pseudobulbar palsy), (2) brain stem disease (lateral medullary syndrome), or (3) peripheral nerve lesions (jugular foramen syndrome). You can test IX and X by asking patients to say “ahhh” or “ehhh” (see Chapter 6 , Questions 51 and 52) while observing whether the velum of the palate rises symmetrically. Alternatively, you can use the gag and palatal reflexes. The latter is elicited by touching the patient’s palate with a cotton swab, which causes elevation of the soft palate and ipsilateral deviation of the uvula. The gag is instead triggered by touching the posterior wall of the pharynx (or alternatively, the tonsillar area or base of the tongue). It causes tongue retraction and elevation/constriction of the pharyngeal musculature. In unilateral CN IX and X paralysis, these reflexes result in deviation of the uvula toward the normal side. Lesions of CN IX also will result in loss of taste in the posterior third of the tongue, and loss of pain and touch sensations in the same area plus the soft palate and pharyngeal walls. Conversely, unilateral paralysis of CN X’s recurrent laryngeal nerve will cause hoarseness. Bilateral paralysis will cause stridor (requiring tracheostomy).

• 65.

  What is pseudobulbar palsy ?

  The result of bilateral damage to the pyramidal tracts supplying the nuclei of CN IX and X. This is due to lacunar disease of the internal capsule, and presents with paralysis of both the palate and pharynx (i.e., loss of the gag reflex), but also the tongue, face, and chewing muscles. As a result, patients will be dysarthric, dysphagic, and unable to control facial expression. There also will be spasmodic (and inappropriate) laughing and crying.

• 66.

  How do you rule out the possibility of aspiration in patients with bilateral strokes?

  By testing for pharyngeal sensation and water swallowing (the latter requires swallowing 50 mL of water in 5-mL aliquots without any choking, gagging, or coughing). Preservation of both functions makes aspiration unlikely; an abnormal water swallow test makes it likely.

• 67.

  And what about the gag reflex?

  It has very little value in predicting the risk of aspiration because swallowing is controlled by different muscles than gagging. Moreover, gag can be absent in many elderly individuals without necessarily increasing the risk of aspiration.

• 68.

  What is the anatomy of CN XI ( spinal accessory nerve)?

  The accessory nucleus comprises motor neurons from both the brain stem and the upper five or six cervical segments (hence, its name). The spinal axons exit the cord and rise in the neck, where they join axons originating from the brain stem, finally emerging together through the foramen magnum as the spinal accessory nerve . This provides motor control to the trapezius and sternocleidomastoids (SCM). The function of the trapezius is to shrug the shoulders. Its weakness will impair shrugging ipsilaterally. Conversely, the SCM’s function is to thrust the head forward , tilt it toward the same side, and turn it toward the opposite side.

• 69.

  How do you test CN XI?

  By first looking for asymmetry in the SCMs and trapezii. Then, by asking patients to shrug their shoulders against resistance (which tests the trapezius ; Fig. 17.3 ) or by having them first turn the head to one side and then attempt to turn it back against your resistance (which tests the SCM; Fig. 17.4 ). To test the right SCM, instruct the patient to turn the head toward the left, hold it there, and to not let you push it back. Then place your hand on the patient’s left cheek, and try to force the head toward the midline. When the right SCM is weak, pushing against your resistance will be impaired. Repeat the same for the opposite side. Note that atrophy of these muscles reflects a “lower” lesion (peripheral nerve or brain stem/cervical spine). Weakness , on the other hand, also may reflect cerebral hemispheric disease (CHD). The latter weakens the contralateral trapezius and the ipsilateral SCM (hence, the patient will be unable to turn the head toward the hemiparetic side). Disease of the accessory nucleus per se (like syringomyelia) weakens instead (and atrophies) both ipsilateral muscles. Hence, the patient will be unable to shrug ipsilaterally or turn the head toward the same side. This also occurs for peripheral nerve lesions.

  
  

• 70.

  How do you test CN XII ( hypoglossal nerve)?

  By testing for movements of the tongue. These are controlled by the genioglossus , which is supplied by CN XII (running just sublingually in the neck – hence, its name). To detect weakness or atrophy, simply ask the patient to stick out the tongue. Hypoglossal weakness will deviate the tongue toward the weak side (because the intact genioglossus muscle pushes the tongue contralaterally without meeting any resistance by the weakened muscle). Weakness may result from (1) a contralateral hemispheric cerebral lesion (causing deviation of the tongue toward the hemiparetic side), (2) an ipsilateral brain stem lesion (such as the medial medullary syndrome), or (3) an ipsilateral peripheral nerve lesion. Noncerebral lesions (i.e., lower motor neuron disease) produce also tongue atrophy and fasciculations .

C

Motor System Examination

• 71.

  Which central nervous system (CNS) areas participate in the creation/coordination of muscle movement?

  • Motor system , both in its pyramidal and extrapyramidal components (for power)

  • Cerebellar system (for rhythmic movement and posture)

  • Vestibular system (for balance and coordination of the eye, head, and body movements)

  • Sensory system (for afferent input to the spinal axis)

• 72.

  What is the motor system made of?

  • The pyramidal component (i.e., the corticospinal level of the motor system). This consists of (1) the upper (cortical ) motor neurons (residing in the posterior regions of the frontal lobes [i.e., the motor cortex]) and (2) the pyramidal tracts (i.e., descending corticospinal pathways).

  • The extrapyramidal component . This has instead its nuclei of origin in the basal ganglia and their complex connections, creating an elaborate neural organization that works closely with other levels of the motor system to achieve muscular control.

  Both pyramidal and extrapyramidal levels converge on the “final common pathway”: the lower motor neurons of the brain stem (cranial nerves) and spinal cord, whose axons go directly out to skeletal muscles. Cord neurons are clustered in nuclei or longitudinal segments of the anterior gray matter, extending one to four spinal segments ( anterior horn cells ).

• 73.

  What is the function of upper motor neurons?

  To exert direct or indirect supranuclear control over the lower (and more caudal) motor neurons. Upper motor neurons reside mostly in the motor cortex , but also in the brain stem .

• 74.

  What are the manifestations of upper motor neuron dysfunction?

  Given their function as modulator of lower motor neurons, disease of upper motor neurons (or their axons) results in muscles that are initially weak and flaccid, but eventually become spastic, hypertonic, and hyperreflexive. This is associated with pathologic reflexes (such as Babinski’s and Hoffmann ) and induced clonus of ankle or wrist. Spasticity is especially prominent in the antigravity muscles (flexors of the upper extremities and extensors of the lower), with a clasp-knife character due to a variable degree of resistance to passive movements.

• 75.

  What are the manifestations of damage to lower motor neurons or their axons?

  Weakness or paralysis of the involved muscles, with flaccidity, hypotonia, diminished or absent stretch reflexes, and eventually atrophy . There also are fasciculations (i.e., visible twitches of small groups of muscle fibers), but no pathologic reflexes (Babinski).

• 76.

  What are the main components of examination of the motor system?

  • Inspection (for atrophy, hypertrophy, and fasciculations)

  • Palpation (for cutaneous reflexes, but also for muscle strength and tone)

  • Percussion (for myotonia and stretch reflexes)