Bedside examination of the patient with cognitive or mental impairment is challenging, because the abilities used by the patient to construct a history and description of symptoms are also the potentially defective abilities that are under scrutiny. Some patients may not have a clear understanding of the reason for attending the clinic. Memory impairment as well as anosognosia (unawareness of deficits), aphasia, and disturbed mood or behavior may lead to an inadequate or unreliable history when obtained from the patient alone. Therefore, also obtaining a history from an informant is of the utmost importance. Whenever possible, the informant interview should be conducted in the patient’s absence. It is particularly helpful in getting an overview of the impact on activities of daily living of the presenting symptoms and in identifying psychotic and behavioral symptoms. Furthermore, discrepancies in the accounts from the patient and the informant help to assess the level of anosognosia.

With practice, a complete CN examination in a cooperative patient can be assessed in less than 90 s.

Examination of CN II may begin with an ophthalmoscopy.² The presence of spontaneous venous pulsations (SVPs) as revealed by ophthalmoscopy is a useful finding in a patient with headache and should be documented in the charts. SVPs occur at the optic disc where the retinal veins leave the orbit (the retinal veins are the darker, broader vessels; the arteries are lighter and thinner). With some practice, SVPs can be detected in nine of ten people. Video demonstrations of SVP can be found on youtoube.com. Venous engorgement and the lack of spontaneous pulsations are the earliest signs of raised intracranial pressure. Full papilledema usually takes a few days to develop and leads to blurring of optic margins, elevation of the optic disc, hemorrhages from congested retinal veins, and nerve fiber damage (cotton wool spots) (Case 3.2). Thus, the presence of SVP suggests that ICP is normal, at least at the time of examination. Although SVPs do not fully exclude an intracranial cause for the patient’s headache, their presence nevertheless allows the conclusion that headache is not due to raised ICP (e.g., as seen with sinus venous thrombosis, a cerebral tumor, or idiopathic intracranial hypertension). This is highly useful when evaluating a patient with headache.

Ophthalmoscopy may also reveal chronic optic neuropathy (small, pale, and atrophic optic disc), drusen (optic disc elevation due to mucoproteins and mucopolysaccharides without other signs of papilledema—usually a normal variant without any pathological value), diabetic and hypertensive changes (retinal hemorrhages, cotton wool spots, and atherosclerotic vascular changes), and optic neuritis (although with retrobulbar neuritis, inspection can be normal). Occasionally, one may see retinitis pigmentosa, cholesterol emboli and retinal infarction, retinal melanoma, and retinal toxoplasmosis.

Testing the visual field is part of a standard neurological examination. For finger perimetry, the examiner uses his visual fields as a reference. If the patient’s history does not suggest any visual field loss, asking the patient if he can see finger movements in each quadrant of the eyes is usually sufficient. Each eye should be assessed independently by covering the other eye. Another more sensitive examination technique is to slowly move a finger or another object from each corner of the periphery toward the center of the patient’s visual field and to ask when the patient can see the object. Visual attention, however, is best tested using double confrontation. Show the patient both hands and ask him to point at the hand where the fingers are moving. Also, move both hands simultaneously at some time during the examination to assess for possible extinction. With complete visual neglect, there is extinction of visual stimuli of one side at all times; with visual hemineglect there is extinction only with double confrontation. Examination of visual fields and visual attention assesses not only CN II but the entire visual system and its cortical projections.

Optic atrophy leads also to an afferent pupillary defect, which can be tested for by applying the swinging-flashlight test. If the optic and oculomotor nerves and their parasympathetic connection (Edinger-Westphal nucleus) are intact, both pupils constrict and stay miotic when moving a flashlight quickly from one eye to the other. This is because of the consensual light response. With unilateral optic dysfunction, however, both pupils will constrict as light falls into the healthy eye, but they will dilate as light falls into the affected eye. The direct and indirect (consensual) pupillary reflexes can also be tested in a well-lit room by first covering one eye and then the other. This is especially useful in small children, who often do not like the glare of a pocket lamp.

In contrast to afferent pupillary defects, efferent pupillary defects are due to CN III palsy, e.g., due to increased ICP, autoimmune mechanisms (Adie pupil), or infections such as neurosyphilis (Argyll-Robertson pupil). Drug intoxication is another cause, with atropine and sympathetic drugs leading to mydriasis and opioids to miosis.

It is important to actively look for Horner’s syndrome, because it is easily missed otherwise. Horner’s syndrome consists of miosis, ptosis, and anhidrosis. See Chap. 2 for a discussion of the relevant neuroanatomy. Anhidrosis is loss of sweating in the upper quadrant of the ipsilateral half of the face. It is tested with the back of the hand or—even better—with a plastic card moving over the forehead. With anhidrosis, the skin is smooth and dry, and the plastic card will not stick to the skin as much as on the unaffected side. When physical activity provokes facial flushing, the affected skin area remains pale. However, anhidrosis can be lacking when the sympathetic fibers traveling along the external carotid artery are spared. Miosis and pupillary efferent dysfunction are most easily assessed in a semi-dark room as miosis is most visible because the contralateral pupil dilates. When the light is turned on, the healthy pupil will constrict as well. (In contrast, mydriasis is most visible in a well-lit room.) Ptosis can be evaluated by comparing the border of the upper eyelids with the level of the pupils when the patient looks straight forward and upward.

Oculomotor function, mediated by CN III, IV, and VI, is assessed by evaluating gaze axis, range of eye movements, smooth pursuit, saccades, and, if present, nystagmus. The examiner moves a finger slowly to both sides and up and down in an H-like movement and asks the patient to follow it. The examiner’s finger should not be held too close to the patient’s eyes. Many patients will instinctively move their head slightly, which the examiner can avoid by fixating the patient’s head with the other hand. Oculomotor function is analyzed according to whether gaze is conjugated or divergent, whether pursuit is smooth or saccadic, and whether the range of movements is full or restricted (Case 3.3). If nystagmus other than end-gaze nystagmus is present, determine whether it is conjugate or unilateral, unidirectional or gaze changing, and horizontal or vertical, whether it occurs after a latent phase of a few seconds or immediately, whether it is positional or independent, and whether it is transient or constant. (The first adjective of each pair is consistent with vestibular nystagmus; the second suggests nystagmus of central origin.) For assessment of saccades, ask the patient to fixate on the examiner’s face. The examiner then holds up his hands and moves them suddenly and in a random manner. The patient has to look at the moving hand and then immediately at the examiner again. Are eye saccades precise, or does the patient need to perform corrections due to either overshoot or hypometric saccades?

Skew deviation may be revealed by asking the patient to fixate on the examiner’s face, while the examiner covers one of the patient’s eyes with his hand. Skew deviation, as well as latent strabismus, is revealed by a corrective movement of the affected eye when the hand is removed (Chap. 2).

The VOR or oculovestibular reflex is a reflex eye movement that stabilizes the image on the retina during head movement by producing an immediate eye movement opposite to the movement of the head. Thereby, the image remains fixed in the center of the visual field. The head impulse test can be used for assessment of the VOR. Again, ask the patient to fixate on your face. Take the patient’s head in both hands and turn the head quickly 10–20° to one side. With vestibular failure, the eyes will follow the head movement for a fraction of a second until a compensatory saccade in the opposite direction allows the patient to fixate on you again. Take care not to miss this compensatory saccade as it is minute.³ With smooth pursuit, in contrast, VOR must be suppressed in order to allow a stable image on the retina. Ask the patient to extend both arms, to put his thumbs together, and to fixate them while you turn the patient en bloc. With correct VOR suppression, the gaze is fixed on the thumbs; with deficient VOR suppression (e.g., in a patient with MS), the patient’s gaze constantly lags behind, and compensatory saccades are necessary to catch up with the moving thumbs.

Oculomotor function is often impaired in neuromuscular junction disorders such as MG. For assessment of fatigability and ptosis, ask the patient to look upward for 60 s and look for occurrence of ptosis (Jolly’s test). When ptosis is subtle, it may be difficult to establish whether or not the Jolly’s test is positive. Ptosis is best detected when focusing on the decreasing gap between the upper eyelid and the upper border of the pupil. For other relevant bedside tests (tensilon test, ice-on-eyes test), consult the differential diagnosis of neuromuscular junction disorders in Chap. 4.

Facial sensation, mediated by CN V, is assessed by touching both halves of the face gently. There is usually no need to test the different qualities of facial sensation. Most sensory disturbances are obvious. One exception is sensory disturbance due to vestibular schwannoma, which initially is subtle and may sometimes only manifest as impaired corneal sensation leading to a decreased corneal reflex. Also, it is crucial not to miss complaints of circumoral sensory symptoms as these may point toward a brainstem lesion, as discussed in Chap. 2. The skin area innervated by V3 ends at the lower mandible; thus, sensory disturbances including areas below the mandible may suggest that these complaints are nonorganic in nature. Also, keep in mind that minor differences in pain and temperature sense between the right and left facial halves are often described by suggestible patients; again, such complaints are seldom due to an underlying organic disorder if the patient has not mentioned them spontaneously during history taking.

The most important question in a patient presenting with a facial palsy (CN VII) is, “Can you wrinkle your forehead?” This distinguishes central from peripheral facial palsy. In a patient with a subtle facial palsy, examine all three CN VII branches. Ask the patient to whistle, to show his teeth, and to repeat this maneuver rapidly, while you look for a slight palsy as revealed by one corner of the mouth lagging behind the other. Sometimes a mild facial palsy (whether central or peripheral in origin) is best detected during observation of spontaneous facial activity. An asymmetry of the nasolabial fissure may also occasionally reveal a facial palsy better than voluntary muscular activity. Facial reflexes are hyperactive with bilateral UMN impairment, e.g., due to multiple vascular lacunes (pseudobulbar palsy) and other neurodegenerative disorders. One of these reflexes is the so-called snout reflex (a frontal release sign), which leads to pouting or pursing of the lips elicited by a slight and constant pressure on the philtrum (essentially a variation of the tactile rooting response). Another example of a frontal release sign is the palmomental reflex, which consists of a twitch of the chin muscle elicited by stroking the thenar eminence and the palm. However, although it is held dear by many neurologists, the palmomental reflex lacks sensitivity, specificity, and localizing value; and therefore it should be considered obsolete (Schott and Rossor, 2016).

In a patient with a peripheral CN VII palsy (e.g., Bell’s palsy), ask about a loss of taste or an unusual metallic taste in the mouth. A useful but uncomfortable examination is the salt test. Ask the patient to protrude his tongue, fixate its tip with your hand (using gloves), and rub salt on the left and right side of the tongue. The patient with a peripheral CN VII palsy that also affects the chorda tympani will report loss of salt taste perception on the ipsilateral side of the tongue. Also test for hyperacusis by clapping your hands together in front of the patient’s ears. Consult Chap. 2 regarding localizing the lesion in peripheral facial palsy.

Lesions of the vestibular part of CN VIII may lead to vestibular ataxia and nystagmus, as discussed earlier. In vestibular damage, horizontal or torsional nystagmus occurs with a latency of a few seconds after position change and is habituating.

Sensorineural deafness (due to injury of the cochlear part of CN VIII) is usually obvious during normal speech. If not, rub your index finger and thumb together in front of the patient’s ears to reveal slight hearing impairment. The Weber and Rinne tests allow distinguishing sensorineural from conductive hearing impairment. During the Weber test, a vibrating tuning fork is placed in the middle of the patient’s head. If available, a 512 Hz tuning fork is preferable; otherwise, a common 256 Hz fork will do as well. With conductive hearing loss, the patient will hear the sound lateralized toward the affected ear, whereas the opposite is true with sensorineural hearing loss. Then, perform the Rinne test by placing the vibrating tuning fork on the patient’s mastoid. When the patient no longer hears the sound, hold the fork in front of the ipsilateral ear. Since air conduction is normally better than bone conduction, the patient should hear the sound again and at least twice as long as with bone conduction. For instance, with conductive hearing loss of the left ear, the Weber test will be lateralized to the left, and, since bone conduction is better than air conduction in this case, the Rinne test will be negative on the left side. In contrast, with left sensorineural hearing loss, the Weber test will be lateralized to the right, while the Rinne test will remain positive (showing that air conduction is still better than bone conduction).

CN IX and CN X are assessed together. In most cases, simply asking the patient to stick out his tongue and say “aaah” and watching whether or not the soft palate and uvula are lifted symmetrically are sufficient. If the patient is able to clear his throat, this suggests preserved diaphragmatic function and sufficient closure of the epiglottis. Chapter 2 discusses the gag reflex and the curtain phenomenon due to ipsilateral uvula paresis. Dysphagia can be assessed at the bedside by having the patient (carefully) drink a glass of water. Dysarthria is usually obvious when taking the history but can be formally tested for by having the patient say “p-p-p” (CN VII), “t-t-t” (CN XII), and “k-k-k” (CN IX/X). The examiner needs to decide whether dysarthria is spastic (high-pitched sounds, e.g., due to supranuclear pseudobulbar palsy), atactic (“eve-ry syl-la-ble-tends-to-be-pro-nounced-by-it-self,” encountered in cerebellar disease or MS), or of the LMN type (flabby and nasal speech, e.g., due to neuromuscular disorders such as ALS and MG).

The examination of motor function includes:

Muscle power can be graded according to the British Medical Research Council (MRC) scale:

The MRC scale was established for quantification of peripheral palsies secondary to military injuries, but it can also be used, albeit somewhat less reliably, for quantification of other neuromuscular and central palsies.

The abovementioned formal power testing is often inferior to other techniques when it comes to detection of slight central palsies. Observation of asymmetries of unrestrained motor movements may reveal such palsies even in cases when formal power testing does not. Isotonic movements include hand and foot tapping, playing the piano, screwing in light bulbs, alternating fast supination and pronation of the hands, and hopping on one foot. Unilateral decrease of fine motor movement suggests a central palsy. Examine each extremity independently, because simultaneous examination tends to lead to synchronization, which may obscure asymmetric motor performance. Isometric techniques include the straight arm test and the flexed leg test.⁴ To perform a straight arm test, ask the patient to close his eyes, lift both arms over his head, and extend the elbow and finger joints with the hands supinated. Finger flexion, pronation of the wrist, elbow flexion, or lowering of the arm occurring on one side suggests a contralateral central lesion. Sometimes the patient may only complain that one arm feels heavier than the other, and if consistent with the history, this is the mildest sign of a central palsy. In contrast to the straight arm test, which is easily performed, the flexed leg test demands greater effort on the patient’s part and should therefore be reserved for cases in which the history suggests a mild central paresis of the lower extremity. The supine patient is asked to lift both legs by flexing 90° at the hips, the knees, and the ankles. Asymmetric weakness suggests a central palsy of the affected leg.

If MG or another neuromuscular junction syndrome is suspected, it is advisable to assess fatigability by counting the number of repetitive movements (e.g., knee bending, neck flexion) the patient is able to perform or by counting the seconds the patient is able to maintain certain postures (e.g., lifting his head off the pillow when lying in bed). These are also excellent ways to clinically monitor the effect of medical treatment. Furthermore, the Cogan lid twitch is a relatively specific sign for MG. It occurs due to transient improvement in eyelid strength after rest of the levator in downgaze, followed by droop in the primary position as the levator fatigues. Patients with ptosis and possible MG are asked to look straight ahead, down, and straight ahead again. The eyes are carefully assessed immediately after this movement for the presence of a brief upward twitch of the upper eyelid, indicating a positive test. Other bedside tests for MG include the tensilon and the ice-on-eyes tests, which will be explained in Chap. 4.

After these general considerations, let us review the practical part of the motor examination. Ideally, the examination should begin with the patient undressed and sitting at the bedside in a well-lit room. If the history suggests LMN impairment, check for possible atrophy and fasciculations. The latter may be very difficult to detect unless enough time is reserved to examine each extremity carefully. Fasciculations can sometimes be elicited by slightly tapping the muscle. Then, proceed with a straight arm test to gain an immediate impression of power in the upper extremities.

Subsequently, formal power testing in the upper extremities should be performed. The following movements may be tested routinely (“UMN” denotes movements especially affected by UMN lesions; key myotomes shown in italics):