Clinical Manifestations

OPTIC NEURITIS

Typically, patients experience relatively abrupt unilateral decrease in central or paracentral vision with pain on movement of the globe; this is a very common MS presentation. At times, symptoms are subtle, with brief episodes of decreased visual acuity provoked by exposure to heat, such as hot showers, followed by prompt resolution. Magnetic resonance imaging (MRI) may show a lesion in the affected optic nerve, and usually, if this is a first attack of MS, other lesions indicative of earlier clinically silent multiple sclerosis activity are seen on brain MRI. Optic neuritis without the concomitant presence of such MRI lesions is seldom an initial sign of MS. Optic disc pallor often develops during recovery.

BRAINSTEM LESIONS

These are common and tend to occur early. Diplopia is usually caused by a lesion affecting the abducens (VI) nerve. Nystagmus is a common sign but is usually asymptomatic. It is a particularly useful sign when it is pronounced in degree and especially when the primary component is vertical.

Internuclear ophthalmoplegia is a classic MS sign indicating involvement of the medial longitudinal fasciculus. Examination reveals paresis of adduction on lateral gaze and associated nystagmus in the abducting eye. Despite the unilateral loss of adduction on lateral gaze the ability to converge (i.e., bilateral adduction) may be preserved.

Vertigo may be difficult to differentiate from a benign labyrinthitis, although a finding of vertical nystagmus points to a CNS rather than a peripheral cause. Trigeminal neuralgia is sometimes confused with idiopathic tic douloureux, a disease primarily of senior adults. Trigeminal neuralgia occurring in young adults is highly suggestive of MS because it is otherwise most atypical in this age group. Similarly, facial weakness may be mistaken for Bell palsy.

CEREBELLAR ATAXIA

This occurs in about 50% of patients. Symptoms include poor balance, intention tremor, dysarthria and, when ataxia is extreme, titubation. Cerebellar symptoms can be severely disabling.

SENSORY SYMPTOMS

Typically occurring early with paresthesias and dysesthesias, often described as constricting or swollen sensations, these symptoms indicate posterior column demyelination in the cervical spinal cord, an area that may be affected early in MS. A hemicircumferential bandlike patch of numbness, usually midtrunk, is frequent but can also be seen with transverse myelitis or spinal cord mass lesions. Often patients forget to mention a very important, clinically useful phenomenon, namely the Lhermitte sign. The physician needs to inquire about this symptom because patients seldom volunteer this information. The Lhermitte sign is typified by momentary electric shocklike sensations shooting or radiating down the arms, back, or legs, precipitated by neck flexion. However, the Lhermitte sign is not diagnostically specific; other posterior cervical spinal cord lesions can provoke it. Examination often reveals diminished vibration and position sense.

CORTICOSPINAL TRACT DYSFUNCTION

This causes muscle fatigue, stiffness, spasticity, and weakness. Hyperreflexia, clonus, and the Babinski sign are frequently elicited. Clonus is a form of movement marked by contractions and relaxations of a muscle occurring in rapid succession. Clonus is most often elicited at the ankle. The Babinski sign is an extension of the great toe and abduction, or fanning, of toes two to five instead of the normal flexion response to plantar stimulation.

Urinary frequency and urgency suggest a hyperreflexic neurogenic bladder. Constipation and sexual dysfunction are also frequent complaints.

Inordinate fatigability is common and can be overwhelming. Demyelinated axons require far more energy to conduct nerve impulses than properly insulated axons; thus conduction may fail with effort. For example, a limp may replace a seemingly normal gait after walking some distance, only to disappear after a rest period. The inefficiency of demyelinated axons worsens as body temperature rises, thus short-lived symptoms, including a transient limp, can be provoked by summer heat, taking hot showers, by fever, or may occur in the late afternoon, when the normally modest diurnal upward body temperature swing peaks, as does MS-related lassitude.

MS patients may experience ill-defined pain, presumably neuropathic in origin. However, one must always seek out other pathophysiologies before presuming that MS is the cause.

DEPRESSION

Occurring at some time in 50% of MS patients, episodes of depression sometimes antedate overt disease onset. The frequency of depression is threefold of that encountered in the overall population. Cardinal features are anger, frustration, irritability, anxiety, and frank panic attacks.

COGNITION

Mildly deficient short-term memory frequently develops early. This can progress to substantial cognitive deficits in later years.

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