MULTIPLE SCLEROSIS

• Onset usually in 20s-40s; slightly more common in women
• Relapsing episodes of paresthesias, visual disturbances, Incoordination
• Genetic susceptibility: 25% concordance among monozygotic twins May have an infectious etiology (viral?)
• Multiple subtypes: Charcot (classic), Marburg (acute), Schilder (diffuse sclerosis), Balo (concentric), Devic (neuromyelitis optica)

AMYOTROPHIC LATERAL SCLEROSIS (ALS)

• Most cases are sporadic, Disease linked to chromosome 21; 10% of cases are autosomal dominant
• Lower motor neuron and upper motor neuron loss; little if any sensory deficits Weakness of the extremities (pyramidal tract involvement), muscle atrophy (hands first), labioglossolaryngeal paralysis (bulbar disturbances)
• On exam, see fasciculations (rapid fine repetitive spontaneous movements of a part of a muscle; manifestation of denervation hypersensitivity, i.e., upper motor neuron lesion), exaggerated deep tendon reflexes
• Median survival: 3 yr (1.5 yr with bulbar involvement)