Amyotrophic Lateral Sclerosis- Lou Gehrig’s Disease



Amyotrophic Lateral Sclerosis- Lou Gehrig’s Disease

I. Most common form of progressive motor neuron disease. A rapidly progressive fatal degenerative neuromuscular disease (or group of diseases) with a striking predilection fro the motor system and sparing of other neurons that affects Both: Patients usually present with 1 but eventually get mixed signs

a. Upper Motor Neurons- hyperreflexia, spasticity, Babinski’s sign

b. Lower Motor neurons- weakness/wasting, fasciculations

II. Amyotrophic Lateral Sclerosis: sporadic and most common form of the disease (90-95%)

a. Only affects motor neurons- selective in neuronal death. Sensation and cognition are intact

III. Familial ALS: autosomal dominant or recessive disease that is clinically similar to sporadic ALS but probably represents a distinct entity pathologically and biochemically

IV. Signs and Symptoms- variable combinations of: cardiac and smooth muscles unaffected. Skeletal is affected

a. Bilateral limb weakness with variable symmetry and distribution with atrophy of muscle groups- hearing, vision, sensation intact

i. Begins in distal arms or legs. May affect 1 or 2 extremities but eventually all

ii. Early symptoms: clumsiness, extremity twitching, cramping, weakness

b. Unexplained weight loss

c. 80% of cases begin between ages- 40-70

d. Difficulty walking

e. Difficulty swallowing and facial paresis- drooling and slurred speech

f. Pseudobulbar affect- pathological laughing or crying

g. Muscle fasciculation (other than calves) is common but may not be apparent to the patient

h. Hyperactive deep tendon reflexes (including jaw jerk)

i. Myalgias and joint pain

j. Respiratory muscles and the vocal cords are affected late- Death from respiratory paralysis

i. Death occurs within 3-5 years of the diagnosis

k. Extraocular muscles, sphincters, autonomic function, cognition, and sensation are spared

i. “Locked in” syndrome- complete voluntary muscle paralysis but sensation/cognition intact and can only blink eyes

V. Etiology

a. Sporadic ALS- idiopathic degeneration of the upper and lower motor neurons with their respective axons; elevated levels of glutamate have been found in serum and CSF- high levels are toxic- glutamate communicates between neurons (too much= death)

b. Familial ALS- a genetically transmitted degenerative disease

VI. Pathophysiology

a. Nerve cell degeneration: loss of Betz’s cells in the motor cortex, atrophic or absent anterior horn cells of spinal cord, atrophic or absent neurons within the motor nuclei of the medulla and pons, degeneration of the lateral columns of the spinal cord, atrophy of the ventral roots

b. Grouped atrophy of muscle (motor units)

VII. Diagnostic Procedures

a. Forced Vital capacity FVC- complete amount of air you expire after a full inspiration. Sensitive indicator of respiratory muscle weakness

i. FVC ................
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