Amyotrophic Lateral Sclerosis

Description

Amyotrophic lateral sclerosis (ALS), also known as Lou GehrigÕs Disease, is a rapidly progressive neuromuscular disease caused by the destruction of nerve cells in the brain and spinal cord. This causes loss of nervous control of the voluntary muscles, resulting in the degeneration and atrophy of the muscles. Eventually the respiratory muscles are affected which leads to death from an inability to breath.

Symptoms

paresis and leg weakness

Signs

marked muscle atrophy, usually upper extremity

accompanied by asymmetrical fasciculations and hyperreflexia

fasciculations of the tongue

lack of sensory abnormality differentiates it from cervical disc disease

Causes

There are three types of ALS: sporadic, familial, and Guamian. The most common form is sporadic. A small number of cases are inherited genetic disorders (familial). A large number of cases, however, occur in Guam and other Pacific territories. The familial type of ALS is caused by a genetic defect in superoxide dismutase, an antioxidant enzyme that continuously removes the highly toxic free radical, superoxide.

The causes of sporadic and Guamian ALS are unknown. Several hypothesis have been proposed including: Glutamate toxicity; Oxidative stress; Mitochondrial dysfunction; Autoimmune disease; Infectious diseases (Lyme disease, poliomyelitis, HIV, and Tertiary syphilis); Toxic chemical exposure (pesticides); Heavy metals toxicity (lead, mercury, aluminum, and manganese); Calcium and magnesium deficiency; Carbohydrate metabolism; and Growth factor deficiency.

Pathophysiology

Degeneration of anterior horn cells and motor BetzÕs cells of cerebrum progressively up from the caudad portion of the body.

Circulating antibody inhibits protein stimulation of axonal sprouting secreted by denervated muscle.

Perhaps a defective glutamate transport system permits neurotoxic levels to build up.

Autoimmune IgG against calcium channels

Conventional Labs

There are no specific lab tests for ALS, although there may be a deficiency in hexosaminidase.

Muscle biopsy shows neuronal degenerative changes

Cord biopsy shows atrophy with decreased anterior horn cells and lipofuscin in degenerated corticospinal tracts

MRI and contrast myelography to visualize the cervical spinal cord.

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