AMYOTROPHIC LATERAL SCLEROSIS 

Lou Gehrig’s Disease

Amyotrophic Lateral Sclerosis (ALS) is a mysterious disease where UMNs (upper motor neurons) and LMNs (lower motor neurons) spontaneously degenerate. There is spastic AND flaccid weakness that onsets slowly and progressively worsens until the patient eventually expires from respiratory insufficiency. Not many diseases affect both UMNs and LMNs, and ALS is the only one that exclusively causes weakness without numbness. Look for hyporeflexia and hyperreflexia. 

Is there sensory involvement?

No. 

Is there cognitive involvement?

No.

Does ALS affect the brainstem?

Sometimes. ALS can “spread up” the spinal cord, and eventually hit the medulla. Damage to the medullary CN’s (9, 10, 11 and 12) is called bulbar palsy. Bulbar palsy consists mostly of dysphagia and dysarthria. 

What are the early symptoms of ALS?

One of the tell-tale signs of ALS is asymmetric weakness in the hands, especially with atrophy of the thenar eminences. The weakness is progressive, unstoppable and inevitably fatal. 

What causes ALS?

Nobody knows. Spooky. Note that about 10% of cases are caused by a mutation of Superoxide Dismutase.