Controversies about amyotrophic lateral sclerosis.

Controversy regarding amyotrophic lateral sclerosis (ALS) concerns aspects of relatively little consequence (such as the role of lead intoxication or trauma in the pathogenesis of the disease) and others of greater relevance, particularly the two following questions regarding treatment options: 1) Are we in a new era of therapy for ALS? Prior to the 1990's no controlled study showed consistent benefit from any of the treatments tried. We have now had announcements of benefit for four entirely different agents: riluzole, insulin-like growth hormone, brain derived neurotrophic hormone and gabapentin. The benefit, at most, is marginal or questionable. The effect is of statistical significance but of little clinical relevance, and 2) what is the role of peripheral nerves in ALS? The syndrome of multifocal motor neuropathy and conduction block (MMNCB) shares some clinical data (active tendon jerks in weak, wasted and fasciculating muscles) and pathological features (anterior horn cell loss and glions) with "typical" ALS. This is relevant because MMNCB is reversible with immunoglobulin therapy. The rigid separation between ALS (a disease of the motor neuron perikaryon) and MMNCB (a disease of the motor neuron axon) is no longer tenable.