Neuromuscular effects of monoamine oxidase inhibitors.

The MAOI class of drugs is known to produce neuromuscular effects at therapeutic and toxic doses when given alone or in combination with other drugs. These effects range from muscle tension and twitches in their mild form to forceful myoclonic jerks. These effects may also be part of a more pervasive toxic syndrome that includes autonomic and mental symptoms as well. There is meager direct and substantial indirect evidence that serotonergic mechanisms play a role in mediating the neuromuscular effects of MAOIs. We have hypothesized that MAOIs produce a condition of heightened neuromuscular excitability due to a combination of increased serotonergic tone and central disinhibition of alpha-motor neuron-mediated spinal activity. Further study is needed utilizing objective pharmacologic and neurophysiologic measures.