A single motor neuron may grow sprouts to innervate five to 10 times more muscle cells than it did originally, creating a giant neuromotor unit. Then after years of functional stability, these enlarged motor units begin to break down, causing new muscle weakness, with or without pain and fatigue. Based on what we know, the lesion is in the motor neurons, but there is no evidence of viral remnants. As to the theory that aggressive rehab and an active lifestyle might be responsible for the ultimate exhaustion of the neuromotor unit, Dr. Halstead says, It s possible, but there s no real evidence. Sometimes help is as simple as having the patient use a cane or a wheelchair, Dr. Vickrey says.
Drugs don t seem to help.
Several small studies suggested that the anticholinesterase drug pyridostigmine might be effective, but a 1999 placebo-controlled trial of 126 PPS patients found no benefit, says Dr. Trojan, the lead author. Patients should be encouraged to remain as active as possible, to stay fit, and control their weight, Dr. Dalakas advises. Exercise is important. For some, perhaps nothing more strenuous than stretching or yoga can be helpful. For others, swimming or more vigorous exercise, including aerobic workouts, might work.