Spinal cord limb motor neurons in dystrophia myotonica.

The total numbers of limb motor neurons have been counted in 20 micron sections of the lumbosacral spinal cord obtained a autopsy from 5 control subjects who showed no evidence of neuromuscular disease and from 5 patients with dystrophia myotonica ranging in age from 42 to 64 years. No significant reduction in the total number or distribution of such neurons was found in the cases of myotonic dystrophy and the quantity of lipofuscin present in the cells was similar to that in controls. Glial cell numbers were, however, significantly increased in the cases of dystrophia myotonica and this increase was not due to shortening or "crowding" of the relevant cord segments; in 2 patients with dystrophia myotonica the cell body area of the motor neurons was reduced by comparison with normal controls.