Muscle morphometry in amyotrophic lateral sclerosis.

Quadriceps muscle biopsies from 24 patients with amyotrophic lateral sclerosis (ALS) and 15 age-matched controls were prepared for histochemistry and analyzed morphometrically. Pathological features for denervation and reinnervation were observed in most ALS patients, although considerable variation between patients was noted. Myopathic changes were also seen in one-third of the cases. The morphometric data were not only related to the duration and mean diameter of type I fiber, but also to the duration and hypertrophy factor of type II fiber, suggesting that the progression and severity of ALS depends on the preservation of both fibers.