Changes in skeletal muscles of young women with anorexia nervosa. An enzyme histochemical study.

Biopsies from four young women with advanced anorexia nervosa were examined to investigate the effect of malnutrition on skeletal muscles. None of the patients showed signs of neuromuscular disease and all were physically active at the time of examination. Cryostat sections from the vastus lateralis muscle were stained with hematoxylin-azophloxin-safran and with stains for myofibrillar ATP-ase activity. In addition to routine examination of the sections, the size and distribution of the type 1 and type 2 fibres were calculated by means of a Kontron Digiplan MOP 02. Routine stained sections showed a small grouped atrophy in three cases and a more diffuse atrophy in the fourth. Enzyme histochemical stains revealed a distinct type 2 atrophy, a finding which should serve to distinguish the changes of pure malnutrition from those of conventional denervation. Exact measurements confirmed the predominant type 2 atrophy but showed definite atrophy also of the type 1 fibres. Compared with normal controls the type 1 fibres were reduced by 46% and the type 2 fibres by 75%. These findings are largely in agreement with the recent observations by Essén et al. (1981) on anorexia nervosa. However, in contrast to Essén et al. we did not find any change in the numerical distribution of the fibre types, especially no increase in type 1 fibres. Thus, we could not confirm the hypotheses of a conversion of the fibre types in cachexia.