Muscle abnormalities in psychotic patients. II. Serum CPK activity, fiber abnormalities, and branching and sprouting of subterminal nerves

The serum creatine phosphokinase (CPK) activity, morphology of skeletal muscle fiber biopsies, and morphology of subterminal motor nerves of 24 psychotic patients of the common 'functional' types and three of their first degree relatives were studied. Sixteen of the 24 patients had increased serum CPK activity, 17 of the 24 patients had muscle fiber abnormalities, and 16 of 24 had pathological changes in the morphology of the subterminal motor nerves. Five of the 24 patients had no abnormalities of any type. Similar abnormalities of muscle fibers and subterminal nerves were present in the relatives of the patients. The abnormalities of the subterminal nerves included branching, sprouting, axonal swelling, and degenerate nerve endings. The Absolute and Functional Terminal Innervation Ratios (ATIR and FTIR, respectively) of the patients and relatives were significantly greater than those of the six controls without psychiatric illness. The increase in the ATIR and FTIR strongly suggests that the muscle fiber abnormalities in psychotic patients and their relatives are neurogenic in etiology. This is supported by the presence of fiber type grouping in several biopsies and the high correlations between the ATIRs and FTIRs and the number of scattered atrophic fibers in the entire group of muscle biopsies. The abnormalities in the subterminal motor nerves may be the most significant example of neuropathology yet found in patients with the so called 'functional' psychoses, which now appear to have more widespread neuropathologic sequelae than were heretofore appreciated.