CHRONIC PROGRESSIVE EXTERNAL OPHTHALMOPLEGIA IN A HEREDO-ATAXIA: NEUROGENIC OR MYOGENIC?

Abstract

A patient with Friedreich's disease and chronic progressive external ophthalmoplegia is descirbed. An investigation was performed into the nature of the ocular motor disorders, which appeared clinically to be supranuclear. The EMG of the ocular muscles suggested myopathy. A specimen of ocular muscle was obtained by biopsy and examined with the light microscope and-for the first time-under the electron microscope. Signs of mitochondrial myopathy were found alongside neurogenic features. Postmortem examination of the central nervous system confirmed the diagnosis of Friedreich's disease with lesions of the motor cells in the anterior horn of the spinal cord. No evidence was found for a supranuclear or inernuclear origin of the ocular palsies, but 20-30 per cent of the neutrons in the nuclei III and IV were atrophic. Lesions of the non-medullated motor nerve fibres were also visible under the electron microscope. That the origin of the c. p. e. o. in this heredo-ataxia is neurogenic-nuclear is postulated on the grounds of the neuropathological and electronmicroscopic findings. Resemblances to the microscopic and submicroscopic and submicroscopic appearance of many types of "ocular myopathy" and "ophthalmoplegia-plus" throw doubt upon the myogenic character of these conditions. Possibly chronic, slowly progressive atrophy in the nuclear areas of the ocular motor nerves must in these cases also be held responsible for the c. p. e. o. Perhaps Moebius's Kern-Schwund theory may be revived after 85 years.