The neuropsychological features of mitochondrial myopathies and encephalomyopathies
L. D. Kartsounis, D. D. Troung, J. A. Morgan-Hughes and A. E. Harding
Department of Clinical Neuropsychology, National Hospitals for Neurology and Neurosurgery, London, United Kingdom.
Detailed testing of higher cerebral function was performed in 36 patients
with mitochondrial myopathies and encephalomyopathies. Fourteen of these
patients were thought to be cognitively impaired on clinical grounds. The
assessments included tests of general intellectual ability and focal tests
of memory, language, and perception. Twenty-one (58%) of the 36 patients
who were tested had evidence of general intellectual deterioration, with
focal cognitive deficits of variable degree. Of the remaining 15 patients
in whom there was no evidence of general intellectual decline, five
displayed focal cognitive deficits. In only 10 patients was there evidence
of cerebral dysfunction. The range and extent of cognitive deficits in
mitochondrial myopathies are greater than predicted by their clinical
presentations.
