External ophthalmoplegia in neuromuscular disorders: case report and review of the literature.

The extraocular muscles have a number of structural and functional properties that distinguish them from skeletal and cardiac muscle and these differences may be important in the differential involvement of extraocular muscles in various disease states. We present a case of congenital external ophthalmoplegia associated with non progressive generalised weakness. Skeletal muscle biopsy at 4 years of age showed type 1 fibre predominance, variation in fibre size and increased interstitial fibrosis, suggestive of a primary myopathic process. During the investigation of this patient we reviewed the differential diagnosis of neuromuscular disorders with extraocular muscle involvement, and developed an algorithm to assist the clinician in investigation and diagnosis of external ophthalmoplegia. Our patient does not satisfy the diagnostic criteria of any previously described disorders and may thus represent a new syndrome.