The course of vision disturbances in a patient with the MELAS syndrome.

BACKGROUND: This article describes the neuropsychological and ophthalmic symptoms presented by a patient with MELAS, a mitochondrial cytopathy. This rare disease is characterized by a remitting-relapsing course against the background of a slowly progressive degenerative process. CASE REPORT: The patient is a 22-year-old Polish female, with initial onset of symptoms in 1994; the clinical diagnosis of MELAS was established in 1998, and confirmed in 2000 by the discovery of a novel mtDNA mutation. Her visual acuity fluctuates from near-normal to near-blindness, often changing dramatically within a matter of weeks; the visual field has more or less steadily narrowed to lunate. Visual evoked potentials show sporadic disturbances, while the nerve fiber layer shows significant attenuation. The evidence points to a complex etiology, involving both cortical damage and attenuation of the optic nerves and neural pathways. A similar two-phase pattern--episodic disturbances with rapid spontaneous recovery against a background of progressive deterioration--occurs in neuropsychological testing, which reveals progressive dementia and episodic aphasia.
CONCLUSIONS: The peculiar pathomechanism of MELAS results in simultaneous insults to various parts of the central and peripheral nervous systems, creating the complex and highly variable pattern seen in this patient. In clinical practice care should be taken not to overlook the possible significance of such a pattern appearing in various systems and on varying levels.