Ethambutol toxicity exacerbating the phenotype of CMT2A2.

INTRODUCTION: CMT2A2 is associated with mutations in the mitofusin 2 gene, which encodes a protein involved in mitochondrial fusion. Ethambutol is an antimycobacterial agent associated with toxic optic neuropathies. Ethambutol-induced optic neuropathy occurs in patients with mutations in a related fusion gene, OPA1, which is responsible for autosomal dominant optic atrophy. METHODS: We describe a patient with CMT2A2 (MFN2 mutation: T669G, F223L) who developed accelerated weakness, vocal cord paralysis, and optic atrophy after receiving ethambutol. RESULTS: Deterioration began within months of initiating ethambutol therapy. After discontinuation of ethambutol, neurologic deterioration stabilized with subsequent improvement in visual fields. CONCLUSIONS: CMT2A2 is part of a group of genetic disorders which share an association with the process of mitochondrial fusion. This case shows that patients with CMT2A2, and possibly other mitochondrial fusion defects, may be uniquely susceptible to ethambutol-induced neurotoxicity. This has implications regarding the underlying pathophysiology of mitochondrial fusion defects.

West Nile virus-associated optic neuritis and chorioretinitis.

PURPOSE: To report the new ocular and neurologic features of West Nile virus (WNV) meningoencephalitis. DESIGN: Observational case report. METHODS: A 55-year-old woman presented with headache, stiff neck, visual loss, and fever 10 days after a weekend camping trip. Examination revealed vitritis, creamy yellow circular chorioretinal lesions, and peripheral visual field loss. RESULTS: Laboratory investigation indicated the patient was suffering from WNV meningoencephalitis with neuro-ocular involvement. CONCLUSION: Ophthalmologists and infectious disease specialists should recognize that the WNV infection spectrum may include ophthalmic findings, specifically optic neuritis and multifocal chorioretinitis.