Subacute peripheral and optic neuropathy syndrome with no evidence of a toxic or nutritional cause

BackgroundThe syndrome of subacute simultaneous peripheral neuropathy and bilateral optic neuropathy is known to occur in tropical countries, probably due to malnutrition or toxicity, but not often seen in developed countries. We report seven patients in London who were not malnourished or alcoholic, and in whom no clear cause was found.MethodsWe retrospectively reviewed the case notes and arranged some further investigations.ResultsAll patients developed peripheral and bilateral optic neuropathy within 6 months. Patients were aged 30-52, and all of Jamaican birth and race but lived in the UK. Most had subacute, painful ataxic sensory axonal neuropathy or neuronopathy, some with myelopathy. Nerve conduction studies revealed minor demyelinating features in two cases. The optic neuropathy was symmetrical, subacute and monophasic, usually with marked reduction in visual acuity. CSF protein concentration was usually elevated but other laboratory investigations were normal. Patients showed only modest improvement at follow-up.ConclusionThese patients share a common clinical and electrophysiological phenotype, age, ethnicity and elevated CSF protein, but otherwise normal laboratory investigations.The syndrome is a cause of significant morbidity in young people. The cause remains uncertain despite thorough investigation.