Atypical periodic alternating nystagmus responding to high-dose intravenous immunoglobulins: a case report

Abstract

BackgroundAcquired periodic alternating nystagmus (PAN) is a rare but well-defined syndrome that consists of a horizontal nystagmus that cyclically reverses its direction. PAN can be caused by degenerative, neoplastic, or toxic diseases of the cerebellum and, in a few cases, by subacute cerebellar ataxia of immune origin.Case presentationA 44-year-old man came to our attention because of rapidly progressive gait instability and blurred vision. Clinical examination showed PAN and a mild pancerebellar syndrome. Eye movement recordings disclosed a short cycle PAN with significant slow-phase velocity only in darkness. Under the effect of a γ-aminobutyric acid type B (GABAB) agonist, PAN was not modified. Right after treatment with intravenous immunoglobulin (IVIg) was started, PAN was essentially eliminated. Three months after last dose of IVIg, this nystagmus reappeared.ConclusionsIVIg resolved PAN in this patient. This finding may point to an autoimmune mechanism underlying this patient’s nystagmus. This case suggests that the usefulness of IVIg at treating PAN might be worth a consideration in similar clinical settings.

Nystagmus

“…Acquired periodic alternating nystagmus (PAN) was linked to autoimmune disorders and long-term lithium intake, promoting the application of intravenous immunoglobulin in the first case [53] and prescription of baclofen in the latter case [54]. In a patient with systemic lupus erythematous and cerebellar atrophy, amantadine reduced PAN, dizziness and oscillopsia [55].…”