E-Pearl of the Week: Periodic Alternating Nystagmus

January 23, 2013


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January 23, 2013

Periodic Alternating Nystagmus

Periodic alternating nystagmus (PAN) is a descriptive clinical sign characterized by involuntary oscillations of the eyes that change directions in cycles. PAN can be congenital or acquired later in life and has been shown to result from instability of brainstem velocity storage mechanisms, which normally regulate nystagmus that is induced by rotation. It has been associated with albinism, ataxia–telangiectasia, hereditary spinocerebellar ataxias, seizures, multiple sclerosis, Ménière's disease, and medications such as lithium and pentobarbital. Baclofen has been reported to be effective in the treatment of PAN.


  1. Razmara A, Mackay D, Galetta SL, Prasad S. Periodic Alternating Nystagmus Evident Only in Darkness. Neurology. 2013; 80: e32.
  2. Furman JM, Wall C 3rd, Pang DL. Vestibular function in periodic alternating nystagmus. Brain. 1990;113:1425–1439.

Submitted by: Jennifer E. Fugate, D.O.

Disclosure: Dr. Fugate served on the editorial team for the Neurology® Resident and Fellow Section.

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