John Libbey Eurotext

Paroxysmal episodes, “re-build up” phenomenon and moyamoya disease Volume 11, numéro 4, December 2009


  • Paroxysmal episodes, « re-build up » phenomenon an moyamoya disease


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Department of Paediatric Neurology, Department of Clinical Neurophysiology, Department of Neuroimaging. Kings College Hospital, London, United Kingdom

Moyamoya disease is an idiopathic cerebral vasculopathy, which may be progressive or non-progressive. Non-idiopathic forms with an associated disease are called moyamoya-like syndrome. The electroencephalographic finding characteristically seen after hyperventilation in about 50% of children with cerebrovascular disease includes gradual frequency decrease and activation of amplitude of slow waves which appear after the disappearance or attenuation of ordinary build up. This is termed the “re-build up” phenomenon, which is rarely seen and therefore may be under-recognized. We present video telemetry during a transient ischaemic event of a child subsequently diagnosed with moyamoya-like syndrome. We highlight the potential for misdiagnosis of organic non-epileptic events. Hyperventilation during EEG should be avoided in children with known moyamoya disease. [Published with video sequences]