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Paroxysmal episodes, “re-build up” phenomenon and moyamoya disease

Epileptic Disorders. Volume 11, Number 4, 324-8, December 2009, Clinical commentary with video sequences

DOI : 10.1684/epd.2009.0276

Summary

Author(s) : Nomazulu Dlamini, Sushma Goyal, Jozef Jarosz, Timothy Hampton, Ata Siddiqui, Elaine Hughes , Department of Paediatric Neurology, Department of Clinical Neurophysiology, Department of Neuroimaging. Kings College Hospital, London, United Kingdom.

Summary : 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]

Keywords : paroxysmal episodes, re-build up, moyamoya disease, EEG hyperventilation, transient ischemic event

Pictures

ARTICLE

Auteur(s) : Nomazulu Dlamini¹, Sushma Goyal², Jozef Jarosz³, Timothy Hampton³, Ata Siddiqui³, Elaine Hughes¹

¹Department of Paediatric Neurology
²Department of Clinical Neurophysiology
³Department of Neuroimaging. Kings College Hospital, London, United Kingdom

Article reçu le 31 Juillet 2008, accepté le 28 Août 2009

Case Report

We report a case of a 6 year old girl who had a normal delivery at term. From 18 months she had episodes termed “funny turns” by her parents. EEG at four years showed slow wave disturbance over the left posterior quadrant with focal epileptiform activity. Neurometabolic investigations were normal. Brain MRI showed right parietotemporal atrophy. She was diagnosed as having epilepsy and started on sodium valproate and subsequently topiramate.

At 5 years of age concerns emerged regarding deterioration in school performance and co-ordination difficulties. Because of concerns regarding clinical history and discordant EEG and MRI findings she had video telemetry which captured a habitual attack precipitated by her crying for 15 minutes (figure 1A, B), with marked truncal ataxia and right sided weakness lasting three minutes (figure 2, see video sequence) accompanied by slowing over the left parietal region. Her EEG then normalised as she settled (figure 3).

Review of previous EEGs (figure 4) showed appearance of generalised delta after the end of hyperventilation lasting for up to three minutes consistent with “re-build up”, and an habitual episode of becoming floppy after hyperventilation (figure 5).

In one of the previous recordings she had been noted to be floppy after hyperventilation.

Telemetry and EEGs were suggestive of transient focal ischaemia in the left parietotemporal region of the left middle cerebral artery.

Review of MRI scans (figure 6) showed multiple bilateral infarcts and flow voids within the basal ganglia secondary to parenchymal collaterals.

Moyamoya disease was confirmed on cerebral angiography (figure 7). Investigations for stroke risk factors were normal. The child had a left ECIC by-pass, with a reduction in transient ischaemic symptoms. She remains on anti-platelet and anti-epileptic medication.

Conclusion

“Re-build-up” may be an unrecognized EEG finding of moyamoya disease. It represents the uncoupling between metabolic demand and blood supply to the cortex (Kuroda et al., 1995, 1996) and cerebrovascular insufficiency. This case highlights the potential for misdiagnosis of organic non-epileptic events and the importance of video telemetry and multidisciplinary review of complex cases. Hyperventilation during EEG should be avoided in children already diagnosed with moyamoya disease.

Legend for video sequence

Disclosure

None of the authors has any conflict of interest to disclose.

References

[Kuroda et al., 1995] Kuroda S, Houkin K, Kamiyama H, Abe H, Mitsumori K. Regional cerebral hemodynamics in childhood moyamoya disease. Childs Nerv Syst 1995; 11: 584-90.

[Kuroda et al., 1996] Kuroda S, Houkin K, Hoshi Y, Tamura M, Kazumata K, Abe H. Cerebral hypoxia after hyperventilation causes “re-build-up” phenomenon and TIA in childhood moyamoya disease. A near-infrared spectroscopy study. Childs Nerv Syst 1996; 12: 448-52 (discussion 453).