What is the role of EEG in the workup of Sturge-Weber syndrome (SWS)?

Updated: Dec 26, 2018
  • Author: Masanori Takeoka, MD; Chief Editor: George I Jallo, MD  more...
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Electroencephalography (EEG) is used for the evaluation of seizures and for the localization of seizure activity in refractory seizures when epilepsy surgery is considered.

Brenner and Sharbrough reported unilateral reduction of background amplitude as the most consistent finding in the waking and sleep states, with activation procedures (hyperventilation and photic driving) decreased on the involved side. [86] EEG findings predated calcifications. Epileptiform activity was limited to the involved hemisphere.

In a study of children with SWS and epilepsy, Sassower et al reported marked voltage attenuation in the region of angioma in 13 of 14 patients; polymorphic delta activity (PDA) occurred in 12 of 14 patients. The PDA was unilateral in 6 of the dozen patients and correlated with the angiomatosis. None of the patients with unilateral PDA had mental retardation. In the 6 patients with bilateral PDA, 4 had mental retardation despite a unilateral angioma. Interictal spikes occurred in only 2 patients and were bilateral in 1 patient with unilateral disease. Seizures were recorded in 4 patients, and the ictal activity came from the periphery of the lesion. The seizures were refractory to treatment in 6 of 14 patients. [87]

Erba and Cavazzuti reported that late in the course of SWS, epileptiform activity might occur from the contralateral cortex. [40]

In a Canadian study, the EEG was normal in only 4%, background suppression occurred in 74% (unilateral in 64% and bilateral in 10%), and epileptiform discharges occurred in 22%.

Jansen et al reported asymmetry in beta activity in SWS, before and after diazepam administration in brain regions that structurally appeared intact. [88] The investigators suggested that diazepam-enhanced EEG may provide information on functional involvement and monitor progression of the disease.

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