Surface EEG False Localization in Patients with Gross Hemispheric Lesions Submitted to Hemispherectomy.
Abstract number :
2.278
Submission category :
Year :
2001
Submission ID :
1943
Source :
www.aesnet.org
Presentation date :
12/1/2001 12:00:00 AM
Published date :
Dec 1, 2001, 06:00 AM
Authors :
M. Argentoni, MD, Neurology, Hospital Brigadeiro, Sao Paulo, Brazil; A. Cukiert, MD, PhD, Neurosurgery, Hospital Brigadeiro, Sao Paulo, Brazil; J.A. Buratini, MD, Neurosurgery, Hospital Brigadeiro, Sao Paulo, Brazil; C. Baudaulf, MD, Neurology, Hospital B
RATIONALE: Surface EEG has represented the gold-standard for focus localization for many years. On the other hand, false localization have already been reported in many patients with gross brain lesions. This paper discusses the neurophysiological findings in a subset of patients with gross hemispheric lesions in whom surface EEG findings were false-localizatory.
METHODS: Four adult patients (mean age = 19 years) were studied. All had daily motor simple partial seizures. Three patients also had complex partial seizures and generalized tonic-clonic seizures. MRI disclosed gross hemispheric brain damage contralateral to the motor simple partial seizures in all patients: advanced Rasmussen[prime]s encephalitis (n=1), callosal agenesis and hemispheric cyst (n=1) and porencephalic cysts due to probable middle cerebral artery infarction (n=2). Interictal EEG disclosed spiking exclusively contralateral to the MRI defined lesion in 3 patients. In one patient, interictal abnormalities were also seen over the damaged hemisphere but clearly predominated over the healthy one. Ictal EEG findings followed the same pattern. All patients were submitted to a functional hemispherectomy.
RESULTS: All patients have been rendered seizure-free after surgery. Contralateral spiking disappeared in three of them and in one, frontal lobe spiking persisted over the healthy hemisphere. In the patient in whom preoperative ipsolateral spiking was seen, residual spiking could be seen over the disconnected residual frontal lobe.
CONCLUSIONS: Neurophysiological findings might not be relevant in patients with gross hemispheric lesions and clinically lateralized simple partial seizures (such as motor simple partial seizures). Neurophysiological findings were not of prognostic significance in this group of patients.