Volume 46, Issue 1 pp. 69-75

Hyperventilation Revisited: Physiological Effects and Efficacy on Focal Seizure Activation in the Era of Video-EEG Monitoring

Mirian S. B. Guaranha

Mirian S. B. Guaranha

Epilepsy Center, Hospital Alemão Oswaldo Cruz

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Eliana Garzon

Eliana Garzon

Epilepsy Center, Hospital Alemão Oswaldo Cruz

Department of Neurology, Escola Paulista de Medicina, Federal University of São Paulo

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Carlos A. Buchpiguel

Carlos A. Buchpiguel

Nuclear Medicine Laboratory, Hospital Alemão Oswaldo Cruz

Nuclear Medicine Laboratory, University of São Paulo Medical School

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Sérgio Tazima

Sérgio Tazima

Nuclear Medicine Laboratory, Hospital Alemão Oswaldo Cruz

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Elza M. T. Yacubian

Elza M. T. Yacubian

Epilepsy Center, Hospital Alemão Oswaldo Cruz

Department of Neurology, Escola Paulista de Medicina, Federal University of São Paulo

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Américo C. Sakamoto

Américo C. Sakamoto

Epilepsy Center, Hospital Alemão Oswaldo Cruz

Department of Neurology, Escola Paulista de Medicina, Federal University of São Paulo

Department of Neurology, Ribeirão Preto School of Medicine, University of São Paulo, Brazil

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First published: 11 January 2005
Citations: 90
Address correspondence and reprint requests to Dr. A. C. Sakamoto at Rua Adolfo Serra 1725, casa 13 Jardim Santa Ângela, Ribeirão Preto-SP CEP:14020-263, Brazil. E-mail: [email protected]

Abstract

Summary: Purpose: Hyperventilation is an activation method that provokes physiological slowing of brain rhythms, interictal discharges, and seizures, especially in generalized idiopathic epilepsies. In this study we assessed its effectiveness in inducing focal seizures during video-EEG monitoring.

Methods: We analyzed the effects of hyperventilation (HV) during video-EEG monitoring (video-EEG) of patients with medically intractable focal epilepsies. We excluded children younger than 10 years, mentally retarded patients, and individuals with frequent seizures.

Results: We analyzed 97 patients; 24 had positive seizure activation (PSA), and 73 had negative seizure activation (NSA). No differences were found between groups regarding sex, age, age at epilepsy onset, duration of epilepsy, frequency of seizures, and etiology. Temporal lobe epilepsies were significantly more activated than frontal lobe epilepsies. Spontaneous and activated seizures did not differ in terms of their clinical characteristics, and the activation did not affect the performance of ictal single-photon emission computed tomography (SPECT).

Conclusions: HV is a safe and effective method of seizure activation during monitoring. It does not modify any of the characteristics of the seizures and allows the obtaining of valuable ictal SPECTs. This observation is clinically relevant and suggests the effectiveness and the potential of HV in shortening the presurgical evaluation, especially of temporal lobe epilepsy patients, consequently reducing its costs and increasing the number of candidates for epilepsy surgery.

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