HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Full Text (PDF) Data Supplement Correspondence: Submit a response Alert me when this article is cited Alert me when Correspondence are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Valentín, A. Articles by Polkey, C. E. Search for Related Content PubMed PubMed Citation Articles by Valentín, A. Articles by Polkey, C. E. Related Collections All Epilepsy/Seizures Cortical localization

Single-pulse electrical stimulation identifies epileptogenic frontal cortex in the human brain

From the Departments of Clinical Neuroscience (Drs. Valentín, Alarcón, Nayak, and Binnie, M.E. Lacruz), Clinical Neuropathology (Dr. Honavar), and Neurosurgery (Dr. Selway), Guy’s, King’s, and St. Thomas’ School of Medicine, King’s College Hospital, London, UK; Facultad de Medicina (Dr. García-Seoane), Universidad Complutense, Madrid, Spain; and Department of Neurology (Dr. Nayak) Kovai Medical Centre and Hospital, Coimbatore, India.

Address correspondence and reprint requests to Dr. G. Alarcón, Department of Clinical Neurophysiology, King’s College Hospital, London, SE5 9RS, UK; e-mail: galarcon{at}aol.com

Objective: To assess the value of single-pulse electrical stimulation (SPES) to identify frontal epileptogenic cortex during presurgical assessment.

Methods: SPES (1-millisecond pulses, 4 to 8 mA, 0.1 Hz) has been used during chronic recordings in 30 patients with intracranial electrodes in the frontal lobes. As a result of presurgical assessment, 17 patients were considered to have frontal epilepsy and 13 extrafrontal epilepsy.

Results: Two types of responses to SPES were seen: 1) early responses: starting immediately after the stimulus and considered as normal responses; 2) late responses: two types of responses seen in some areas after the initial early response: a) delayed responses: spikes or sharp waves occurring between 100 milliseconds and 1 second after stimulation. Frontal delayed responses were seen in 11 frontal patients and 1 extrafrontal patient, whereas extrafrontal delayed responses were seen in 1 frontal and 10 extrafrontal patients. b) Repetitive responses: two or more consecutive sharp-and-slow-wave complexes, each resembling the initial early response. Repetitive responses were seen only when stimulating the frontal lobes of 10 frontal patients. Among the 17 frontal patients, 13 had late responses exclusively in the epileptogenic frontal lobe, whereas only 3 showed them in both frontal lobes. Frontal late responses were associated with neuropathologic abnormalities, and complete resection of abnormal SPES areas was associated with good postsurgical seizure outcome.

Conclusions: Single-pulse electrical stimulation (SPES) could be an important additional investigation during presurgical assessment to identify frontal epileptogenicity. SPES can be useful in patients who have widespread or multiple epileptogenic areas, normal neuroimaging, or few seizures during telemetry.

Additional material related to this article can be found on the Neurology Web site. Go to www.neurology.org and scroll down the Table of Contents for the August 9 issue to find the title link for this article.

Funded by the Fund for Epilepsy, UK.

Disclosure: The authors report no conflicts of interest.

Received September 4, 2004. Accepted in final form April 18, 2005.

This article has been cited by other articles:

				D. Fabo, Z. Magloczky, L. Wittner, A. Pek, L. Eross, S. Czirjak, J. Vajda, A. Solyom, G. Rasonyi, A. Szucs, et al. Properties of in vivo interictal spike generation in the human subiculum Brain, February 1, 2008; 131(2): 485 - 499. [Abstract] [Full Text] [PDF]