Investigation into the mechanisms of vagus nerve stimulation for the treatment of intractable epilepsy, using 99mTC-HMPAO SPET brain images

Vagus nerve stimulation (VNS) has gained recognition as a treatment for refractory epilepsies where surgical treatment is not possible. While it appears that this treatment is effective in some patients, the mechanism of action is not clearly understood. The purpose of this study was to clarify find...

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Bibliographic Details
Published in:European journal of nuclear medicine and molecular imaging 2003-02, Vol.30 (2), p.301-305
Main Authors: BARNES, Anna, DUNCAN, Roderick, CHISHOLM, Jennifer A, LINDSAY, Kenneth, PATTERSON, James, WYPER, David
Format: Article
Language:English
Subjects:
Adult
Biological and medical sciences
Brain - blood supply
Brain - diagnostic imaging
Brain - physiopathology
Cerebrovascular Circulation
Chronic Disease
Electric Stimulation Therapy - methods
Epilepsy - diagnostic imaging
Epilepsy - physiopathology
Epilepsy - therapy
Female
Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy
Humans
Investigative techniques, diagnostic techniques (general aspects)
Limbic System - blood supply
Limbic System - diagnostic imaging
Limbic System - physiopathology
Male
Medical sciences
Nervous system
Nervous system (semeiology, syndromes)
Neurology
Radionuclide investigations
Radiopharmaceuticals
Technetium Tc 99m Exametazime
Tomography, Emission-Computed, Single-Photon - methods
Vagus Nerve - physiopathology
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Summary:Vagus nerve stimulation (VNS) has gained recognition as a treatment for refractory epilepsies where surgical treatment is not possible. While it appears that this treatment is effective in some patients, the mechanism of action is not clearly understood. The purpose of this study was to clarify findings of other positron emission tomography and single-photon emission tomography (SPET) investigations by measuring the acute effect of VNS on patients who have normal cerebral anatomy on magnetic resonance imaging and who have not previously been exposed to VNS. We investigated six subjects (two males and four females, mean age 29.5 years, range 21-39 years) with intractable epilepsy. One patient had primary generalised epilepsy causing generalised tonic-clonic seizures; the remaining five patients had localisation-related epilepsy causing complex partial seizures. SPET imaging was performed using 250 MBq of (99m)Tc-HMPAO and a four-scan paradigm - two with and two without stimulation. The stimulation began at VNS current levels of 0.25 mA and was increased according to the limit of patients' tolerance, usually defined by coughing or discomfort. The stimulating waveform was of continuous square wave pulses of 500 micro s duration at 30 Hz. Image analysis was by SPM99. Reduced perfusion during stimulation was observed in the ipsilateral brain stem, cingulate, amygdala and hippocampus and contralateral thalamus and cingulate. The study provides further evidence of the involvement of the limbic system in the action of vagal nerve stimulation.
ISSN:1619-7070
1619-7089
DOI:10.1007/s00259-002-1026-8