Original ArticlesThe Practical Utility of Performing Peri-Ictal SPECT in the Evaluation of Children With Partial Epilepsy
Introduction
Peri-ictal single-photon emission computed tomography (SPECT) involves the intravenous injection of a radionuclide, such as technetium-99m hexamethylpropylene amine oxime (99mTc-HmPAO) or technetium-99m-ethyl cysteinate diethylester (99mTc-ECD), which has a rapid first-pass brain uptake with minimal redistribution. The resultant image provides a “snapshot” of the peri-ictal cerebral blood flow pattern that was present within 30-60 seconds of the injection 1, 2. Partial seizures have long been known to be associated with a transient focal increase in cerebral blood in the region of the seizure focus 3, 4, 5, 6, and this technique is becoming established as a useful test in the presurgical evaluation of partial epilepsy in adults, particularly in the lateralization of temporal lobe seizures 2, 7, 8, 9, 10, 11. More recently, extratemporal seizures have also been reported to be successfully localized with ictal SPECT 12, 13, 14, 15, 16.
However, ictal SPECT has been less well studied in children 12, 17, 18, 19, 20, 21. Obtaining an ictal injection and acquiring SPECT images pose a greater challenge in pediatric than in adult patients, and few reports have specifically addressed the practical aspects of this technique in children. The purpose of this report is to review our experience with peri-ictal SPECT in pediatric patients, especially regarding the success rate of performing an ictal injection and of acquiring satisfactory images, as well as the sensitivity and specificity of the SPECT localization.
Section snippets
Patients
All patients less than 18 years of age admitted to the Epilepsy Monitoring Unit at Mayo Medical Center, Rochester, from June 1993 to April 1997 with the presumed diagnosis of partial epilepsy, who had been scheduled to have a peri-ictal SPECT performed, were retrospectively identified. We determined the proportion of these patients in whom a successful peri-ictal injection was obtained and then the proportion of these that had a true ictal injection performed (i.e., while there was continuing
Clinical Information and Seizure Timing
Medical records were abstracted for demographic and clinical information. Seizure length and timing of injection were assessed by review of videotape of the injected seizures. The reviewer did not know the patients’ clinical history, the results of the SPECT imaging, the electroencephalogram (EEG) recordings, the magnetic resonance imaging (MRI) findings, and the surgical outcome. Seizure onset was considered to be the time of earliest indication of a warning (verbalized or pushing the call
Demographic and SPECT Injection Information
During the study period, ictal SPECT was scheduled for 71 admissions involving 59 pediatric patients. The mean age of these patients was 10 years 11 months, with a range of 1 year 6 months to 17 years (20.3%, 0-6 years; 40.7%, 7-12 years; and 40%, 13-17 years). Thirty-two were male, and 27 were female. A peri-ictal SPECT injection was successfully obtained during 48 (67.6%) of these admissions on 43 (72.9%) of the patients. The mean length of hospital stay was significantly longer for the
Discussion
This study represents the largest consecutive series of peri-ictal SPECT in children with partial epilepsy. More important, it is the first report that has specifically investigated the practical utility of performing peri-ictal SPECT in pediatric patients. Although a few studies have evaluated the sensitivity and specificity of peri-ictal SPECT images in selected groups of children 12, 17, 18, 19, 20, 21, none has reported their overall success rate of accomplishing a peri-ictal injection and
Acknowledgements
The authors acknowledge Timothy Hardyman, Division of Nuclear Medicine, Mayo Clinic, for technical assistance and advice and Dennis Hanson and Dr. Richard Robb, PhD, Department of Biomedical Imaging, for providing computer software and hardware support.
References (28)
- et al.
Oxygen availability and blood flow in the temporal lobes during spontaneous epileptic seizures in man
Brain Res
(1976) - et al.
Assessing changes over time in temporal lobectomyoutcome by scoring seizure frequency
Epilepsy Res
(1997) Neuroimaging in the evaluation of children and adolescents with intractable epilepsy: I. Magnetic resonance imaging and the substrates of epilepsy
Pediatr Neurol
(1997)- et al.
Localization of epileptic foci using SPECT
- et al.
Single photon emission computed tomography
Neuroimaging Clin N Am
(1995) An address on the origin and seat of epileptic disturbance
Br Med J
(1892)- et al.
Regional cerebral blood flow in focal cortical epilepsy
Arch Neurol
(1976) - et al.
Cerebral blood flow during induced epileptiform seizures in animal and man
J Neurophysiol
(1939) - et al.
Dystonia, clinical lateralisation and regional cerebral blood flow changes in temporal lobe seizures
Neurology
(1992) - et al.
Postictal switch in blood flow distribution and temporal lobe seizures
J Neurol Neurosurg Psychiatry
(1992)
The relative contributions of MRI, SPECT, and PET imaging in epilepsy
Epilepsia
Utility of ictal SPECTperi-ictal, post-ictal
Acta Neurol Scand
Comparison of ictal SPECT and interictal PET in the presurgical evaluation of temporal lobe epilepsy
Ann Neurol
Frontal lobe epilepsyclinical seizure characteristics and localization with ictal 99mTc-HMPAO SPECT
Neurology
Cited by (54)
Seizure Freedom in Children with Pathology-Confirmed Focal Cortical Dysplasia
2015, Pediatric NeurologySPECT (Single photon emission computed tomography) in pediatrics
2013, Handbook of Clinical NeurologyExtratemporal epilepsies
2012, Handbook of Clinical NeurologySISCOM in children with tuberous sclerosis complex-related epilepsy
2011, Pediatric NeurologyCitation Excerpt :Developmental delay was classified as absent if the estimated developmental quotient was greater than 70, as mild if the estimated developmental quotient was between 50 and 70, and as moderate to severe if the estimated developmental quotient was less than 50. The ictal single-photon emission computed tomography injection of technetium-99 radioisotope was performed by trained EEG technicians during the prolonged scalp EEG monitoring as previously described [38,40-43]. An interictal single-photon emission computed tomography study was performed after the patient had been seizure-free for at least 24 hours.
Structural and functional imaging: Particularities in children
2008, Neurochirurgie