Surgery for Intractable Infantile Spasms: Neuroimaging Perspectives

Abstract

Twenty-three infants and children underwent cortical resection (n = 15) or hemispherectomy (n = 8) for intractable infantile spasms. Infantile spasms were present at the time of surgery in 17 of the 23 patients; in six, spasms had evolved to other seizure types during surgical evaluation. Children with a remote history of infantile spasms were excluded from this study. Focal or hemispheric lesions were identified by magnetic resonance imaging in seven children; an additional two showed focal atrophy without a discrete lesion. Positron emission tomography (PET) showed lateralized or localized abnormalities of cerebral glucose utilization in all patients; in 14, PET was the only neuroimaging modality to identify the epileptogenic cortex. When this occurred, neuropathological examination of resected brain tissue typically showed malformative and dysplastic cortical lesions. Focal interictal and/or ictal electrographic abnormalities were present in all patients, and corresponded well with localization from neuroimaging. None of the patients were subjected to chronic invasive electrographic monitoring with intracranial electrodes. At follow-up (range 4-67 months; mean 28.3 months), 15 children were seizure-free, three had 90% seizure control, one had 75% seizure control, and four failed to benefit from surgery with respect to seizure frequency.

A systematic review of the effectiveness and cost-effectiveness of neuroimaging assessments used to visualise the seizure focus in people with refractory epilepsy being considered for surgery

“…The combination of MRI and CT, however, correctly localised only 17% of patients; the majority of scans were non-localising with 21% partially localised and no incorrectly localised scans. 38 NIRS localised a seizure focus in all patients, with 28 of the 29 scans being correctly localised and one incorrectly localised.…”

“…A number of other studies reported one or more evaluations for which it was not possible to calculate an RR, but other evaluations that were included. 29,38,40,62 None of the studies included in this section included an appropriate patient spectrum. Twenty-four studies defined a good outcome following surgery as Engel class I or II and the remaining eight studies defined a good outcome as being seizure free following surgery.…”

“…34,38,54,112 Three evaluated combinations of different tests: one a combination of MRI, CT and SPECT for the localisation of the epileptic focus, 54 the second a combination of MRS and MRI for the lateralisation of the epileptic focus in patients with TLE 34 and the third a combination of MRI and CT in the localisation of the epileptic focus in children with a recent history of infantile spasms. 38 The final study evaluated NIRS in the lateralisation of the epileptic focus. 112 Only the study evaluating the combination of MRI and CT looked at the association of the imaging tests evaluated with outcome following surgery.…”

“…34 The fourth study used site of surgery as the reference standard. 38 Interictal EEG was considered an inappropriate reference standard. Partial verification bias did not appear to be a problem in any of these studies.…”

The American Epilepsy Society: An Historic Perspective on 50 Years of Advances in Research

“…Some children with infantile spasms show areas of regional hypometabolism on PET, and surgical resection of these areas has been associated with dramatic improvement in some instances (56). PET is also a useful research tool for performing in vivo neuropharmacologic studies in patients with epilepsy, and the effects of AEDs (57), localized upregulation of opiate receptors (58), and locally decreased benzodiazepine receptors (59) have been demonstrated.…”