Infantile spasms with predominantly unilateral cerebral abnormalities

Cortical thickness reduction of normal appearing cortex in patients with polymicrogyria

OBJECTIVE

To examine cortical thickness and volumetric changes in the cortex of patients with polymicrogyria, using an automated image analysis algorithm.

METHODS

Cortical thickness of patients with polymicrogyria was measured using magnetic resonance imaging (MRI) cortical surface-based analysis and compared with age- and sex-matched healthy subjects. We studied 3 patients with disorder of cortical development (DCD), classified as polymicrogyria, and 15 controls. Two experienced neuroradiologists performed a conventional visual assessment of the MRIs. The same data were analyzed using an automated algorithm for tissue segmentation and classification. Group and individual average maps of cortical thickness differences were produced by cortical surface-based statistical analysis.

RESULTS

Patients with polymicrogyria showed increased thickness of the cortex in the same areas identified as abnormal by radiologists. We also identified a reduction in the volume and thickness of cortex within additional areas of apparently normal cortex relative to controls.

CONCLUSIONS

Our findings indicate that there may be regions of reduced cortical thickness, which appear normal from radiological analysis, in the cortex of patients with polymicrogyria. This finding suggests that alterations in neuronal migration may have an impact in the cortical formation of the cortical areas that are visually normal. These areas are associated or occur concurrently with polymicrogyria.

Role of subcortical structures in the pathogenesis of infantile spasms: what are possible subcortical mediators?

Infantile spasms present a constellation of symptoms and laboratory findings that suggest a role of subcortical circuits in the pathogenesis of this illness. The clinical features of spasms and the influence of subcortical circuits in the regulation of the electroencephologram, along with frequent abnormalities in subcortical structure and functional anatomy, brain stem electrophysiology, sleep regulation, and subcortical neurotransmitter levels, point to the importance of subcortical circuits in the generation of spasms. Furthermore, laboratory evidence shows that modulation of subcortical nuclei may attenuate and ameliorate seizures. We review clinical evidence indicating abnormal function in subcortical circuits and present a hypothesis that the development of infantile spasms requires dysfunction in both cortical and subcortical circuits. The confluence of evidence suggesting a role of subcortical structures in the origin of spasms and laboratory data indicating an anticonvulsant role on some subcortical nuclei raise the possibility of novel approaches to the treatment of infantile spasms.

Treatment of infantile spasms with zonisamide

We determined the efficacy of and tolerability to zonisamide (ZNS) in newly diagnosed patients with infantile spasms. ZNS, 4-20 mg/kg per day, was introduced as an add-on therapy or monotherapy in 27 children with infantile spasms (cryptogenic, 2; symptomatic, 25). The dosage was initially 2-4 mg/kg per day, and then was increased by 2-5 mg/kg every 2-4 days until the seizures disappeared. Nine (33.3%) out of the 27 patients who were administered ZNS exhibited the disappearance of seizures. ZNS was effective in all the cryptogenic cases and seven (28.0%) of the symptomatic cases. The effective daily doses were 5-12.5 mg/kg (mean, 7.8 mg/kg), and the daily dosages were 40-100 mg (mean, 61.1 mg). The steady-state plasma ZNS concentrations were almost within the therapeutic range. The mean time interval between the start of ZNS therapy and the seizure disappearance was 5.0 days. Six (75.0%) of eight effective cases, the exception being one for whom EEG was not performed after the therapy, showed the disappearance of hypsarrhythmia. The recurrence of seizures were observed in four of the nine cases. No adverse reaction to ZNS was noted in any patient. In conclusion, ZNS treatment is considered to be worthwhile trying, for early stage therapy for infantile spasms.

Neuroradiologic aspects of West syndrome

Cranial computed tomography (CT) or magnetic resonance imaging (MRI), or both, of 143 patients with West syndrome were retrospectively reviewed. Twenty-four children had normal CT scans. The most striking findings on pathologic scans were cerebral atrophy, ventricular enlargement, and encephalomalacia. Of 78 children who underwent MRI, 14 had normal scans. Cerebral malformations, cerebral atrophy, and delayed myelination were the most common pathologic findings and were observed in 25, 20, and 16 of the cases, respectively. MRI was found to be more informative in 21 of the 27 patients who underwent both neuroimaging methods. In fact, in two patients with normal CT scans, MRI revealed delayed myelination and hyperintensity of the hippocampal area on T2-weighted images in one and increased intensity of basal ganglia on T1-weighted images in the other. On the basis of all data, four patients were classified as cryptogenic and 126 as symptomatic. The most frequent etiologic factors were perinatal asphyxia, cerebral malformations, and infections, encountered in 34, 25, and 24 of the children, respectively. Twenty-one cases could be classified solely on the basis of the data obtained with neuroimaging modalities. The data confirm and provide additional details of the ways in which neuroimaging, especially MRI, is useful in distinguishing between cryptogenic and symptomatic cases of West syndrome.

Recent advances and some problems in the delineation of epileptic syndromes in children

The current International Classification of Epilepsies and Epileptic Syndromes has classified a number of age-related epileptic syndromes in children, but some of these entities have not been well delineated and many syndromes not included in the International Classification have been proposed. This article is intended to supplement some of the currently listed childhood epileptic syndromes, discuss certain problems with the classification system, and review some of the proposed pediatric syndromes.