Cerebellar and subcortical blood flow abnormalities in children with partial epilepsy

Clinical features of epilepsy in patients with cerebellar structural abnormalities in a referral center

PURPOSE

The objective of this study was to describe epilepsy localization, clinical features and surgery outcome in patients with epilepsy and cerebellar structural abnormalities.

METHODS

We identified 10 patients with cerebellar lesions and epilepsy from our epilepsy database. Patients with only cerebellar atrophy were excluded. Medical records were reviewed for demographic data, seizure history, examination findings, EEG findings, epilepsy treatment and course. We reviewed imaging data for cerebellar structural findings, as well as cerebral abnormalities.

RESULTS

Out of 2288 epilepsy patients in the database, 10 had epilepsy and cerebellar structural abnormalities other than atrophy. Their ages ranged from 26 to 52 years. The most common cerebellar malformations included Dandy-Walker malformation, cerebellar tumors and posterior fossa arachnoid cyst. Epilepsy was classified as generalized in one patient. Nine patients had focal epilepsy: the localization was temporal in five, frontal in one, occipital in one, and unclassified in two. A cerebral structural abnormality considered responsible for epilepsy was identified in six patients; four had hippocampal sclerosis, one had a hippocampal malformation, and one had a temporal pole cortical malformation. Presurgical evaluation was done in six patients. Surgery was performed in five, with excellent outcome in four.

CONCLUSION

In this small series, epilepsy associated with cerebellar malformations was usually focal, most often with a temporal lobe focus. The cerebellar lesions did not adversely affect surgical success.

Developmental changes of cortical and cerebellar motor control: a clinical positron emission tomography study with children and adults

Functional neuroimaging data regarding the development of motor organization in normal children and adolescents are virtually unavailable because of ethical concerns. As an alternative approach, we studied child and adult lesion patients, focusing on movement of the hand ipsilateral to the lesion and on brain activations in the contralesional hemisphere. [15O]-water positron emission tomography was performed during rest and sequential finger-thumb tapping in 10 children (aged 6 to 14 years) and 15 adults (aged 18 to 74 years) with unilateral lesion. We expected more distinct activation/deactivation patterns during movement in adults than in children. While there were no group differences in activation of primary and secondary motor cortices, deactivations in nonmotor cortex were significantly more pronounced in adults than in children. This indirectly supports our hypothesis of developmental focalization of cerebral motor control. Activations in the cerebellum and vermis were significantly stronger in the adults than in the children, possibly reflecting normal developmental patterns.

Asymmetries of benzodiazepine receptor binding potential in the inferior medial temporal lobe and cerebellum detected with 123I-iomazenil SPECT in comparison with 99mTc-HMPAO SPECT in patients with partial epilepsy

We examined the relation between regional 123I-iomazenil (IMZ) parameters and cerebral blood flow (CBF) to evaluate the difference between the quantitative parameters of IMZ and the CBF in detecting epileptic abnormality. Seventeen patients with unilateral partial epilepsy were subjected to 99mTc-hexamethylpropylene amine oxime (HMPAO) SPECT, and early and delayed IMZ SPECT. Then we quantitatively obtained the blood-to-brain transfer constants (K1) and binding potentials (BP) for nine regions of interest, and the regional CBF was also by using the simple angiographic method. From our data, significant asymmetries of BP in the inferior medial temporal lobe and cerebellum were shown and may be related to a remote effect such as crossed cerebellar diaschisis. In conclusion, the asymmetry of BP with iomazenil SPECT was demonstrated in patients with unilateral epilepsy that was not detectable by HMPAO SPECT.

Brain organization of language after early unilateral lesion: a PET study

Neuropsychological studies suggest that good long-term language outcome is possible following extensive early left-hemisphere damage. We explored the brain organization for language in children with early unilateral lesion, using [15O]-water PET. In 12 patients with left lesion (LL) and 9 patients with right lesion (RL), cerebral blood flow changes during listening to sentences and repetition were studied. A rightward shift of language activations in the LL group was found in perisylvian areas and multiple other, mostly temporo-parietal, regions. The hypothesis of intrahemispheric reorganization in the LL group found only limited support. The number of activated regions was overall greater in the RL group. Unexpected findings included a stronger subcortical and cerebellar language involvement in the RL group. We suggest that (a) early left lesion is associated with enhanced language participation of the right hemisphere in and beyond the classical language areas, and (b) postlesional effects are in part additive (recruitment of noncanonical areas), in part subtractive (functional depression in areas normally involved in language).