White matter density is increased in patients with hypothalamic hamartoma and multiple seizure types.

Many patients with hypothalamic hamartomas present in infancy with gelastic seizures of subcortical origin, but later develop additional seizure types, including complex partial, tonic, and generalized tonic-clonic seizures. The basic cellular mechanisms responsible for this evolution in seizure types are unknown. Using voxel-based morphometry of T1 weighted MRI scans we compared eight patients with only gelastic seizures with 16 age-matched patients with multiple seizure types and found significantly greater white matter density in the temporal lobes and cerebellum in those with multiple seizure types. This suggests that increased white matter density, perhaps resulting from maturational changes and resulting in increased brain connectivity, is associated with a higher likelihood of cortical involvement in epilepsy resulting from hypothalamic hamartoma.

Endoscopic resection of hypothalamic hamartomas for refractory symptomatic epilepsy.

BACKGROUND: Hypothalamic hamartomas (HHs), rare developmental abnormalities of the inferior hypothalamus, often cause refractory, symptomatic, mixed epilepsy, including gelastic seizures. We present 37 patients with HH who underwent transcortical transventricular endoscopic resection. METHODS: Between October 2003 and April 2005, 42 consecutive patients with refractory epilepsy who underwent endoscopic resection of HH were studied prospectively. The endoscope was held by an articulated pneumatic arm and tracked with a frameless stereotactic neuronavigation system. Data collection and follow-up were performed by personal interview. Five patients were excluded. The remaining 37 patients (22 males, 15 females; median age 11.8 years; range 8 months to 55 years) had frequent and usually multiple types of seizures. RESULTS: Postoperative MRI confirmed 100% resection of the HH from the hypothalamus in 12 patients. At last follow-up (median 21 months; range 13-28 months), 18 (48.6%) patients were seizure free. Seizures were reduced more than 90% in 26 patients (70.3%) and by 50% to 90% in 8 patients (21.6%). Overall, the mean postoperative stay was shorter in the endoscopic patients compared with our previously reported patients who underwent transcallosal resection (mean 4.1 days vs 7.7 days, respectively; p = 0.0006). The main complications were permanent short-term memory loss in 3 patients and small thalamic infarcts in 11 patients (asymptomatic in 9). CONCLUSIONS: Endoscopic resection of hypothalamic hamartoma (HH) is a safe and effective treatment for seizures. Its efficacy seems to be comparable to that of transcallosal resection of HH, but postoperative recovery time is significantly shorter.

Hypothalamic hamartomas: Correlation of MR imaging and spectroscopic findings with tumor glial content.

BACKGROUND AND PURPOSE: There is variability in the literature concerning the appearance and histology of hypothalamic hamartomas. This study correlates the MR imaging and proton MR spectroscopic properties of hypothalamic hamartomas with histopathologic findings. METHODS: Studies were performed with 3T and 1.5T scanners. Single voxel hamartoma spectra were acquired by using short-echo-time point-resolved spectroscopy sequences (PRESS). 2D PRESS chemical shift imaging (CSI) spectroscopic sequences were also obtained for comparison of tumor-derived spectra with normal gray matter of the amygdala. Sequences were used to compare choline (Cho), N-acetylaspartate (NAA), and myoinositol (mI) resonances by using a creatine (Cr) reference. Spectral ratios and T2 signal intensity ratios of the hamartomas were then compared with histopathologic findings. RESULTS: Data from single voxel spectroscopic sequences demonstrated a statistically significant decrease in NAA/Cr and an increase in mI/Cr ratios in tumor tissue when compared with values in normal gray matter of the amygdala. In addition, Cho/Cr ratios were also increased when compared with those in normal gray matter controls. Among the 14 hamartomas sampled, a spectrum of increased mI/Cr ratios was seen. Those tumors with markedly elevated mI/Cr demonstrated an increased glial component when compared with the remaining tumors. Increased glial component was also found to have a positive correlation with hyperintensity of lesions on T2-weighted images. CONCLUSION: We have identified a correlation between the glial/neuronal fraction as determined by histopathology and MR spectral and T2 hyperintensity variations among hypothalamic hamartomas.

Ganaxolone for treating intractable infantile spasms: a multicenter, open-label, add-on trial.

This is a multicenter, open-label, add-on trial, investigating the safety and efficacy of ganaxolone (GNX) in a population of children with refractory infantile spasms, or with continuing seizures after a prior history of infantile spasms. A total of 20 children aged 7 months to 7 years were enrolled in this dose-escalation study, after baseline seizure frequencies were established. Concomitant antiepilepsy drugs were maintained throughout the study period. The dose of GNX was progressively increased to 36 mg/kg/d (or to the maximally tolerated dose) over a period of 4 weeks, then maintained for 8 weeks before tapering and discontinuation. Seizure diaries were maintained by the families, and spasm frequency was compared with the baseline period. The occurrence of adverse events was clinically monitored, and global evaluations of seizure severity and response to treatment were obtained. A total of 16 of the 20 subjects completed the study, 15 of whom had refractory infantile spasms at the time of study enrollment. Spasm frequency was reduced by at least 50% in 33% of these subjects, with an additional 33% experiencing some improvement (25-50% reduction in spasm frequency). Ganaxolone was well tolerated, and adverse events attributed to GNX were generally mild. Ganaxolone was safe and effective in treating this group of refractory infantile spasms patients in an open-label, add-on trial. Further investigation with randomized, controlled study design is warranted.

Fumaric aciduria: clinical and imaging features.

Fumaric aciduria (fumaric acidemia, fumarase deficiency) is a rare inborn error of metabolism caused by deficient activity of fumarate hydratase, one of the constituent enzymes of the Krebs tricarboxylic acid cycle. We describe the clinical and imaging features of this disease arising from a consanguineous pedigree in 8 patients in the southwestern United States. Thirteen patients have been previously described in the medical literature. Our patients presented with an early infantile encephalopathy with profound developmental retardation and hypotonia, and most experienced seizures. Previously unreported characteristics described here include structural brain malformations, dysmorphic facial features, and neonatal polycythemia. Magnetic resonance imaging showed multiple abnormalities, including diffuse polymicrogyria, decreased cerebral white matter, large ventricles, and open opercula. Fumaric aciduria should be included in the differential diagnosis of inborn errors of metabolism that cause cerebral malformations and dysmorphic features. The possibility that inborn errors of energy metabolism may cause structural malformations deserves increased recognition.

Regional cerebral glucose metabolism in clinical subtypes of cerebral palsy.

Twenty-three children with 4 clinical subtypes of cerebral palsy were studied using 2-deoxy-2(18F)fluoro-D-glucose (FDG) and positron emission tomography (PET). Subtypes included spastic quadriparesis (N = 6), spastic diplegia (N = 4), infantile hemiplegia (N = 8), and choreoathetosis (N = 5). FDG-PET images were correlated with magnetic resonance imaging or computed tomography. Although the location of glucose metabolic abnormalities corresponded, in general, to abnormalities of brain structure demonstrated by structural imaging studies, the distribution of metabolic impairment almost invariably extended beyond the region of anatomic involvement. The following observations in specific subtypes of cerebral palsy were determined with FDG-PET: (1) In spastic diplegic patients, PET revealed focal areas of cortical hypometabolism in the absence of apparent structural abnormality; (2) A relatively normal pattern of cortical metabolism was observed in most patients with choreoathetoid cerebral palsy, despite marked hypometabolism in the thalamus and lenticular nuclei; and (3) In patients with infantile hemiplegia, FDG-PET disclosed symmetric cerebellar glucose metabolism with absence of crossed cerebellar hypometabolism (diaschisis). This finding is contrary to the typical persistence of crossed cerebellar diaschisis in adult patients with acquired cerebral lesions and suggests metabolic recovery due to developmental plasticity. The possibility that FDG-PET may be clinically useful in identifying the cerebral palsy patient with potential learning handicap and in the study of functional recovery or sparing following brain injury should be explored further.