[Contribution of diffusion tensor magnetic resonance imaging to the diagnosis of focal cortical dysplasias]

INTRODUCTION

Focal cortical dysplasias (FCD) are cortical malformations and, although they display typical characteristics in conventional magnetic resonance imaging (MRI), the precise determination of the epileptogenic zone remains a controversial issue. The less favourable progress during the post-operative period with respect to other symptomatic epilepsies could be explained by the existence of epileptogenic areas that do not show up in conventional MRI. Diffusion tensor imaging (DTI) is sensitive to subtle microstructural abnormalities, and fractional anisotropy, which is an indirect indicator, shows areas with reductions in the underlying white matter that go beyond the alterations detected with conventional MRI in isolated cases in previous works.

AIM

In this study we analyse the characteristics of fractional anisotropy in a series of patients with FCD in order to evaluate the contribution made to diagnosis by MRI by DTI.

SUBJECTS AND METHODS

Twenty-one controls and eleven patients with FCD that was visible in MRI were scanned, and clinical and imaging variables were both recorded. A visual analysis of the fractional anisotropy maps was conducted to search for asymmetries between hemispheres and biases in the clinical or structural MRI data.

RESULTS

Two females and nine males, aged 30 ± 9.7 years took part in the study; time to progression of epilepsy: 22 ± 9.3 years; average frequency of the seizures: 3/month (range: 0.16-8/month). All of them showed inter-hemispheric asymmetries, which went beyond the structural limits of FCD in the case of 10 of the patients (90%). None of the controls displayed asymmetries in the fractional anisotropy. No significant relation was found with the variables that were compared.

CONCLUSIONS

Further studies need to be conducted with larger numbers of patients in order to evaluate the usefulness of DTI in defining the location and extension of the epileptogenic zone in this population.

Clinical spectrum and difficulties in management of hypothalamic hamartoma in a developing country

AIM

We describe the clinical features, treatment and prognosis in a series of patients with epilepsy secondary to hypothalamic hamarthomas (HH) in a developing country.

MATERIALS AND METHODS

Eight patients with epilepsy and HH were included between 1997 and 2006. We analyzed gender, age, age at seizure onset (ASO), seizure types (ST), mental retardation (MR), precocious puberty (PP), electroencephalogram (EEG)-magnetic resonance imaging (MRI) features and response to treatment.

RESULTS

Mean age 25.1 years, 2/6 female/male, none had PP, ASO 4.5 years. Complex partial seizure were the most frequent (100%), mean similar to those seen in temporal (62.5%) or frontal lobe epilepsy (37.5%). Exactly 87.5% developed gelastic seizures (GS). Half of the patients showed MR. Mild-to-severe MR was associated with the presence of multiple ST including atonic and complex partial seizures with frontal semiology. Interictal EEG was abnormal in 87.5% patients. Video EEG was performed in three cases with unspecific findings. HH were small and sessile in seven patients whereas large and pedunculated in one. All patients were refractory to medical treatment. In five, an additional procedure was performed without any significant improvement.

CONCLUSION

These series show the heterogeneous spectrum of this entity and the difficulties in its treatment in a developing country.