Abstracts

Rationale: Human hippocampus plays an essential role in epileptogenesis, being hippocampal sclerosis the most common disorder associated with temporal lobe epilepsy. Hippocampal malrotation (HiMAL) has been described in patients with epilepsy, isolated or associated with other developmental brain abnormalities, but also in non-epileptic subjects without obvious developmental anomalies. The aim of this study is to describe our series of patients with HiMAL and epilepsy.Methods: We studied all adult patients seen at the Epilepsy clinic during one year. We reviewed Brain MRI of all these patients to identify HiMAL. The examinations were performed on 1.5 T magnets, using the epilepsy protocol. The criteria for HiMAL included unilateral involvement and incomplete rotation of a hippocampus that is normal in size and signal intensity, but abnormally rounded or pyramidal in shape or with blurred internal structure. In addition, ipsilateral findings of a vertical collateral sulcus angle or skew or vertical position of long axis of the choroidal fissure were also noted. Results: We found 12 patients that presented hippocampal malrotation in MRi. Of these, 11 patients presented epilepsy and 1 patient was diagnosed of paroxismal non-epileptic seizures. Of the 11 patients with epilepsy, 4 were men and 7 women. Mean age at onset of epilepsy was 21.1 17.3, range 2-64. 4 patients had a positive family history for epilepsy. 1 patient had a positive history for febrile seizures and another patient presented a West syndrome during childhood. Mental state was normal in 10 patients except the patient diagnosed with West Syndrome who presented mild retardation. Of these 11 patients, 1 presented simplex partial seizures and 10 complex partial seizures, 3 of them with secondary generalization. Regarding to MRi findings, 1 case had bilateral malrotation, 1 right HiMAL and 9 left HiMAL and lastly 1 was associated with right hippocampus hypoplasia. In 9 of the 11 patients (82%), there were EEG correlate. 4 patients had ictal EEG recordings with seizure onset localized to the ipsilateral temporal lobe and in 5 patients interictal EEG discharges were ipsilateral to the HiMAL. Conclusions: We presented a series of 11 patients with temporal lobe epilepsy and HiMAL. In our series, 82% of patients had EEG correlate and we did not find any other possible aetiology for their seizures, so we hypothesized that HiMAL in our series could play an important role in temporal lobe epilepsy. There are few studies about the role of HiMAL in epilepsy with contradictory results. The prevalence of HiMAL in populations without seizures has also been studied and it has been concluded that is a rare finding in patients without epilepsy. This fact may also support the idea that HiMAL, if not the basic cause, but may be a sign of a developmental disorder and patients with HiMAL and epilepsy should undergo a more detailed examination.