The quest of cavum septi pellucidi: obscure chance event discovery or the result of some encoded disturbance? Developmental cerebral dysplasias, cavum septi pellucidi and epilepsy: clinical, MRI and electrophysiological study.

OBJECTIVES: Developmental cerebral dysplasias are frequent causes of epilepsy. The early stage of gestation, mainly the period of neural crest separation and neuroblast migration (disturbance of midline structures, heterotopias, cortical dysplasias and disturbance of the ventricular and vascular formation), may be considered as a cause of serious cerebral dysplasia. The aim of the study was focused on frequent simultaneous occurrences of epileptic seizures and the defect or abnormality of the ventricular system - cavum septi pellucidi (CSP).

MATERIAL AND METHOD: In our study the clinical symptoms, EEG and somatosensory evoked potentials (SEP's) following median nerve stimulation and MRI pictures in the group of patients with CSP (n= 35), were analyzed. In the SEP analysis, a control group of normal, healthy volunteers (n = 40) and a group of age matched patients with epileptic seizures of different origin, without structural lesions evident on MRI (n=21), were used.

RESULTS: Analysis of the patient population with CSP (CSP was confirmed by MRI) showed that approximately in 2/3 cases, different types of cranio-cerebral dysplasias were evident on MRI. More than 2/3 of the patients with CSP showed epilepsy and an abnormal EEG record, however, focal EEG changes were seen more frequently in the group of patients with epilepsy without CSP, than in patients with CSP. The SEP's in patients with CSP showed a statistically significant prolongation of latency of thalamic P15 waves, however these changes were not present in the group of patients with epilepsy of a different origin.

CONCLUSIONS: In a group of patients with CSP, dysplastic MRI changes, together with the prolongation of thalamic wave latencies according SEP, were examined. These clinical symptoms may be considered the result of disturbances of early gestation and of lesions of midline structures. CSP became an interesting model opportunity for us, and allowed for the clinical, MRI and electrophysiological examination of developmental cerebral dysplasias. We believe that there is an important role for septal and diencephalic midline structures in cerebral electrogenesis, and possibly in the origin of epileptic seizures too.

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