Circulating immune complexes C3b and magnetic resonance imaging in temporal lobe epilepsy

Abstract EN

Background : Temporal lobe epilepsy (TLE) is a multifactorial disease often involving the hippocampus.

So far the etiology of the disease has remained elusive.

Neuroimaging studies using structural and functional techniques play an important role in the evaluation of patients with localization related epilepsy.

Magnetic resonance imaging (MRI) is an attractive tool to identify the presence and development of cerebral damage in patients with epilepsy as it is readily available, non invasive, and acceptable to the patients.

Aims: The present study aimed to investigate the involvement of the immune system in the epilepsy disorder through evaluating concentrations of circulating immune complexes-C3b (CIC-C3b) in patients with TLE and to relate the findings to the characteristics of seizure disorder.

Also, we aimed to assess magnetic resonance imaging (MRI) changes in patients with TLE and the relation of the findings to the concentrations of the immune parameter measured (CIC-C3b), the clinical characteristics of patients and the degree of seizure control.

Methods : The study included 50 children and adolescents (mean age 7.

07 ± 4.

5 years) with TLE and 30 clinically healthy control subjects.

Patients were diagnosed as TLE patients according to seizures' semiology and EEG findings.

Serum CIC-C3b was assayed in sera of patients and controls by enzyme linked immunosorbent essay technique.

A special MRI technique for visualization of the hippocampus was used to detect hiippocampal pathology in patients.

Results: Serum concentrations of CIC-C3b were significantly higher in patients than in controls (P=<0.01), especially so in uncontrolled patients.

A significant negative correlation was found between CIC-C3.b concentrations and the duration since last seizure.

CIC-C3b concentrations were not affected by the age or gender.

Also seizure duration and severity seemed no to have a significant effect on the measured marker.

M Rl findings of hippocampal pathology were found in 9 (18 %) of the patients, 6 of wish had evidence of showed high signal intensity in the hippocampus while 3 showed reduced hippocampal size of lateral ventricles No other significant differences in (age, sex, family history of epilepsy, past history of febrile convulsions, history of parents consanguinity, age of onset, disease duration, seizures severity, CIC-C3b concentrations and response to treatment) were found between patients with MRI findings suggestive of hippocampal pathology (MRI positive patients) and those with no MRI findings suggestive of such pathology( MRI negative ones).

It is noteworthy to mention that 31 patients (62 % of studied patients and 75.6 % of MRI positive patients) were controlled while only 10 patients (20% of studied patients and 24.4 % MRI negative patients) were uncontrolled.

Conclusion: The elevated concentrations of CIC-C3b in epileptic patients are not caused by the original pathology resulting in the epilepsy disorder itself, but it is a rather a temporary finding caused by immunological events taking place during a single seizure episode.

MRI is not to be overlooked as a diagnostic and prognostic tool in the management of TLE.