Abstracts

Rationale: Arachnoid cyst(AC)represents approximately 1% of intracranial space occupying lesions. This incidental finding many times raises the question whether there is any association between epilepsy and arachnoid cyst. The main objective of our study is to investigate the relationship between epilepsy location and concordance of arachnoid cysts on neuroimaging in children with epilepsy. It also aims to study the outcome of seizures in patients who underwent surgical intervention. Methods: After IRB approval, the neuroradiology database from 2000 to 2006 for patients with AC was reviewed for pediatric patients aged 18 years and below. From the list, children who had neuroimaging for evaluation of epilepsy were selected for our study. Patient’s demographics, clinical features, seizure semiology, EEG interictal and ictal findings were analyzed. Results: Fifty-five patients (45 MRI/10 CT, 34 males) with AC and epilepsy were found on approximately 7000 neuroimaging studies (0.8 %). Average seizure-onset age was 7 years (range 0-16). Associated findings included spasticity (21%), developmental delay (18%), headaches (7.2%), microcephaly (7.2), hydrocephalus (5.4%), ADHD (3.6%), scoliosis (1.8%), and macrocephaly (1.8%). AC was located in the middle cranial fossa (MCF) in 21 (40%) patients. Bilateral MCF arachnoid cysts were seen in (14%). AC was also found in the posterior fossa in 18 (34%), frontal lobe in 6 (11.3%), cavum velum interpositum 4 (7.5%), choroidal fissure in 2 (3.7%), and other locations (1-corpus callosum, 1-Interventricular). Cysts locations were not available for 2 patients. Co-existing neuroimaging findings with AC were seen in 26 (49%) patients. These include malformation of cortical development, thin corpus callosum, white matter abnormalities, venous angioma, pineal cyst, cerebellar changes, ventriculomegaly, hippocampal signal changes, encephalomalacia and oligoastrocytoma. EEG (51/55 patients) showed focal interictal epileptiform discharges (IED) (29%), generalized IED (29%), diffuse or focal slowing (15%) and was normal in 25%. Only one patient showed interictal and ictal EEG findings concordant with the localization of the AC. This patient also had malformation of cortical development in the MRI. Five patients underwent surgical intervention. Fenestration of AC was done in three patients and two patients underwent fenestration and epilepsy surgery. Good seizure control was attained for a patient who underwent epilepsy surgery along with fenestration of large arachnoid cyst. Isolated fenestration of AC had no impact on seizure control. Conclusions: In most patients with AC and epilepsy, no association between the two was seen. In our small cohort of epilepsy patients who underwent surgical intervention for AC, patients without dual pathology had a significant improvement in seizure control. Neurosurgical evaluation is considered in cases with significant symptoms or signs of increased ICP, progressive neurological dysfunction, intractable epilepsy and cysts with significant midline shift.