Abstracts

Rationale: Previous studies have reported a 3-7% incidence of epilepsy in neurofibromatosis type 1. The underlying causative lesion is often a supratentorial non-optic glioma tumor or unknown. To our knowledge only one case of mesial temporal sclerosis has been reported concurrent with NF 1. Our goal was to identify the characteristics and the associated potentially causative MRI lesions in patients with epilepsy and NF 1. Methods: We performed a retrospective review of 175 consecutive patients seen in the NF clinic at Duke University over a period of 1 year ending in November 2010. Two groups of patients were compared - those who manifested seizures at some time in their history (30 patients, 27 of whom had MRIs) and those who did not (145 patients, 110 with MRIs). Additional analyses of the clinical findings of the seizure group were also performed. Results: 27/175 had epilepsy (15.4%) and 3 additional patients had provoked seizures only; 2 had febrile seizures and 1 had a single postoperative non-febrile seizure. In the epilepsy group mean age at first seizure (available in 23 of them) was 6.6 years (range = 1 month - 30 yrs). The age breakdown was: 0-12 months (6/23), 13-36 months (4/23), 3-10 years (7/23), 11-18 years (4/23), 18+ years (2/23, p = 0.51). In the 27 epilepsy patients focal (complex partial) seizures were the most common seizure type (12/27, 44.4 %), followed by absences (6/27, 22.2%), generalized tonic-clonic (3/27, 11.1%), simple partial (2/27, 7.4%), and tonic seizure (1/27, 3.7%). 3/27 patients had the MRI findings of mesial temporal sclerosis (MTS, 1/3) or MTS-like findings (increased signal in the hippocampus and medial temporal lobe without associated volume loss, 2/3), Only 1/110 non-seizure patients had MRI findings of MTS (p-value = 0.008, X2= 7.019). None of the 3 MTS patients had history of febrile seizures. 8/27 patients with epilepsy and 11/101 without epilepsy had supratentorial non-optic glioma tumors likely to represent the epileptogenic lesion (p = 0.0126). Of the 27 epilepsy patients, 1 had an infarct, 1 a malformation of cortical development, and 9 (33.35%) had neurofibromatosis bright objects (NBOs). 65/110 (50.7%) patients without epilepsy had NBOs (p = 0.016, X2 = 5.79, indicating a negative relation of epilepsy and NBOs). Conclusions: In our series of consecutive neurofibromatosis patients we demonstrated the novel finding of a statistically significant association with MTS related epilepsy. We also demonstrated a positive association of NF related epilepsy with tumors and no association with NBOs. In fact, NBOs appeared to be negatively correlated with the occurrence of epilepsy.