Abstracts

Progressive myoclonic epilepsy (PME) is a neurologic syndrome with myoclonic and mixed seizures and progressive neurologic decline (usually cerebellar symptoms and dementia). PME is caused by a variety of diseases and represents a heterogeneous group. The seizures in PME are notoriously refractory to treatment. In 2001 we reported the early efficacy of zonisamide in the treatment of seizures in 8 patients with PME¹. With short term follow up, 6 had improved seizure control, 1 deteriorated, and 1 died. Five of the 6 responders had improved overall neurologic function. This study reports the longer term followup of the 7 surviving patients with PME. Seven patients (4 males, 3 females, mean age at diagnosis 5.6 y) treated with ZNS were followed for a mean of 3.63 years (range 3.33-4 years). Seizure types included myoclonic (6/7), tonic/tonic-clonic (4/7), drop (5/7), partial (3/7), and absence (2/7). Medications were adjusted as clinically indicated. Seizure control and overall neurologic function were assessed serially. Overall improved seizure control was sustained in 4 of the 6 early responders. 4/6 had [gt]90% decrease in myoclonic seizures; 2 /4 had [gt]90% decrease in tonic/tonic clonic seizures; 3/5 had [gt]90% decrease in drop seizures; 0/3 had a dramatic change in partial seizures. 2/2 had a complete resolution of absence seizures. Ataxia was better in 3, stable in 1 and worse in 3 patients. Cognitive function, while normal in none, improved in 3, was stable in 1 and deteriorated in 3. All 4 of the patients who had a sustained improvement in seizure control also had an apparent stabilization in neurologic function. Two patients who initially had an improvement in seizure control gradually deteriorated. The mean dosage of ZNS with short term follow up was 5.6 mg/kg/d (range 2-10) and longer term was 5.9 mg/kg/d (range 0.5-11.6). Mean number of AED short term was 2.7 (range 2-3) and at most recent follow up was 2.7 (range 2-4). ZNS was well tolerated and effective in treating seizures in 4 of 7 patients with PME. 4 of 6 early responders had a sustained response. The group of patients segregated into two groups: [ldquo]responders[rdquo] who had an apparent stabilization of neurologic function, and those who had deterioration in neurologic function in addition to poorly controlled seizures. Multiple different underlying defects caused the PME in this group of patients, and no [ldquo]definitive[rdquo] treatment of the underlying defect was given to any of the patients. This population suggests that stabilization of seizure control may be an important factor in the arrest of neurologic decline. Zonisamide appears to have an important role in the sustained control of seizures in some patients with PME.
ref: 1. Conry JA, Reigle SC, Gaillard WD, Pearl PL, Weinstein SL, Krohn K. Efficacy of zonisamide in progressive myoclonic epilepsy: A case series. Ann Neurol 2001; 5(3):S104.