Abstracts

RATIONALE: Baclofen induced status epilepticus has been reported in a small number of case reports. The goal of our study was to investigate the incidence of status epilepticus in a series of 81 patients with multiple sclerosis (MS) treated with intrathecal baclofen.
METHODS: Data were obtained from the Mellen Center Intrathecal Baclofen Therapy Registry. The registry contains records of all patients since 1990 with a definite clinical diagnosis of MS who had an intrathecal baclofen pump implanted.
RESULTS: Eighty-one patients underwent implantation of a baclofen pump between October 1990 and January 2002. At the time of surgery, mean age was 49.9 +/- 7.4 years, and mean disease duration was 16.9 +/- 8.4 years. 78% were non-ambulatory. Mean baclofen rate on the most recent follow-up was 266.8 +/- 239.8 mcg/day. A total of 320 cumulative baclofen pump years were reviewed. Two out of 81 patients (2.4%) went into status epilepticus. Both patients had no previous seizures.
The first case was a 46 year old female with secondary progressive MS since 18 years. An intrathecal baclofen pump was implanted and started at a rate of 88 mcg/day. Three months after implantation, she presented with a prolonged episode of confusion and hypothermia lasting 7 days. EEG showed continuous slow, generalized sharp waves as well as generalized clinical and subclinical seizure at a frequency of 4-10 per hour. The baclofen pump was discontinued temporarily without improvement. She was treated with intravenous phenytoin, phenobarbital and later valproic acid with slow improvement over three weeks. Additionally, persistent high fever throughout the hospital stay was treated with IV antibiotics. MRI demonstrated MS-typical lesions and restricted cortical diffusion which resolved on follow-up. The patient remained seizure free on valproic acid during the remainder of hospital stay and was continued on 50 mcg/day intrathecal baclofen.
The second case was a 51 year old female with secondary progressive MS for 26 years. She became unresponsive immediately after baclofen pump implantation. Evaluation of the pump reservoir revealed that she had accidentally received a 10 fold (2050 mcg) of the programmed initial bolus. EEG monitoring demonstrated subclinical generalized seizures which resolved within 24 hours after discontinuation of the baclofen pump and treatment with IV fosphenytoin. On follow-up the patient remained seizure free on gabapentin and on intrathecal baclofen 100 mcg/day.
CONCLUSIONS: Intrathecal baclofen application bears a low but definite risk of status epilepticus. Whereas one case immediately responded to lowering of the baclofen dose, a relationship between status epilepticus and intrathecal baclofen remains unclear in our second case. None of both patients had a preexisting epilepsy. In both cases, additional aggravating factors (coexisting fever and overdose) may have precipitated status epilepticus.
[Supported by: This work was supported by Innovative Medizinische Forschung, WWU Münster (FoeKz. LO 610101) and NRW-Nachwuchsgruppe Kn2000, Federal Ministry of Education and Research (Foe.1KS9604/0), Interdisciplinary Center of Clinical Research Münster (IZKF Project NWG2).]