Abstracts

Rationale: Sialidosis (OMIM# 256550) is a lysosomal storage disorder caused by a deficiency of the enzyme ?-N-acetyl neuraminidase resulting from mutations in the NEU1 gene. Its prevalence is estimated at 0.02-0.05/100,000 live births. We report status epilepticus (S.E.) occurring in a patient with sialidosis type II with good response to topiramate. Methods: Clinical observations of a patient. Results: A 16-year-old female patient weighing 30 kg was admitted to our emergency unit due to S.E. She was in optimized treatment with valproic acid 30 mg/kg/day, primidone 10 mg/kg/day, and clobazan 0.20 mg/kg/day. She was still presenting weekly myoclonic seizures when she developed S.E. She was diagnosed with sialidosis type II when she was 7 years old. The patient presented delay in neuropsychological development, short stature, and mild dysostosis multiplex. In the emergency room, we observed the occurrence of seizures about every five to ten minutes. Continuous intravenous midazolam was started and increased to 0.4 mg/kg/hour without any benefit. Extensive evaluation for possible causes of S.E. other than sialidosis was negative. MRI revealed only mild cerebellar and brain atrophy. Seizures, lasting up to 30 seconds, were provoked by tactile stimuli and were characterized by an extensor tonic spasm in the upper and lower extremities followed by tonic arm flexion and facial mimic muscle contraction. These movements were followed by several massive generalized myoclonic jerks. Ictal EEG showed a train of 15 Hz rhythmic spikes, predominantly in frontal regions. This rhythm rapidly evolved to a polyspike-slow wave complex with fast fading away and was then replaced by a generalized depression of background activity. Valproic acid was increased to 75 mg/kg/day without benefit. Next day we introduced topiramate 2.5 mg/kg/day. There was an evident improvement in seizure control and about 8 hours later she was seizure free. Conclusions: Treatments approved by the United States Food and Drugs Administration (F.D.A.) for the treatment of S.E. are phenytoin, bezodiazepines, barbiturates, and propofol. However, treatment of S.E. in myoclonic progressive epilepsies has not been completely established. Midazolam was not effective in suppressing seizures in the present patient. We could have opted for the use of propofol or barbiturates; however, the patient was already taking barbiturates and had not improved with previous dosage increases. Propofol would be useful during the acute phase but is not an option for long-term seizure control. Phenytoin could aggravate myoclonic seizures, the type of seizure affecting our patient. Newer agents for S.E. treatment might be an interesting option. These drugs are also useful as antiepileptic drugs after S.E. We tried topiramate and it worked. Based on our observations, we suggest that topiramate may be used for the treatment of both S.E. and seizures observed in patients with sialidosis or other forms of progressive myoclonic epilepsies. Further studies are necessary to confirm our clinical observations. This work was supported by CNPq.