Abstracts

Rationale: Iso-dicentric chromosome 15 syndrome (idic 15) is a unique genetic syndrome with mental retardation, dysmorphism, autism, cardiac dysrhythmia, sudden death, and epilepsy (often LGS). Although patients have atonic seizures, to our knowledge corpus callosotomy (CC) has not been reported as a treatment specifically for idic 15-related LGS. The issue of "complete" versus staged callosal sectioning for idic 15-LGS also has not been addressed. Methods: We treated a 25 year-old woman with intractable epilepsy and idic 15 with CC. The patient developed clinical seizures at age 18. These were complex partial seizures, generalized convulsions, tonic seizures, and atonic seizures with falls. Her epilepsy was progressive and when most severe, she had up to 10 atonic seizures and multiple generalized convulsions daily. She had recurrent tachycardia not related to seizures. More than 7 "AED"s failed to control seizures. Vagal nerve stimulation (output 1.25 mA, signal on 30 sec / off 180 sec) for 1 year failed to produce a clear benefit. Preoperative EEG revealed background disorganization, diffuse slowing, spike-wave and polyspike-and-slow-wave discharges and atonic seizures with generalized voltage attenuation and evolving fast frequency activity. Preoperative MRI was normal. Preoperative echocardiography was normal; repeated ECGs revealed sinus tachycardia. Corpus callosotomy was performed under general anesthesia. The patient was not tachycardic during the procedure but was during the post-operative period. A stereotactically-guided greater than 3/4 sectioning of the callosum was performed. The patient remained on levetiracetam, topiramate, and valproate before, during and after the surgery. Results: Postoperatively, she was mute and profoundly hypokinetic, unable to follow commands, would not visually track, had apraxia of eye closure, and required comprehensive care and a PEG tube for feeding. This clinical state lasted more than 4 weeks. Post-operative EEG revealed diffuse and focal slowing, and rare focal sharp waves. Within 6 weeks, with daily rehabilitation, she regained the ability to walk and speak. Finally, more than 2 months after surgery, she was more alert than when at her prior baseline (without changes in her medications). All seizure types remitted. The patient was noted to occasionally slowly lose tone in her legs during rehabilitation but had no falls or loss of consciousness. Despite vigilant monitoring by staff and family, no definite seizures occurred since callosotomy. Conclusions: “Complete” CC is an appropriate treatment for LGS associated with idic 15. There are informal accounts of idic 15 patients who underwent anterior 1/3 CC and recovered quickly but had early seizure relapse. The risk of cardiac death during surgery should be mitigated with pre-operative cardiac evaluation. Corpus callosotomy for idic 15-related LGS should likely be an aggressive single-staged procedure; prolonged recovery is expected.