Abstracts

Rationale: While vagal nerve stimulation has been widely used to treat epilepsy, other cranial nerve stimulation methods, specifically trigeminal nerve stimulation, have been successful in rodent models of epilepsy. Trigeminal manipulations and pilot studies with transcutaneous electrical stimulation have explored the possibility that trigeminal nerve stimulation in humans may benefit refractory epilepsy. One of the authors (MC) has experience accessing the trigeminal nerve in a novel manner to place a stimulation system for the mandibular branch of the trigeminal (V3) nerve for patients with trigeminal neuralgia. Here we present what we believe to be the first such report of a surgically implanted device for trigeminal nerve stimulation in human epilepsy. Methods: The patient is a 40-year-old woman with medically refractory epilepsy. Her seizures have involved clustered nocturnal events early in sleep of dystonic posturing of the right arm and leg with occasional generalization, often preceded by a sensory change in the face. They had been nightly with perimenstrual worsening despite three AEDs. MRI revealed a focal cortical dysplasia in the left precentral gyrus. Prior surgical work-up included subdural grid LTM. Seizure onsets involved the left primary sensory cortex. She underwent multiple subpial transections of the sensory cortex with transient abolition of seizures. Due to continued refractory seizures, she underwent percutaneous placement of bilateral Medtronic (model 37712) subcompact electrodes that pass immediately adjacent to the mandibular branch of V3. The patient had her usual seizures until the initiation of stimulation, 8 days post-op, with continuous mode bilateral stimulation at 100 Hz with amplitude adjusted to sub-threshold of sensation. The patient s seizure frequency, seizure types, and side effect burden have been monitored in this unblinded pilot. Results: Lead placement was well tolerated. Postoperative local pain was manageable and improved over time. Tongue tingling and enhanced salivation were reported as mild side effects. Seizures lessened in frequency and in severity within days of activation. Seizures became every 2-3 days (instead of daily), and changed to complex partial events of staring only, though continued to arise from sleep. Seizures still clustered at 0-3 per night when present. Conclusions: Direct bilateral stimulation of the trigeminal nerve is feasible and well-tolerated in a patient with refractory epilepsy, just as in those with trigeminal neuralgia. Side effects were mild and tolerable. Seizures were notably diminished both in number and in severity. This percutaneous technique presents advantages to vagal nerve stimulation and transcutaneous trigeminal stimulation. Leads are easily placed and removed, in comparison with vagal nerve stimulation. They are cosmetically inconspicuous and likely will permit lower current settings and greater durability than transcutaneous methods. This report will likely stimulate a broader evaluation of the acceptability and applicability of this method in refractory epilepsy.