Neuromodulation for Epilepsy: How Vagal Nerve Stimulation and Deep Brain Stimulation Work

The best candidates are cases with good concordance between where the seizure semiology points, what the MRI shows, and what the EEG confirms, for example a right temporal lobe abnormality on MRI matching a right temporal EEG focus. Temporal lobe epilepsy accounts for 70 to 80% of these good-responder cases, typically treated with temporal lobectomy along with amygdalohippocampectomy. Teenagers can absolutely undergo the surgery, but medical management is always tried first.

Sodium valproate and levetiracetam both cover a broad spectrum and rank as the top two choices for most epilepsy types, including generalised tonic-clonic and atonic seizures. For focal seizures with secondary generalisation, carbamazepine is slightly preferred, though sodium valproate also works well. Lacosamide is a newer add-on drug, used alongside a first-line drug rather than as initial therapy. Perampanel is particularly useful when the epilepsy is related to a brain tumour or damaged brain tissue.

No, not at this centre. In neurosurgery, robotic assistance is currently limited to placing spine screws. No brain surgery is done with a robot here, though other centres may use it differently.

The drugs the patient was already on before surgery are continued unchanged for the first 10 to 15 days. After that, one drug is withdrawn at a time, slowly, rather than stopping everything at once. The patient is kept on at least one drug for about a year while seizure-free, and full withdrawal is only considered around the two-year mark, since these are patients who were having seizures despite medication before the operation.

The exact mechanism is not fully understood, but the proposed explanation is that it is a parasympathetic stimulation. Stimulating the vagus nerve sends signals back to the brain, and the brain's electrical activity is reduced as a result. Deep brain stimulation works on a related principle: stimulating the anterior thalamic nucleus also reduces the spread of epileptic activity.

The right vagus nerve supplies the heart's SA node, so stimulation is placed on the left vagus nerve to avoid affecting heart rhythm.

Dr. Rattnani reports a 70 to 80% success rate.

The anterior thalamic nucleus, referred to as the ATN, which differs from the subthalamic nucleus and globus pallidus targets used for Parkinson's disease and essential tremor.

Essential tremor, Parkinson's disease, dystonia, obsessive-compulsive disorder and epilepsy.

Patients whose MRI shows no lesion to resect and no clear structure to disconnect, but who remain uncontrolled on antiepileptic medication.