Question 1

With the limited tests available, how should doctors decide when to refer a patient with seizures to a neurosurgeon or a neurologist?

Dr. Dinesh Rattnani · Accepted Answer

If the MRI is normal, continue the standard antiepileptic drugs, such as levetiracetam, phenytoin and valproate, dosed by body weight. If the MRI shows an abnormality, such as mesial temporal lobe sclerosis (classically a difference of more than 10% in hippocampal volume between the right and left sides, which acts as a scar from which the epilepsy is generated), neurocysticercosis, a lesion such as a brain tumour particularly close to the motor cortex, or a head injury with a contusion, depressed fracture or healed scar irritating the cortex, these can be a source of seizures. With a normal MRI, manage conservatively with drugs at adequate dosage; most patients respond well. If seizures continue despite a minimum of two appropriately chosen drugs at their maximum allowed doses, refer the patient. If there is an abnormality in the brain, surgery can help.

Question 2

How do you prevent neurological complications from dissecting brain tissue during epilepsy surgery?

Dr. Dinesh Rattnani · Accepted Answer

Follow the basic principles: do not breach the arachnoid plane, use navigation in as many cases as possible, be very selective, and rely on electrocorticography so the work is complete without harming the patient. Anatomy is the key. In the medial temporal lobe, the anterior choroidal artery lies beyond the hippocampal artery, and if the dissection goes medial to the tentorial notch it reaches vital structures: the brainstem, the third nerve as it emerges, the posterior communicating artery and the anterior choroidal artery. If the plane is not breached, complications are very unlikely. Problems arise when bleeding is profuse and the surgeon, in panic, goes beyond the arachnoid; once it is breached, the anatomy becomes very difficult to read. The vein of Labbe must be preserved in a temporal lobectomy. The other concern is tissue left behind, with seizures recurring, because the operation is expected to be fully successful. Following the basic principles reduces complications.

Question 3

What happens to the patient after a hemispherectomy?

Dr. Dinesh Rattnani · Accepted Answer

Hemispherectomy carries the highest complication risk. In its modern form, hemispherotomy, the brain is not removed entirely. These patients have very resistant epilepsy arising from one damaged hemisphere, already on four or five drugs and still having seizures, and their life is miserable. The surgery disconnects the affected hemisphere from the rest of the brain, cutting its connections through the corpus callosum and the deep white matter, and removes only a limited part of the tissue, so the seizure cannot spread. Seizures mostly start at a focal point and then generalise. A hemispherectomy does not always mean the patient comes off antiepileptic drugs; with the drugs, the seizures may then be controlled. It is a major operation, but it is worth considering when there is no other option.

Question 4

How do you reduce the risk of paralysis on the contralateral side after hemispherectomy?

Dr. Dinesh Rattnani · Accepted Answer

Patients selected for hemispherectomy usually already have weakness on the opposite side, because that hemisphere is already badly damaged. The disconnection does not cut the corticospinal tracts; it stays in the white matter, which is mostly sensory and carries the seizure spread, so the operation does not automatically add paralysis on the opposite side. Hemispherectomy does not mean removing the entire frontal, parietal or temporal lobe; in the modern disconnection operation only limited tissue is removed.

Question 5

Is epilepsy surgery available only in India?

Dr. Dinesh Rattnani · Accepted Answer

No. It is practised all over the world wherever neurosciences centres exist, including the US, UK and Canada; these are standard procedures. In India it is done at more than 40 to 50 centres.

Question 6

What is the prognosis of epilepsy surgery, and what complications are associated with it?

Dr. Dinesh Rattnani · Accepted Answer

Prognosis depends on the underlying problem. Hemispherectomy is kept as a reserve when there is no other choice, and its results are not good, but the results of surgery for mesial temporal sclerosis, lesionectomy, vagal nerve stimulation and deep brain stimulation are good and satisfactory. The complications are infection, bleeding and meningitis, and more importantly weakness, hemiparesis, hemiplegia and memory loss. Another important complication is failure of the surgery, where seizure frequency is not reduced. In one of my patients, operated on before navigation was available, we had to take him back to theatre and remove the most medial part, after which he improved. Not getting the expected result can happen in maybe 5% of cases.

Question 7

Which epilepsy cases need surgery, and can a teenager undergo it?

Dr. Dinesh Rattnani · Accepted Answer

First the epilepsy must be labelled drug-resistant, and then there must be good concordance: the EEG localises the seizure source (right temporal, left temporal, occipital or elsewhere) and the MRI shows pathology there. If the MRI shows a right temporal lobe problem and the EEG focus is right temporal, that is the best case: a temporal lobectomy with hippocampectomy or amygdalohippocampectomy. Temporal lobe epilepsy accounts for 70 to 80% of cases, and these patients respond well. Teenagers can definitely undergo surgery, but medical management is tried first.

Question 8

So medical management comes first, alongside tests such as EEG and MRI?

Dr. Dinesh Rattnani · Accepted Answer

Even when going for medical management, once a patient is diagnosed with epilepsy an EEG and an MRI must be done. If the MRI is completely normal, the only surgical options are vagal nerve stimulation or deep brain stimulation (neuromodulation). Disconnection, in the form of corpus callosotomy, can occasionally be used for atonic seizures to stop the spread, but it is mostly not done. Medical management must be given, and if a pathology is present there is a chance that surgery will help.

Question 9

What are the recommended antiepileptic drugs for a patient with a normal EEG and a normal MRI?

Dr. Dinesh Rattnani · Accepted Answer

It depends on the type of epilepsy: generalised tonic-clonic, focal with secondary generalisation, or atonic. Sodium valproate and levetiracetam both have a very good spectrum and rank first and second, so either can be started. For focal seizures with secondary generalisation, carbamazepine is slightly preferred, but valproate is also good. We normally use levetiracetam in post-operative cases. The top three drugs are levetiracetam, valproate and carbamazepine. Lacosamide is coming up as an add-on drug, not first-line therapy. Perampanel is an add-on drug and has shown promising results in seizures due to brain tumours and damaged brain tissue.

Question 10

Is robotic surgery used for epilepsy surgery?

Dr. Dinesh Rattnani · Accepted Answer

It is not done at our centre, though other centres may be doing it. In neurosurgery here, robotics is used only in the spine, to place some spine screws; no brain surgery is done with the robot.

Question 11

What is the post-operative management of these patients?

Dr. Dinesh Rattnani · Accepted Answer

The drugs are reduced slowly; they are not stopped the day after surgery. These are drug-resistant cases, so for the first few days the same drugs are continued, and after 10 to 15 days one drug is slowly withdrawn. Most patients say they feel better after surgery, particularly with mesial temporal lobe sclerosis. The drugs are not stopped completely: the patient is kept on one drug for at least about a year and must be seizure-free, and at around the end of two years the drug can be stopped completely, because before surgery the patient was having seizures despite medication.

Question 12

How does vagal nerve stimulation help control seizures?

Dr. Dinesh Rattnani · Accepted Answer

No one fully understands how it helps, but the proposed mechanism is parasympathetic stimulation: stimulating the vagus sends signals back to the brain, and the electrical activity is reduced. In deep brain stimulation, the target is the anterior thalamic nucleus (ATN); stimulating it also reduces the spread of epileptic activity.

Question 13

What drug do you prefer, and is robotic surgery an option here?

Dr. Dinesh Rattnani · Accepted Answer

Sodium valproate is the preferred drug of choice. Robotic surgery is still not used at this centre for brain procedures.

Question 14

Are terahertz waves useful in managing epilepsy?

Dr. Dinesh Rattnani · Accepted Answer

I do not know about terahertz waves and will read about it. If you are able to manage the epilepsy medically, that is fine; only if it cannot be managed does the patient need to be sent for surgery. Try whatever medical management is possible, and if the patient is controlled, there is no rush for surgery. If there is an abnormality in the brain, then go ahead with surgery.

Question 15

Are there advances that could make a patient seizure-free for the rest of their life?

Dr. Dinesh Rattnani · Accepted Answer

We are all working along those lines. The goal is to make patients seizure-free, but it may or may not be achieved: sometimes we succeed, sometimes we do not. It is worth trying.

Question 16

Based on your experience, what has your success rate been for these surgeries?

Dr. Dinesh Rattnani · Accepted Answer

I personally feel it is about 80%: in 80% we achieve a desirable result, or at least reduce the antiepileptic drugs the patient was on. In 90 to 95% we can at least be sure we will not cause harm. We cannot guarantee the patient will be seizure-free or free of antiepileptic drugs, but even with drugs the seizures can be controlled. The aim is to improve the quality of life the patient has now.

Question 17

These patients need a multidisciplinary approach. What about post-operative management with regard to rehabilitation?

Dr. Dinesh Rattnani · Accepted Answer

Almost all these cases need a multidisciplinary approach: neurologist, neurosurgeon, neuropsychiatrist and psychologist are all important in assessment. If a complication happens it can be a disaster, because it can greatly decrease the quality of life. We have a good neurology team, and we discuss each case first with the neurologist, then the neuropsychiatrist and the psychologist; only once they give a green signal do we go ahead with surgery.

Question 18

Is a funded scholarship available to come and learn brain surgery at your centre?

Dr. Dinesh Rattnani · Accepted Answer

Ours is a private institution, so what we can offer at most is an observership to come and see brain surgery here. Government institutions such as the All India Institute of Medical Sciences and Sri Chitra may be worth trying.

Live Discussion with Dr. Dinesh Rattnani