Sahyadri Hospital,Pune,is a leading institution for treatment of epilepsy, especially refractory epilepsy in adults and children. Treatment of refractory epilepsy requires a team of medical experts and technicians across various disciplines. Sahyadri has a very well-co-ordinated team, which is also one of the most experienced team of physicians, surgeons and technicians in the city. Sahyadri is the only hospital to offer complicated paediatric epilepsy surgery in Pune.
This article refers what makes epilepsy surgery a very effective treatment option in certain circumstances. Lets have a bird’s eye view of the different types of epilepsy surgery.
When surgery is considered a good treatment?
Epilepsy is a condition that afflicts approximately one in every 200 persons in India. There are different types of epilepsy, and not everybody with epilepsy needs a surgery. Most cases of epilepsy respond to epilepsy medication (AEDs, i.e. antiepileptic drugs). Only 15 to 20% cases amongst children and about 30% cases in adults do not respond to treatment by medication. They are categorised as cases of refractory epilepsy. Refractory literally means stubborn. These stubborn epilepsy cases are considered for surgical treatment.
So do all cases of refractory epilepsy benefit from surgery? The answer once again is ‘no’. In the early days of epilepsy surgery, doctors were forced to take a shot in the dark while deciding on surgery. Some operations succeeded, some failed. However, with the amazing developments in diagnostic technology over the years, we now have the means of predicting the success percentage with a fair degree of accuracy.
In a very broad classification, there are two types of epilepsy seizures. They are:
Epilepsy is a result of abnormal electrical activity in the brain. When this abnormal electrical activity originates in the entire brain simultaneously, it is a generalised seizure. If the abnormal activity originates in just one part of the brain, it is a partial seizure. In a partial seizure, the abnormal activity can spread from one part to a larger area of the brain.
Surgery is not a preferred treatment option in a generalized seizure. It is a good treatment option in certain types of partial seizures.
How do doctors select the right case?
Doctors need to select the right cases for epilepsy surgery to ensure a fair degree of success after surgery. Selecting the right patient for epilepsy requires pre-surgical evaluation from a team consisting of neurologist, radiologist, neuro-psychologist, electro-physiologist and a neurosurgeon.
A patient has to undergo several diagnostic tests and thorough physical observation before doctors can recommend surgery for refractory epilepsy.
Focus on the focus
The diagnostic tests for epilepsy are all directed towards identifying the part of the brain where the abnormal electrical activity starts. This is called the focus of the seizure. The focus can either be in the eloquent area, i.e. brain areas which are not responsible for crucial functions like motor movement, memory, speech etc. or in the non-eloquent areas, i.e. areas which control crucial brain functions. Surgery is considered only if it can be done without affecting the crucial functions.
Structural abnormalities of the brain can often be responsible for epilepsy seizures. Seizures resulting from structural abnormalities have a structural focus of the seizure. The functional focus of a seizure is defined by the functions that get disrupted during the seizure. If the structural and functional focus is the same, surgery is usually successful.
If we have to mention that surgery is successful if structural and functional focus is the same, we will need to briefly explain what the meaning of structural focus and functional focus is. I don’t know if the above description is correct. Please replace it with whatever is correct.
Apart from identifying the type of seizure, doctors also look at the frequency of seizures and the extent of damage suffered by a patient. When seizures are frequent and damage is considerable, a surgical option has to be considered
Tests Required for Epilepsy Surgery
Doctors carry out a battery of tests to understand if surgery is a good treatment option in a particular case. The role of these tests is to determine the focus of the epileptic seizure and understand if surgery can achieve good results without affecting vital brain functions.
Doctors will recommend the following tests before deciding on epilepsy surgery.
MRI
An MRI is used to get a very detailed image of the brain structure. A 3T MRI scanner is usually preferred for this test. A 3T MRI has the capability of showing even minute details of the brain’s structure. An MRI helps doctors to identify abnormality in the brain in great detail. It is a tool that can help doctors to identify the structural focus.
VIDEO EEG RECORDING
An EEG or Electroencephalogram records brain waves through electrodes placed on the scalp. The EEG can thus record any abnormal brain activity. For Video EEG recording, the patient is connected to an EEG machine and observed for a period of 24 to 72 hours. Patient’s movements are recorded through a video camera. The actual seizure is captured on the video and its time (time of occurrence/timing?) is linked to the EEG changes in the recorder. This helps to understand the electral focus.
PET SCAN
During a seizure, the seizure-focus records hyper-metabolism, i.e. too much activity. Consequently, that very part records hypo- metabolism (reduced activity) after the seizure. It is not feasible to do a test during the seizure. Hence doctors look for areas of hypo-metabolism. A PET Scan can help the doctors to locate areas of hypo- metabolism. These areas are suggestive of the areas of seizure activity.
NEUROPSYCOLOGICAL TEST:
Doctors study the possible neuro- psychological impact the surgery may have on the patient. Neuropsychological tests identify the functional loss or preservation of functions pre surgically. It is vital that critical brain functions such as memory, speech, hearing and sight etc. should not get adversely affected by the surgery. Understanding the pre-surgical functional loss also helps to identify the focus.
When all three – MRI, EEG and PET Scan indicate a result in favour of surgery, and the neuropsychological test gives a green signal, the chances of good recovery after surgery are close to 95%. If the results are mixed, doctors may recommend further investigations. Reports from all investigations may then strengthen or weaken the case for surgery
Types of Epilepsy Surgery
There are two types of epilepsy surgery:
1. Resective surgery 2. Disconnection surgery
In a resective surgery, the legion (affected part, i.e. the focus) is resected (surgically removed). A resective surgery can be curative in nature.
The purpose of disconnection surgery is to disrupt the pathway of seizures, thereby reducing their spread in the brain. A disconnection surgery is usually palliative in nature. It can reduce, but does not eliminate seizures. However, it does aim at a significant reduction in seizures, while at the same time, preserving as much brain function as possible.
Resective Surgery
Temporal Lobe Epilepsy Surgery
The cerebrum of the brain is divided into four lobes. The temporal lobe seen in the figure is located on either side of the brain, just above the ears. This lobe controls hearing, language, and memory. The most common type of epilepsyin teens and adults has a focus in the temporal lobe.
In a temporal lobe resection surgery, the seizure focus in the temporal lobe is resected, or cut away. While doing so, the surgeon has to take care to ensure that the vital functions of hearing, language and memory are not affected. Anterior (front) and mesial (deep middle) portions of the temporal lobe are usually the focus areas of epilepsy seizures. The prognosis (possibility of success) of a temporal lobe surgery is very high, especially so in mesial temporal scleroses.
Extratemporal Resections
Other areas of the brain like frontal lobe, parietal lobe or occipital lobe are also resected depending on the region of the focus. However, these surgeries are more complicated, as preservation of functions is of the utmost importance. Disconnection Surgeries.
Disconnection Surgeries
Functional Hemispherectomy
An epilepsy condition called Rasmussen’s encephalitis is a type of epilepsy seen in children, though it can continue into adulthood for some. Those affected severely by this condition experience cognitive decline (decline in the ability to understand), loss of speech and partial vision loss as well as paralysis of one side. Epileptic seizures are a major part of this condition. The seizures involve continuous twitching or jerking of one side called epilepsia partialis continua. (Epilepsia partialis continua is the continuous focal jerking of a body part, usually localized to a distal limb (hand/feet), occurring over hours, days or even years. Rasmussen’s Encephalitis is a result of inflammation (swelling) in one hemisphere of the brain. As you know, the brain has two hemispheres, the left and the right.
Rassmussen’s encephalitis affects one of them. If the damage from this condition is very severe and doctors fear that the damage will be permanent, a surgery called functional hemispherectomy is recommended. In this procedure, the cortex (brain’s outer layer of neural tissue) is disconnected from all sub-cortical (inside) structures, and the interhemispheric commissures (tracts that connect the hemispheres) are divided. This disconnects the rest of the brain from the affected part, and patient gets relief from seizures.
Functional hemispherectomy can also be advised for other types of epilepsy where an entire hemisphere is affected.
Multiple Subpial Transection (MST)
Cortical displesia is a condition resulting from enlarged neurons due to a congenital abnormality. Such malformation is commonly found near the cortex (outer layer of the brain). Multiple Subpial Transection (MTS) is a surgical treatment advised for cortical displesia. MST is also advised if partial seizures originate in the eloquent areas of the brain (areas which are responsible for vital brain functions). In this procedure, shallow cuts (transections) are made into the brain’s cortex .These cuts interrupt the fibres connecting different parts of the brain. The procedure has proved to be successful in controlling seizures without causing any long-lasting impairment to vital functions. Language function though, can at times get mildly disrupted.
Corpos Collostomy
The corpus callosum is a band of nerve fibers connecting the two halves (hemispheres) of the brain. A corpus callosotomy interrupts the spread of seizures from hemisphere to hemisphere.
Corpos Collosotomy is advised as a palliative surgery for children who suffer from severe drop attacks; these attacks can often reach a figure of twenty to thirty attacks in a day. Children exhibiting retarded behaviour and severe lack of focus on account of seizures can also benefit from this surgery. Seizures do not stop completely after this procedure. They continue on the side of the brain in which they originate. However, the seizures become less severe, as they cannot spread to the other side.
Who will not benefit from surgery?
Not all cases of refractory epilepsy have the capacity to benefit from a surgery. Cases with refractory epilepsy secondary to (as a consequence of) a degenerative brain disorder, or those with progressive myoclonic epilepsy (a rare epilepsy syndrome caused by a variety of genetic disorders), will not benefit from epilepsy surgery.
To sum up, epilepsy surgery is a treatment option when other options fail to bring relief from epileptic seizures. Surgery can be curative or palliative depending on the kind of epilepsy afflicting a patient. Deciding on a surgery is a process that involves specialised investigations. Sahyadri Hospital is well equipped with a very competent and experienced team and state-of-art facilities for epilepsy surgery.
Why Sahyadri for epilepsy surgery?
Epilepsy is a result of disruption in the electrical activity of the brain leading to seizures. Epilepsy surgery is a part of neurosurgery. Sahyadri Hospital is a leading hospital in the State of Maharashtra for treatment of neurological problems.
The hospital has a very competent and experienced team for epilepsy treatment including epilepsy surgery. We are the only hospital in Pune to offer complicated paediatric epilepsy surgery. The hospital has state-of-art machines for brain surgery and for all diagnostic testing needed for epilepsy surgery. All tests needed for epilepsy surgery are done in-house. In the past one year 16 epilepsy surgeries were done at Sahyadri, out of which 4 were very complex in nature.
