|Year : 2019 | Volume
| Issue : 2 | Page : 287-292
Epilepsy surgery in India
George C Vilanilam
Department of Neurosurgery, R Madhavan Nair Comprehensive Epilepsy Care Centre, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala, India
|Date of Submission||02-Dec-2019|
|Date of Decision||10-Dec-2019|
|Date of Acceptance||10-Dec-2019|
|Date of Web Publication||16-Dec-2019|
Prof. Dr. George C Vilanilam
Department of Neurosurgery, R Madhavan Nair Comprehensive Epilepsy Care Centre, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Trivandrum, Kerala
Source of Support: None, Conflict of Interest: None
The history of epilepsy surgery dates back to the era before computerized tomography, magnetic resonance imaging (MRI), positronemission tomogram imaging, and electroencephalogram (EEG). Victor Horsley's resection of a cortical scar in 1886, based purely on localization is considered as the first epilepsy surgery recorded in history. In India, Prof. Jacob Chandy performed a pediatric hemispherotomy in 1952 at the Christian Medical College, Vellore. Prof. Malla Bhaskar Rao did a cortico-amygdalohippocampectomy in 1995 for hippocampal sclerosis at Sree Chitra Institute, Trivandrum. With over 1 million patients suitable for epilepsy surgery in India, the burden of disease is alarmingly high. The spectrum of epilepsy surgery resections in India has expanded tremendously over the past decade, but the centers performing them are few and far in between. Hence, the “surgical gap” (which includes eligible patients awaiting surgery) is ever increasing. With just around 1000 procedures performed every year, the surgical epilepsy programs in India need a massive overhaul in terms of skilled workforce and infrastructure. Sophisticated presurgical workup modalities, such as MEG, stereo-EEG, EEGfunctional MRI, etc., are have already been popularized in India. The results of epilepsy surgery in India are also at par with the world's state-of-art centers. As medical and surgical epileptology grows further over the years in India, the surgical treatment gap hopes to be effectively addressed.
Keywords: Epilepsysurgery, history, India, seizure outcome
|How to cite this article:|
Vilanilam GC. Epilepsy surgery in India. Arch Med Health Sci 2019;7:287-92
| Introduction|| |
“The farther back you can look, the farther forward you are likely to see.”
The history of surgery for epilepsy has been fascinating and wrought with trials, tribulations, and ecstatic success stories.,,,, It is, perhaps, as old as the history of neurosurgery itself. It is older than the history of cranial imaging, that is, the computerized tomography (CT) scan (1974), magnetic resonance imaging (MRI) (1977), and positron-emission tomogram (PET) (1973). It is also older than the electroencephalogram (EEG) (1932) and all the other adjuncts that epilepsy surgery takes assistance from, in the current era.,,,
In India too, epilepsy surgery began almost as early as the earliest neurosurgical procedures, in a quiet and unassuming way.,, The earliest procedures were seldom reported and hence lost credit to find an official place in history.
Epilepsy surgery is more than 100 years old and has become the standard of care for “surgically remediable epilepsy syndromes.” Heyman, in 1831, was the first one to perform a surgery to an epileptic patient due to a brain abscess. Victor Horseley's resection of an epileptogenic posttraumatic cortical scar in 1886 at London is often regarded as the first-ever epilepsy surgery procedure. This resection in the pre-CT, pre-MRI, and pre-EEG era was purely based on cortical localization guided by John Hughlings Jackson.
The science and art of epilepsy surgery has progressed by leaps and bounds over the past century. With changing concepts on pharmacoresistant epilepsy and improved safety of microneurosurgical procedures, resective surgery for epilepsy has established its effectiveness beyond doubt. One out of three patients with drug resistant, thus requiring a presurgical workup to assess surgical candidacy. The presurgical work which primarily relies upon the MRI and video EEG is centered on the search for the “epileptogenic zone” and its relation to the functional cerebral cortex.
| The Problem Statement|| |
It is estimated epidemiogically that about 50 million people with epilepsy live worldwide and about 25%–40% of them may be surgical candidates. Globally, 10.1 million patients with epilepsy may be surgical treatment candidates, and 1.4 million new surgically treatable epilepsy cases are added annually to this pool. The incidence is higher in low middle-income countries like India (82/10,000 person-years compared to 46/100,000 person-years in high-income countries). The economic burden of epilepsy in India, direct and indirect, is 88.2% of Gross National Product (GNP) per capita, 0.5% of the GNP, and most of it would be due to intractable epilepsy.
With a population of 1.37 billion people in 2019, India is estimated to have a large burden of drug-resistant epilepsy. On the basis of a prevalence rate of 5/1000 person-years and an incidence rate of 50/100,000 person-years, it is estimated that at any given time, India will have at least 5 million people. With active epilepsy, to which nearly 500,000 people are added annually. Conservative epidemiological estimates suggest that 1.8 million people with drug-resistant epilepsy live in India, and of these, about 1.3–1.5 million could benefit from epilepsy surgery. As the number of epilepsy surgery procedures being done at the established centers in India is about 1000 per year, this “surgical gap” of epilepsy surgery patients is growing significantly. Till July 31, 2016, approximately 7143 epilepsy surgeries have been performed in India. Rathore and Radhakrishnan report that only 2 in 1000 eligible patients in India undergo epilepsy surgery because of which the enormous surgical treatment gap continues to persist.
Prof. Jacob Chandy, in 1952, performed a hemispherotomy for infantile hemiplegia at Christian Medical College, Vellore, which is the first record of epilepsy surgery in India. After a brief lull, epilepsy surgery in India was resurrected again in 1995 at Sree Chitra Tirunal Institute by Prof. K Radhakrishnan and Dr. Malla Bhaskar Rao. About 7143 epilepsy surgery procedures have been performed in India, and it is estimated that there are about 39 centers that have performed these procedures till date. Sanyal reports the need for a 2-tiered epilepsy surgery system with the most common, temporal resections to be done at the tier 1 centers as well. Tier 2 centers need to look into more complex cases and the ones that may need chronic invasive EEG monitoring [Table 1] and [Table 2].
|Table 2: Number of epilepsy surgery procedures done at Indian centers (as on July 31, 2016) (compiled by Rathore and Radhakrishnan)|
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Among the epilepsy surgery centers in India, four started in the period 1995–1999, six in the period 2000–2004, five in the period 2005–2009, and three during 2010–2012 [Table 1].
| Recap of Basic Concepts and Their Historical Evolution|| |
The International League Against Epilepsy defines pharmacoresistant epilepsy as a failure of adequate trials of two tolerated and appropriately chosen and used antiepileptic drugs (whether as monotherapies or in combination) to achieve sustained seizure freedom. It is estimated that 1 in 3 people with epilepsy will eventually become drug resistant.,,
Concept of surgically remediable epilepsy
Shewmon and Engel (1995) proposed the concept of surgically remediable epilepsy., This involves the concept of early referrals for surgery if the pathology involved has a natural history of medically intractable seizures, good seizure outcome after epilepsy surgery, and the seizure associated disability is high. Mesial temporal sclerosis is the prototype of surgically remediable epilepsy. The treatment gap for surgically referrals is alarmingly high and varies from 12 to 15 years. Late referrals could also lead to poor surgical outcomes due to secondary epileptogenesis, thus leading to “surgically refractory epilepsy.”,,
Presurgical workup and spectrum of procedures
The concept of the epileptogenic zone (EZ) is the cornerstone for the success of epilepsy surgery [Figure 1]. EZ refers to the area of the cortex responsible for ictal onset and resection of which results in seizure freedom. It is not equivalent to the MRI abnormality.,
|Figure 1: The epileptogenic zone concept (Rosenow and Luders, Brain 2001)|
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Presurgical workup is done to assess the surgical candidacy by delineating the EZ and its relation to the functional cortex. Phase 1 investigations such as MRI (as per epilepsy protocol) and video-EEG with concordance of their data would be suitable to recruit almost 80% of epilepsy surgery patients. Few require further workup such as interictal PET or ictal single-photon emission computed tomography and further invasive intracranial EEG monitoring. Invasive monitoring with subdural electrodes or stereo-EEG is done to delineate the ictal onset zone and identify functional cortex. MRI negative focal epilepsy is forming a part of the surgical resection spectrum in the stereo-EEG era.,,
Epileptogenic lesions include:
- Malformations of cortical development, for example, focal cortical dysplasia and hemimegalencephaly
- Tumors, for example, ganglioglioma and Dysembryoplastic neuroepithelial tumor (DNET)
- Vascular malformations, for example, arteriovenous malformations and cavernomas
- Inflammatory, for example, tubercular, cysticercal granulomas, and Rasmussen's encephalitis
- Posttraumatic/postischemic, for example, cortical scars, gliosis, and porencephalic cysts
- Miscellaneous, for example, hippocampal sclerosis.
Curative surgical resections [Figure 2] and [Table 3] could range from a simple lesionectomy (ganglioglioma), extended lesionectomy (with surrounding cortical dysplasia), unilobar, multilobar (two or more lobes), or hemispheric resections.
|Figure 2:Resective surgery for epilepsy (volume of resections - schematic)|
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Surgical outcome – Seizure benefits and adverse events
In extratemporal resections, Engel Class 1 outcome is reported in 60%–70%, while the results are more encouraging in temporal resections (80%–90%) and hemispherotomy (75%–90%). Major adverse events are reported in the range of 2%–6% in several large series.,,
Reoperations and failed surgery
In Engel Class III and IV outcome patients, a presurgical workup is reinitiated to assess the scope for reoperation. Surgical failure could be due to incomplete resections, wrong localization, multiple pathologies, etc.
| Stimulation/resection/ablation?|| |
Newer modalities such as deep-brain stimulation of the anterior thalamic nucleus, gamma knife ablation for hippocampal sclerosis, radiofrequency ablation for hypothalamic hamartomas, and LASER interstitial thermal therapy are emerging.
History of temporal lobe resections
Bailey and Gibbs in 1951 used EEG as a guide to perform temporal lobe surgery; Murray Falconer, a neurosurgeon from New Zealand working in London, introduced the en bloc anterior temporal lobe resection and the term mesial temporal sclerosis in 1953. Niemeyer, in 1958, introduced the concept of selective mesial temporal resections.
In India, temporal resections as part of glioma surgery and traumatic contusion decompression were in vogue since the 1970s. However, from an epilepsy perspective, the first anterior temporal resection and amygdalohippocampectomy were done in March 1995 by Dr. Malla Bhaskar Rao under the leadership of Prof. K. Radhakrishnan at R. Madhavan Nair Center for comprehensive epilepsy care, Sree Chitra Tirunal Institute. The procedure has now been standardized and has become routine at several centers all over the country. Selective mesial temporal resections (transcortical, transsylvian, and subtemporal) have been done at several centers such as SCTIMST, AIIMS, and NIMHANS [Table 1] and [Table 2]. The seizure outcome benefits range from 80%–90%. Engel Class 1 outcome with adverse event rate is reported in the range of 2%–4%.
History of extratemporal resections
The concept of operating the epileptogenic focus was introduced by Gibbs and Lennox in 1938. This sets the stage for extratemporal resections. In India, most centers ventured into extratemporal resections only after acquiring sufficient experience in temporal resections.,, From 1998 onward, extratemporal resections came about and included unilobar resections, multilobar resections, lesionectomies, and insular resections.
History of hemispheric resections
At the beginning of the 20th century, Dandy (1886–1946) introduced hemispherectomy as a neurosurgical procedure in 1923 for gliomas. Later, anatomic hemispherectomy for epilepsy was introduced by McKenzie and Krynauw in 1950. Later in the 1970s, Rasmussen and further Villemure (1993) and Delalande (1992) popularized the horizontal and vertical hemispherotomies.
In 1998, hemispherotomy was resurrected by Prof. Bhaskar Rao under the guidance of Prof. H. Silfenius from Sweden at Sree Chitra Tirunal Institute for Medical Sciences and Technology (SCTIMST), Trivandrum. The procedures have undergone subtle modifications over time at different centers with both the Delalande's vertical hemispherotomy and the Villemure's horizontal hemispherotomy being performed at high-volume epilepsy centers. Prof. Chandra from AIIMS, New Delhi, has also described an endoscope-assisted hemispherotomy and callosotomy in 2015.
History of chronic invasive electroencephalogram monitoring
In 1957, Jean Tailarach published his stereotactic Atlas More Details that set the stage for the present-day stereo-EEG. Chronic invasive EEG monitoring came into practice in India in 2000–2002 and soon became a standard of care in patients with unclear localization/lateralization, eloquent cortex proximity of EZ and multiple lesions. Strip, grid, and depth electrodes were used commonly. In the recent past, stereo-EEG has been used at several centers and the practice was pioneered by AIMS, Kochi.
History of palliative procedures
Van Wagenen and Herren (1897–1961), Chief of Neurosurgery at the University of Rochester Medical Center, performed and perfected the procedure of callosotomy. In 1969, Morell and Hanbrey introduced “multiple subpial transection” (MST) for eloquent cortex foci. Penry et al. ushered in the modern clinical application of VNS in 1988 using an implanted device, the vagal nerve stimulator to treat epilepsy.
In India, callosotomy was done for atonic seizures at SCTIMST in 2003 and VNS in 2005. These procedures soon picked up and were in practice in other high volume centers too.
Pioneers of epilepsy surgery in India
Dr. Jacob Chandy performing a hemispherotomy on a patient with infantile hemiplegia in 1952 marks a special place in the history of epilepsy surgery in India. There was a recedence in the enthusiasm about epilepsy surgery and its utilization in the period from 1960-1994, during the period when it set foot firmly in the developed world. Temporal resections and hemispheric disconnections which were the 'trademark procedures' in epilepsy surgery grew further in North America and Europe during the 70s. In India, epilepsy surgery was resurrected by Prof. K. Radhakrishnan (Professor of Neurology) and Dr. Malla Bhaskar Rao, who did a cortico-amydalohippocampectomy for hippocampal sclerosis on 20 March,1995 at the R. Madhavan Nair Centre for comprehensive epilepsy care, Sree Chitra Tirunal Institute, Trivandrum. In the same year, Dr. V. P. Singh started the epilepsy surgery program at AIIMS Delhi.
Further on, epilepsy surgery programs were started at NIMHANS Bengaluru(1998), KEM hospital Mumbai (2001), CMC Vellore (2004), Nizams Hyderabad (2010) and other institutes [Table 3]. The torch of epilepsy surgery at Sree Chitra Institute kept shining further under the leadership of Prof. Mathew Abraham, Prof. Sanjeev Thomas, Dr. Ashalatha Radhakrishnan and Dr. C. Rathore. At AIIMS Delhi, Prof. Sarat Chandra innovated hemispheric disconnections and initated several basic science epilepsy research programs along with Prof. Manjari Tripathi. At NIMHANS Bengaluru, Prof. B. A. Chandramouli, Prof. Satish Chandra, Prof. Sanjib Sinha and Dr. Arivazhagan took epilepsy surgery to greater heights. The contributions of Dr. Manas Panigrahi, Dr. Sita Jayalakshmi (Hyderabad), Dr. D. Mazumdar, Dr. S. Rawat (Mumbai), Dr. Ashok Pillai, Dr. Vinayan, Dr. Siby Gopinath (Kochi), Prof. BRM Rao, Dr. Dinesh Nayak (Trivandrum, Bangalore), Prof. Girish Menon (Trivandrum, Manipal), Dr. Ari Chacko (Vellore), Dr. George Vilanilam, Dr. Ramshekhar Menon, Dr. Ajith Cherian (Trivandrum), Dr. Amit Dhakoji (Pune), Dr. Nilesh Kurwale (Pune) and several others are noteworthy, in making epilepsy surgery accessible, safer and affordable to the masses. Stereo-EEG and robotic epilepsy surgery was pioneered in India by Dr. Ashok Pillai (AIMS, Kochi) in 2016-17. At present the established tertiary centres in India are high volume referral centres doing about 150-200 epilepsy surgery operations every year [Figure 3].
Centres like Sree Chitra, AIIMS, Delhi and others have trained young faculty from developing countries for the establishment of epilepsy programs in Sri Lanka, Bangladesh, Nepal, Indonesia and other developing nations. Several other institutes like SGPGI Lucknow and AIIMS, Jodhpur have recently started epilepsy surgery programs
| Future Perspectives|| |
To meet the surgical epilepsy burden, India should have at least 60 state-level epilepsy surgery centers (with each undertaking at least 50 surgeries per year) and 6 national centers of excellence, as suggested by Rathore and Radhakrishnan. Despite the advent of newer gadgets and sophisticated infrastructure in developed countries, epilepsy surgery needs more cost-effective options for developing nations. Expensive investigations as in a state-sponsored or insurance-funded health-care system like the developed nations may not be suitable for India. The fact remains that about 80% of candidates for epilepsy surgery can be recruited on the basis of the easily available MRI (as per a suitable epilepsy protocol) and video telemetry. Thus, as more centers take up the challenges of the surgical burden of epilepsy better days are perhaps not far away.
| Conclusion|| |
Better seizure outcomes and safer surgical techniques are evolving continuously in the care of surgically remediable epilepsy syndromes. As more MRI negative cases are being recruited based on stereo-EEG evaluation and other modalities, many more are being offered a chance of a cure. As the burden of surgically remediable epilepsy in India has crossed 1 million, many more neurosurgeons need to take up this subspeciality and more epilepsy centers are the need of the hour.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]