[Downloaded free from http://www.neurologyindia.com on Monday, April 04, 2016, IP: 14.139.245.2] NI Feature: CENTS (Concepts, Ergonomics, Nuances, Therbligs, Shortcomings) ORIGINAL ARTICLE Endoscopic epilepsy surgery: Emergence of a new procedure Sarat P. Chandra, Manjari Tripathi1 Departments of Neurosurgery and 1Neurology, All India Institute of Medical Sciences, New Delhi, India ABSTRACT Background: The use of minimally invasive endoscopic surgery is fast emerging in many subspecialties of neurosurgery as an effective alternative to the open procedures. Objective: The author describe a novel technique of using an endoscope for performing a corpus callosotomy and hemispherotomy. A description of endoscopic disconnection for a hypothalamic hamartoma (HH) and a review of the literature is also presented. Materials and Methods: Thirty four patients underwent endoscopic procedures between January 2010 and March 2015. These included endoscopic‑assisted inter‑hemispheric trans‑callosal hemispherotomy (EH; n = 11), endoscopic‑assisted corpus callosotomy with anterior/posterior commissurotomy (CCWC; n = 16), and endoscopic disconnection for HH (n = 7). EH and CCWC were performed with the use of a small craniotomy (4 cm × 3 cm). The surgeries were performed using a rigid high‑definition endoscope, bayonetted self‑irrigating bipolar forceps, and other standard endoscopic instruments along with the guidance of intra‑operative magnetic resonance imaging and neuronavigation. HH disconnection was performed using endoscopic neuronavigation through a burr hole. Results: Hemispherotomy: Sequelae of middle cerebral artery infarct (5), Rasmussen’s syndrome (3), and hemimegalencephaly (3). Outcome: Class I Engel (9) and class II (2), mean follow‑up of 8.4 months, range: 3–18 months. Mean blood loss: 85 cc, mean operating time: 210 min. CCWC: All had a diagnosis of Lennox‑Gastaut syndrome (LGS), with etiologies of hypoxic insult (10), lissencephaly (2), bilateral band heterotropia (2), microgyria and pachygyria (2). Mean follow‑up: 18 ± 4.7 (16–27 months). Drop attacks stopped in all the patients. Seizure frequency and duration decreased >90% (11) and >50% (5). HH: Type II (2), Type III (2), Type IV (3). 5 had IA outcome. Conclusion: The article emphasizes the role of endoscopic procedures for epilepsy surgery and provides a review of literature. This experience may subserve to coin the term "endoscopic epilepsy surgery" for a fast emerging subspeciality in the field of epilepsy surgery. Key words: Commissurotomy; corpus callosotomy; endoscopic assistance; endoscopy; hemispherotomy; hypothalamic hamartoma Access this article online Introduction Website: Quick Response Code www.neurologyindia.com The use of endoscopy is now accepted in a number of neurosurgical procedures like pituitary surgery, skull base DOI: surgery, disc prolapse, etc. Endoscopic assistance is also a 10.4103/0028-3886.162056 frequent accompaniment of many of the micro‑neurosurgical procedures. Improved technology like the use of high definition cameras, three‑dimensional visualization systems Address for correspondence: Dr. Sarat P. Chandra, Room 7, 6th floor, CN Center, AIIMS, New Delhi ‑ 110 029, India. E‑mail: [email protected] Neurology India / July 2015 / Volume 63 / Issue 4 571 [Downloaded free from http://www.neurologyindia.com on Monday, April 04, 2016, IP: 14.139.245.2] Chandra and Tripathi: Endoscopic epilepsy surgery and better optics has further helped to amalgamate this tool the patients remained on anti‑epileptic medication prior to into the neurosurgical armamentorium. surgical intervention, as recommended by the International League Against Epilepsy (ILAE),[12‑16] was usually 2 years. In The use of an endoscope in epilepsy surgery is currently some children, however, the waiting period was reduced limited and not frequently practiced.[1‑8] This could be due significantly to even weeks to months depending on the to several reasons: (1) Most of the epilepsy surgeries are severity of epilepsy, the underlying substrate, and the onset “parenchymal” surgeries not involving an empty space, of epileptic encephalopathy.[1,5,17‑23] ventricle or cistern; (2) most of the epilepsy surgeons, during their residency or fellowship, have either limited or The preoperative investigations usually included a interictal no training in endoscopy; (3) most of the epilepsy surgeries electroencephalography (EEG), a video EEG (VEEG) recording utilize extensive brain mapping prior to surgical resection at least 3 habitual seizures, a magnetic resonance imaging and hence, surgeons do not find any relevance of endoscopic (MRI; at least 1.5T) using an epilepsy protocol with thin intervention, especially for neocortical epilepsies. sections passing perpendicular to the hippocampus. Further investigations were required depending on the MRI findings. The utilization of an endoscope for epilepsy surgery was Most of the cases requiring a hemispherotomy and having a initially used for disconnecting or resecting a hypothalamic pathology like a post infarct sequel or hemimegalencephaly, hamartoma (HH). This was possible for Type II, III, and some do not require any further investigations. Patients with a of Type IV hamartomas as these lesions projected into the disease like Rasmussen’s syndrome usually benefited by ventricle. In an earlier study, we, for the first time, described the performance of a positron emission tomography (PET) the use of an endoscope for performing a hemispherotomy scan as it often showed the areas of hyper‑metabolism (this using an inter‑hemispheric trans‑callosal approach.[9] investigation was, however, optional). The presence of HHs also did not require any additional investigations. However, Before this publication, only a conceptual procedure had patients undergoing a corpus callosotomy required a detailed been reported in a small cadaveric study by Bahuleyan et al.[10] investigational work‑up as this was a procedure performed in They described a 2‑port endoscopic technique in order to patients disabled with drop attacks with no localizing focus/ perform a lateral hemispheric disconnection. However, this networks. The patients undergoing a corpus callosotomy in technique has not been clinically used till date. The possible our set up, therefore, further underwent a PET scan, an ictal reason could be that the technique involves a route through subtracted single photon emission computed tomography, and the brain parenchyma. While this technique may be possible a magnetoencephalography. It was also important to discuss in a patient with an “atrophic” (e.g., patients with epilepsy these cases in an epilepsy surgery conference where the surgical presenting as a post infarct sequel) brain, it would be very strategy was planned out. In MRI negative cases (especially difficult, if not impossible, to conduct this procedure in if the MRI was performed in another center or without a patients with hemimegalencephaly where the ventricles will proper epilepsy protocol), a repeat MRI was always performed usually be slit‑like. Following this, we described a minimally especially on a 3 Tesla (T) scanner. This is because it may often invasive endoscopic assisted procedure for performing a pick up subtle substrates like Type I cortical dysplasias.[11,24 ‑33] complete corpus callosotomy with commissurotomy (CCWC), for the first time in the literature (under publication). We had Assessment and surgical planning were performed in the also earlier published our initial experience with the use of an epilepsy surgery conference. Patients without any definitive endoscope for resecting HHs.[11] Utilizing this experience, this localization on all investigations[24,25,27,28,31] and having may be the appropriate time to coin, in this review article, bi‑hemispheric seizure activity were considered for CCWC. the term “endoscopic epilepsy surgery” to indicate a new A detailed counseling and informed consent were taken as subspecialty of epilepsy surgery that is now emerging as an per the institute protocol for epilepsy surgery patients. exciting field in its own right. The inclusion criteria for an endoscopic hemispherotomy (EH) Materials and Methods included:[9,25,34] • Pan‑hemispheric pathology like Rasmussen’s syndrome, Patient selection hemimegalencephaly, and post infarct sequel All the patients subjected to surgery were diagnosed to be • Concordance of the MRI with the VEEG findings having “drug‑resistant epilepsy” by the neurologist, that • Pediatric age group (preferably below 9 years of is, the patient should have failed at least 2 anti‑epileptic age) except for post infarct sequel. It is important to medications given to him/her in an optimal dosage and remember that hemispherotomy is a procedure that is combination. The duration of the waiting period, while usually performed in the pediatric age group where a 572 Neurology India / July 2015 / Volume 63 / Issue 4 [Downloaded free from http://www.neurologyindia.com on Monday, April 04, 2016, IP: 14.139.245.2] Chandra and Tripathi: Endoscopic epilepsy surgery significant recovery due to neuronal plasticity may be the endoscope with the left hand as a free hand tool. The expected. Adults may also often have the same degree endoscope may also be supported by the assistant or held of recovery with a holding device. A self‑irrigating bayonetted bipolar was • Presence of hemiparesis. Although this fact does not always used with the right hand. This technique serves to facilitate hold true, the presence of hemiparesis does seem to both