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NI Feature: CENTS (Concepts, Ergonomics, Nuances, Therbligs, Shortcomings)

ORIGINAL ARTICLE

Endoscopic surgery: Emergence of a new procedure

Sarat P. Chandra, Manjari Tripathi1 Departments of 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 (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. 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 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, 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]

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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 (EEG), a video EEG (VEEG) recording utilize extensive brain mapping prior to surgical resection at least 3 habitual , 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 . sections passing perpendicular to the . 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 . 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

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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 dissection as well as haemostasis. The irrigation from suggest that there is significant dysfunction of the affected the bipolar forceps aids in the general irrigation as well. The hemisphere, and that the opposite healthy hemisphere is medial part of the hemisphere is dissected from the falx under likely to have taken up the functions of the contralateral endoscopic guidance, and the (CC) is exposed. side. Motor recovery usually occurs within a period of 6 months but the pincer grip usually does not improve. The entire surgery was carried out in 3 basic steps [Figure 2]: We have seen that further worsening may be precipitated, (1) Complete corpus callosotomy; (2) anterior and middle especially when the motor power is fully well‑preserved. disconnection; and, (3) posterior disconnection. However, in cases where there is hemiparesis, especially in patients with epilepsy presenting as post infarct sequel, First, a corpus callosotomy is performed. This is performed by further weakness usually does not occur. exposing the CC by gently retracting the hemisphere by a few centimeters [Figure 2a‑e]. It is important to ensure using the The inclusion criteria for a CCWC included: endoscope that no bridging veins are getting stretched due to • No single lateralization/localization of the epileptiform the retraction, both in front and behind the craniotomy. Next, zone/network using a fine dissector and also micro‑scissors, the hemisphere • Drop attacks as the predominant seizure type is separated from the falx. The CC may be identified at the • Intelligence/social quotient <50 depth as it appears white and pale when compared to rest of • High seizure frequency defined as at least 1–2/day the cortex [Figure 2]. We prefer to expose the CC first from the • Parental consent for the procedure. anterior to the posterior aspect and then start the disconnection in postero‑anterior direction [Figure 2b and c]. It is important to In general, we preferred performing CCWC in cases with realize that corpus callosotomy performed for a hemispherotomy a severe Lennox‑Gastaut syndrome (LGS) with severe to is different from that performed as a stand‑alone procedure. profound mental retardation especially in the pediatric In the former, the surgeon has to ensure that he/she opens population. For HHs, the Delande’s grading was used to the CC until the body of the ventricle on the affected side is choose our patients for surgery.[35,36] The endoscopic approach reached, as this procedure will allow him/her to perform further was preferred for a small hamartoma that was situated either hemispheric disconnection. On the other hand, in stand-alone on the floor or on the wall of the ventricle (Type II); or, a corpus callosotomy, the surgeon should ensure that he/she is in hamartoma on the floor projecting inferiorly (Type III). For perfect midline so that the cavum may be opened. Once the CC a Type IV hamartoma, we preferred an endoscopic‑assisted is exposed, the corpus callosotomy is performed with the aid of trans‑callosal approach.

Surgical procedures Endoscopic inter‑hemispheric trans‑callosal hemispherotomy The patient is placed in a supine position with the head slightly flexed and in a neutral position. A transverse skin incision is marked over the coronal suture, and a 4 cm × 3 cm flap is raised just lateral to the midline with the medial border just over the lateral part of the sagittal sinus. The sagittal sinus is just exposed by 1–2 mm. Neuronavigation is utilized in all the cases to mark the exact position of the bone flap and to avoid a major vein draining the region. Mannitol infusion is started just prior to the skin incision to provide a lax brain. The craniotomy is performed using a high‑speed drill. The dura is opened in a C‑shaped manner with the base over the sinus. The medial margin of the hemisphere is retracted using a brain retractor. Figure 1: The position of the endoscope while performing endoscopic- A rigid 0° high‑definition pituitary endoscope (Karl Storz) assisted hemispherotomy and corpus callosotomy. Note that the endoscope is usually placed anterior to the surgeon’s working instruments. In addition, is then brought in, and rest of the surgery is carried out the monitor should be placed in an ergonomically efficient position in front under its visualization [Figure 1]. The author prefers to hold of the surgeon

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a b c

d e f

g h i Figure 2: The intra-operative steps of endoscopic-assisted hemispherotomy. (a) First, the corpus callosum is exposed; (b) the exposure of the splenium; (c) the splenium being divided; (d) genu exposed; (e) genu being divided; (f) anterior disconnection is started anterior to the caudate head and then is carried out lateral to the caudate head; (g) middle disconnection being carried out till (h) the hippocampus is being exposed; and, (i) the posterior disconnection between the splenium and the choroid plexus is the final step

bipolar forceps and micro‑scissors. The posterior part including At this stage, the anterior cerebral arteries (ACAs) and the the splenium is divided first, followed by the genu up to the distal part of the optic may be visualized through the . Compared to the microsurgical approach, arachnoid. The disconnection next proceeds laterally from just we have discovered that the endoscopic‑assisted approach anterior to the caudate head to the lateral part of the lesser provides better visualization. This advantage is particularly wing of the sphenoid, and then turns posteriorly to reach the evident while dividing the terminal part of the splenium. sphenoid ridge. The middle cerebral artery (MCA) was visualized at the level of the sphenoid ridge. The anterior disconnection Following a complete corpus callosotomy, the anterior and is completed at the level of the MCA thereby disconnecting the middle disconnection was carried out. The anterior and middle frontal lobe. The middle disconnection is started at the sphenoid disconnection, starts at the beginning of the genu of the CC and ridge. The disconnection next continues posteriorly. The bulk of passes on to the floor of the anterior skull base at the level of the basal nuclei lie here. The middle disconnection is completed the lesser wing of the sphenoid and the planum, first remaining by dividing the hemisphere lateral to the and the anterior to the head of the caudate nucleus, then curving lateral choroidal fissure, till the atrium is reached. Division is carried to it and passing posteriorly, where it joins the body of the lateral out at the level of the atrium both superiorly and posteriorly ventricle to the temporal horn and then terminates at the atrium, until it is completed, and the temporal horn is connected with just lateral to the thalamus. The anterior disconnection starts the body of the lateral ventricle. This procedure disconnects the at the genu. Disconnection is carried from the surface until the amygdala, hippocampus, and anterior temporal connections. anterior skull base over the planum is reached. Neuronavigation is used to reach this bony landmark. Once reached, the resection The posterior disconnection [Figure 2i] involves division is carried out to the posterior part of the gyrus rectus, similar to of a short segment of tissue consisting of the posterior that done in the standard vertical hemispherotomy approach. part of the fornix, which mostly lies between the choroid

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plexus at the atrium and the posterior‑most part of the Endoscope‑assisted corpus callosotomy with splenium. The division was performed up to the underlying commissurotomy arachnoid. Caution must be exercised, as the Galenic veins The craniotomy and dural opening are as described for EH. The lie just underneath. There is usually a small piece of tissue inter‑hemispheric fissure is accessed, and the cisternal CSF is present under the choroid plexus that may be easily missed. released to make the brain lax [Figure 5]. The hemisphere The endoscope is particularly useful in visualizing and is retracted to one side, and the CC was reached. The ACAs dividing this portion. The posterior division completes the are separated. First, the CC is exposed from the anterior to disconnection of rest of the temporal lobe. posterior end. Following this, the disconnection is started from the splenial part and then is extended anteriorly. Division The postoperative MRI also provides the surgeon with feedback of the splenial part is performed till the arachnoidal sleeve regarding the feasibility of the surgical procedure using the containing the internal cerebral veins is visualized. Once the endoscope [Figures 3 and 4]. We have used an intra‑operative CC is sectioned completely, the septae on either side of the MRI in all these cases. We do agree that this is an expensive cavum are separated. The anterior commissure is then divided. tool. However, if it is not available, a neuronavigation is This was followed by division of the posterior commissure mandatory. In addition, reaching proper anatomical landmarks after entering the third ventricle through its roof [Figure 5]. will ensure that the disconnection is complete. All our patients were placed on elective ventilation for at least 24 h after surgery. The patients underwent routine Following the surgery, the dura is closed primarily. An evaluations on surgical rounds for any possible complications. intra‑ventricular drain is left inside for the next 24–48 h to A thorough neurological evaluation was performed for drain out the blood stained cerebrospinal fluid (CSF). The persistent neurological deficits before discharge. drain is removed earlier if the CSF clears completely, or is delayed up to 72 h, if the CSF remains blood stained. Hypothalamic hamartoma Endoscopic surgery for a HH should be carefully planned.[19,35‑45] The use of neuronavigation is mandatory as the ventricles are usually small. The use of rod lens obturator scopes is also useful to access the ventricles [Figure 6]. The approach is such that the line of disconnection is along the axis of the trajectory. A burr hole is made usually at the level of the coronal suture. The exact position is again planned using neuronavigation so that any draining veins can be avoided. a b The dura is opened widely and cauterized to avoid stripping and causing a possible epidural hematoma. The obturator with the sheath is introduced into the ventricle. Once the lateral ventricle is accessed, a 4 mm diagnostic scope is introduced. The scope is advanced into the third ventricle. The direction of approach cannot be overemphasized. For example, if the hamartoma is arising from the floor and the left lateral wall, the c d direction of the approach is from the right side. The hamartoma Figure 3: A 5-year-old male child presented with 10–15 episodes/day is visualized as a bulge on the floor and lateral wall of the predominantly involving the right side with 1–2 generalizations/day. Positron emission tomography showed an area of hypermetabolism in the ventricles. The margins of the lesion are again confirmed using right hemisphere. Video electroencephalography showed lateralization neuronavigation by moving the scope inferiorly and laterally. to the right hemisphere predominantly involving the frontal and Next, a depth electrode is introduced into the hamartoma, and temporal lobes. Magnetic resonance imaging (MRI) showed evidence of an EEG recording is performed. A hamartoma is quite active right hemimegalencephaly. However, the ventricles were also enlarged [28] (a). The child underwent a right endoscopic-assisted hemispherotomy. electrically and will produce multiple polyspikes (grade 5). The procedure was performed using image guidance with the use of intra- Following this, a biopsy is taken. If the hamartoma is small, it operative MRI. An MRI performed immediately after surgery demonstrated is removed using a biopsy forceps. The tissue is initially held, adequate disconnection. Coronal images show adequate anterior (b), middle (c), and posterior (d) disconnection. As it can be seen, the use of an rotated to avulse it from the wall and then removed piecemeal. endoscope causes such minimal retraction that even the inter-hemispheric The lesion is usually avascular or very mildly vascular, hence tract of access cannot be made out on the MRI. Following surgery, the child there is usually no problem with hemostasis. In larger lesions, became completely seizure free. He developed, immediately, a hemiparesis of 3/5 (MRC) on the left side, which improved almost completely at 3 months a disconnection from the surrounding area is also performed. follow-up. The pincer grip, however, did not improve The disconnection is usually performed laterally and anteriorly

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a b c

d e f Figure 4: Intra-operative diffusion tensor imaging (DTI) is useful in determining the completeness of hemispherotomy. (a and d) The preoperative DTI images. Following surgery (b and e), the tracts on the opposite side were not visible except on the frontal side where some tracts were still seen. A re-exploration was performed which revealed some connections still persisting in the fronto-basal area. Following disconnection of these tracts, a repeat DTI imaging showed complete disconnection (c and f)

Results

Thirty four patients (from January 2010–March 2015) underwent endoscopic procedures for epilepsy. These included endoscope‑assisted inter‑hemispheric trans‑callosal hemispherotomy (EH), (n = 11), endoscope‑assisted CCWC (n = 16), and endoscopic disconnection/excision a b for a HH (n = 7).

Endoscopic hemispherotomy group Of the 11 patients, who underwent EH (8 males), 9 underwent a right sided procedure. The mean age of seizure onset was 1.52 ± 0.99 years (range 0.8–2.9 years). The mean age c d of surgery was 9.4 ± 6.1 years (range 0.4–18 years). The Figure 5: (a) Magnetic resonance imaging showing section of the genu, mean frequency of seizures was 17.25 ± 16.1/day, excluding splenium, and the posterior commissure. (b) The size of the craniotomy which is used for both endoscopic-assisted hemispherotomy and corpus callosotomy 1 patient who presented with status epilepticus. The (with commissurotomy). (c) The intra-operative view of the corpus callosal pathologies included post infarct epilepsy (5), Rasmussen’s sectioning which passes through the cavum, splitting the septum on either syndrome (3), and hemimegalencephaly (3). side. (d) The intra-operative view of posterior commissural sectioning

but not posteriorly as here the lesion merges with midbrain Two patients had prolonged fever (1–2 weeks) after surgery. The structures.[35,40,41,43,45] CSF counts and cultures were negative. All the investigations for blood and urine were negative. Following 1 week of antibiotics, Outcome assessment the fever was treated symptomatically with paracetamol and cold Seizure outcome was assessed using the Engel sponging. The mean blood loss was 85 ± 48.4 cc and mean classification.[15] The postoperative neuropsychological operating time was 210 ± 42 min. None of the patients required assessment was performed as described earlier. any blood transfusions. The mean hospital stay was 8.5 days.

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a b c d

e f g Figure 6: A 9-year-old boy (a) presented with gelastic seizures and precocious puberty (as evidenced by the growth of secondary sexual characteristics) and (b) supernumerary finger. His luteinizing hormone/follicle-stimulating hormone was raised. His testosterone levels were very high (711 ug/ml). Magnetic resonance imaging (MRI) (c and d) showed a Type III hypothalamic hamartoma attached to the left side of third ventricle and the floor. An endoscopic disconnection was planned. Since the lesion was arising from the left ventricular wall, it was decided to approach the lesion from the right side as the axis of vision would be along the plane of disconnection (d and e). A neuronavigation-guided endoscopic disconnection was performed through a right posterior frontal burr hole (f). Following surgery, the hormones reduced significantly. He was, in addition, started on chemotherapy. Postoperative MRI (g) showed an adequate disconnection

The follow‑up ranged from 5 to 16 months with a mean quotient (IQ) less than 20 was encountered in 7 patients, of 8.4 ± 4.1 months. 9 patients had Class I Engel’s severe mental retardation with an IQ between 20–34 was outcome and 2 (with hemimegalencephaly) had Class II seen in 7 patients and moderate mental retardation with an outcome. The mean Stanford‑Binet Kamat Test score IQ between 35–49 was seen in 2 patients. was 62 ± 12.64 before surgery and 64.25 ± 4.99 at follow‑up (normal range 85–100). The improvement was The mean follow‑up was 18 ± 4.7 months not significant (P = 0.05). (range 16–27 months). There was complete improvement in drop attacks in all patients. A significant decrease (>90%) Endoscopic corpus callosotomy with anterior and posterior in seizure frequency was reported in 11 patients, moderate commissurotomy group reduction (>50%) in 5 patients, while an increased Sixteen patients underwent CCWC. The mean age was seizure frequency was noted in one patient. The decrease 10 ± 5.9 years (range: 2-15 years; 6 males). Seizure onset in frequency was observed in all types of seizures in occurred within 1 month after birth in 3 patients. In others, it these patients including tonic, tonic‑clonic, absence, and ranged from birth to 5.5 years (mean 24.37 ± 34.76 months). myoclonic seizures. The mean duration of epilepsy was 9.2 ± 5.2 years. The mean seizure frequency was 21.2 ± 17.3/day (range 1–45 days). Aggression in their behavior for an initial period of 3 months was Etiological causes included previous hypoxic insult in 10 reported in 8 patients, which gradually reduced in 6–9 months patients (due to forceps delivery), meconium aspiration, in 3 patients. The mean preoperative IQ was 25.23 ± 10.71. hypoglycemia, and low birth weight with breech presentation. This improved to a mean score of 26.43 ± 11.41 in 6 months Changes in the type of seizures were encountered in 3 and to 26.87 ± 11.95 in 1 year. Behavioural improvement, patients. A delayed development was seen in all patients. On in particular, in the domains of social contact, attention span, admission, profound mental retardation with an intelligence and learning were reported in 6 patients.

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Hypothalamic hamartoma group insular disconnection[54,74] is required to achieve the best Four patients underwent a pure endoscopic approach possible seizure outcome. Interestingly, when Delande et al. (Type II: 2; Type III: 2). Three patients underwent an developed this procedure, they started an inter‑hemispheric endoscopic‑assisted trans‑callosal approach. The follow‑up approach but gave it up to prefer a trans‑cortical approach ranged from 9.2 ± 1.46 months (range 6–24 months). Five due to the issue of the bridging veins.[35] Development of of them had Engel IA outcome, 1 had grade II outcome, and neuronavigation has solved this problem. Thus, key hole‑sized 1 had a poor outcome (Type III, patient with grade IV HH). may be effectively planned to avoid the bridging Three patients showed improvement in learning and behavior. veins. If the surgeon does not have access to neuronavigation, Schooling was started for them. Their rage and aggression we suggest that he/she should use the preoperative MRI to showed a significant improvement. EEG recordings in plan the site of craniotomy. various stages of follow‑up showed variable normalization of background activities. One patient, who had precocious The authors present a novel pilot technique consisting puberty, had significant improvement. His testosterone level of an endoscopic‑assisted approach utilizing a small normalized from a value of 711 ug/ml. He was, in addition, craniotomy (4 cm × 3 cm). The approach involves a route also given chemotherapy [Figure 6]. through the inter‑hemispheric trans‑callosal corridor to achieve a hemispheric disconnection.[9] Till date, there has Postoperative follow‑up been only one study of endoscopic‑assisted hemispherotomy All the patients were continued on their respective described in the literature, and this was a cadaveric concept anticonvulsants. A repeat MRI was scheduled after 3 months. study.[10] Our technique is the first of its kind to be described in the literature in terms of both concept and clinical Discussion application. However, a word of caution is that an endoscopic procedure should be initially performed using a larger bone Endoscopic hemispherotomy flap. The initial cases should preferably be done on patients Hemispherotomy has an excellent outcome when it is suffering from post‑ infarct sequel, and the surgeon should performed with proper surgical indications.[46‑53] In the not shy away from using the microscope in combination with literature, the incidence of freedom from seizures as a the endoscope. result of the hemispheric resection and disconnective procedures is reported to vary from 54% to 89%.[35,49,53‑61] Hemispherotomy can achieve excellent outcomes Better success rates are seen when the insula is also when performed in optimally indicated disconnected. These procedures have been mainly been patients.[34,48,51‑53,55,58,60,62,63,74‑85] Since the introduction of indicated in children having severe catastrophic epilepsy functional by Rasmussen, its morbidity and in the presence of either a congenital or an acquired mortality have steadily reduced.[34,35,53,55,57,58,75‑79,86] However, hemispheric pathology.[35,40,46‑53,58,62,63] When first introduced, this procedure still cannot be considered as trivial surgery, as hemispherectomy was associated with significant short and most of the surgeries are performed in children who cannot long term complications. Specially noteworthy was the tolerate blood loss and are prone to other perioperative occurrence of hemosiderosis, which occurs due to the morbidities such as hypothermia, electrolyte disturbances, presence of the dead space produced by removal of the and other problems associated with operating on pediatric entire hemisphere.[46,64,65] In 1983, Rasmussen introduced a patients. functional hemispherectomy based on the partial excision of certain areas and disconnection of the major lobes.[64] This Following an examination of these issues, the existing lead to the usage of the term “hemispherotomy” instead of literature, and also our own experience,[24,34] we decided “hemispherectomy,” which was first suggested by Olivier that the best option for EH would be an “endoscope‑assisted Delalande in 1992.[55,66] Further evolution lead to the surgery” utilizing the inter‑hemispheric route through a development of two basic procedures. A vertical approach small craniotomy. was suggested by Delalande[35,53,55] and a peri‑insular approach was suggested by Villemure et al.[58‑60,67,68] Most of the An inter‑hemispheric endoscope‑assisted hemispherotomy modifications are based on these two procedures.[25,34,57,61,69‑73] has the advantage of providing a “cisternal to ventricular Delande et al., felt that their technique was better as it access.” This is unlike the technique described by Delalande involved a cortical pathway that avoided major blood et al.,[53,55] which consists of a parenchymal‑to‑ventricular vessels and was performed through a trajectory that access. This is also in contrast to the concept described by included landmarks easily identifiable by surgeons. Overall, Bahuleyan et al.,[10] in which ventricular access would be it is important to realize that a complete hemispheric and difficult to obtain in the presence of small ventricles.

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Endoscopic callosotomy Endoscopic approach to hamartoma A drop attack is a postural seizure (mostly due to atonia) A gelastic seizure is the hallmark presentation of these caused by a rapid generalization of epileptiform activity tumors, which has now been proven to be originating in the to contralateral hemisphere mostly through the CC (that hamartoma itself and spreads to the adjoining cingulate gyrus is considered as the largest inter‑hemispheric propagation through the mammillothalamic tracts. Hence, attachments to pathway). Complete callosal sectioning is a very effective mammillary bodies are essential for epileptogenesis in HH. “palliative” procedure for breaking secondary bilateral We also demonstrated that depth electrode recordings from synchrony and alleviating the drop attacks with more than the hamartoma show continuous epileptiform discharges. 90% improvement in the drop attacks with a reasonable This forms the anatomical and electrophysiological basis long‑term remission.[87‑92] Most of these above‑mentioned of disconnection surgery in HH, which actually aims at authors, however, report the presence of 10–20% of primary removing the epileptogenic lesion from the epileptic non responders; and, close to 30% of patients further relapse networks.[40,41,44,45,99,100] In 1998, Delalande et al.[35] described in the next few years with the outcome thereafter remaining this novel technique of simple disconnection of the [91,93] stable. The common reasons cited for the failure of callosal hamartoma from the hypothalamus and reported complete sectioning in alleviating the drop attacks or their recurrence is seizure freedom in 3 of the five patients with more than 90% the possibility of transmission of epileptiform activity through reduction in seizure burden in the other 2 patients. In 2003, other inter‑hemispheric pathways like the anterior, posterior, Choi et al.[101] also described a good outcome of seizure [93‑96] [94] and habenular commissures. Adam has demonstrated reduction after successful endoscopic disconnection of a HH. the role of the anterior commissure in inter‑temporal lobe This was also demonstrated in other studies.[11,38,44] communication. Plausibly, these otherwise nonfunctional commissures attain propagating ability over time in the We believe that the trans‑callosal approach gives a direct absence of CC and may continue the spread of epileptiform entry into the third ventricle and provides an unobstructed activity to the contralateral hemisphere causing a recurrence view of the disconnection line thereby decreasing the [97] of drop attacks over a time course. Harbaugh et al. in manipulation of hypothalamus and obviates any need early eighties reported multiple forebrain commissurotomies for resection of the hamartoma. In addition, the use of including that of CC, anterior commissure, and posterior endoscopic assistance further reduces the size of the commissure, mainly for akinetic seizures and reported a craniotomy. In our study, we have used trans‑callosal good outcome in the magnitude of 80% with the procedure. endoscopic assistance in Type IV; and, a pure endoscopic Although we observed acute disconnection syndromes approach in Type II and III cases. mostly manifesting as prolonged confusional states in kids and nondominant facio‑brachial apraxia, it did not alter Conclusions the functional status of our patients. While all our patients had severe to profound mental retardation with severe In the current paper, the authors have described 2 novel epilepsy, there was a definite improvement at follow‑up in techniques that utilize an endoscope for performing a their cognitive functions. On the contrary, relief of disabling hemispherotomy and corpus callosotomy. In addition, seizures was perceived as the biggest factor responsible for they have described for the first time, a combination of the postoperative improvement as perceived by the parents. corpus callosotomy combined with commissurotomy for better control of seizures in patients with LGS with severe Our study is the first of its kind to demonstrate the utility to profound mental retardation. They have also described and safety of this approach for CC and commissurotomy. We believe that a “key hole” endoscopic‑assisted approach helps their experience with the use of an endoscope for HHs. The in minimizing unnecessary brain exposure and reduces the utilization of the endoscope for all the three approaches has blood loss. led to their coining the term “endoscopic epilepsy surgery” to denote the emergence of a new subspeciality of epilepsy Neurological complications in all major series have an surgery. incidence of 2–5% with a permanent sequel in 5% of patients.[87,88,98] We did not encounter any motor deficits. References However, postoperative akinetic state, apathy and sometimes aggression, buccal apraxia manifesting as drooling of 1. Menon RN, Radhakrishnan K. A survey of epilepsy surgery in India. Seizure 2015;26:1‑4. saliva, and memory deficits were common. These resolved 2. Rathore C, Radhakrishnan K. Concept of epilepsy surgery and completely over a period of time. presurgical evaluation. Epileptic Disord 2015;17:19‑31.

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3. Shah R, Botre A, Udani V. Trends in pediatric epilepsy surgery. Indian emission tomography, and electrocorticographic data for neocortical J Pediatr 2015;82:277‑85. lesional epilepsies may improve the localization of the epileptogenic 4. Singh G, Chowdhary AK. Epilepsy surgery in context of focus: A pilot study. World Neurosurg 2014;82:110‑7. neurocysticercosis. Ann Indian Acad Neurol 2014;17:S65‑8. 28. Tripathi M, Garg A, Gaikwad S, Bal CS, Chitra S, Prasad K, et al. 5. Santhosh NS, Sinha S, Satishchandra P. Epilepsy: Indian perspective. Intra‑operative electrocorticography in lesional epilepsy. Epilepsy Res Ann Indian Acad Neurol 2014;17:S3‑11. 2010;89:133‑41. 6. Banerjee J, Chandra SP, Kurwale N, Tripathi M. Epileptogenic networks 29. Tripathi M, Jain DC, Devi MG, Jain S, Saxena V, Chandra PS, et al. and drug‑resistant epilepsy: Present and future perspectives of epilepsy Need for a national epilepsy control program. Ann Indian Acad Neurol research‑Utility for the epileptologist and the epilepsy surgeon. Ann 2012;15:89‑93. Indian Acad Neurol 2014;17:S134‑40. 30. Tripathi M, Padhy UP, Vibha D, Bhatia R, Padma Srivastava MV, 7. Radhakrishnan K. Presidential oration: The 18 Annual Conference of the Singh MB, et al. Predictors of refractory epilepsy in north India: A Indian Academy of Neurology, Trichi, Tamil Nadu, September 24‑26, case‑control study. Seizure 2011;20:779‑83. 2010, Epilepsy care in developing countries. Ann Indian Acad Neurol 31. Tripathi M, Singh MS, Padma MV, Gaikwad S, Bal CS, Tripathi M, 2010;13:236‑40. et al. Surgical outcome of cortical dysplasias presenting with chronic 8. Tandon PN. Prof. B. Ramamurthi: Contributions to Indian neurosurgery intractable epilepsy: A 10‑year experience. Neurol India 2008;56:138‑43. (a personal tribute). Neurol India 2004;52:18‑20. 32. Tripathi M, Singh PK, Vibha D, Choudhary N, Garg A, Bal CS, et al. 9. Chandra PS, Kurwale N, Garg A, Dwivedi R, Malviya SV, Electrophysiological characteristics of seizure clusters. Clin EEG Tripathi M. Endoscopy‑assisted interhemispheric transcallosal Neurosci 2010;41:143‑6. hemispherotomy: Preliminary description of a novel technique. 33. Tripathi M, Vibha D, Choudhary N, Prasad K, Srivastava MV, Bhatia R, Neurosurgery 2015;76:485‑94. et al. Management of refractory status epilepticus at a tertiary care centre 10. Bahuleyan B, Manjila S, Robinson S, Cohen AR. Minimally invasive in a developing country. Seizure 2010;19:109‑11. endoscopic transventricular hemispherotomy for medically intractable 34. Chandra PS, Padma VM, Shailesh G, Chandreshekar B, Sarkar C, epilepsy: A new approach and cadaveric demonstration. J Neurosurg Tripathi M. Hemispherotomy for intractable epilepsy. Neurol India Pediatr 2010;6:536‑40. 2008;56:127‑32. 11. Dagar A, Chandra PS, Chaudhary K, Avnish C, Bal CS, Gaikwad S, et al. 35. Delalande O, Fohlen M, Bulteau C, Jalin C. Surgery for intractable focal Epilepsy surgery in a pediatric population: A retrospective study of 129 epilepsy in children. Rev Neurol (Paris) 2004;160:5S195‑202. children from a tertiary care hospital in a developing country along with 36. Delande O, Rodriguez D, Chiron C, Fohlen M. Successful surgical relief assessment of quality of life. Pediatr Neurosurg 2011;47:186‑93. of seizures associated with hamartoma of the floor of the fourth ventricle 12. Duchowny MS. Surgery for intractable epilepsy: Issues and outcome. in children: Report of two cases. Neurosurgery 2001;49:726‑30. Pediatrics 1989;84:886‑94. 37. Bragatti Winckler MI, Dos Santos Riesgo R, Ohlweiler L, Ranzan J, 13. Duncan JS. Epilepsy surgery. Clin Med 2007;7:137‑42. Tellechea Rotta N. Surgical indications in pediatric epilepsy. 14. Dunkley C, Kung J, Scott RC, Nicolaides P, Neville B, Aylett SE, et al. Medicina (B Aires) 2007;67 (6 Pt 1):614‑22. Epilepsy surgery in children under 3 years. Epilepsy Res 2011;93:96‑106. 38. Calisto A, Dorfmüller G, Fohlen M, Bulteau C, Conti A, Delalande O. 15. Engel J Jr. Concepts of epilepsy. Epilepsia 1995;36 Suppl 1:S23‑9. Endoscopic disconnection of hypothalamic hamartomas: Safety and 16. Fang M, Xi ZQ, Wu Y, Wang XF. A new hypothesis of drug refractory feasibility of robot‑assisted, thulium laser‑based procedures. J Neurosurg epilepsy: Neural network hypothesis. Med Hypotheses 2011;76:871‑6. Pediatr 2014;14:563‑72. 17. Bhatia M, Singh VP, Jain S, Gaekwad S, Bal CS, Sarkar C, et al. Epilepsy 39. Chandra PS, Gulati S, Kalra V, Garg A, Mishra NK, Bal CS, et al. Fourth surgery in India: All India Institute of Medical Sciences experience. ventricular hamartoma presenting with status epilepticus treated with J Assoc Physicians India 1999;47:492‑5. emergency surgery in an infant. Pediatr Neurosurg 2011;47:217‑22. 18. Gadgil P, Udani V. Pediatric epilepsy: The Indian experience. J Pediatr 40. Dorfmüller G, Delalande O. Pediatric epilepsy surgery. Handb Clin Neurosci 2011;6:S126‑9. Neurol 2013;111:785‑95. 19. Jayalakshmi S, Panigrahi M, Nanda SK, Vadapalli R. Surgery for 41. Guénot M. Surgical treatment of epilepsy: Outcome of various childhood epilepsy. Ann Indian Acad Neurol 2014;17:S69‑79. surgical procedures in adults and children. Rev Neurol (Paris) 20. Jayalakshmi S, Vooturi S, Vadapalli R, Somayajula S, Madigubba S, 2004;160:5S241‑50. Panigrahi M. Outcome of surgery for temporal lobe epilepsy in adults‑A 42. Harvey AS, Cross JH, Shinnar S, Mathern GW, ILAE Pediatric Epilepsy cohort study. Int J Surg 2015. doi: 10.1016/j.ijsu.2015.05.006. Surgery Survey Taskforce. Defining the spectrum of international 21. Kar AM, Garg RK, Verma R. Refractory epilepsy: Diagnosis and practice in pediatric epilepsy surgery patients. Epilepsia 2008;49:146‑55. management. J Indian Med Assoc 2002;100:290‑2, 294. 43. Kim SK, Wang KC, Hwang YS, Kim KJ, Chae JH, Kim IO, et al. 22. Rathore C, Rao MB, Radhakrishnan K. National epilepsy surgery Epilepsy surgery in children: Outcomes and complications. J Neurosurg program: Realistic goals and pragmatic solutions. Neurol India Pediatr 2008;1:277‑83. 2014;62:124‑9. 44. Procaccini E, Dorfmüller G, Fohlen M, Bulteau C, Delalande O. 23. Wieser HG, Silfvenius H. Overview: Epilepsy surgery in developing Surgical management of hypothalamic hamartomas with epilepsy: The countries. Epilepsia 2000;41 Suppl 4:S3‑9. stereoendoscopic approach. Neurosurgery 2006;59:ONS336‑44. 24. Chandra PS, Bal C, Garg A, Gaikwad S, Prasad K, Sharma BS, et al. 45. Shim KW, Chang JH, Park YG, Kim HD, Choi JU, Kim DS. Treatment Surgery for medically intractable epilepsy due to postinfectious modality for intractable epilepsy in hypothalamic hamartomatous etiologies. Epilepsia 2010;51:1097‑100. lesions. Neurosurgery 2008;62:847‑56. 25. Chandra PS, Tripathi M. Epilepsy surgery: Recommendations for India. 46. Adams CB. Hemispherectomy – A modification. J Neurol Neurosurg Ann Indian Acad Neurol 2010;13:87‑93. Psychiatry 1983;46:617‑9. 26. Chandra PS, Vaghania G, Bal CS, Tripathi M, Kuruwale N, Arora A, 47. Beardsworth ED, Adams CB. Modified hemispherectomy for epilepsy: et al. Role of concordance between ictal‑subtracted SPECT and PET Early results in 10 cases. Br J Neurosurg 1988;2:73‑84. in predicting long‑term outcomes after epilepsy surgery. Epilepsy Res 48. Bulteau C, Otsuki T, Delalande O. Epilepsy surgery for hemispheric 2014;108:1782‑9. syndromes in infants: Hemimegalencepahly and hemispheric cortical 27. Chandra SP, Bal CS, Jain S, Joshua SP, Gaikwad S, Garg A, et al. dysplasia. Brain Dev 2013;35:742‑7. Intraoperative coregistration of magnetic resonance imaging, positron 49. Carson BS, Javedan SP, Freeman JM, Vining EP, Zuckerberg AL,

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Chandra and Tripathi: Endoscopic epilepsy surgery

Lauer JA, et al. Hemispherectomy: A hemidecortication approach and et al. Cerebral hemispherectomy in pediatric patients with epilepsy: review of 52 cases. J Neurosurg 1996;84:903‑11. Comparison of three techniques by pathological substrate in 115 patients. 50. Cosgrove GR, Villemure JG. Cerebral hemicorticectomy for epilepsy. J Neurosurg 2004;100:125‑41. J Neurosurg 1993;79:473‑4. 75. Althausen A, Gleissner U, Hoppe C, Sassen R, Buddewig S, von Lehe M, 51. Daniel RT, Villemure JG. Hemispherotomy techniques. J Neurosurg et al. Long‑term outcome of hemispheric surgery at different ages in 61 2003;98:438‑9. epilepsy patients. J Neurol Neurosurg Psychiatry 2013;84:529‑36. 52. De Ribaupierre S, Delalande O. Hemispherotomy and other 76. Anan M, Kamida T, Abe E, Kubo T, Abe T, Hikawa T, et al. disconnective techniques. Neurosurg Focus 2008;25:E14. A hemispherotomy for intractable startle epilepsy characterized by 53. Delalande O, Dorfmüller G. Parasagittal vertical hemispherotomy: infantile hemiplegia and drop attacks. J Clin Neurosci 2009;16:1652‑5. Surgical procedure. Neurochirurgie 2008;54:353‑7. 77. Andrade DM, McAndrews MP, Hamani C, Poublanc J, Angel M, 54. Cats EA, Kho KH, Van Nieuwenhuizen O, Van Veelen CW, Gosselaar PH, Wennberg R. Seizure recurrence 29 years after hemispherectomy for Van Rijen PC. Seizure freedom after functional hemispherectomy and a Sturge Weber syndrome. Can J Neurol Sci 2010;37:141‑4. possible role for the insular cortex: The Dutch experience. J Neurosurg 78. Basheer SN, Connolly MB, Lautzenhiser A, Sherman EM, Hendson G, 2007;107:275‑80. Steinbok P. Hemispheric surgery in children with refractory epilepsy: 55. Delalande O, Bulteau C, Dellatolas G, Fohlen M, Jalin C, Buret V, et al. Seizure outcome, complications, and adaptive function. Epilepsia Vertical parasagittal hemispherotomy: Surgical procedures and clinical 2007;48:133‑40. long‑term outcomes in a population of 83 children. Neurosurgery 79. Beier AD, Rutka JT. Hemispherectomy: Historical review and recent 2007;60:ONS19‑32. technical advances. Neurosurg Focus 2013;34:E11. 56. Kestle J, Connolly M, Cochrane D. Pediatric peri‑insular hemispherotomy. 80. Ghatan S, McGoldrick P, Palmese C, La Vega‑Talbott M, Kang H, Pediatr Neurosurg 2000;32:44‑7. Kokoszka MA, et al. Surgical management of medically refractory 57. Schramm J, Kuczaty S, Sassen R, Elger CE, von Lehe M. Pediatric epilepsy due to early childhood stroke. J Neurosurg Pediatr 2014;14:58‑67. functional hemispherectomy: Outcome in 92 patients. Acta 81. Granata T, Matricardi S, Ragona F, Freri E, Casazza M, Villani F, et al. Neurochir (Wien) 2012;154:2017‑28. Hemispherotomy in Rasmussen encephalitis: Long‑term outcome in an 58. Villemure JG, Daniel RT. Peri‑insular hemispherotomy in paediatric Italian series of 16 patients. Epilepsy Res 2014;108:1106‑19. epilepsy. Childs Nerv Syst 2006;22:967‑81. 82. Guan Y, Zhou J, Luan G, Liu X. Surgical treatment of patients with 59. Villemure JG, Meagher‑Villemure K, Montes JL, Farmer JP, Broggi G. Rasmussen encephalitis. Stereotact Funct Neurosurg 2014;92:86‑93. Disconnective hemispherectomy for hemispheric dysplasia. Epileptic 83. Kawai K, Morino M, Iwasaki M. Modification of vertical hemispherotomy Disord 2003;5 Suppl 2:S125‑30. for refractory epilepsy. Brain Dev 2014;36:124‑9. 60. Villemure JG, Vernet O, Delalande O. Hemispheric disconnection: 84. Lew SM, Koop JI, Mueller WM, Matthews AE, Mallonee JC. Fifty Callosotomy and hemispherotomy. Adv Tech Stand Neurosurg consecutive hemispherectomies: Outcomes, evolution of technique, 2000;26:25‑78. complications, and lessons learned. Neurosurgery 2014;74:182‑94. 61. Shimizu H, Maehara T. Modification of peri‑insular hemispherotomy 85. Daniel RT, Villemure JG. Peri‑insular hemispherotomy: Potential pitfalls and surgical results. Neurosurgery 2000;47:367‑72. and avoidance of complications. Stereotact Funct Neurosurg 2003;80:22‑7. 62. Dorfer C, Czech T, Dressler A, Gröppel G, Mühlebner‑Fahrngruber A, 86. Schramm J, Clusmann H. The surgery of epilepsy. Neurosurgery Novak K, et al. Vertical perithalamic hemispherotomy: A single‑center 2008;62 Suppl 2:463‑81. experience in 40 pediatric patients with epilepsy. Epilepsia 87. Jalilian L, Limbrick DD, Steger‑May K, Johnston J, Powers AK, 2013;54:1905‑12. Smyth MD. Complete versus anterior two‑thirds corpus callosotomy 63. Matheson JM, Truskett P, Davies MA, Vonau M. Hemispherectomy: A in children: Analysis of outcome. J Neurosurg Pediatr 2010;6:257‑66. further modification using omentum vascularized free flaps. Aust N Z 88. Kasasbeh AS, Smyth MD, Steger‑May K, Jalilian L, Bertrand M, J Surg 1993;63:646‑50. Limbrick DD. Outcomes after anterior or complete corpus callosotomy 64. Rasmussen T. Hemispherectomy for seizures revisited. Can J Neurol in children. Neurosurgery 2014;74:17‑28. Sci 1983;10:71‑8. 89. Maehara T, Shimizu H. Surgical outcome of corpus callosotomy in 65. Wilson PJ. Cerebral hemispherectomy for infantile hemiplegia. A report patients with drop attacks. Epilepsia 2001;42:67‑71. of 50 cases. Brain 1970;93:147‑80. 90. Shim KW, Lee YM, Kim HD, Lee JS, Choi JU, Kim DS. Changing 66. Lüders HO. Epilepsy Surgery. Philadelphia: Lippincott Williams and the paradigm of 1‑stage total callosotomy for the treatment of pediatric Wilkins; 2001. generalized epilepsy. J Neurosurg Pediatr 2008;2:29‑36. 67. Villemure JG. Surgery of epilepsy in children: Who, when, how, and 91. Sunaga S, Shimizu H, Sugano H. Long‑term follow‑up of seizure why. Rev Med Suisse Romande 2003;123:577‑81. outcomes after corpus callosotomy. Seizure 2009;18:124‑8. 68. Villemure JG, Mascott CR. Peri‑insular hemispherotomy: Surgical 92. Tanriverdi T, Olivier A, Poulin N, Andermann F, Dubeau F. Long‑term principles and anatomy. Neurosurgery 1995;37:975‑81. seizure outcome after corpus callosotomy: A retrospective analysis of 69. Caraballo R, Bartuluchi M, Cersósimo R, Soraru A, Pomata H. 95 patients. J Neurosurg 2009;110:332‑42. Hemispherectomy in pediatric patients with epilepsy: A study of 93. Wong TT, Kwan SY, Chang KP, Hsiu‑Mei W, Yang TF, Chen YS, et al. 45 cases with special emphasis on epileptic syndromes. Childs Nerv Corpus callosotomy in children. Childs Nerv Syst 2006;22:999‑1011. Syst 2011;27:2131‑6. 94. Adam C. How do the temporal lobes communicate in medial temporal 70. Holthausen H, Pieper T. Complications of Hemispherectomy. 2nd ed. lobe seizures?. Rev Neurol (Paris) 2006;162:813‑8. Philadelphia: Lippincott Williams and Wilkins; 2001. 95. Gloor P, Salanova V, Olivier A, Quesney LF. The human dorsal 71. Jadhav T, Cross JH. Surgical approaches to treating epilepsy in children. hippocampal commissure. An anatomically identifiable and functional Curr Treat Options Neurol 2012;14:620‑9. pathway. Brain 1993;116(Pt 5):1249‑73. 72. Steinhoff BJ, Staack AM, Bilic S, Kraus U, Schulze‑Bonhage A, 96. Wada JA. Transhemispheric horizontal channels for transmission of Zentner J. Functional hemispherectomy in adults with intractable epileptic information. Jpn J Psychiatry Neurol 1991;45:235‑42. epilepsy syndromes: A report of 4 cases. Epileptic Disord 2009;11:251‑7. 97. Harbaugh RE, Wilson DH, Reeves AG, Gazzaniga MS. Forebrain 73. Wiebe S, Berg AT. Big epilepsy surgery for little people: What’s the full commissurotomy for epilepsy. Review of 20 consecutive cases. Acta story on hemispherectomy? Neurology 2013;80:232‑3. Neurochir (Wien) 1983;68:263‑75. 74. Cook SW, Nguyen ST, Hu B, Yudovin S, Shields WD, Vinters HV, 98. Spencer SS, Spencer DD, Sass K, Westerveld M, Katz A, Mattson R.

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Anterior, total, and two‑stage corpus callosum section: Differential and Endoscopic disconnection for hypothalamic hamartoma with intractable incremental seizure responses. Epilepsia 1993;34:561‑7. seizure. Report of four cases. J Neurosurg 2004;100:506‑11. 99. Incorpora G, Pavone P, Castellano‑Chiodo D, Praticò AD, Ruggieri M, Pavone L. Gelastic seizures due to hypothalamic hamartoma: Rapid resolution after endoscopic tumor disconnection. Neurocase 2013;19:458‑61. How to cite this article: Chandra SP, Tripathi M. Endoscopic epilepsy surgery: Emergence of a new procedure. Neurol India 2015;63:571-82. 100. Shields WD. Surgical treatment of refractory epilepsy. Curr Treat Options Neurol 2004;6:349‑56. 101. Choi JU, Yang KH, Kim TG, Chang JH, Chang JW, Lee BI, et al. Source of Support: Nil, Conflict of Interest: None declared.

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