Intraoperative direct electrocortical stimulation for glioma surgery

see also Awake surgery for glioma.

see also Resting-state functional magnetic resonance for glioma surgery.


Stimulation-induced seizures (SISs) are rare but serious events during electrocortical stimulation (ECS) mapping. SISs are most common when mapping the frontal lobe. Greater stimulation current is not associated with the identification of more cortical functional sites during glioma surgery 1).


Glioma surgery represents a significant advance with respect to improving resection rates using new surgical techniques, including intraoperative functional mappingmonitoring, and imaging. Functional mapping under awake craniotomy can be used to detect individual eloquent tissues of speech and/or motor functions in order to prevent unexpected deficits and promote extensive resection. In addition, monitoring the patient’s neurological findings during resection is also very useful for maximizing the removal rate and minimizing deficits by alarming that the touched area is close to eloquent regions and fibers. Assessing several types of evoked potentials, including motor evoked potentials (MEPs), sensory evoked potentials (SEPs), and visual evoked potentials (VEPs), is also helpful for performing surgical monitoring in patients under general anesthesia (GA) 2).


The greater extent of resection (EOR) of low-grade gliomas is associated with improved survival. Proximity to eloquent cortical regions often limits resectability and elevates the risk of surgery-related deficits. Therefore, functional localization of eloquent cortex or subcortical fiber tracts can enhance the EOR and functional outcomeImaging techniques such as functional MRI and diffusion tensor imaging fiber tracking, and neurophysiological methods like navigated transcranial magnetic stimulation and magnetoencephalography, make it possible to identify eloquent areas prior to resective surgery and to tailor indication and surgical approach but also to assess the surgical risk. Intraoperative monitoring with direct cortical stimulation and subcortical stimulation enables surgeons to preserve essential functional tissue during surgery. Through tailored, pre-and intraoperative mapping and monitoring the EOR can be maximized, with reduced rates of surgery-related deficits 3).


As the most accurate and reliable method of brain functional area positioning, Intraoperative direct electrocortical stimulation is able to determine in real-time the parts of the brain necessary for such functions as movementsensationlanguage, and even memory. A meta-analysis suggested that it could also improve the degree of resection of glioma while reducing the incidence of permanent neurological dysfunction 4).


Findings suggest that surgeons using Intraoperative direct electrocortical stimulation and awake craniotomy during their resections of high-grade glioma in eloquent areas experienced better surgical outcomes: a significantly longer overall postoperative survival, a lower rate of postoperative complications, and a higher percentage of GTR 5).


Resting-state functional magnetic resonance imaging likely reflects similar neural information as detected with intraoperative direct electrocortical stimulation (DES), but in its current form does not reach the spatial resolution of DES. 6).


1)

Muster RH, Young JS, Woo PYM, Morshed RA, Warrier G, Kakaizada S, Molinaro AM, Berger MS, Hervey-Jumper SL. The Relationship Between Stimulation Current and Functional Site Localization During Brain Mapping. Neurosurgery. 2021 May 13;88(6):1043-1050. doi: 10.1093/neuros/nyaa364. PMID: 33289525; PMCID: PMC8117445.
2)

Saito T, Muragaki Y, Maruyama T, Tamura M, Nitta M, Okada Y. Intraoperative Functional Mapping and Monitoring during Glioma Surgery. Neurol Med Chir (Tokyo). 2015;55 Suppl 1:1-13. PMID: 26236798.
3)

Ottenhausen M, Krieg SM, Meyer B, Ringel F. Functional preoperative and intraoperative mapping and monitoring: increasing safety and efficacy in glioma surgery. Neurosurg Focus. 2015 Jan;38(1):E3. doi: 10.3171/2014.10.FOCUS14611. PMID: 25552283.
4)

De Witt Hamer PC, Robles SG, Zwinderman AH, Duffau H, Berger MS. Impact of intraoperative stimulation brain mapping on glioma surgery outcome: a meta-analysis. J Clin Oncol. 2012;30:2559–2565. doi: 10.1200/JCO.2011.38.4818.
5)

Gerritsen JKW, Arends L, Klimek M, Dirven CMF, Vincent AJE. Impact of intraoperative stimulation mapping on high-grade glioma surgery outcome: a meta-analysis. Acta Neurochir (Wien). 2019 Jan;161(1):99-107. doi: 10.1007/s00701-018-3732-4. Epub 2018 Nov 21. PMID: 30465276; PMCID: PMC6331492.
6)

van Lieshout J, Debaene W, Rapp M, Noordmans HJ, Rutten GJ. fMRI Resting-State Connectivity between Language and Nonlanguage Areas as Defined by Intraoperative Electrocortical Stimulation in Low-Grade Glioma Patients. J Neurol Surg A Cent Eur Neurosurg. 2021 Feb 22. doi: 10.1055/s-0040-1721757. Epub ahead of print. PMID: 33618418.

Gelatin Sponge

Gelatin Sponge

see Spongostan.

see also Hemostat.


Expanding the range of medical sponges and researching new excipients for their manufacture are a promising area of modern medicine and pharmacy 1).


Gelatin sponge is a non-antigenic protein that can absorb 45 times its weight in blood, and, when wet, is plastered to the irregularities of the bleeding surface. It enables the repair of torn veins, such as the superior sagittal sinus, without compromising the patency of the vessel 2).


Many ablative procedures are effective for hemifacial spasm (HFS) (including sectioning of divisions of the facial nerve), however, this leaves the patient with some degree of facial paresis. The current procedure of choice for HFS is microvascular decompression (MVD) wherein the offending vessel is physically moved off of the nerve, and a sponge (e.g. Ivalon®, polyvinyl formyl alcohol foam) is interposed as a cushion.


For Chang et al. from the Department of Neurosurgery Xinhua Hospital in hemifacial spasm (HFS) patients undergoing microvascular decompression (MVD) , using Teflon plus gelatin sponge can remarkably reduce the incidence of recurrence, facial palsy, and hearing loss compared with those using Teflon alone 3).


A study proves that, during the dural closure, placing a thin layer of gelatin sponge in the subdural space is a safe and effective method for preventing meningocerebral adhesions 4)


1)

Pavliuk B, Chubka M, Hroshovyi T, Stechyshyn I. Characteristics of structured medical hemostatic sponges as a medical devices for stop bleeding and for close the wound. Pol Merkur Lekarski. 2020 Dec 22;48(288):422-426. PMID: 33387430.
2)

Signorelli F, Montano N. Use and Efficacy of Hemostats in Neurosurgery. Surg Technol Int. 2020 Nov 28;37:414-419. PMID: 32944921.
3)

Chang B, Tang Y, Wei X, Li S. A New Application of Gelatin Sponge in the Treatment of Hemifacial Spasm by Microvascular Decompression: A Technical Note. J Neurol Surg A Cent Eur Neurosurg. 2021 May 19. doi: 10.1055/s-0040-1720994. Epub ahead of print. PMID: 34010981.
4)

Gonzalez-Lopez P, Harput MV, Türe H, Atalay B, Türe U. Efficacy of placing a thin layer of gelatin sponge over the subdural space during dural closure in preventing meningo-cerebral adhesion. World Neurosurg. 2015 Jan;83(1):93-101. doi: 10.1016/j.wneu.2014.02.032. Epub 2014 Feb 19. PubMed PMID: 24560706.

Anterior transpetrosal approach

Anterior transpetrosal approach

see Anterior petrosectomy.

In 1985Takeshi Kawase from the Department of Neurosurgery, Keio University School of Medicine, Tokyo, and Ashikaga Red Cross Hospital, AshikagaJapan 1) published an anterior petrosal approach to expose the posterior cranial fossa and to minimize retraction of the temporal lobe for upper petroclival


Anterior subtemporal and transpetrous apex approaches let us some exposure of deep region, however they require an unacceptable temporal lobe retraction and provide an extremely narrow surgical corridor in cases of large tumors mainly located in the infratentorial space 2) 3).

This approach requires epidural subtemporal procedures to expose the petrous apex adequately. The petrous apex must be totally resected and the dura of the temporal lobe and posterior fossa is then cut to ligate the superior petrosal sinus and tentorium. In this procedure, the most important things are to preserve the internal carotid artery (C2 segment) and greater superficial petrosal nerve (GSPN). To identify the GSPN, facial nerve integrity monitor (Medtronic Inc, Dublin, Ireland) is very useful. In the extradural bone removal, Sonopet Ultrasonic Aspirator (Stryker Ltd, Portage, Michigan) is a very excellent surgical tool for avoiding the injury of the internal carotid artery. As demonstrated by Cavalcanti, ATPA is particularly useful for accessing lesions located in the upper ventral pons via the supratrigeminal zone because it provides a wide and shallow surgical field above the trigeminal nerve without requiring retraction of the cerebellum 4).


Several neurosurgeons still have difficulty with removing tumors through an anterior petrosal approach, because a complete understanding of the Kawase pyramid has not been achieved. Jung et al. hypothesized that if anterior petrosectomy is performed with a three-dimensional understanding of the Kawase pyramid, it would have a positive effect on the extent of tumor resection.

They performed a retrospective study of patients who underwent surgical treatment for meningioma through an anterior petrosal approach. Patients were divided into total resection and subtotal resection groups, and statistical differences between the two groups were analyzed. To identify factors predictive of complete tumor removal, univariable and multivariable logistic regression analyses were performed.

The width and height of the drilled internal acoustic canal (IAC) of the total resection group were significantly longer than those of the subtotal resection group (p=0.001, p=0.033). The operative angle of the total resection group was significantly larger than that of the subtotal resection group (p<0.001). Regression analyses showed only drilled IAC width to be predictive of complete tumor removal, increasing the likelihood thereof by 2.778-fold with an increase in drilled IAC width by 1 mm (p=0.023).

Insufficient petrosectomy during an anterior petrosal approach adversely affects the extent of tumor resection. Furthering a three-dimensional understanding of the Kawase pyramid could help complete tumor resection and better outcomes without causing damage to the surrounding organs 5).


see Anterior transpetrosal transtentorial approach.

see Anterior transpetrosal approach indications.

A study of Shibao et al., included 126 patients treated via the ATPA. The bridging vein (BV) and the tentorial sinus (TenS) located in the operative fields were analyzed. Furthermore, in the preoperative evaluation, the cross-sectional shapes of the intradural vein and the interdural sinus were analyzed by curved planar reconstruction (CPR), and the flattening rate was calculated. Flattening rate = (a-b)/a = 1-b/a (a: long radius, b: short radius).

Seventeen BVs and 18 TenS were identified. The bridging site was divided into two groups: tentorial and middle fossa. The middle fossa group was divided into three subgroups: cavernous sinus, middle fossa dural sinus, and middle fossa dural adherence. Five isolated TenS were sacrificed and no venous complications were observed. The mean flattening rate was 0.13 in the intradural vein and 0.51 in the interdural sinus, respectively (P = 0.0003).

They showed classification of the BV, and preservation of the BV and TenS during the ATPA. Furthermore, they found that the interdural sinus was significantly flatter than the intradural veins. Measuring the flattening rate by CPR may be useful to identify BVs preoperatively 6).


1)

Kawase T, Toya S, Shiobara R, Mine T. Transpetrosal approach for aneurysms of the lower basilar artery. J Neurosurg. 1985 Dec;63(6):857-61. PubMed PMID: 4056899.
2)

Bambakidis NC, Gonzalez LF, Amin‐Hanjani S, et al: Combined skull base approaches to the posterior fossa. Technical note. Neurosurg Focus 19:E8, 2005
3)

Yang J, Ma SC, Fang T, et al: Subtemporal transpetrosal apex approach: study on its use in large and giant petroclival meningiomas. Chin Med J (Engl) 124:49‐55, 2011
4)

Yokoyama K, Kawanishi M, Sugie A, Yamada M, Tanaka H, Ito Y, Yamshita M. Microsurgical Resection of a Ventral Pontine Cavernoma via Supratrigeminal Zone by Anterior Transpetrosal Approach: 2-Dimensional Operative Video. Oper Neurosurg (Hagerstown). 2018 Jul 19. doi: 10.1093/ons/opy177. [Epub ahead of print] PubMed PMID: 30032310.
5)

Jung IH, Yoo J, Roh TH, Park HH, Hong CK. Importance of sufficient petrosectomy in an anterior petrosal approach relightening of the Kawase pyramid. World Neurosurg. 2021 May 15:S1878-8750(21)00712-9. doi: 10.1016/j.wneu.2021.05.017. Epub ahead of print. PMID: 34004357.
6)

Shibao S, Toda M, Fujiwara H, Jinzaki M, Yoshida K. Bridging vein and tentorial sinus in the subtemporal corridor during the anterior transpetrosal approach. Acta Neurochir (Wien). 2019 Feb 23. doi: 10.1007/s00701-019-03857-w. [Epub ahead of print] PubMed PMID: 30798482.
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