How should visual function monitoring be performed and interpreted in surgery for suprasellar tumors?

OBJECTIVE: Preservation of visual function is important in surgery for suprasellar tumors. Visual evoked potentials (VEPs) are expected to play an important role in monitoring visual function during surgery. Given the lack of information in this field, the authors aimed to investigate the effects of optic nerve compression caused by suprasellar tumors to understand the possible usefulness of VEP monitoring using off-response (OFR) VEP. METHODS: Eleven healthy volunteers who underwent surgery for standard record confirmation and 32 patients with optic chiasm lesions who underwent surgery were examined. Preoperative, postoperative, and intraoperative VEPs were recorded. Propofol anesthesia was administered during intraoperative VEP monitoring. Patients who underwent surgery were monitored using the same stimulation method during surgery. Light stimulation was given from a luminant pad on the eyelids, and low-intensity stimulation with continuous 500-msec emission and 500 msec off was performed. The luminescence intensity of the stimulation was at a maximum of 8000 lx with three attenuation steps, each of which was recorded repeatedly. RESULTS: The OFR potentials and delay latencies decreased as stimulus intensity decreased. In the patient with temporal hemianopia, monocular stimulation produced the highest OFR in the contralateral occipital lobe of the stimulated eye. The authors recorded preoperative, intraoperative, and postoperative VEP in 32 patients and observed intraoperative changes in 23 patients. In the cases where VEP declined during intraoperative recording, it recovered when surgery was discontinued. Furthermore, 3 patients eventually achieved a higher VEP than that achieved at the beginning of the surgery, and rapid recovery was confirmed with visual field examination immediately after surgery. Of the 5 patients in whom VEP did not recover during surgery, 3 showed decreased visual field and acuity after surgery. In 15 cases, potential dropped temporarily but returned to the original potential, and their visual field recovered after surgery. CONCLUSIONS: OFR has a diagnostic element in the visual field, in which the maximal potential was recorded on the opposite side of the stimulus with monocular stimulation. Unambiguous determination required stimulation of different intensities in both eyes or 1 eye and multiple recording electrodes placed in the occiput. Monitoring the OFR provides real-time alerts, making it a valuable tool for visual function evaluation in suprasellar surgery.

Sternocleidomastoid muscle-splitting method for high cervical carotid endarterectomy: illustrative cases.

BACKGROUND: The number of cervical carotid endarterectomies (CEAs) has decreased as carotid artery stenting (CAS) has increased. However, CEA and CAS both have advantages and disadvantages; therefore, appropriate procedures must be selected for individual patients. High-positioned carotid artery stenosis presents technical challenges for CEA and is occasionally managed by performing CAS. However, CAS is associated with a high risk of thrombosis in patients with soft plaques, suggesting a clinical need for a better procedure. Consequently, appropriate surgical treatment for patients requiring high-level CEAs is essential. OBSERVATIONS: In this study, a novel and straightforward method was devised. The primary concept underlying this technique is separation of the sternocleidomastoid muscle (SCM) from other anatomical structures to ensure a wider surgical field. By anatomically separating the SCM into the sternal and clavicular head groups, the objective of the wider surgical field can be met. Herein, we report technical innovations in high-positioned carotid artery stenosis and evaluate their efficacy in two patients. LESSONS: In conclusion, high CEA surgery using this new method is valuable and may eliminate barriers to more advanced approaches.

Injury of the Internal Carotid Artery During Dissection of a Craniopharyngioma via the Pterional Approach: Case Report.

Among the various causes of intraoperative neurosurgical complications, a major arterial injury is one of the most devastating. Herein, the authors present a case of a 76-year-old patient who underwent removal of a craniopharyngioma via the pterional approach and experienced severe damage of her sclerotic left internal carotid artery because it was retracted excessively by a brain spatula, which resulted in complete sacrifice of the vessel. Despite stable parameters on intraoperative monitoring of motor evoked potentials and sufficient collateral blood flow, confirmed by Doppler flowmetry, a large infarct in the left cerebral hemisphere was noted after surgery. Although retraction of movable arteries, veins, and cranial nerves can often be done safely during neurosurgical procedures for effective exposure of the operative field, forced displacement of a sclerotic internal carotid artery in its paraclinoid portion anchored to the fixed distal dural ring should definitely be avoided because it poses a significant risk of major vessel damage.

Postoperative Intratumoral or Peritumoral Hematomas After Vestibular Schwannoma Resection.

BACKGROUND: Surgical removal of a vestibular schwannoma is a complex and challenging procedure, which may be complicated by development of postoperative hematomas, particularly after incomplete resection of the tumor. OBJECTIVE: To investigate the occurrence of postoperative intra- or peritumoral hematomas after surgery for a vestibular schwannoma. METHODS: This retrospective study evaluated 49 patients (age range 17-78 years) with a vestibular schwannoma, who were treated surgically via the lateral suboccipital approach between 2011 and 2016. The tumors ranged in size from 0 mm (in a case of an intracanalicular lesion) to 56 mm. In 30 cases (61%), total or near-total resection was accomplished, and in 19 cases (39%), subtotal or partial resection was done. On the basis of their bleeding tendency during tumor removal, the patients were divided into a "less-bleeding" (38 cases; 78%) and a "more-bleeding" (11 cases; 22%) subgroups. RESULTS: A maximal vestibular schwannoma diameter >30 mm, patient age >60 years, and more bleeding during tumor removal were significantly associated with incomplete (subtotal or partial) resection. In six cases (12%), serial computed tomography after surgery demonstrated a postoperative hematoma, which was caused by insufficient irrigation of the surgical field (in two cases) or resulted from peritumoral hemorrhage (in two cases), intratumoral hemorrhage (in one case), or both intra- and peritumoral hemorrhage (in one case). The latter patient required urgent reoperation. In all cases, postoperative hematomas occurred after incomplete (subtotal or partial) resection of a vestibular schwannoma, and their development was significantly associated with more bleeding during tumor removal. CONCLUSION: For avoidance of postoperative hematomas, careful hemostasis is required after completion of vestibular schwannoma removal, especially in cases with incomplete resection and an excessive bleeding tendency of the tumor tissue.

The efficacy of a visiting surgical service versus that of a hospital-based surgical service in providing endoscopic endonasal surgery to remove nonfunctioning pituitary adenomas in rural communities.

PURPOSE: To satisfy the increasing demand for endoscopic endonasal approach (EEA) to treat pituitary tumors, especially in rural areas, the "mobile EEA" system, a visiting surgical service, has been established We report this unique system for maintaining community healthcare and evaluate the surgical results of mobile EEA. METHODS: A retrospectively acquired database of 225 consecutive cases of EEA at Shinshu University Hospital (i.e., "home EEA") and its affiliated hospitals (i.e., "away EEA") between May 2018 and May 2022 was reviewed. A total of 105 consecutive patients who fulfilled the criterion of a diagnosis of new-onset nonfunctioning pituitary adenoma (PA) were included. Clinical characteristics and postoperative clinical outcomes were statistically compared between the home EEA and away EEA groups to assess the presence of a home advantage and/or an away disadvantage. RESULTS: Patients were stratified into two cohorts: patients treated at our hospital (home EEA: n = 41 [39.0%]) and those treated in the visiting surgical service at an affiliated hospital (away EEA: n = 64 [61.0%]). Postoperative clinical outcomes, such as the extent of tumor resection (p = 0.39), operation time (p = 0.80), visual function (p = 0.54), and occurrence of surgical complications (p = 0.53), were comparable between the groups. There were no visiting surgical service-related adverse events or accidents caused by physicians' driving to away hospitals. CONCLUSION: Pituitary surgeries performed via the mobile EEA system for nonfunctioning PAs may help maintain local community healthcare. Furthermore, this system can also contribute to the efficient training of surgeons by the same experienced pituitary surgeon using the same protocol.

A novel needle holder for suturing in a deep and narrow surgical field: a technical note.

Microvascular anastomosis is a standard procedure in neurosurgery that is applied to various lesions, such as those of ischemic disease and moyamoya disease. The depth of an anastomosis can be superficial or deep. At deeper sites, the procedure becomes challenging, as the operative field is usually narrow. Among the anastomotic approaches, suturing is the most challenging in a limited and deeper field. Additionally, since the suturing device is inevitably long, the delicate procedure becomes challenging. To overcome this technical difficulty and suture more efficiently, even in a narrow and deep field, the authors developed a needle holder, the REVOLD-HS, that allows rotational motion without moving the holder. This new needle holder is uniaxial and allows the forceps at the tip to be manipulated by operating the rotor in the hand. There is a mechanism for opening, closing, and rotating the holder via the surgeon's finger without moving the holder. Based on suture experiments in simulated blood vessels while using the holder, some situations may necessitate the use of this needle holder. This novel smart device may assist in deep vascular anastomosis in microsurgery, suturing of the carotid artery in carotid endarterectomy, and dural repair in endoscopic surgery.

The Current Status in Intraoperative Image-Guided Neurosurgery Associated with Progressive Operating Rooms: A Retrospective Analysis.

OBJECTIVE: Shinshu University Hospital has advanced operating rooms including a mobile computed tomography (mCT) room, Smart Cyber Operating Theater (SCOT) with intraoperative magnetic resonance imaging, hybrid operating room (hOR) with intraoperative image-guided surgery, and conventional operating rooms. We investigated the characteristics of cases assigned to each operating room. METHODS: Five hundred forty neurosurgery cases from January 2018 to April 2021 were analyzed. We analyzed the selection of operating room according to pathology, surgical device requirement, and urgency, and we examined associations between operating room characteristics and these factors. RESULTS: Neurological surgeries were performed in an mCT room, an hOR, a SCOT, and a conventional operating room in 333 (61.7%), 64 (11.9%), 49 (9.1%), and 94 (17.4%) cases, respectively. mCT rooms were more frequently selected than other rooms for vascular/extra-axial tumors, which have a lower need for intraoperative image guidance. Spinal surgeries with segment diagnosis or intraoperative bone removal tended to be performed in the hOR. The rate of SCOT use tended to be higher for intra-axial tumors with poorly circumscribed borders than for vascular/extra-axial tumors. Endoscopic procedures were more frequently performed in the SCOT and mCT rooms than in hORs and conventional operating rooms. Emergency surgeries were often performed in the conventional operating rooms, even in cases where SCOT and hOR seemed suitable. CONCLUSIONS: Intraoperative image-guided surgeries were performed according to the characteristics of each operating room best suited for various diseases and operative methods. Further research is needed to prove whether operating room selection improves neurosurgical outcomes.

Cerebral Edema Due to Chemotherapeutic Wafer Implantation for Malignant Glioma: Registry Study of Correlation with Perioperative Epileptic Seizures.

Factors predicting adverse events following implantation with wafers containing 1,3-bis(2-chloroethyl)-1-nitrosourea (carmustine, BCNU), which is used in local chemotherapy for malignant gliomas (MGs), are unknown. The association between cerebral edema (CE), which often occurs after implantation, and perioperative seizures, which are often observed in MG cases, is under debate. This study investigated risk factors for CE associated with BCNU wafer implantation and their relationship with perioperative seizures. A total of 31 surgical cases involving 28 adult patients who underwent BCNU wafer implantation for MGs were investigated and classified into those with and without postoperative transient CE. We assessed the correlations between CE caused by BCNU implantation and various factors, including postoperative epileptic seizures. World Health Organization (WHO) grade III MGs significantly affected postoperative CE (p = 0.003) and the occurrence of seizures (p = 0.0004). Factors predictive of postoperative seizures were WHO grade III MGs (p = 0.0026), increased postoperative CE (p = 0.0272), and history of preoperative seizures (p = 0.0316). Postoperative CE, WHO grade III MGs, and a history of preoperative seizures might predict the postoperative occurrence of seizures, necessitating stringent management of seizures and CE in the affected patients.

A preliminary study of the diagnostic efficacy and safety of the novel boring biopsy for brain lesions.

Existing methods for biopsy of intraparenchymal brain lesions, including stereotactic biopsy and open block biopsy, have advantages and disadvantages. We propose a novel biopsy method, called "boring biopsy," which aims to overcome the drawbacks of each conventional method. This method is less invasive and allows obtaining continuous specimens of sufficient volume. We aimed to assess the feasibility and efficacy of using boring biopsy for intraparenchymal brain lesions. We included 26 consecutive patients who underwent boring biopsy for intraparenchymal lesions. Columnar continuous specimens from the surface of the normal brain tissue to the tumor margin and the center of the lesion were obtained using the boring biopsy method. We used a catheter introducer with original modifications to create a cylindrical biopsy tool for surgery. Columnar continuous specimens were successfully obtained. Histopathological diagnosis was based on cellular changes and differentiation from normal tissues to the core of the lesion and established in all cases. No permanent deficits, major adverse outcomes, or deaths were observed. This novel technique may improve diagnostic accuracy and reduce invasiveness associated with brain biopsy. This method may become the next standard procedure, particularly in some cases where histological evaluation is paramount, and conventional biopsy methods are not suitable.

Intraoperative Image-Guided Surgery for Gliomas in the Smart Cyber Operating Theater (SCOT): A Preliminary Clinical Application.

BACKGROUND: Various devices exist for glioma image-guided surgery to improve tumor resection. These devices work as stand-alone units, making the flow of operative information complicated and disjointed. A novel networked operating room, the Smart Cyber Operating Theater (SCOT), has been developed, integrating stand-alone medical devices using the OPeLiNK communication interface. We report and evaluate the impact of SCOT for glioma surgery and our initial experiences. METHODS: Patients with gliomas who underwent tumor resection in SCOT between July 2018 and June 2021 were retrospectively reviewed. Various types of intraoperative information were integrated, managed, and shared with the surgical strategy desk using OPeLiNK. Patients' demographics, tumor characteristics, treatment details, and outcomes were obtained. The impact of the SCOT system was evaluated. RESULTS: Twenty-seven patients, with a mean age of 48.6 years (range, 13-88 years), met the inclusion criteria. We successfully completed all the surgical procedures using SCOT. The mean operation time was 420.6 minutes (range, 225-667 minutes).Gross total resection was accomplished in 13 patients (48.1%), subtotal resection in 4 (14.8%), and partial resection in 10 (37.0%). The main surgeon in the operating room and other neurosurgeons at the strategy desk shared and discussed the information in real time during the procedures. CONCLUSIONS: The use of SCOT was shown to be safe and feasible in glioma surgery. This study suggests that SCOT may improve surgical outcomes and educational impact by sharing information in real time with the strategy desk.

Intraoperative Low-Field Magnetic Resonance Imaging-Guided Tumor Resection in Glioma Surgery: Pros and Cons.

BACKGROUND: Intraoperative magnetic resonance imaging (MRI) is useful for identifying residual tumors during surgery. It can improve the resection rate; however, complications related to prolonged operating time may be increased. We assessed the advantages and disadvantages of using low-field intraoperative MRI and compared them with non-use of iMRI during glioma surgery. METHODS: The study included 22 consecutive patients who underwent total tumor resection at Shinshu University Hospital between September 2017 and October 2020. Patients were divided into two groups (before and after introducing 0.4-T low-field open intraoperative MRI at the hospital). Patient demographics, gross total resection (GTR) rate, postoperative neurological deficits, need for reoperation, and operating time were compared between the groups. RESULTS: No significant differences were observed in patient demographics. While GTR of the tumor was achieved in 8/11 cases (73%) with intraoperative MRI, 2/11 cases (18%) of the control group achieved GTR (p=0.033). Seven patients had transient neurological deficits: 3 in the intraoperative MRI group and 4 in the control group, without significant differences between groups. There was no unintended reoperation in the intraoperative MRI group, except for one case in the control group. Mean operating time (465.8 vs. 483.6 minutes for the intraoperative MRI and control groups, respectively) did not differ. CONCLUSIONS: Low-field intraoperative MRI improves the GTR rate and reduces unintentional reoperation incidence compared to the conventional technique. Our findings showed no operating time prolongation in the MRI group despite intraoperative imaging, which considered that intraoperative MRI helped reduce decision-making time and procedural hesitation during surgery.

Correlations Among Consistency, Computed Tomography Values, and Histopathological Subtypes of Spinal Meningioma.

The consistency of spinal meningiomas is important to consider when performing tumor removal surgery. This study evaluated the correlations between spinal meningioma consistency and both preoperative computed tomography (CT) values and histopathological subtypes. Fifteen consecutive patients who underwent surgical resection of spinal meningioma at our institution were identified, and preoperative CT values and the signal intensity of T2-weighted magnetic resonance images of the tumor were determined retrospectively. The consistency of the spinal meningioma was defined based on the ultrasonic surgical aspirator output during tumor debulking. Patients were assigned to 2 groups: a soft group (n=4) and a hard group (n=11). The T2 signal intensity was significantly higher in the soft group than in the hard group (p=0.001). While the CT values were considerably higher in the hard group, the difference was not significant (p=0.19). Regarding the histopathological subtypes, psammomatous meningioma exhibited significantly higher CT values than meningothelial meningioma (p=0.019); however, there was a higher frequency of hard tumors in meningothelial meningioma cases than in psammomatous meningioma cases. Although neither robust correlations between tumor consistency and CT values nor a relationship between tumor consistency and histopathological subtype has been established, these results might help with the perioperative manegement of spinal tumors.

Comparison Between Conventional Flash and Off-Response Intraoperative Visual Evoked Potential Monitoring for Endoscopic Endonasal Surgery.

BACKGROUND: Intraoperative flash stimulation visual evoked potential (VEP) monitoring has been used for endoscopic endonasal approach (EEA). Recently, off-response VEP, which is recorded when the light stimulus is turned off, was introduced to monitor visual function intraoperatively. OBJECTIVE: To evaluate off-response VEP monitoring in comparison with the conventional flash stimulation VEP monitoring for EEA. METHODS: From March 2015 to March 2020, 70 EEA surgeries with intraoperative VEP monitoring (140 eyes) were performed. Light stimuli were delivered by a pair of goggle electrodes. Recording electrodes were placed on the scalp over the occipital region. The warning signal was prompted by a reduction of the peak-to-peak amplitude of the VEP by more than 50% compared to the initial amplitude. Visual function was assessed pre- and postoperatively. Results of flash and off-response VEP monitoring were compared. RESULTS: VEP was recorded in 134 eyes. Warning signal occurred in 23 eyes (transient in 17 eyes and permanent in 6 eyes). Two eyes showed permanent VEP attenuation for flash VEP monitoring, in which one patient had postoperative visual function deterioration. Four eyes showed permanent VEP attenuation for off-response VEP monitoring, where 2 patients had postoperative visual function deterioration. Sensitivity, specificity, positive predictive value, and negative predictive value were 100%, 98.9%, 50%, and 100%, respectively, for flash stimulation VEP, and 100%, 97.8%, 50%, and 100%, respectively, for off-response VEP. CONCLUSION: VEP monitoring was useful to monitor visual function in EEA surgery. Off-response VEP monitoring was not inferior to conventional flash stimulation VEP monitoring.

Surgical strategy for symptomatic pineal cyst: is endoscopit third ventriculostomy necessary in addition to cyst fenestration?

Symptomatic large pineal cyst (PC) remains a rare entity. The stable natural course of asymptomatic PCs is well established. However, large cysts may cause pressure-related symptoms necessitating surgical intervention. The surgical strategy for symptomatic PCs is still controversial. Regardless of the approach, total resection of the cyst is not mandatory. The endoscopic approach allows cyst fenestration in patients with associated obstructive hydrocephalus. On the other hand, the necessity of simultaneous endoscopic third ventriculostomy (ETV) is still debatable. Here, we report a case of a woman who underwent endoscopic cyst fenestration, biopsy, and third ventriculostomy for a large symptomatic PC and discuss the surgical strategy. A 30-year-old woman presented with headache and diplopia, MRI showed a large PC and accompanying obstructive hydrocephalus. Simultaneous cyst fenestration, biopsy and ETV with endoscopy was successfully completed. She had an uneventful recovery period with immediate relief of symptoms. Although, the aqueduct was communicated due to cyst shrinkage, the patency of the third ventricular stoma was demonstrated in long-term follow-up scans. Based on clinical course of the present case, we concluded that ETV in addition to cyst fenestration should be considered necessary and beneficial in cases of large symptomatic PC with associated hydrocephalus whenever an endoscopic intraventricular approach is considered.

Microscopic Navigation-Guided Fence Post Technique for Maximal Tumor Resection During Glioma Surgery.

BACKGROUND: The fence post technique, which involves insertion of catheters as fence posts around a tumor, has been widely used to demarcate the tumor border for maximal resection of intraparenchymal tumors, such as gliomas. However, a standard procedure for fence post insertion has not been established, and there are some limitations. To overcome this problem, a simple microscopic navigation-guided fence post technique was developed. The feasibility and efficacy of this novel technique during glioma surgery were assessed. METHODS: The microscopic navigation-guided fence post technique was used in 46 glioma surgeries performed in 42 patients. Intraoperatively, the preplanned trajectory was overlaid on the microscopic surgical field, and the microscope angle was changed until the entry and target points of the trajectory overlapped. A fence post catheter was inserted as planned under microscopic view, and the tumor was resected with fence post guidance. Preoperative tumor characteristics and surgical outcomes were evaluated. RESULTS: Mean age of patients was 50 years (range, 16-78 years), and 19 (45%) of 42 patients were women. Maximal safe resection was successfully achieved in 45 surgeries (97.8%), which was planned preoperatively with identification of the tumor border with fence posts without adverse effects of brain shift. No surgical complications attributable to fence post insertion occurred. CONCLUSIONS: Clinical experience indicated that the microscopic navigation-guided fence post technique, in which fence posts can be placed without requiring the surgeon to take their eyes off the microscope, is safe and useful in glioma surgery.

Effectiveness of the intraoperative magnetic resonance imaging during endoscopic endonasal approach for acromegaly.

PURPOSE: Acromegaly is an acquired disorder usually caused by growth hormone-secreting pituitary adenoma, resolution of which requires correction of the excess hormone production. Recently, intraoperative magnetic resonance imaging (iMRI) was reported to be useful during the endoscopic endonasal approach (EEA) for pituitary adenoma. The present study was performed to quantitatively assess the role of iMRI in improving surgical outcomes in EEA for acromegaly. METHODS: Twenty surgeries for acromegaly in EEA performed at Shinshu University Hospital between April 2016 and March 2020 were reviewed retrospectively. The inclusion criteria were cases without severe cavernous sinus tumor invasion (Knosp grade 0 - 3) or history of prior pituitary surgery. Fifteen consecutive patients were enrolled in this study. Clinical characteristics and postoperative clinical outcomes were compared between patients with and without use of iMRI during EEA for acromegaly. RESULTS: Conventional navigation-guided surgery was performed in nine patients, and six underwent iMRI-guided EEA for acromegaly. Gross total resection (GTR) was obtained in the six (100%) patients in the iMRI group, and in four (44.4%) patients in the conventional group without iMRI. Postoperative clinical outcomes, including hormonal remission rate and surgical complications, were comparable between the two groups. CONCLUSION: Although iMRI significantly increased the GTR rate, we found no direct evidence of increased hormonal remission rate by use of iMRI. It is important to confirm complete tumor resection carefully with not only iMRI findings, but also with intraoperative high-definition endoscopic direct visualization to increase the hormonal remission rate of acromegaly.

Prospective, Multicenter Clinical Study of Microvascular Decompression for Hemifacial Spasm.

BACKGROUND: Microvascular decompression (MVD) is the most effective procedure for hemifacial spasm (HFS). MVD results from nonspecialized or low-volume institutes are not always reliable. Most studies on MVD for HFS are retrospective and single centered; to the best of our knowledge, no prospective, multicenter studies exist. OBJECTIVE: To evaluate short- and long-term outcomes and complications in patients who underwent MVD for HFS in specialized Japanese institutions, in this multicenter, prospective, cohort study. METHODS: Included patients had undergone MVD for HFS in study centers between April 2012 and March 2015. Patients' postoperative grade of involuntary movements and complications were recorded postoperatively at 7 d (short-term) and at 1 (mid-term) and 3 (long-term) yr. RESULTS: A total of 486 patients (150 men, 336 women; mean age 53.9 yr with 181 patients over 60 yr) were enrolled during the study period. Neuromonitoring was used in 96.3% of the cases. The complete cure rate of symptom relief, mortality rate, and complication rate at short-term follow-up were 70.6%, 0%, and 15%, respectively. The long-term follow-up was completed by 463 patients (95.3%); the complete cure rate of symptom relief and complication rate were 87.1% and 3.0%, respectively. CONCLUSION: Our study revealed that under expert guidance and intraoperative neuromonitoring, the long-term curative effect rate of MVD for HFS is high, while complications are uncommon and usually transient. Our results indicate that MVD is an effective and safe treatment for patients with HFS, including elderly patients.

Endoscopic Endonasal Approach in the Smart Cyber Operating Theater (SCOT): Preliminary Clinical Application.

BACKGROUND: A next-generation networked operating room, Smart Cyber Operating Theater (SCOT), has been developed in cooperation with medical engineers that integrates standalone medical devices, including intraoperative magnetic resonance imaging (MRI) using the OPeLiNK communication interface. Here, we report the application of this newly developed advanced type of operating theater for the endoscopic endonasal approach (EEA), along with an evaluation of our initial experiences. METHODS: The study population consisted of 18 patients with parasellar tumor. All patients underwent surgery via the EEA in SCOT. During all procedures, various types of intraoperative information, including electrophysiologic monitoring, anatomic orientation with navigation system, intraoperative MRI, and endoscopic images of the operative field, were collected and stored by OPeLiNK. Furthermore, the intraoperative information was shared with the surgical strategy desk, where a senior neurosurgeon can direct and manage the surgical procedure in real-time. RESULTS: We successfully completed the surgical procedures in SCOT in all cases. Using OPeLiNK, operators in SCOT were able to share various data, such as images obtained intraoperatively and surgical instrument position from navigation systems, as well as images of the surgical field, with senior neurosurgeons at the surgical strategy desk in all cases. Surgically relevant information from these sources was transmitted through an application and displayed to all surgical staff. The necessary nuances were reflected in the surgical procedures. CONCLUSIONS: SCOT, which is considered an innovative operation system in neurosurgery, enables both quality and safety in the EEA. Furthermore, the use of SCOT may also contribute to the education of young neurosurgeons.

Petroclival tension pneumocephalus: an unrivalled life threatening complication linked to molecular-targeted therapy.

A 73-year-old man with a petroclival tumor (metastatic renal cell carcinoma) presented with a progressive consciousness disturbance attributed to tension pneumocephalus during molecular-targeted therapy following low-dose fractionated radiotherapy for a petroclival tumor. The skull base defect was successfully reconstructed vi an endoscopic endonasal approach.

Intraoperative Lumbar Muscle Motor Evoked Potential Monitoring With Transcortical Stimulation.

BACKGROUND: Stimulating electrodes for lower extremity motor-evoked potential (LE-MEP) monitoring with transcortical stimulation are usually placed on the medial side of motor cortex convexity, which is not lower extremity but lumbar motor area. Lumbar MEP may be elicited with lower stimulation intensity than LE-MEP through this location, and it is useful to monitor lower extremity motor function intraoperatively. METHODS: Intraoperative lumbar and LE-MEP monitoring with transcortical stimulation during surgery of 12 patients with lesions involving the motor cortex from January 2012 to February 2019 at Shinshu University Hospital were reviewed retrospectively. Stimulations were delivered by a train of 5 pulses of anodal constant current stimulation. Stimulating electrode position was determined by motor cortex mapping. Recording needle electrodes were placed on bilateral lumbar muscles and contralateral leg muscles. The threshold-level stimulation method was used for MEP monitoring. The thresholds, monitoring result, and postoperative motor function of lumbar and lower extremities were compared. RESULTS: The mean baseline thresholds were 19.9 ± 8.9 mA for lumbar MEP and 26.5 ± 11.5 mA for LE-MEP (P = 0.02). Patterns of intraoperative monitoring changes were the same between lumbar and LE-MEP monitoring. CONCLUSIONS: Lumbar MEP was stimulated with lower stimulation intensity than the LE-MEP with the same intraoperative pattern of waveform changes in 12 patients. Lumbar MEP monitoring may be useful for preserving the corticospinal tract of lower extremities intraoperatively.