[Malignant transformation of Ollier disease-related multiple glioma with IDH1 p.R132C mutation].

A 21-year-old man who was diagnosed with Ollier disease at the age of 1 year developed incidental multiple gliomas at the age of 15 years. Subsequently, the multiple gliomas enlarged and the patient underwent three surgical removals. Genetic analysis revealed the IDH1 p.R132C mutation in the gliomas, and histopathology showed malignant transformation. Despite multimodality treatment, the gliomas could not be controlled, and the patient died at the age of 23 years. Ollier disease is a rare disease with IDH1/2 mutations and is often associated with gliomas. However, there are very few reports on genetic analysis of IDH1/2 mutations and long-term follow-up in Ollier disease-related gliomas. Genetic analysis of IDH mutations may contribute to the elucidation of its pathogenesis. The cross-departmental collaboration is required for long-term follow-up of Ollier disease-related gliomas.

Endoscopic Evacuation of Putaminal Hemorrhage Using the Trans-Middle Temporal Gyrus Approach: Technical Notes and Case Presentations.

BACKGROUND: The development of minimally invasive endoscopic neurosurgery has enabled widespread application of endoscopic surgery via the ipsilateral transfrontal approach for putaminal hematoma evacuation. However, this approach is unsuitable for putaminal hematomas that extend into the temporal lobe. We adopted the endoscopic trans-middle temporal gyrus approach, instead of the conventional surgical approach, for the management of these complicated cases and determined its safety and feasibility. METHODS: Twenty patients with putaminal hemorrhage underwent surgical treatment at the Shinshu University Hospital between January 2016 and May 2021. Of these, two patients with left putaminal hemorrhage that extended into the temporal lobe underwent surgical treatment using the endoscopic trans-middle temporal gyrus approach. The procedure entailed the use of a thinner transparent sheath to reduce the technique's invasiveness, a navigation system to determine the location of the middle temporal gyrus and the sheath's trajectory, and an endoscope with a 4K camera for higher image quality and utility. The sylvian fissure was compressed superiorly using our novel "port retraction technique" (i.e., by tilting the transparent sheath superiorly) to avoid damage to the middle cerebral artery and Wernicke's area. RESULTS: The endoscopic trans-middle temporal gyrus approach allowed sufficient hematoma evacuation and hemostasis under endoscopic observation without any surgical complexities or complications. The postoperative course was uneventful in both patients. CONCLUSION: The endoscopic trans-middle temporal gyrus approach for putaminal hematoma evacuation helps avoid damage to normal brain tissue, which could result from the wide range of motion of the conventional technique, particularly when the hemorrhage extends to the temporal lobe.

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.

Surgical Trapping of a Cavernous Carotid Aneurysm Causing Carotid Cavernous Fistula After Flow Diverter Placement: Technical Note and Literature Review.

BACKGROUND: Flow diverter (FD) treatment is a promising therapeutic strategy for intracranial aneurysms such as cavernous carotid aneurysms (CCAs). Direct cavernous carotid fistula (CCF) caused by delayed rupture of FD-treated CCAs has been reported, and endovascular therapy has been used in the literature. Surgical treatment is warranted for patients who have failed or are ineligible for endovascular treatment. However, no studies have evaluated surgical treatment to date. Here, this paper presents the first case of direct CCF due to delayed rupture of an FD-treated CCA managed with surgical internal carotid artery (ICA) trapping with bypass revascularization, in which the intracranial ICA with FD placement was successfully occluded with aneurysm clips. METHODS: A 63-year-old man with a diagnosis of large symptomatic left CCA underwent FD treatment. The FD was deployed from the supraclinoid segment of the ICA distal to the ophthalmic artery to the petrous segment of the ICA. Since angiography 7 months after the FD placement showed progressive direct CCF, left superficial temporal artery-middle cerebral artery bypass followed by ICA trapping was performed. RESULTS: The intracranial ICA proximal to the ophthalmic artery where the FD was placed was successfully occluded using two aneurysm clips. The postoperative course was uneventful. Follow-up angiography 8 months after the surgery confirmed complete obliteration of the direct CCF and CCA. CONCLUSIONS: The intracranial artery in which the FD was deployed was successfully occluded with two aneurysm clips. ICA trapping can be a feasible and useful therapeutic option to treat direct CCF caused by FD-treated CCAs.

Surgical revascularization for quasi-moyamoya disease associated with polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes (POEMS) syndrome: a case report and literature review.

POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal gammopathy, and skin changes) syndrome is a rare multisystem disease characterized by plasma cell dyscrasia and overproduction of vascular endothelial growth factor, which is related to disease activity. Recent treatment strategies have improved survival of patients suffering from this disorder; however, ischemic stroke remains a poor prognostic factor. POEMS patients with ischemic stroke frequently develop cerebral large artery stenosis/occlusion, followed by progressive stroke. Post literature review, we present an ischemic stroke case of quasi-moyamoya disease linked with this syndrome that was successfully treated with surgical revascularization. A 41-year-old woman diagnosed with POEMS syndrome developed progressive ischemic stroke due to quasi-moyamoya disease, despite decreased vascular endothelial growth factor level with lenalidomide and dexamethasone treatment. She underwent superficial temporal artery to middle cerebral artery bypass with encephalo-duro-myo-synangiosis bilaterally. The postoperative course was uneventful. Two years and five months after the stroke, neuroimaging demonstrated bypass patency, neovascularization after encephalo-duro-myo-synangiosis, and no recurrence of stroke. Our case is the first to report successful surgical revascularization for a POEMS patient. Surgical revascularization may be a useful treatment option for patients with quasi-moyamoya disease associated with POEMS syndrome, especially for those who develop refractory ischemic stroke despite reduced vascular endothelial growth factor level.

Brain metastasis of chondrosarcoma: A case report and literature review.

Brain metastases of a chondrosarcoma are extremely rare, and treatment remains controversial. A 54-year-old woman had undergone surgical treatment for a femoral chondrosarcoma and its lung metastases. She presented with visual disturbance and dizziness 22 months after the initial surgery; imaging studies of the brain revealed a metastatic tumor in the left parieto-occipital lobe. Surgical tumor resection was performed; however, only 2 months after gross total resection of the tumor, rapid tumor recurrence was observed. Surgical resection was performed again, followed by intensity-modulated radiation therapy. Three months later, another small brain lesion was detected in the right parietal lobe and was treated with gamma knife stereotactic radiosurgery. No recurrence has been reported 20 months after this radiosurgery for brain metastasis. Thus, surgical treatment combined with several adequate radiation therapy sessions may be a viable treatment strategy for brain metastases of chondrosarcomas.

Intraspinal canal platform system for coil embolization of anterior spinal artery aneurysm associated with spinal cord arteriovenous malformation: a case report and literature review.

BACKGROUND: The prognosis for spinal artery aneurysms associated with spinal cord arteriovenous malformations (AVMs) is poor because of the high rupture rate of aneurysms. However, endovascular treatment remains technically difficult because the catheter system must be constructed via the small-caliber anterior spinal artery (ASA) or posterior spinal artery (PSA), which feeds functionally eloquent spinal cord. A 2.6F Carnelian HF-S microcatheter (Tokai Medical Products, Aichi, Japan) has been specifically designed to assist a 1.6F Carnelian MARVEL S microcatheter (Tokai Medical Products) as a small-profile 'platform catheter' close to the target lesion. Here we present a prenidal ASA aneurysm treated using a 2.6F Carnelian HF-S microcatheter as an intraspinal canal platform catheter and review related literature. CASE PRESENTATION: A 50-year-old man presented with a subarachnoid haemorrhage due to cervical spinal cord AVM. Diagnostic vertebral angiography revealed the AVM supplied by the PSA originated from the right C2 segmental artery and ASA arising from the right V4 segment. Superselective angiography for each feeder was achieved through a 2.6F Carnelian HF-S microcatheter, and a prenidal ASA aneurysm was diagnosed, which was clinically consistent with haemorrhagic origin. A 1.6F Carnelian MARVEL S microcatheter was cannulated into the aneurysm through the 2.6F Carnelian HF-S microcatheter positioned at the ASA. The aneurysm coiling was successfully performed without system instability or periprocedural complications. CONCLUSIONS: Only a few cases have described endovascular treatment for spinal artery aneurysms. To date, no reports have been published regarding the use of an intraspinal canal platform catheter to treat spinal artery aneurysms. A 2.6F Carnelian HF-S microcatheter served as a useful intraspinal canal platform catheter for coil embolization of the ASA aneurysm. This system can provide excellent accessibility and controllability for endovascular treatment of spinal artery lesions.

Endoscopic endonasal transsphenoidal surgery in acromegaly with conchal sphenoid sinus.

BACKGROUND: A conchal non-pneumatized sphenoid sinus tends to be considered as unfavorable for transsphenoidal surgery because of procedural difficulties. Especially in acromegalic patients, the proportion of the conchal type of sphenoid sinus is potentially high compared with that of other patients who have a pituitary tumor. This report investigates the characteristics and surgery of the conchal type of sphenoid sinus in acromegaly along with the internal bone properties. CLINICAL PRESENTATION: A 70-year-old man with acromegaly underwent endoscopic endonasal transsphenoidal surgery. Intraoperatively, the anterior wall of the non-pneumatized sphenoid was cortical, however, the cancellous bone was very soft, included fatty tissue, and was easily removed by suction. The sellar lesion could be reached without any problems, and finally, total tumor resection was achieved. CONCLUSION: Based on this surgical case, the conchal sphenoid sinus of acromegaly is not always homogeneous solid bone but may contain soft fatty tissue. Therefore, although the sphenoidal characteristics may have an impact on the surgical procedures, precise assessment pre- and intraoperatively can make transsphenoidal surgery with conchal sphenoid sinus feasible.

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.

Evaluation of the nutrient foramen as a suitable landmark in spinal surgery.

BACKGROUND CONTEXT: The posterior cervical approach is a very popular surgical procedure. Because of the slope-shaped laminae, a suitable landmark for laminectomy, laminoplasty, and pedicle screw placement does not exist. PURPOSE: We investigated the association between the nutrient foramen and spinal canal, and the safety of bone gutter placement using nutrient foramina for safe and effective spinal surgery. STUDY DESIGN: Observational SETTING: University Hospital PATIENT SAMPLES: Two hundred and sixty-six consecutive patients treated for cervical pathologies in our university hospital between January 2005 and December 2019. OUTCOME MEASURES: We identified the location of nutrient foramina and their anatomical association with the spinal canal using preoperative three-dimensional CT scanning. METHODS: We studied the distance between each foramen and the spinal canal, and the angle of the nutrient foramen at each vertebral level. RESULTS: The nutrient foramina were always located outside the spinal canal, with an average distance of +3.06±1.74 mm. The lower the spinal level, the closer the nutrient foramen to the spinal canal. CONCLUSIONS: The nutrient foramen can be considered a reliable landmark when using the posterior cervical approach.

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.

Endoscopic diving technique for surgery of brain abscess.

BACKGROUND: Recent advances in neuroendoscopic surgery have led to the minimally invasive treatment of brain abscesses using various endoscopy techniques. The endoscopic diving technique (EDT) involving the formation of fluid lenses to improve the visibility of the endoscope has been reported to be useful in the endoscopic endonasal approach (EEA) for pituitary and midline cranial base lesions. Here, we report a case of brain abscess treated endoscopically using EDT in cylinder surgery. CLINICAL PRESENTATION: A 29-year-old man with 11q trisomy syndrome developed a fever and progressive right hemiparesis was observed. A diagnosis of a brain abscess was made based on neuroradiological imaging, and endoscopic irrigation and drainage with EDT via a transparent endoscopic sheath were performed, which provided a clear operative field and allowed satisfactory irrigation without bacterial contamination. The bacterium identified by PCR was Streptococcus intermedius, and antibiotic therapy was administered. Postoperatively, his symptoms gradually improved. CONCLUSION: This is the first technical case report describing the clinical experience of EDT in brain abscess surgery. EDT may be a useful technique not only in EEA but also in cylinder surgery for brain abscesses.

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.

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.