Primary intraosseous cavernous hemangioma of the clivus: A case report and literature review.

Background: The radiographic presentation of the primary intraosseous cavernous hemangiomas (PICHs) is nonspecific. We report a case of clival PICH mimicking a chordoma with a literature review. Case Description: A 57-year-old woman presented with diplopia that started a few days before the presentation. She had transient diplopia at the right lateral gaze and upper gaze with normal eye movement. The symptoms disappeared spontaneously 1 week later. She had no other complaints or neurological deficits. Computed tomography revealed an intraosseous mass lesion and bone erosion of the middle and lower clivus, extending laterally to the right occipital condyle. Magnetic resonance imaging (MRI) showed hyperintense and hypointense components on T2- and T1-weighted images, respectively. The lesion was larger than on MRI performed 10 years earlier. Chordoma or chondroma was considered a possible preoperative diagnosis. An endoscopic transsphenoidal approach removed the tumor. In the operating view, the lesion appeared as "moth-eaten" bony interstices filled with vascular soft tissue. Histologically, an intraosseous cavernous hemangioma was diagnosed. Conclusion: Diagnosis before surgery is difficult without characteristic radiographic findings. When making a differential diagnosis of malignant skull lesions, PICH should be considered.

The importance of preserving the superior hypophyseal artery infundibular branch in craniopharyngioma surgery.

PURPOSE: Postoperative pituitary dysfunction, a critical problem in the treatment of craniopharyngiomas, can occur even when the pituitary stalk is preserved. We hypothesized that compromise of the primary superior hypophyseal artery (pSHA) might be related to this occurrence. METHODS: We performed a retrospective review of 131 patients with craniopharyngioma who underwent surgery from April 2009 to September 2021. The inclusion criteria were initial surgery, endoscopic transsphenoidal surgery, preoperative normal pituitary function or pituitary dysfunction in one axis, and morphological preservation of the pituitary stalk. The branches of the pSHA consist mainly of the chiasmatic branches (Cb), infundibular branches (Ib), and descending branches (Db). We analyzed the association between postoperative pituitary function and preservation of these branches. RESULTS: Twenty patients met the criteria. Preoperative anterior pituitary function was normal in 18 patients, and there was isolated growth hormone deficiency in two patients. No patient had preoperative diabetes insipidus (DI). Anterior pituitary function was unchanged postoperatively in eight patients. Of these eight patients, bilateral preservation of pSHA Ib was confirmed in seven patients. Bilateral preservation of pSHA Ib was the only factor associated with preserved anterior pituitary function (p < 0.01). Fifteen patients were free of permanent DI, and the preservation of any given pSHA branch produced no significant difference in the postoperative occurrence of permanent DI. CONCLUSIONS: Our study shows that bilateral preservation of pSHA Ib provides favorable postoperative anterior pituitary function in craniopharyngioma surgery; however, such preservation may have little effect on the postoperative occurrence of DI.

Chordoma of the Clivus with Metastasis to Femur.

Chordomas are aggressive and invasive tumors that are notoriously famous for their recurrence and metastasis. They present with diverse manifestations, usually with lower cranial nerve involvement. Here, we present the first reported case of chondroid chordoma with femur metastasis. A 71-year-old lady presented to us with a headache and diplopia. MRI of the brain revealed an enhanced broad and destructive mass in the infrasellar region with complete destruction of the clivus, right cavernous sinus. She underwent multiple surgeries along with gamma knife and proton therapy. The patient later presented with a trochanteric fracture and needed a hip replacement. Biopsy curettage of the femur lesion revealed a chondroid chordoma of the femur. The patient died later of a chest infection. Multimodality treatment is required in chordoma management, including surgery, gamma knife, and proton therapy. A firm discerning eye is required in the elderly toward metastatic spread to the femur in cases presenting with fractures of long bones.

Combined Exoscopic and Endoscopic Two-Step Keyhole Approach for Intracranial Meningiomas.

The advantages of neuroendoscopic surgery are the wide viewing angle and the freedom of an axis of view with minimal surgical trauma. With the advent of the exoscope, which has similar advantages to endoscopy, such as a small body and ergonomically superior heads-up surgery, it has become possible to add a field of view that is similar to that of microsurgery to endoscopic surgery. By taking advantage of the features of these scopes, we report the usefulness of the minimally invasive combined exoscopic and endoscopic two-step keyhole approach (EEKA) for various types of meningiomas. We reviewed data from 34 consecutive cases of EEKA for various types of intracranial meningiomas compared with that of conventional microsurgery. All of the tumors were resected as planned without severe complications. Significantly better outcome data were obtained in terms of the blood loss and the surgical time in the EEKA group, in addition to the craniotomy size. The well-illuminated fine vision in the deep corners by the endoscope enabled radical resection of the tumors with minimum burden on the patients. This technique has the potential for minimally invasive surgery in intracranial meningioma patients, including the older population.

Skull Base Reconstruction Using a Temporoparietal Galeal Flap in Simultaneous Transnasal and Transcranial Surgery for the Prevention of Carotid Blowout Syndrome: A Report of 3 Cases.

Background Carotid blowout syndrome (CBS) is a rare complication that usually occurs after removal of head and neck tumors. Since transnasal skull base surgery allows a wide exposure of the ventral skull base, neurosurgeons should pay attention to prevent this devastating complication. We present, three cases involving exposure of the internal carotid artery (ICA) at the skull base during the simultaneous transnasal and transcranial approach. Case Description The first patient was a 69-year-old man with a recurrent chordoma. The exposed ICA was covered by an abdominal fat graft and nasoseptal flap, but he experienced CBS 2 months later and died. The second patient was a 66-year-old man with an intraosseous cavernous angioma of the petrous bone. The exposed ICA was covered by a temporoparietal galeal flap (TPGF), abdominal fat graft, and nasoseptal flap. The third patient was a 73-year-old man with skull base radiation necrosis and intracerebral abscess after proton beam therapy for orbital adenoid cystic carcinoma. The exposed ICA was covered by TPGF. The second and third patients' postoperative courses were uneventful. Conclusion Based on our experience, a nasoseptal flap alone may be insufficient to protect ICA. TPGF is therefore another available reconstruction option that may help prevent CBS.

Combined Transcranial-endonasal Reconstructive Surgery for Cerebrospinal Fluid Leakage Resulting from Traumatic Anterior Skull Base Fractures Involving the Parasellar Region.

Extensive traumatic anterior skull base fractures from the frontal sinus to the parasellar region are frequently accompanied by multiple dural defects that cause persistent cerebrospinal fluid (CSF) leakage. Conventional transcranial reconstruction using a frontal periosteal flap is frequently insufficient, and parasellar dural defects are often deep, complex, and difficult to identify. In this report, we describe a combined transcranial-endonasal reconstructive technique and report our experience. Simultaneous combined transcranial and endoscopic surgery was performed in three patients with CSF leakage resulting from traumatic anterior skull base fractures. Dural defects were thoroughly identified from the transcranial and endonasal surgical fields, and covered using a multilayer sealing technique. The anterior regions of the anterior skull base were reconstructed using a free fascial flap and frontal periosteal flap; posterior and parasellar regions were reconstructed using a fat graft, vascularized nasoseptal flap, and endonasal balloon. Suturing the transcranial grafts to the parasellar dura mater was performed collaboratively by the transcranial and endonasal surgeons. In our cases, complete cessation of CSF leakage was achieved without perioperative lumbar drainage in all patients. Mean time to postoperative ambulation was 7 days (range, 3-11). No surgical complications occurred. Simultaneous transcranial and endonasal procedures were helpful to detect all sites of CSF leakage and secure reconstructive grafts. The combined transcranial and endonasal reconstructive technique achieved secure skull base reconstruction without recurrence of CSF leakage, and allowed early postoperative ambulation. This technique can be a reliable surgical option to repair CSF leakage resulting from extensive anterior skull base fractures.

[Ependymoma of the Sella Turcica and Suprasellar Region].

An ependymoma of the sella turcica and the suprasellar region has been described by only 10 reports in the available literature. We describe similar pathology in a 70-year-old woman who presented with dementia and visual disturbance. Magnetic resonance imaging with gadolinium revealed a mixed contrast-enhanced lesion(maximum diameter 3.5 cm)in the sella turcica and suprasellar area associated with a noncommunicating hydrocephalus. The patient was preoperatively presumptively diagnosed with a craniopharyngioma. The lesion was adherent to the hypothalamus, and the third ventricular floor was completely resected via an endoscopic endonasal transsphenoidal approach. Histopathological findings confirmed an ependymoma. Although her visual disturbance improved, the patient developed postoperative panhypopituitarism. She has had no recurrence for 7 years postoperatively. An ependymoma of the sella turcica and the suprasellar region is extremely rare; establishing the preoperative diagnosis is challenging in such patients. Maximum tumor resection and long-term follow-up are essential for good prognosis.

A novel needle electrode for intraoperative fourth cranial nerve neurophysiological mapping.

OBJECTIVES: Trochlear nerve (CN-IV) mapping method has not been confirmed to date. The compound muscle action potential (CMAP) of CN-IV cannot be recorded because of the low mapping sensitivity and anatomical characteristics of the superior oblique muscle (SOM). The aim of this study was to evaluate the effectiveness of a novel needle electrode (NNE), for the intraoperative mapping of CN-IV. MATERIALS AND METHODS: The NNEs were inserted in the target extraocular muscles in 19 patients. We compared the CMAP amplitude of the NNE with that of the conventional needle electrode (CNE). Furthermore, we investigated the dissimilarity between the CMAP of the CN-IV and other extraocular cranial nerves (ECNs) and the correlation between the readings of the CN-IV mapping and its postoperative functional outcome. RESULTS: The CMAP of CN-IV has been measured in nine patients (47.4%). The CMAP of CN-IV was distinguishable from other ECNs. The CMAP of the NNE was found to be three times higher than that of the CNE. Although the NNE has shown the potential to record the CN-IV's CMAP, 4 cases ended up having a CN-IV postoperative dysfunction. CONCLUSIONS: For the first time, we confirmed the possibility of intraoperative mapping the CN-IV using an NNE inserted into the SOM. The NNE can also be useful for other neurophysiological monitoring methods.

A Practice Survey to Compare and Identify the Usefulness of Neuroendoscope and Exoscope in the Current Neurosurgery Practice.

BACKGROUND: The present era is of new tools and technique. Handling of new challenges require, better understanding of microscopic anatomy, which requires better magnification and light. Microscope has played significant role in this, use of endoscope and introduction of exoscope have given new dimensions to this field. AIM: This study aims to compare and see the advantages, disadvantages of endoscope with exoscope, will analyze the difference in terms of ergonomics, learning curve, opportunities for training, operating time, magnification, and image quality. MATERIALS AND METHODS: This study was conducted in the Department of Neurosurgery, Bantane Hospital Fujita Health University, Japan. Apart from comparing the specifications of available systems, we conducted a worldwide survey of the two systems through sending questionnaire through mail collected responses and analyzed them. RESULTS: Learning curve, magnification, image quality, and ergonomics favors exoscope but depth perception and maneuverability, hand eye coordination, tactile sensation, and usage of different angulation tubes favored endoscope to be superior to exoscope. CONCLUSION: There is more scope for modifications and research in both the instruments. These instruments are not replacement of either and should be used according to their indications.

Non-brain-exposure Exoscopic and Endoscopic Volume Reduction Surgery for Benign Meningioma En Plaque in an Elderly Patient: A Case Report.

Meningioma en plaque (MEP) often needs invasive surgery to resect totally because of its widespread proliferation along the dura mater. We report a minimally invasive surgical technique for non-brain-exposure exoscopic and endoscopic volume reduction in an elderly patient with MEP. An 83-year-old woman presented with gait disturbance and cognitive dysfunction that had progressed over 6 months. Magnetic resonance imaging (MRI) revealed a large MEP on the right frontal lobe with peritumoral edema. On confirming the benign nature of the tumor (WHO grade 1) by biopsy, the main feeders and tumor were transarterially embolized. Volume reduction surgery was performed under the assistance of an exoscope and an endoscope while being careful not to expose and damage the cortex. Her symptoms completely resolved postoperatively. This surgical technique without exposing the brain may be a treatment choice for elderly patients with benign symptomatic convexity MEP.

The Pituitary Is a Candidate Organ That Modulates Circulating Klotho Levels.

CONTEXT: The antiaging protein Klotho is shed and released into the blood stream (soluble Klotho). Growth hormone (GH) is considered an active Klotho regulator, because growth retardation is described in Klotho-deficient mice. The origin of circulating Klotho is, however, not fully understood. OBJECTIVES: Our objective was to analyze a possible role of the pituitary in regulating soluble Klotho in patients with pituitary adenomas. PATIENTS DESIGN AND SETTING: We analyzed serum levels of soluble Klotho, GH, and insulin-like growth factor 1 (IGF-1) from 21 consecutive patients in our center with pituitary tumor, 7 with GH-producing adenomas (GHomas), and 14 with non-GH-producing pituitary adenomas (non-GHomas), before and after endoscopic transsphenoidal surgery (eTSS). MAIN OUTCOME MEASURE: Soluble Klotho levels were determined by ELISA with antihuman Klotho antibodies. RESULTS: Baseline soluble Klotho levels in all patients, those with GHoma and those with non-GHoma, were 542 (median) (interquartile range: 403, 652), 1083 (425, 1213), and 525 (399, 590), respectively. A drastic reduction in Klotho levels was identified in those with GHoma, accompanied by decreases in GH and IGF-1 levels, after eTSS. Interestingly, patients with non-GHoma had significant declines in soluble Klotho without any significant changes in GH levels. Moreover, an oral glucose tolerance test revealed that soluble Klotho levels decreased, whereas a paradoxical GH peak was observed after glucose intake in a patient with GHoma. CONCLUSIONS: Our data suggest that the pituitary may be a key organ that regulates circulating Klotho concentrations, implying that the pituitary possibly controls circulating Klotho through GH-dependent and/or GH-independent mechanisms.

Role of transcranial sphenoidotomy in skull base surgery: classification of surgical techniques based on the surgical anatomy of the sphenoid sinus.

OBJECTIVEAlthough sphenoidotomy is more commonly performed via the transnasal approach than via the transcranial approach, transcranial sphenoidotomy (TCS) remains indispensable for en bloc resection of locally advanced sinonasal malignant tumors (SNMTs) extending to the skull base. TCS also enables transsphenoidal transposition of the temporoparietal galeal flap (TPGF) to compensate for the lack of vascularized reconstructive tissue after endoscopic transnasal skull base surgery. The objective of this study was to review the authors' surgical experience using TCS with an emphasis on the surgical anatomy of the sphenoid sinus and on the purpose of TCS. Relevant anatomy is further illustrated through cadaveric dissection and photo documentation.METHODSThe authors reviewed the records of 50 patients who underwent TCS at the Nagoya University Hospital, Fukushima Medical University Hospital, or Aichi Medical University Hospital over the course of 7 years (between January 2011 and November 2017). The authors also performed cadaveric dissection in 2 adult cadaveric skull base specimens.RESULTSOf the 50 patients included in this study, 44 underwent craniofacial resection (CFR) for en bloc resection of SNMTs involving the anterior and/or lateral skull base, and 6 underwent transsphenoidal transposition of the TPGF flap. The authors categorized the TCS procedures according to the portion of the sphenoid sinus wall involved (i.e., superior, lateral, and superolateral). Superior sphenoidotomy was used in patients requiring anterior CFR. Lateral sphenoidotomy was further divided into 2 subtypes, with type 1 procedures performed for the transsphenoidal transpositioning of the TPGF, and type 2 procedures used in patients requiring lateral CFR. Superolateral sphenoidotomy was used in anterolateral CFR.CONCLUSIONSTCS still represents a useful tool in the armamentarium of neurosurgeons treating central skull base lesions. The newly proposed surgical classification facilitates a profound understanding of TCS and how to incorporate this technique into clinical practice.

Multiple Surgical Treatments for Repeated Recurrence of Skull Base Mesenchymal Chondrosarcoma.

We report a case of a young male who received multiple surgical treatments for repeated recurrence of skull base mesenchymal chondrosarcoma (MC). When the patient was 18 years old, we subtotally removed the skull base MC and he was treated with stereotactic radiosurgery for remnant tumors in the left cavernous sinus. After 30 months, we removed residual tumors that had regrown partially, via combined endonasal endoscopic and orbitozygomatic approaches. Over the next 65 months, the patient refused radical resection, and received six salvage surgeries, two stereotactic radiotherapies, and five stereotactic radiosurgeries for repeated recurrence. At 95 months after initial surgery, the tumors had extended to the skull base and nasal cavities. As a result, the left eye had been blinded and right visual acuity was deteriorated. We performed left anterior-middle cranial base resection, removal of nasal and intradural tumors, high flow bypass, en-bloc resection of the left cavernous sinus and clivus, and reconstruction using an abdominal flap. Even though the main tumors were removed with safety margins, tumors around the right optic nerve were removed by piecemeal to preserve right eye function. Six months after the radical resection, tumors in the right orbital apex recurred because we had been unable to remove the tumor with adequate safety margins. Skull base MC has a high tendency to recur locally, so these tumors should be radically removed with safety margins as early as possible to prevent recurrence.

Neuroendoscopic Cylinder Surgery and 5-Aminolevulinic Acid Photodynamic Diagnosis of Deep-Seated Intracranial Lesions.

BACKGROUND: Microscopic detection of intracranial brain tumors with 5-aminolevulinic acid (5-ALA) has proven extremely useful, and reports the use of 5-ALA have recently increased. However, few reports have described 5-ALA photodynamic diagnosis (PDD) using a neuroendoscope. We performed neuroendoscopic 5-ALA PDD for various brain lesions and present a procedure using only a neuroendoscope. METHODS: We describe the diagnosis of 20 intracranial brain lesion cases with a 5-ALA-guided fluorescence endoscope. A light-emitting diode that emitted either white light or 400- to 410-nm violet light was attached to a neuroendoscope. We performed cylinder surgery with a transparent sheath under observation with a rigid neuroendoscope. RESULTS: Neuroendoscopic biopsies were performed in 11 patients, and resections were performed in 9 patients. All lesions were observed with a neuroendoscope under sequential white light and violet light. We confirmed the presence of a red fluorescent lesion under violet light in 15 patients, including 4 of 5 glioblastoma cases (80%); 1 of 2 anaplastic astrocytoma cases (50%); 4 of 5 diffuse large B cell lymphoma cases (80%); 2 of 2 metastatic brain tumors; 1 of 1 case each of diffuse astrocytoma, pilocytic astrocytoma, inflammatory change, and germinoma (100%); and no cases of anaplastic ependymoma or cysticercosis. Pretargeted lesions were accurately harvested from all biopsy specimens. Gross total resection was achieved in 5 of 9 patients using a resection procedure. CONCLUSIONS: Our described method offers a promising technique for achieving precise brain tumor biopsies and safe resection.

[Primary Pituitary Malignant Lymphoma that was Difficult to Differentiate from Nonfunctioning Pituitary Adenoma:A Case Report].

We report a rare case of primary pituitary lymphoma in a 75-year-old immunocompetent woman. The patient was blind in the right eye and presented with visual disturbance in the left eye that started 2 months previously. She also exhibited right third and fifth cranial nerve palsy. Magnetic resonance imaging(MRI)revealed an intrasellar mass lesion with right cavernous sinus invasion and suprasellar extension with compression of the optic chiasm. The mass lesion was isointense on both T1WI and T2WI, and showed less enhancement than a normal pituitary gland on gadolinium-enhanced T1WI. We therefore suspected the tumor to be a nonfunctioning pituitary adenoma. The patient underwent endoscopic endonasal transsphenoidal surgery. The tumor was firm and grayish, and had an ill-defined border along the normal pituitary gland. Histological examination revealed a malignant CD5-positive diffuse large B-cell lymphoma. After surgery, the patient received both chemotherapy and radiotherapy. Although the visual acuity of the right eye did not improved, other symptoms improved. At the 34-month follow-up, no recurrence was detected on serial MRI. Patients with primary pituitary lymphoma often exhibit ophthalmoplegia and/or panhypopituitarism more frequently than expected from radiological findings. In cases of pituitary tumors with atypical symptoms, a biopsy and general physical examination should be performed immediately to determine the diagnosis and perform adjuvant therapy even when the tumor is assumed as nonfunctioning pituitary adenoma from the image findings.

Intracranial hemorrhage and platelet transfusion after administration of anti-platelets agents: Fukushima Prefecture.

We conducted a case series study to assess intracerebral hemorrhage (ICH) in the context of anti-platelets agents (APAs) and platelet (PLT) transfusion in Fukushima Prefecture.This study included patients who were newly diagnosed with ICH between January 2008 and June 2014 in the neurosurgical hospitals of Fukushima Prefecture.　Four of ten neurosurgical hospitals responded to our questionnaire.　Of 287 ICH patients, 51 (20.6%) were on APA therapy, of whom PLT transfusion was given to only one persistently bleeding patient who was on dual anti-platelet therapy.　In a follow-up survey, 30 out of 51 ICH patients on APA therapy, average age 75 years, were analyzed, of whom 21 (70%) were male.　The predominant underlying disease was diabetes mellitus.　It is interesting to note that peripheral artery disease and aortic aneurysm were among the indications for APAs.　ICH was mainly observed supratentorially.　Hematoma enlargement was observed in 13 (44.8%) cases.　By day 7, 3 patients (10%) had died from complications of ICH.　In this study, we show that ICH during APA therapy matched what was observed in Kanagawa Prefecture.　Whether or not a national survey differs, we anticipate greater statistical validity and an opportunity to improve patient outcomes in Japan and around the world.

[A case of orbital apex syndrome due to aspergillus infection that avoided loss of visual acuity by optic canal decompression].

A 71-year-old woman was admitted to our hospital complaining of left orbital pain, headache, diplopia and left-sided ptosis, which she had suffered for two months. On examination, the patient had loss of visual acuity, left-sided ptosis, lateral gaze disturbance, and was diagnosed as having left orbital apex syndrome. An abnormal signal to the left orbital cone was detected on MRI. Serum ß-D-glucan was increased, and serum Aspergillus antigen and antibody were both positive. Although antifungal drugs (voriconazole and liposomal amphotericin B) were administered, the symptoms deteriorated. The patient then underwent optic nerve decompression surgery and was treated with intravenous methylprednisolone, which gradually improved the patient's symptoms, Aspergillus hyphae were confirmed by pathological examination. To obtain good prognosis for patients with orbital apex syndrome associated with Aspergillus infection, optic nerve decompression surgery should be considered.

OUTCOME OF CLIVAL CHORDOMAS AFTER SKULL BASE SURGERIES WITH MEAN FOLLOW-UP OF 10 YEARS.

BACKGROUND AND OBJECTIVE: Skull base chordomas are clinically malignant because of the difficulty of total removal, high recurrence rate, and occasional drop metastasis. Although aggressive surgical resection and postoperative radiation have been recommended, the long-term outcome remains unsatisfactory. METHODS: From 1992 to 2011, we treated 24 patients with skull base chordoma using aggressive surgical removal as a principal strategy. Skull base approaches were selected according to tumor extension to remove the tumor and surrounding bone as completely as possible. After surgery, all patients were closely observed with MRI to find small and localized recurrent tumors, which were treated with gamma-knife radiosurgery or surgical resection. The mean postoperative follow-up duration was 10.2 years (range, 1-17.2 years). RESULTS: The 5-, 10-, and 15-year overall survival rates were 86%, 72%, and 72%, respectively. The 5- and 10-year progression-free survival rates were 47% and 35%, respectively. Tumor extension to the brainstem and partial tumor removal were the factors related to poor survival. CONCLUSIONS: Our results suggest that aggressive surgical removal improves the long-term outcome of patients with skull base chordoma. We would like to emphasize that skull base chordomas should be aggressively removed using various skull base approaches.

Endoscopic resection of cystic pontine tumour: three case reports and a proposal for minimally invasive dual-endoscopic surgery.

OBJECTIVE AND IMPORTANCE: We describe a new endoscopic technique, the dual-endoscopic method, in which two independent endoscopic systems are simultaneously used in the subtemporal space and intraparenchymal field for patients with pontine cystic tumours. Tumours were successfully removed through a sheath placed in the brainstem via the subtemporal keyhole approach, with safety ensured by the second subtemporal endoscope. CLINICAL PRESENTATION: A purely endoscopic subtemporal approach was performed in three cases of pontine cystic tumour, including two low-grade gliomas and a recurrent chordoma. The gliomas showed nodules. Recurrent chordoma consisted of a mucinous component. TECHNIQUE: Using a keyhole subtemporal approach and a 4.0-mm rigid endoscope with a high-definition camera, a transparent puncture needle containing a 2.7-mm rigid endoscope was inserted into the cyst. The tumour was removed using suction, biopsy forceps, and scissors simultaneously placed with the 2.7-mm endoscope in a transparent sheath. CONCLUSION: Since the 4.0-mm endoscope placed in the subtemporal space monitored all procedures of the 2.7-mm endoscope, tumour removal was performed safely without damaging the pons, cranial nerves, or vessels. We safely and successfully removed a cystic pontine tumour using a dual-endoscopic method. This new method ensures the safety of deep-seated endoscopic procedures via a minimally invasive transcranial approach.