Cortical Hyperperfusion on MRI Arterial Spin-Labeling during the Interictal Period of Patients with Migraine Headache.

BACKGROUND AND PURPOSE: Concentrations of calcitonin gene-related peptide, a neuropeptide and potent endogenous vasodilator, are reportedly higher in patients with migraine than in healthy subjects, both during and between migraine attacks, reflecting ongoing activation of the trigeminal nervous system. In this prospective study, we measured CBF during the interictal period of patients with migraine after considering insomnia and depression and examined the effects of ongoing activation of the trigeminal nervous system, including during the interictal period, on CBF. MATERIALS AND METHODS: In a total of 242 patient with migraine (age range, 18-75 years), CBF was measured by MR imaging arterial spin-labeling during the interictal period and was compared with results from 26 healthy volunteers younger than 45 years of age as control subjects (age range, 22-45 years). Cortical hyperperfusion was defined as identification of ≥2 cerebral cortical regions with regional CBF values at least 2 SDs above the mean regional CBF in control subjects. RESULTS: The overall frequency of cortical hyperperfusion was significantly higher in patients with migraine (115 of 242, 48%) than in control subjects (1 of 26, 4%). Multivariable analysis revealed the 18- to 40-year age group and patients with migraine without insomnia as significant positive clinical factors associated with cortical hyperperfusion. Among patients with migraine without insomnia, the frequency of cortical hyperperfusion was >92% (89 of 97). One-way ANOVA showed that in all ROIs of the cortex, regional CBF was significantly higher in patients with migraine without insomnia than in patients with migraine with insomnia or control subjects. In patients with migraine without insomnia, cortical hyperperfusion findings showed a sensitivity of 0.918 and a specificity of 0.962 for migraine in the interictal period, representing excellent accuracy. In contrast, among patients with migraine with insomnia, sensitivity was only 0.179 but specificity was 0.962. CONCLUSIONS: Patients with migraine without insomnia may have cortical hyperperfusion during the interictal period; however, the findings of the present study need to be prospectively validated on a larger scale before clinical applicability can be considered.

Reversible Cerebral Vasoconstriction Syndrome Patients with a History of Migraine: A Retrospective Case-control Study.

Objective We investigated the clinical characteristics of patients with reversible cerebral vasoconstrictor syndrome who had a history of migraine before the onset and considered the relationship between these two pathologies. Methods We investigated 98 patients who underwent magnetic resonance angiography within 14 days of the onset of reversible cerebral vasoconstriction syndrome at our hospital. Of these, 11 cases involved recurrences, so data from 87 patients were analyzed. Materials All consecutive patients diagnosed with reversible cerebral vasoconstrictor syndrome at our institution between October 2010 and July 2021. Results Fifty of the 87 patients (57%) had a history of migraine. A multivariate analysis revealed that the following clinical factors were significantly more frequent in patients with a history of migraine than in those without such a history: female sex; emotional situations as a trigger of the onset; presence of deep and subcortical white matter hyperintensity, absence of vasoconstriction in the M1 portion of the middle cerebral artery, and absence of other cerebral lesions on initial magnetic resonance imaging; absence of vasoconstriction of the basilar artery on follow-up magnetic resonance imaging; and progression of deep and subcortical white matter hyperintensity in the chronic stage. Conclusion Reversible cerebral vasoconstrictor syndrome patients with a history of migraine showed clinical features of migraine, including one aspect of cerebral small-vessel disease due to endothelial dysfunction, as a common causative condition.

Possibility of arterial spin labeling perfusion magnetic resonance imaging sequences with steroid therapy for Tolosa-Hunt syndrome: A case report and review of literature.

BACKGROUND: The diagnostic criteria for Tolosa-Hunt syndrome (THS) were updated in 2013 in the 3rd Edition of the International Classification of Headache Disorders. It is now possible to diagnose THS based on the presence of granulomatous inflammation demonstrated on magnetic resonance imaging (MRI) without confirmation by biopsy. No previous study has reported the use of arterial spin labeling (ASL) perfusion MRI for diagnosing THS. Here, we report a case of THS in which ASL was used in the initial identification and to monitor therapeutic response following steroid therapy. CASE DESCRIPTION: An 86-year-old man was complaining chiefly of the left orbital pain, as well as occipital pain, nausea, epiphora, and diplopia. Neurologically, his eye movements showed left adduction disorder and palsy of the right cranial nerve III. Magnetic resonance angiography revealed no abnormality in the left internal carotid artery. Contrast-enhanced MRI showed a region of slightly high signal in the left cavernous sinus. ASL was obtained using pCASL (TR/TE, 9000/98. 48 ms; postlabeling delay: 1525 ms; axial plane) revealed hyperperfusion from the intercavernous sinus to the vicinity of the left cavernous sinus due to a local increase in cerebral blood flow. The symptoms disappeared on day 62 of the treatment and he was in complete remission. Follow-up ASL was performed every other month showed reduced perfusion as the symptoms improved and confirmed the absence of a tumor over the follow-up period. CONCLUSION: This simple technique will play an important role in confirming no recurrence after steroid therapy treatment.

Scoring system for intraoperative diagnosis of intracranial schwannoma by squash cytology.

OBJECTIVE: To assess the utility of a newly developed squash cytology (SC)-based scoring system for accurate intraoperative diagnosis of schwannoma. METHODS: We first compared SC-based and frozen section (FS) diagnoses with final pathological diagnoses of schwannoma (16 cases), meningioma (39 cases) and low-grade astrocytoma (16 cases). Then, by logistic regression modeling, we identified features of SC preparations that were independently predictive of schwannoma. To develop a diagnostic scoring system, we assigned one point to each feature, and performed receiver operating characteristic analysis to determine the score cut-off value that was most discriminatory for differentiating schwannoma from the other tumour types. We then compared accuracy, sensitivity, and specificity of diagnosis before and after the application of the scoring system. RESULTS: Overall diagnostic concordance rates for SC and FS were almost the same, at 73.2% (52/71) and 77.5% (55/71 cases), respectively. Of the 16 SC features entered into the analysis, the following nine were found to independently predict schwannoma, and were thus incorporated into the scoring system: smooth cluster margins, few or no isolated tumour cells, fibrillary stroma, spindle-shaped nuclei, parallel arrangement of stroma, parallel arrangement of nuclei, presence of anisonucleosis, absence of nucleoli, and hemosiderin deposition. A cut-off score of four items yielded the best sensitivity, specificity and predictive values for prediction of schwannoma. Use of the scoring system improved accuracy of intraoperative diagnosis from 80.3% to 94.4%, sensitivity from 56.2% to 93.8%, and specificity from 87.3% to 94.5%. CONCLUSION: Our proposed SC-based scoring system will increase accuracy of intraoperative diagnosis of schwannoma vs non-schwannoma tumours.

Hyperintense posterior cerebral artery sign in patients with reversible cerebral vasoconstriction syndrome.

BACKGROUND: This study investigated hyperintense vessel signs (HVS) on fluid-attenuated inversion recovery imaging in the P1-2 portions of posterior cerebral arteries (PCAs) as a "hyperintense PCA sign" and HVS of cortical arteries. We retrospectively examined whether these signs would be useful in diagnosing reversible cerebral vasoconstriction syndrome (RCVS) in the acute phase. METHODS: Eighty patients with RCVS who underwent initial magnetic resonance imaging (MRI) within 7 days of onset were included in this study. HVS and related clinical factors were examined. RESULTS: On initial MRI of RCVS patients, hyperintense PCA sign and HVS of cortical arteries were seen in 21 cases (26%) and 38 cases (48%), respectively. In patients showing hyperintense PCA sign, vasoconstriction of the A2-3 portion was a significant clinical factor. Conversely, vasoconstriction of the M1 and P1 portions and the presence of white matter hyperintensity on initial and chronic-stage MRI were significantly associated with the presence of HVS in cortical arteries. CONCLUSION: Because rich collateral flow exists around PCAs, the frequency of hyperintense PCA sign is not high. However, hyperintense PCA sign findings in patients with suspected RCVS offer credible evidence of extreme flow decreases due to vasoconstriction in peripheral PCAs and other arteries associated with the collateral circulation of PCAs. Conversely, HVS in cortical arteries tend to reflect slow antegrade circulation due to vasoconstriction of peripheral vessel and major trunks. Both signs appear useful for auxiliary diagnosis of acute-phase RCVS.

A Case of Endovascular Treatment for In-Hospital Stroke with COVID-19 under Protected Code Stroke.

Objective: Coronavirus disease 2019 (COVID-19) is characterized by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and presents with respiratory symptoms. Overall, 5.7% of COVID-19 patients with severe respiratory status have been reported to develop acute cerebrovascular diseases (CVDs), and 41.3% of COVID-19 cases were considered nosocomial infections. Therefore, Protected Code Stroke, which is a guideline for acute stroke management that takes into account the safety of healthcare workers, has been developed. We created an operational manual for COVID-19 in the endovascular treatment center of our hospital and report our experience treating acute stroke in a COVID-19 patient. Case Presentation: A 67-year-old man presented with a 5-day history of fever. Chest CT showed ground glass opacity (GGO) on admission, and the polymerase chain reaction (PCR) test for COVID-19 was positive. Dysarthria, right-sided hemiparesis, and aphasia were discovered on the morning of the third day after hospitalization. MRI showed an acute ischemic stroke at the left corona radiata and occlusion of the left middle cerebral artery (MCA). Progression of right-sided hemiparesis and exacerbation of respiratory status developed after the MRI. Tracheal intubation was performed, and the patient was treated with intravenous alteplase and mechanical thrombectomy (MT). Recanalization of blood flow was not obtained, and the neurological deficits remained. Conclusion: MT was performed for large-vessel occlusion (LVO) in a COVID-19 patient during the COVID-19 pandemic. Safety for healthcare workers and appropriate rapid treatment for acute stroke patients are both vital in the current environment.

Intraoperative squash cytology provides a qualitative intraoperative diagnosis for cases in which frozen section yields a diagnosis of equivocal brain tumour.

OBJECTIVE: We assessed whether intraoperative squash cytology could provide surgeons with a qualitative diagnosis of brain lesions when frozen section diagnosis is equivocal. METHODS: The study included 51 lesions that were diagnosed intraoperatively as equivocal brain tumour on the basis of frozen section. We retrospectively classified the lesions into five groups according to the final histopathological diagnoses (I: malignant lymphomas; II: diffuse astrocytic and oligodendroglia tumours; III: pituitary adenomas, IV: metastatic carcinomas; V: others). We assessed the squash cytology features of Groups I-IV and of the specific lesion types, and compared features among the groups. RESULTS: The four groups differed in a range of salient cytomorphological features: lymphoglandular bodies in Group I (eight of nine cases), cytoplasmic fibrillary processes in Group II (six of eight cases), low-grade nuclear atypia in Group III (seven of seven cases), and large nuclei (approximately 80 µm2 ) and nuclear crush artefacts in Group IV (seven of nine cases). CONCLUSION: Findings of lymphoglandular bodies on intraoperative squash cytology can be considered characteristic of malignant lymphomas, while cytoplasmic fibrillary processes indicate diffuse astrocytic and oligodendroglial tumours. We conclude that squash cytology could yield a qualitative intraoperative diagnosis in over 25% of cases for which frozen section yields a diagnosis of equivocal brain tumour.

Clinical Significance of the CSF Pulsation Flow Sign in the Foramen of Monro on FLAIR in Patients with Aneurysmal SAH -Preliminary Report.

It is known that the cerebrospinal fluid (CSF) pulsation flow sign in the lateral ventricles directly above the foramen of Monro (CPF-M) on axial fluid attenuated inversion recovery (FLAIR) is a normal physiological finding as an artifact of FLAIR. In this study, whether CPF-M can be used as a neuroradiological finding related to pathological conditions in patients with acute aneurysmal subarachnoid hemorrhage (aSAH) was investigated. CPF-M-related clinical features were retrospectively evaluated in 147 aSAH patients who underwent adequate serial MRI examinations without massive intraventricular hemorrhage (IVH) of the lateral ventricle within 48 h of ictus. The frequency of the CPF-M in the control group was 32% (57/178), 33% (40/123), and 38% (45/117) for the normal control, chronic cerebral infarction, and deep white matter lesion (WML) groups, respectively. In aSAH patients, the overall prevalence of the CPF-M was 57% (84/147), significantly higher than in the three control groups. Multivariate analysis showed that age <70 years, lower IVH Hijdra score of the fourth ventricle, absence of T1-FLAIR mismatch, deep WMLs, old infarction, diffuse brain swelling, symptomatic delayed cerebral ischemia (DCI), shunt-dependent chronic hydrocephalus (SDCH), and favorable outcome were significantly associated with the CPF-M. Although limited to SAH patients without massive IVH of the lateral ventricles, one can conclude that, in acute aSAH, the presence of CPF-M on admission MRI suggests that the circulatory dynamics of the CSF from the basal cistern to the ventricles are approximately normal. Thus, this finding may appear to offer an indicator of a good outcome without DCI and SDCH.

Vessel Morphologies of the Brain in Cytological Squash Preparations Are Useful for Intraoperative Diagnosis of High-Grade Astrocytomas.

OBJECTIVE: The aim of this study was to determine whether intraoperative cytological evaluation of squash preparations is of benefit for differentiating high-grade from low-grade astrocytomas. METHODS: Squash preparations of 42 astrocytomas were classified histologically according to the World Health Organization (WHO) 2007 classification system as grade II (n = 12), grade III (n = 11), and grade IV (n = 19) and were divided into 2 groups, namely a low-grade group (grade II) and a high-grade group (grades III and IV). The focus was on morphological cell and vessel characteristics, namely nuclear atypia, chromatin pattern, nuclear enlargement, variation in nuclear size, the presence of nucleoli, mitosis, tumor necrosis, cell density, multibranched vessels, and vascular dilatation, and these characteristics were compared between the low- and high-grade groups. RESULTS: Nuclear atypia, the presence of coarse chromatin, variations in nuclear size, and cell density ≥200 per high-power field were significantly more prevalent in high- than in low-grade astrocytomas (p = 0.0407, p < 0.01, p < 0.01, and p < 0.01, respectively). Vessels with > 3 branches and a mean vessel diameter ≥20 µm were more prevalent in high- than in low-grade astrocytomas (p < 0.01). CONCLUSION: Squash preparation cytology provides added benefit for the intraoperative identification of high-grade astrocytoma.

Clinical significance of centripetal propagation of vasoconstriction in patients with reversible cerebral vasoconstriction syndrome: A retrospective case-control study.

Introduction We previously reported centripetal propagation of vasoconstriction at the time of thunderclap headache remission in patients with reversible cerebral vasoconstriction syndrome. Here we examine the clinical significance of centripetal propagation of vasoconstriction. Methods Participants comprised 48 patients who underwent magnetic resonance angiography within 72 h of reversible cerebral vasoconstriction syndrome onset and within 48 h of thunderclap headache remission. Results In 24 of the 48 patients (50%), centripetal propagation of vasoconstriction occurred on magnetic resonance angiography at the time of thunderclap headache remission. The interval from first to last thunderclap headache in patients with centripetal propagation of vasoconstriction (14 ± 10 days) was significantly longer than that of patients without centripetal propagation of vasoconstriction (4 ± 2 days). In the patients with centripetal propagation of vasoconstriction at the time of thunderclap headache remission, the incidence of another cerebral lesion (38%, 9 of 24 cases) was significantly higher than in patients without centripetal propagation of vasoconstriction (0%). From findings of sequential magnetic resonance angiography before and after thunderclap headache remission, we observed tendencies in which centripetal propagation of vasoconstriction gradually progressed after the onset of reversible cerebral vasoconstriction syndrome and peaked at the time of thunderclap headache remission. The progress of centripetal propagation of vasoconstriction concluded with thunderclap headache remission. Conclusions Centripetal propagation of vasoconstriction has clinical significance as an indicator of the severity of reversible cerebral vasoconstriction syndrome. The presence of centripetal propagation of vasoconstriction is associated with an increased risk of brain lesions and a longer interval from first to last thunderclap headache. Moreover, repeat magnetic resonance angiography to assess centripetal propagation of vasoconstriction during the time from onset to thunderclap headache remission can help diagnose reversible cerebral vasoconstriction syndrome.

Retrospective review of previous minor leak before major subarachnoid hemorrhage diagnosed by MRI as a predictor of occurrence of symptomatic delayed cerebral ischemia.

OBJECTIVE This study attempted to determine whether a previous minor leak correlated with the occurrence of symptomatic delayed cerebral ischemia (sDCI). METHODS The authors retrospectively evaluated sDCI-related clinical features and findings from MRI, including T1-weighted imaging (T1WI)-FLAIR mismatch at the time of admission, in 151 patients admitted with subarachnoid hemorrhage (SAH) within 48 hours of ictus. RESULTS The overall incidence of sDCI was 23% (35 of 151 patients). In all subjects, multivariate analysis revealed that World Federation of Neurosurgical Societies Grades II-V, age 70 years or older, presence of rebleeding after admission, a previous minor leak before the major SAH attack as diagnosed by T1WI-FLAIR mismatch, acute infarction on diffusion-weighted imaging, and CT SAH score were significantly associated with occurrence of sDCI. In patients with no previous minor leak before major SAH as diagnosed by T1WI-FLAIR mismatch, the incidence of sDCI was only 7% (7 of 97 patients). CONCLUSIONS A previous minor leak before major SAH as diagnosed by T1WI-FLAIR mismatch represents an important sDCI-related factor. When the analysis was restricted to patients with true acute SAH without a previous minor leak diagnosed by T1WI-FLAIR mismatch, the incidence of sDCI was extremely low.

Endoscopic extradural supraorbital approach to the temporal pole and adjacent area: technical note.

The authors' initial experience with the endoscopic extradural supraorbital approach to the temporal pole and adjacent area is reported. Fully endoscopic surgery using the extradural space via a supraorbital keyhole was performed for tumors in or around the temporal pole, including temporal pole cavernous angioma, sphenoid ridge meningioma, and cavernous sinus pituitary adenoma, mainly using 4-mm, 0° and 30° endoscopes and single-shaft instruments. After making a supraorbital keyhole, a 4-mm, 30° endoscope was advanced into the extradural space of the anterior cranial fossa during lifting of the dura mater. Following identification of the sphenoid ridge, orbital roof, and anterior clinoid process, the bone lateral to the orbital roof was drilled off until the dura mater of the anterior aspect of the temporal lobe was exposed. The dura mater of the temporal lobe was incised and opened, exposing the temporal pole under a 4-mm, 0° endoscope. Tumors in or around the temporal pole were safely removed under a superb view through the extradural corridor. The endoscopic extradural supraorbital approach was technically feasible and safe. The anterior trajectory to the temporal pole using the extradural space under endoscopy provided excellent visibility, allowing minimally invasive surgery. Further surgical experience and development of specialized instruments would promote this approach as an alternative surgical option.

How I do it: endoscopic microvascular decompression for hemifacial spasm associated with the vertebral artery.

BACKGROUND: Microvascular decompression (MVD) of hemifacial spasm (HFS) associated with the vertebral artery (VA) shows higher rates of incomplete cure and complications compared to non-VA-related HFS. METHOD: Purely endoscopic MVD for VA-associated HFS via a retrosigmoid keyhole was performed. Neurovascular conflicts by a directly offending artery and VA around the root exit zone of the facial nerve were clearly demonstrated under 30° endoscopic view without significant cerebellar retraction. The VA and directly offending artery were safely transposed with preservation of perforators under excellent view. CONCLUSION: Endoscopic MVD offers reliable decompression for VA-associated HFS with minimal invasiveness.

Endoscopic Middle Cranial Fossa Reconstruction with a Subtemporal Keyhole.

BACKGROUND: Skull base reconstruction is an essential technique for repairing cerebrospinal fluid (CSF) leakage. A reliable method for middle cranial fossa (MCF) reconstruction with minimal invasiveness has not been reported. An initial case of endoscopic MCF reconstruction with a subtemporal keyhole is described. CASE DESCRIPTION: A 57-year-old man developed severe meningitis and was diagnosed with spontaneous CSF leakage from bone defects on the tegmen tympani. Endoscopic MCF reconstruction with a subtemporal keyhole was carried out. Three skin incisions, including 1 subtemporal incision for a subtemporal keyhole and 2 temporal line incisions on the superior temporal line, were made, and a 0-degree endoscope was introduced into the subcutaneous space. The deep temporal fascia (DTF) was bluntly dissected and separated from the superficial temporal fascia and the temporal muscle, and the DTF was incised to shape a pedicled flap under endoscopic view. Blood supply to the pedicled DTF flap was confirmed with indocyanine green angiography. A subtemporal keyhole was then made, and a 30-degree endoscope was used to explore the extradural space of the MCF floor, visualizing the bone defects on the tegmen tympani. The vascularized DTF flap passed easily through the subtemporal keyhole and adequately overlaid the bone defects. The patient's postoperative course was uneventful, and the CSF leakage disappeared without mastication problems. CONCLUSIONS: This purely endoscopic technique using a vascularized DTF flap provided reliable MCF reconstruction through a subtemporal keyhole. This technique is also expected to be applicable for MCF reconstruction after subtemporal keyhole surgery for skull base tumors.

Endoscopic Microvascular Decompression with Transposition for Trigeminal Neuralgia and Hemifacial Spasm: Technical Note.

Background Endoscopic microvascular decompression (MVD) offers reliable identification of neurovascular conflicts under superb illumination, and it provides minimally invasive surgery for trigeminal neuralgia and hemifacial spasm. Transposition techniques have been reported as a decompression method to prevent adhesion and granuloma formation around decompression sites, providing better surgical outcomes. The feasibility and effects of transposition under endoscopic MVD were evaluated. Material and Methods Fully endoscopic MVD was performed using 4-mm 0- and 30-degree endoscopes. The endoscope was fixed with a pneumatic holding system, and a bimanual technique using single-shaft instruments was performed. Transposition was performed with Teflon felt string and fibrin glue. Surgical results were evaluated using the scoring system proposed by Kondo et al. Results The endoscope was introduced via a retrosigmoid keyhole. The 0-degree endoscope was advanced through the lateral aspect of the cerebellar tentorial surface to the trigeminal nerve in cases of trigeminal neuralgia and through the petrosal surface of the cerebellum to the facial nerve in cases of hemifacial spasm. Neurovascular conflicts and perforators from the offending artery were clearly demonstrated under the 30-degree endoscopic view, and transposition of the offending artery was safely performed with preservation of perforators. Clinical symptoms improved without permanent complications. Conclusion Endoscopic MVD with the transposition technique is feasible. Superb endoscopic views demonstrate perforators arising from the offending artery behind the corner, allowing damage to perforators to be avoided during the transposition technique. Endoscopic MVD using the transposition technique is expected to offer excellent surgical results.

Endoscopic Endonasal Repair of Cerebrospinal Fluid Leakage Caused by a Rare Traumatic Clival Fracture.

An 89-year-old male presented with cerebrospinal fluid (CSF) rhinorrhea associated with head trauma sustained as a pedestrian in a traffic accident. Computed tomography (CT) showed pneumocephalus and multiple cranial bone fractures, including the clivus. Although the CSF rhinorrhea was treated conservatively for a week, clinical symptoms did not improve and surgical repair was performed. Preoperative thin-sliced bone CT and steady-state magnetic resonance images revealed a bone defect at the middle clivus and a collection of CSF fluid from the clival fistula in the sphenoid sinus. Endoscopic endonasal reconstruction was performed, and the 3-mm diameter dural tear and bone defect at the middle clivus were well visualized. The fistula was repaired using a pedicled nasoseptal mucosal flap. The CSF rhinorrhea completely disappeared as a result of the endoscopic endonasal surgery. The present report describes a rare case of CSF rhinorrhea caused by a traumatic clival fracture and surgical management by endoscopic endonasal surgery.

Cranial Reconstruction in a Pediatric Patient Using a Tissue Expander and Custom-made Hydroxyapatite Implant.

A tissue expansion technique in conjunction with a custom-made artificial bone implant was effective for a large cranial reconstruction in a pediatric patient. The patient was an eight-year-old boy with cranial bone fracture, acute subdural hematoma in the left lobe, and acute epidural hematoma in the right lobe due to an accident. Wound dehiscence and artificial dura infection were observed as postoperative complications. Because of insufficiency of the skin flap caused by scar contracture, a scalp skin expansion using a tissue expander was necessary before reconstruction with the artificial bone implant. This combined procedure provided safe coverage of the implant and resulted in good wound healing. There are relatively few reports involving the use of tissue expanders for cranioplasty; furthermore, our search of the literature did not reveal any reports involving children. We believe that this procedure is safe and effective for early rehabilitation in pediatric patients.

Endoscopic endonasal approach to the middle cranial fossa through the cavernous sinus triangles: anatomical considerations.

The lateral limit of endoscopic endonasal surgery has yet to be defined. The aim of this study was to investigate the lateral limit of endoscopic endonasal surgery at the level of the sphenoid sinus. Access from the sphenoid sinus to the middle cranial fossa through the cavernous sinus triangles was evaluated by cadaver dissection. Anatomical analysis demonstrated that the medial temporal dura mater was exposed through the anterior area of the clinoidal triangle, anteromedial triangle, and superior area of the anterolateral triangle, indicating potential corridors to the middle cranial fossa. This study suggests that the cavernous sinus triangles are applicable in selected cases to manage middle cranial fossa lesions by endoscopic endonasal surgery.

Identification of the internal carotid artery at the superior part of the cavernous sinus during endoscopic endonasal cavernous sinus tumor surgery.

BACKGROUND: Identification of the internal carotid artery (ICA) is essential for successful endoscopic endonasal cavernous sinus tumor surgery. This study aimed to develop a method for identifying the ICA in cavernous sinus tumors at the superior part of the cavernous sinus. METHODS: Ten fresh cadavers were studied with a 4-mm 0° and 30° endoscope to identify surgical landmarks of the ICA in the cavernous sinus. Clinical cases of cavernous sinus tumors were surgically treated using an endoscopic transpterygoid approach. RESULTS: Anatomical study indicated the ICA at the superior part of the cavernous sinus can be identified using three steps: 1) exposure of the optic nerve sheath by drilling the optic canal; 2) identification of the proximal orifice of the optic nerve sheath at the transition of the optic nerve sheath and dura mater of the tuberculum sellae; and 3) identification of the clinoid segment of the ICA at the distal dural ring just below the proximal orifice of the optic nerve sheath. Although the ICA was encased and transposed by tumors in preliminary surgical cases, the clinoid segment of the ICA was safely exposed at the superior part of the cavernous sinus using this method. CONCLUSIONS: Dural structures around the cavernous sinus are key to identifying the ICA at the superior part of the cavernous sinus. This method is expected to reduce the risk of ICA injury during endoscopic endonasal surgery for cavernous sinus tumors.

Endoscopic endonasal approach to the middle cranial fossa through the cavernous sinus triangles: anatomical considerations.

The lateral limit of endoscopic endonasal surgery has yet to be defined. The aim of this study was to investigate the lateral limit of endoscopic endonasal surgery at the level of the sphenoid sinus. Access from the sphenoid sinus to the middle cranial fossa through the cavernous sinus triangles was evaluated by cadaver dissection. Anatomical analysis demonstrated that the medial temporal dura mater was exposed through the anterior area of the clinoidal triangle, anteromedial triangle, and superior area of the anterolateral triangle, indicating potential corridors to the middle cranial fossa. This study suggests that the cavernous sinus triangles are applicable in selected cases to manage middle cranial fossa lesions by endoscopic endonasal surgery.