A novel theory for rapid localization of the transverse-sigmoid sinus junction and "keyhole" in the retrosigmoid keyhole approach: micro-anatomical study, technique nuances, and clinical application.

To determine a rapid and accurate method for locating the keypoint and "keyhole" in the suboccipital retrosigmoid keyhole approach. (1) Twelve adult skull specimens were selected to locate the anatomical landmarks on the external surface of the skull.The line between the infraorbital margin and superior margin of the external acoustic meatus was named the baseline. A coordinate system was established using the baseline and its perpendicular line through the top point of diagastric groove.The perpendicular distance (x), and the horizontal distance (y) between the central point of the "keyhole" and the top point of the digastric groove in that coordinate system were measured. The method was applied to fresh cadaveric specimens and 53 clinical cases to evaluate its application value. (1) x and y were 14.20 ± 2.63 mm and 6.54 ± 1.83 mm, respectively (left) and 14.95 ± 2.53 mm and 6.65 ± 1.61 mm, respectively (right). There was no significant difference between the left and right sides of the skull (P > 0.05). (2) The operative area was satisfactorily exposed in the fresh cadaveric specimens, and no venous sinus injury was observed. (3) In clinical practice, drilling did not cause injury to venous sinuses, the mean diameter of the bone windows was 2.0-2.5 cm, the mean craniotomy time was 26.01 ± 3.46 min, and the transverse and sigmoid sinuses of 47 patients were well-exposed. We propose a "one point, two lines, and two distances" for "keyhole" localization theory, that is we use the baseline between the infraorbital margin and superior margin of the external acoustic meatus and the perpendicular line to the baseline through the top point of the digastric groove to establish a coordinate system. And the drilling point was 14.0 mm above and 6.5 mm behind the top point of the digastric groove in the coordinate system.

Surgical Management of Complex Skull Base Tumor Using Preoperative Multimodal Image Fusion Technology.

OBJECTIVE: To review our single-institution experience in the surgical management of complex skull base tumors using multimodal image fusion technology. METHODS: From October 2019 to January 2022, 7 cases of complex skull base tumors that performed preoperative multimodal image fusion in Zhuhai People's Hospital neurosurgery department were involved in this study. The image data were uploaded to the GE AW workstation. Corresponding image sequences were opened in the workstation to complete registration fusion and 3D reconstruction. We retrospectively reviewed the clinical and imaging data, and surgical strategy, respectively. RESULTS: one case of recurrent C2 schwannoma, 1 case of recurrent spindle cell tumor of the left cranio-orbital communication, 1 case of lobular malignant tumor of the left infratemporal fossa, 1 case of central giant cell repairing granuloma, 1 case of mesenchymal malignant tumor in left pharyngeal process, 1 case of meningioma in jugular foramen, and 1 case of hemangioblastoma with vascular malformation in fourth ventricular. All cases underwent preoperative multimodal image fusion for the surgical plan and all cases had gross total resection. Except for one case of mesenchymal malignant tumor in left pharyngeal process that had dysphagia and one case of hemangioblastoma that had discoordination, others cases were without postoperative complication. CONCLUSIONS: Preoperative multimodal image fusion and surgical approach simulation benefit complex skull base tumor surgical treatment. Individually multiple image assessment of complex skull base tumors to determine the specific surgical strategy is more rational and should be recommended (Supplemental Digital Content 1, Supplementary Video, http://links.lww.com/SCS/F936).

Combination of Preoperative Multimodal Image Fusion and Intraoperative Dyna CT in Percutaneous Balloon Compression of Trigeminal Ganglion for Primary Trigeminal Neuralgia: Experience in 24 Patients.

Objective: We retrospectively assessed the surgical results of PBC with preoperative multimodal image fusion and intraoperative Dyna Computed Tomography (CT) in 24 patients with primary trigeminal neuralgia (PTN) to explore a valuable aid for Percutaneous balloon compression (PBC). Methods: We studied the data of 24 patients with PTN. All patients underwent PBC and were assessed with preoperative multimodal image fusion [computed tomography (CT) and magnetic resonance imaging (MRI)] and intraoperative Dyna CT in the Department of Neurosurgery of Zhuhai People's Hospital between October 2020 and September 2021. Multimodal image fusion-three-dimensional (3D) reconstruction of CT and MRI data-was performed using 3D-Slicer software, and preoperative evaluation was performed according to the results of image fusion. Dyna CT was used to dynamically observe the position and shape of the metallic hollow introducer and Fogarty catheter and balloon during the operation to guide the operation in real time. We performed follow-up assessments each month and summarized the clinical characteristics, surgical effects, and complications in all patients. Results: Surgery was successful for all patients; the patients reported immediate pain relief. Surgical complications included facial numbness in 24 patients (100%), mild masseter weakness in three (12.5%), herpes zoster in three (12.5%), and balloon rupture in one (4.2%). None of the patients had serious surgical complications. The mean follow-up time was 9.6 ± 2.7 months. During the follow-up period, 22 patients (91.7%) experienced no recurrence of pain, and two patients (8.3%) experienced recurrence of pain, of which one underwent secondary PBC surgery. Conclusions: Preoperative multimodal image reconstruction can help fully evaluate PBC surgery, clarify the etiology, and predict the volume of contrast medium required during the operation. It provided important assistance for PBC treatment of trigeminal neuralgia patients when preoperative multimodal image fusion is combined with intraoperative Dyna CT.