Background: The third segment of the vertebral artery (V3) is vulnerable during far lateral and retrosigmoid approaches. Although the suboccipital triangle (SOT) is a useful anatomical landmark, the relationship between V3 and the muscles forming the triangle is not well-described. We aimed to demonstrate the relationship between the V3, surrounding muscles, and SOT in clinical cases. Methods: Operative videos of patients with the vertebral artery (VA) and posterior inferior cerebellar artery (PICA) aneurysms treated with occipital artery-PICA bypass through the far lateral approach were examined. Videos from January 2015 to October 2021 were retrospectively reviewed to determine anatomy of the V3 and the SOT. Results: Fourteen patients were included in this study. The ipsilateral V3 was identified without injury in all patients using the bipolar cutting technique. The lateral 68.2% of the horizontal V3 segment, including the V3 bulge, was covered by the inferomedial part of the superior oblique muscle (SO). The medial 23.9% was covered by the inferolateral part of the rectus capitis posterior major muscle. The inferomedial part of the horizontal V3 segment is located within the SOT. Conclusion: Most of the V3, including the V3 bulge, were located beneath the SO and the inferomedial part of V3 located within the SOT. Elevation of the SO should be performed carefully using the bipolar cutting technique to avoid injury to the V3. To the best of our knowledge, this is the first description of the V3 relative to the SOT in the clinical setting.

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Objective: To evaluate the incidence of nerve injury and pedicle breach after pedicle screw fixation (PSF) with intraoperative triggered electromyography (tEMG) monitoring.Material and Methods: All patients who underwent PSF with intraoperative tEMG at Vajira Hospital between October 2018 and March 2020 were included. Patients with dysmorphic pedicle features, preoperative infection, or incomplete follow-up data were excluded. PSF was done with intraoperative tEMG. The stimulation threshold was recorded. Stimulation threshold <7 mA was not allowed to proceed with the procedure and required reposition of pedicle screw immediately. Post-operative nerve injury was evaluated by physical examination and computer tomography of the spine was done to detect any pedicle breaches. The sensitivity and specificity of intraoperative tEMG to detect pedicle breach were calculated. The risk factors associated with pedicle breach were analyzed.Results: The records of thirty-six patients with 278 pedicle screws were analyzed. No post-operative nerve injuries were found. The incidence of pedicle breach was 2.2%. The sensitivity and specificity were 83.0% and 91.0%, respectively. The risk factors associated with pedicle breach were degenerative disease and tumor(s) (odds ratio (OR) 3.05, 95% confidence interval (CI) 1.11-8.41, p-value=0.030) and stimulation threshold 7-10 mA (OR 0.02, 95% CI 0.00-0.19, p-value< 0.001). Conclusion: PSF with intraoperative tEMG was safe for neural integrity. Intraoperative tEMG had the ability to detect pedicle breaches with fair sensitivity and high specificity. Patients with degenerative disease, tumors, or stimulation threshold less than 11 mA had a higher risk of pedicle breach.

Objective: The objective of the study was to evaluate the outcome and related factors in patients with aneurysmal subarachnoid hemorrhage (aSAH). Materials and Methods: Clinical data of 221 patients who were diagnosed with spontaneous SAH due to ruptured intracranial aneurysm and surgically treated at Vajira Hospital between January 2013 and May 2016 were retrospectively reviewed. Patient and aneurysm characteristics, clinical status at presentation, treatment, and status at discharge and 1 year after discharge were recorded. Outcomes 1 year after surgery were assessed using the Glasgow Outcome Scale (GOS). Patients were divided into two groups according to the GOS score: the favorable outcome group (GOS scores 4 and 5) and unfavorable outcome group (GOS scores 1–3). Results: Among the 221 study patients, 158 were classified in the favorable outcome group and 63 in the unfavorable outcome group. Patient age, Hunt and Hess grade, aneurysm size, use of Vitamin C solution irrigation in the subarachnoid space, and GOS score 1 year after surgery significantly differed between the two groups. Conclusions: Numerous factors analyzed in this study were significantly associated with 1-year outcome in surgically treated aSAH patients, including subarachnoid Vitamin C irrigation. Further study of subarachnoid Vitamin C irrigation is warranted.