Surgical microanatomy of the occipital artery for suboccipital muscle dissection and intracranial artery reconstruction.

BACKGROUND: The occipital artery (OA) is an important donor artery for posterior fossa revascularization. Harvesting the OA is difficult in comparison to the superficial temporal artery because the OA runs between suboccipital muscles. Anatomical knowledge of the suboccipital muscles and OA is essential for harvesting the OA during elevation of the splenius capitis muscle (SPL) for reconstruction of the posterior inferior cerebellar artery. We analyzed the running pattern of the OA and its anatomic variations using preoperative and intraoperative findings. METHODS: From April 2012 to March 2018, we surgically treated 162 patients with suboccipital muscle dissection by OA dissection using the lateral suboccipital approach. The running pattern and relationship between the suboccipital muscles and OA were retrospectively analyzed using the operation video and preoperative enhanced computed tomography (CT) images. The anatomic variation in the running pattern of the OA was classified into two types: lateral type, running lateral to the muscle and medial type, running medial to the longissimus capitis muscle (LNG). RESULTS: The medial pattern was observed in 107 (66%) patients and the lateral pattern in 54 (33.3%); 1 (0.6%) patient had the OA running between the LNGs. CONCLUSION: Preoperative CT is effective in determining the running course of the OA, which is important for safely harvesting the OA during SPL elevation. There is a risk of causing OA injury in patients with the lateral pattern. This is the first report showing that the OA rarely runs in between the LNGs.

Preoperative Predictors and Prognosticators After Microsurgical Clipping of Poor-Grade Subarachnoid Hemorrhage: A Retrospective Study.

BACKGROUND: Contrary to expectations, some patients with poor-grade subarachnoid hemorrhage (SAH) show favorable outcomes. However, the factors predictive of good prognosis are unclear. The purposes of this study were to identify factors related to poor-grade SAH and to analyze preoperative prognostic factors. METHODS: We included 186 patients with SAH who underwent surgical clipping or conservative treatment immediately after SAH diagnosis. Physiologic, radiographic, and blood examination data were collected retrospectively. Factors related to poor World Federation of Neurological Societies (WFNS) grade (WFNS IV and V) and poor outcome (modified Rankin Scale scores 3-6) were analyzed. RESULTS: The patients (mean age, 61.6 years) included 134 women (72%). Seventy patients (38.2%) had poor WFNS scores. On multivariate analysis, age ≥70 years (adjusted odds ratio [OR], 3.73), midline shift (OR, 4.89), and the absence of cerebrospinal fluid in the high-convexity cortical sulci (OR, 5.47) and ambient cistern (OR, 4.83) were predictive of poor WFNS scores. Age ≥70 years (OR, 8.36), WFNS grade 5 (OR, 15.35), intracerebral hematoma (OR, 3.32), and Evans index (EI) ≥0.3 (OR, 4.40) were predictive of poor outcome. Body mass index (OR, 0.87), intraventricular hemorrhage (OR, 3.86), glycated hemoglobin level (OR, 2.78), and age ≥70 years (OR, 4.12) were predictive of EI ≥0.3. CONCLUSIONS: Poor outcomes correlated with older age, brain-destructive hemorrhage, and EI ≥0.3. The EI reflects both hydrocephalus and the patient's frailty. Radiographic signs of poor-grade SAH were not correlated with poor outcome, suggesting that early decompressive surgery may improve outcome.

Morphological parameters as factors of 12-month neurological worsening in surgical treatment of patients with unruptured saccular intracranial aneurysms: importance of size ratio.

OBJECTIVE: It is well known that larger aneurysm size is a risk factor for poor outcome after surgical treatment of unruptured saccular intracranial aneurysms (USIAs). However, the authors have occasionally observed poor outcome in the surgical treatment of small USIAs and hypothesized that size ratio has a negative impact on outcome. The aim of this paper was to investigate the influence of size ratio on outcome in the surgical treatment of USIAs. METHODS: Prospectively collected clinical and radiological data of 683 consecutive patients harboring 683 surgically treated USIAs were evaluated. Dome-to-neck ratio was defined as the ratio of the maximum width of the aneurysm to the average neck diameter. The aspect ratio was defined as the ratio of the maximum perpendicular height of the aneurysm to the average neck diameter of the aneurysm. The size ratio was calculated by dividing the maximum aneurysm diameter (height or width, mm) by the average parent artery diameter (mm). Neurological worsening was defined as an increase in modified Rankin Scale score of 1 or more points at 12 months. Clinical and radiological variables were compared between patients with and without neurological worsening. RESULTS: The median patient age was 64 years (IQR 56-71 years), and 528 (77%) patients were female. The median maximum size, dome-to-neck ratio, aspect ratio, and size ratio were 4.7 mm (IQR 3.6-6.7 mm), 1.2 (IQR 1.0-1.4), 1.0 (IQR 0.76-1.3), and 1.9 (IQR 1.4-2.8), respectively. The size ratio was significantly correlated with maximum size (r = 0.83, p < 0.0001), dome-to-neck ratio (r = 0.69, p < 0.0001), and aspect ratio (r = 0.74, p < 0.0001). Multivariate logistic regression analysis showed that the specific USIA location (paraclinoid segment of the internal carotid artery: OR 6.2, 95% CI 2.6-15, p < 0.0001; and basilar artery: OR 8.4, 95% CI 2.8-25, p < 0.0001), size ratio (OR 1.3, 95% CI 1.1-1.6, p = 0.021), and postoperative ischemic lesion (OR 9.4, 95% CI 4.4-19, p < 0.0001) were associated with neurological worsening (n = 52, 7.6%), and other characteristics showed no significant differences. CONCLUSIONS: The present study showed that size ratio, and not other morphological parameters, was a risk factor for 12-month neurological worsening in surgically treated patients with USIAs. The size ratio should be further studied in a large, prospective observational cohort to predict neurological worsening in the surgical treatment of USIAs.

Evaluation of Microsurgery for Managing Giant or Complex Cerebral Aneurysms: A Retrospective Study.

OBJECTIVE: Surgical or endovascular treatment for giant or complex aneurysms is challenging. The aims of this study were to evaluate clinical outcomes and factors affecting the prognosis of giant or complex aneurysms and to better establish the role of microsurgery in the management strategy. METHODS: One hundred fifty-nine patients with surgically treated complex aneurysms were included. Thirty-two patients (20.1%) had giant aneurysms (≥25 mm) and 57 (35.8%) had large aneurysms (≥15 mm). Poor outcome was defined as modified Rankin Scale scores of 3-6. RESULTS: The mean aneurysm size was 17.0 mm (range, 1.6-47.5 mm). One hundred and sixteen aneurysms (80.0%) were in the anterior circulation and 43 (27.0%) were in the posterior circulation. One hundred and thirty-eight (86.8%) aneurysms were completely occluded without residual aneurysms. Nineteen (11.9%) had minor aneurysm remnants; 2 (1.3%) had incomplete occlusion. Two patients (1.3%) with giant basilar artery (BA) trunk aneurysms experienced rupture of the treated aneurysm and died. Bypass surgery was combined with microsurgery in 148 patients (93.1%). Perforating artery infarction was observed postoperatively in 42 patients (26.4%), and poor outcome was observed in 29 (18.2%). Male sex (P = 0.016; adjusted odds ratio [OR], 4.524 [1.949-10.500]), perforating artery infarction (P < 0.001; adjusted OR, 13.625 [5.329-34.837]), and BA aneurysm location (P = 0.003; adjusted OR, 56.333 [6.830-464.657]) were significantly related to poor outcome. The aneurysm size (P = 0.017; adjusted OR, 1.064 [1.021-1.107]), C1 aneurysm location (P = 0.042; adjusted OR, 2.591 [0.986-6.811]), and BA aneurysm location (P = 0.033; adjusted OR, 12.956 [3.197-52.505]) were significantly related to perforating artery infarction. CONCLUSIONS: Microsurgery with bypass is effective for many different complex aneurysms, except BA aneurysms.