Prediction of contralateral progression in patients with bilateral nonhemorrhagic moyamoya disease following unilateral revascularization surgery.

OBJECTIVE: This study was designed to identify predictive factors associated with substantial contralateral progression in adult patients with bilateral nonhemorrhagic moyamoya disease (MMD) who undergo revascularization surgery (RS) on one hemisphere. METHODS: The authors retrospectively analyzed 174 contralateral hemispheres of patients with bilateral nonhemorrhagic MMD (non-hMMD) who underwent RS on one side. The primary endpoint was defined as substantial contralateral progression requiring additional RS 6 months after the initial RS. The annual risk and predictive factors for contralateral progression were also analyzed. RESULTS: Of 174 patients included in the study, 57 (32.8%) experienced contralateral progression over a mean follow-up of 45.3 ± 31.6 months (range 12-196 months). The annual risk for contralateral progression after initial unilateral RS was 7.7% per person-year. Multivariable analysis revealed that age (HR 0.967, 95% CI 0.944-0.992; p = 0.009) and a BMI ≥ 25 (HR 1.946, 95% CI 1.126-3.362; p = 0.017) were significant predictors of contralateral progression. Specifically, the annual risk of contralateral progression was 12.1% in the higher BMI (≥ 25) group and 4.0% in the lower BMI (< 25) group per person-year. CONCLUSIONS: The study revealed a 7.7% per person-year rate of contralateral progression in patients with bilateral non-hMMD following unilateral RS. Younger age and a BMI ≥ 25 were identified as significant risk factors. For these patients, careful weight management and the use of antilipid agents may be crucial strategies for reducing the risk of contralateral progression after unilateral RS.

The Usefulness of Extradural Anterior Clinoidectomy for Lower-Lying Posterior Communicating Artery Aneurysms : A Cadaveric Study.

Objective: To confirm the usefulness of the extradural anterior clinoidectomy during the clipping of a lower riding posterior communicating artery (PCoA) aneurysm through cadaver dissection. Methods: Anatomic measurements of 12 adult cadaveric heads (24 sides total) were performed to compare the microsurgical exposure of the PCoA and internal carotid artery (ICA) before and after clinoidectomy. A standard pterional craniotomy and transsylvian approach were performed in all cadavers. The distance from the ICA bifurcation to the origin of PCoA (D1), pre-anterior clinoidectomy distance from the ICA bifurcation to tentorium (D2), post-anterior clinoidectomy distance from the ICA bifurcation to tentorium (D3), pre-anterior clinoidectomy distance from the tentorium to the origin of PCoA (D4) and post-anterior clinoidectomy distance from the tentorium to the origin of PCoA (D5) and the distance of the ICA obtained after anterior clinoidectomy (D6) were measured. We measured the precise thickness of the blade for the Yasargil clip with a digital precision ruler to confirm the usefulness of the extradural anterior clinoidectomy. Results: Twenty-four sites were dissected from 12 cadavers. The age of the cadavers was 79.83±6.25 years. The number of males was the same as the females. The space from the proximal origin of the PCoA to the preclinoid-tentorium (D4) was 1.45±1.08 mm (max: 4.01, min: 0.56). After the clinoidectomy, the space from the proximal origin of the PCoA to the postclinoid-tentorium (D5) was 3.612±1.15 mm (max: 6.14, min: 1.83). The length (D6) of the exposed proximal ICA after the extradural clinoididectomy was 2.17±1.04 mm on the lateral side and 2.16±0.89 mm on the medial side. The thickness of the Yasargil clip blade used during the clipping surgery was 1.35 mm measured with a digital precision ruler. Conclusion: The proximal length obtained by performing an external anterior clinoidectomy is about 2 mm, sufficient for proximal control during PCoA aneurysm surgery, considering the thickness of the aneurysm clips. In a subarachnoid hemorrhage, performing an extradural anterior clinoidectomy could prevent a devastating situation during PCoA aneurysm clipping.

Cadaveric analysis of transcranial versus endoscopic transorbital petrosectomy: comparison of surgical maneuverability and brainstem exposure.

Introduction: While accessing the posterior fossa, the anterior transpetrosal approach (ATPA) and endoscopic transorbital approach (ETOA) use the same bony landmarks during petrous apex drilling. However, owing to their contrasting surgical axes, they are expected to show differences in surgical view, maneuverability, and clinical implications. This study aimed to investigate the feasibility of ETOA in accessing the brainstem and to compare the surgical view and maneuverability of each approach. Methods: ATPA and ETOA were performed in four human cadaveric heads (eight sides and four sides in each procedure). The angle of attack (AOA) and surgical depth were measured at the target of interest (root exit zone [REZ] of cranial nerve [CN] V, VI, and VII). When measuring the area of exposure, the brainstem was divided into two areas (anterior and lateral brainstem) based on the longitudinal line crossing the entry zone of the trigeminal root, and the area of each was measured. Results: ATPA showed significantly greater value at the trigeminal REZ in both vertical (31.8 ± 6.7° vs. 14.3 ± 5.3°, p=0.006) and horizontal AOA (48.5 ± 2.9° vs. 15.0 ± 5.2°, p<0.001) than ETOA. The AOA at facial REZ was also greater in ATPA than ETOA (vertical, 27.5 ± 3.9° vs. 8.3 ± 3.3°, p<0.001; horizontal, 33.8 ± 2.2° vs. 11.8 ± 2.9°, p<0.001). ATPA presented significantly shorter surgical depth (CN V, 5.8 ± 0.5 cm vs. 9.0 ± 0.8, p<0.001; CN VII, 6.3 ± 0.5 cm vs. 9.5 ± 1.0, p=0.001) than ETOA. The mean area of brainstem exposure did not differ between the two approaches. However, ATPA showed significantly better exposure of anterior brainstem than ETOA (240.7 ± 9.6 mm2 vs. 171.7 ± 15.0 mm2, p<0.001), while ETOA demonstrated better lateral brainstem exposure (174.2 ± 29.1 mm2 vs. 231.1 ± 13.6 mm2, p=0.022). Conclusions: ETOA could be a valid surgical option, in selected cases, that provides a direct ventral route to the brainstem. Compared with ATPA, ETOA showed less surgical maneuverability, AOA and longer surgical depth; however, it presented comparable brainstem exposure and better exposure of the lateral brainstem.

Augmentation of Supratemporal Hollowing With Silicone Block During Autologous Cranioplasty After Decompressive Craniectomy With Additional Temporalis Resection.

ABSTRACT: Decompressive craniectomy is a potentially life-saving neurosurgical procedure. In cases of insufficient decompression, uncontrolled intracranial pressure even after sufficient decompression, or when the intracranial pressure is increased due to external factors such as intramuscular hematoma in the temporal muscle, additional temporalis resection may be necessary. However, the hollowing of the supratemporal fossa that occurs after additional temporalis resection can create a major cosmetic problem. Several alternatives are available to fill the hollowing of the supratemporal fossa during cranial reconstruction, but each has a disadvantage, whether it is expensive or difficult to shape for bilateral symmetry. The author solved the cosmetic problem by using a properly carved silicone block to fill the supratemporal fossa while conducting cranioplasty, and here reports it with a literature review.

Ten-Year Experience of Dural Reconstruction Using a Collagen Matrix Inlay Graft in Posterior Fossa Surgery: A Propensity Score-Matched Study.

BACKGROUND: Considering that primary watertight dural closure is not always possible following posterior fossa surgery, several methods of dural reconstruction were proposed to reduce the risk of cerebrospinal fluid (CSF) leakage. This study aimed to evaluate the efficacy of collagen matrix inlay graft compared with other techniques in a propensity score-matched cohort. METHODS: Between 2000 and 2019, 176 consecutive patients who underwent posterior fossa surgery were enrolled. Of these, 103 patients underwent dural reconstruction with collagen matrix inlay graft (inlay group). After propensity score matching, 67 pairs were derived. The primary outcome was the development of CSF leakage. Pseudomeningocele and surgical site infection were also investigated. RESULTS: Median follow-up period was 53.9 months. None of the patients in the inlay group had CSF leakage; however, leakage was evident in 5 patients (6.8%) who underwent dural reconstruction without a collagen matrix inlay graft (no-inlay group; P = 0.011). Pseudomeningocele was noted in 1 (1.4%) patient in the no-inlay group, while surgical site infection was noted in 3 (3.0%) patients in the inlay group and 4 (5.5%) patients in the no-inlay group. None of the surgical site infections were related to the use of the inlay graft. After propensity score matching, CSF leakage was still prevalent in the no-inlay group (P = 0.042). CONCLUSIONS: Dural reconstruction using a collagen matrix inlay graft efficiently reduces CSF leakage after posterior fossa surgery and does not increase the risk of postoperative infection and inflammation. It seems to be a feasible option for dural reconstruction.

Characteristics and Clinical Course of Fusiform Middle Cerebral Artery Aneurysms According to Location, Size, and Configuration.

OBJECTIVE: To analyze the angiographic features and clinical course, including treatment outcomes and the natural course, of fusiform middle cerebral artery aneurysms (FMCAAs) according to their location, size, and configuration. METHODS: We reviewed the literature on adult cases of FMCAAs published from 1980 to 2018; from 25 papers, 112 FMCAA cases, for which the location, size, and configuration could be identified, were included in this study. Additionally, 33 FMCAA cases in our hospital were included, from which 16 were assigned to the observation group. Thus, a total of 145 adult FMCAA cases were included. We classified the FMCAAs according to their location (l-type 1, beginning from prebifurcation; l-type 2, beginning from bifurcation; l-type 3, beginning from postbifurcation), size (small, <10 mm; large, ≥10 mm; giant, ≥25 mm), and configuration (c-type 1, classic dissecting aneurysm; c-type 2, segmental ectasia; c-type 3, dolichoectatic dissecting aneurysm). RESULTS: The c-type 3 was more commonly diagnosed with ischemic symptoms (31.8%) than hemorrhage (13.6%), while 40.9% were found accidentally. In contrast, c-type 2 was more commonly diagnosed with hemorrhagic symptoms (14.9%) than ischemic symptoms (10.6%), and 72.3% were accidentally discovered. According to location, ischemic symptoms and hemorrhage were the most frequent symptoms in l-type 1 (28.6%) and l-type 3 (34.6%), respectively. Most of l-type 2 FMCAAs were found incidentally (68.4%). Based on the size of FMCAAs, only 11.1% of small aneurysms were found to be hemorrhagic, while 18.9% and 26.0% of large and giant aneurysms were hemorrhagic, respectively. Although four aneurysms of the 16 FMCAAs in the observation group increased in size and one aneurysm decreased in size during the observation period, no rupture was seen in any case and there were no significant predictors of aneurysm enlargement. Of 104 FMCAAs treated, 14 cases (13.5%) were aggravated than before surgery and all the aggravated cases were l-type 1. CONCLUSION: While ischemic symptoms occurred more frequently in l-type 1 and c-type 3, hemorrhagic rather than ischemic symptoms occurred more frequently in l-type 3 and c-type 2. In case of l-type 1 FMCAAs, more caution is required in determining the treatment due to the relatively high complication rate.

Intraoperative neuromonitoring during microsurgical clipping for unruptured anterior choroidal artery aneurysm.

OBJECTIVE: To investigate the safety and unexpected finding of the intraoperative neuromonitoring (IONM) including somatosensory evoked potentials (SSEPs) and motor evoked potentials (MEPs) during microsurgical clipping of an unruptured anterior choroidal artery (AChA) aneurysm. PATIENTS AND METHODS: From January 2011 to March 2018, the neurophysiological, clinical, and radiological data of 115 patients who underwent microsurgical clipping for an unruptured AChA aneurysm under IONM were retrospectively analyzed. The incidence of ischemic complications after microsurgical clipping of unruptured AChA aneurysms as well as the false-negative rate, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of IONM during surgery were calculated. RESULTS: Ischemic complications after the microsurgical clipping of an AChA aneurysm under IONM occurred in 7 of 115 patients (6.08%). Among them, 3 were symptomatic (2.6%). The false-negative rate of IONM for ischemic complications was 6.08% (7 patients). High specificity; 100% (95% confidence interval [95% CI] = 0.972-1.000), PPVs; 100% (95% CI = 0.055-1.000), and NPVs; 93% (95% CI = 0.945-0.973) with low sensitivity; 11.1% (95% CI = 0.006-0.111) were calculated. CONCLUSIONS: IONM including transcranial MEP during microsurgical clipping of unruptured AChA aneurysm might have limited usefulness. Therefore, other MEP monitoring using direct cortical stimulation or modified transcranial methodology should be considered to compensate for it.

Pathogenesis of dorsal internal carotid artery wall aneurysms based on histopathologic examination and microscopic configuration.

Blood blister-like aneurysms (BBAs) are an important cause of subarachnoid hemorrhage (SAH), but proper treatment is uncertain due to the poor prognosis of these aneurysms. The pathogenesis of BBAs remains unclear and few studies have reported on histological examinations of BBAs because it is difficult to obtain a specimen due to a high risk of intraoperative bleeding. In this report, BBAs were histopathologically examined in two patients who presented with SAH due to rupture of a BBA that was treated with surgical trapping and bypass surgery. BBA specimens including the adjacent internal carotid artery (ICA) walls were obtained intraoperatively. We suggest the pathogenesis of BBAs based on histopathologic examination and microscopic configuration.

Surgical Treatment of Adult Moyamoya Disease.

PURPOSE OF REVIEW: Moyamoya disease (MMD) is being increasingly diagnosed with the development of radiological surveillance technology and increased accessibility to medical care. Accordingly, there have been several recent reports on treatment outcomes in MMD. In this review, we summarize recent advances in surgical treatment and outcomes of adult MMD, while addressing related controversies. RECENT FINDINGS: Recent studies suggest that revascularization surgery leads to significantly more favorable outcomes for stroke prevention, angiographic and hemodynamic changes, and clinical outcomes than does conservative treatment for adult patients with ischemic MMD. Moreover, direct revascularization methods should be considered as the first-line treatment over indirect methods, although the latter may be considered if a direct method is not possible. In cases of hemorrhagic MMD, several studies have demonstrated that surgical treatment is more effective than conservative treatment in preventing further hemorrhage. In addition to revascularization surgery, endovascular treatment is emerging as a breakthrough therapy for hemorrhagic MMD. Accumulating evidence regarding the surgical treatment of adult MMD suggests the benefit of revascularization over conservative management for both ischemic and hemorrhagic patients. However, the benefit of revascularization in asymptomatic adult MMD remains unclear.

The incidence of and risk factors for ischemic complications after microsurgical clipping of unruptured middle cerebral artery aneurysms and the efficacy of intraoperative monitoring of somatosensory evoked potentials: A retrospective study.

OBJECTIVES: Ischemic complications (ICs) account for 6.7% after microsurgical clipping of unruptured intracranial aneurysms. This study aimed to evaluate the efficacy of somatosensory evoked potential (SSEP) monitoring during microsurgical clipping of unruptured middle cerebral artery (MCA) aneurysms and evaluate the incidence of and risk factors for ischemic complications after clipping of unruptured MCA aneurysms. PATIENTS AND METHODS: Herein, 1208 patients with cerebral aneurysms and treated with microsurgical clipping between May 2003 and February 2015 were enrolled. Those with multiple aneurysms, history of head trauma, subarachnoid hemorrhage, bypass and/or endovascular treatment, and intraoperative rupture were excluded. Subsequently, 411 patients with single unruptured MCA aneurysms treated with simple microsurgical clipping were enrolled. Patients were divided into two groups based on the application of SSEP monitoring during surgery. RESULTS: The IC rate was 0.9% and 5.6% in the SSEP and non-SSEP groups, respectively. Univariate analysis revealed that age≥62.5years, aneurysm size≥4.15mm, temporary clipping, history of hyperlipidemia and stroke, and no-SSEP monitoring were risk factors for ICs. Multivariate logistic regression analysis showed that age≥62.5years (odds ratio [OR]=7.7; 95% confidence interval [95% CI]=1.5-37.7; P=0.011), previous stroke (OR=26.8, 95% CI=2.4-289.2, P=0.007), and inversely SSEP monitoring (OR=0.14, 95% CI 0.02-0.72, P=0.019) were independent risk factors for ICs. CONCLUSION: Clinicians should consider the possibility of IC during microsurgical clipping of unruptured MCA aneurysms in patient≥62.5years and/or a history of stroke. Intraoperative SSEP monitoring is an effective and feasible tool for preventing IC.