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Mikhail Chernov

Object.

Radical removal of meningiomas involving the major dural sinuses remains controversial. In particular, whether the fragment invading the sinus must be resected and whether the venous system must be reconstructed continue to be issues of debate. In this paper the authors studied the effects, in terms of tumor recurrence rate as well as morbidity and mortality rates, of complete lesion removal including the invaded portion of the sinus and the consequences of restoring or not restoring the venous circulation.

Methods.

The study consisted of 100 consecutive patients who had undergone surgery for meningiomas originating at the superior sagittal sinus in 92, the transverse sinus in five, and the confluence of sinuses in three. A simplified classification scheme based on the degree of sinus involvement was applied: Type I, lesion attachment to the outer surface of the sinus wall; Type II, tumor fragment inside the lateral recess; Type III, invasion of the ipsilateral wall; Type IV, invasion of the lateral wall and roof; and Types V and VI, complete sinus occlusion with or without one wall free, respectively. Lesions with Type I invasion were treated by peeling the outer layer of the sinus wall. In cases of sinus invasion Types II to VI, two strategies were used: a nonreconstructive (coagulation of the residual fragment or global resection) and a reconstructive one (suture, patch, or bypass). Gross-total tumor removal was achieved in 93% of cases, and sinus reconstruction was attempted in 45 (65%) of the 69 cases with wall and lumen invasion. The recurrence rate in the study overall was 4%, with a follow-up period from 3 to 23 years (mean 8 years). The mortality rate was 3%, all cases due to brain swelling after en bloc resection of a Type VI meningioma without venous restoration. Eight patients—seven of whom harbored a lesion in the middle third portion of the superior sagittal sinus—had permanent neurological aggravation, likely due to local venous infarction. Six of these patients had not undergone a venous repair procedure.

Conclusions.

The relatively low recurrence rate in the present study (4%) favors attempts at complete tumor removal, including the portion invading the sinus. The subgroup of patients without venous reconstruction displayed statistically significant clinical deterioration after surgery compared with the other subgroups (p = 0.02). According to this result, venous flow restoration seems justified when not too risky.

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Mikhail Chernov, Yoshihiro Muragaki, and Hiroshi Iseki

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Mikhail Chernov, Yoshihiro Muragaki, and Hiroshi Iseki

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Benjamin Brokinkel, Johanna Sicking, Dorothee Cäcilia Spille, Katharina Hess, Werner Paulus, and Walter Stummer

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Mikhail F. Chernov, Shuji Kamikawa, Fumitaka Yamane, Shoichiro Ishihara, and Tomokatsu Hori

Object. The purpose of this study was to evaluate an original neurofiberscope-guided strategy for the management of slit-ventricle syndrome that occurs after shunt placement.

Methods. Between 1995 and 2003 15 patients with slit-ventricle syndrome (mean age 14.2 years) underwent endoscopic third ventriculostomy (ETV) and shunt removal. During the initial surgical procedure a neurofiberscope with a small outer diameter was inserted along the shunt tube into the collapsed ventricle for endoscopically controlled removal of the ventricular catheter and evaluation of brain compliance. If the latter was sufficiently preserved, primary ETV and shunt removal were performed (four cases). If brain compliance seemed to be significantly reduced, endoscopically controlled replacement of the ventricular catheter and implantation of the Codman-Hakim programmable valve shunt device were performed (11 cases). In these patients, delayed ETV and shunt removal were performed later (mean period of 16.3 months).

No medical or surgical complications occurred in any case. Follow up ranged from 6 to 84 months (mean 31.1 months; median 22 months). All patients became shunt independent and 13 became symptom free. Overall, the size of the ventricles returned to normal in five cases, became slightly dilated in nine, and moderately dilated in one.

Conclusions. Neurofiberscope-guided treatment of slit-ventricle syndrome involving shunt removal and ETV appears to be beneficial; all patients in this series were symptom free and shunt independent at the end of follow up.

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James Drake

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Tomokatsu Hori, Mikhail Chernov, Yasir A. Alshebib, Yuichi Kubota, Seigo Matsuo, Hideki Shiramizu, and Yoshikazu Okada

OBJECTIVE

The objective of this study was to evaluate the long-term outcomes after resection of brainstem cavernous malformations (BSCMs) and to assess the usefulness of the Lawton grading system in these cases.

METHODS

This retrospective study analyzed 46 consecutive patients with BSCMs operated on between July 1990 and December 2020. Outcomes at the last follow-up were defined as favorable (modified Rankin Scale [mRS] score 0–2) or unfavorable (mRS score > 2).

RESULTS

The study cohort comprised 24 men (52%) and 22 women (48%), ranging in age from 8 to 78 years old (median 37 years). In 19 patients (41%), the preoperative mRS score was > 2. All patients had hemorrhagic BSCM. There were 12 (26%) mesencephalic, 19 (41%) pontine, 7 (15%) medullary, and 8 (17%) cerebellar peduncle lesions, with a maximal diameter ranging from 5 to 40 mm (median 15 mm). In total, 24 BSCMs (52%) had bilateral extension crossing the brainstem midline. Lawton grades of 0, I, II, III, IV, V, and VI were defined in 3 (7%), 2 (4%), 10 (22%), 11 (24%), 8 (17%), 7 (15%), and 5 (11%) cases, respectively. Total resection of BSCMs was attained in 43 patients (93%). There were no perioperative deaths. Excluding the 3 most recent cases, the length of follow-up ranged from 56 to 365 months. The majority of patients demonstrated good functional recovery, but regress of the preexisting oculomotor nerve deficit was usually incomplete. No new hemorrhagic events were noted after total resection of BSCMs. In 42 patients (91%), the mRS score at the time of last follow-up was ≤ 2 (favorable outcome), and in 18 (39%), it was 0 (absence of neurological symptoms). Forty-four patients (96%) demonstrated clinical improvement and 2 (4%) had no changes compared with the preoperative period. Multivariate analysis revealed that only lower Lawton grade had a statistically significant independent association (p = 0.0280) with favorable long-term outcome. The area under the receiver operating characteristic curve for prediction of favorable outcome with 7 available Lawton grades of BSCM was 0.93.

CONCLUSIONS

Resection of hemorrhagic BSCMs by an experienced neurosurgeon may be performed safely and effectively, even in severely disabled patients. In the authors’ experience, preexisting oculomotor nerve palsy represents the main cause of permanent postoperative neurological morbidity. The Lawton grading system effectively predicts long-term outcome after surgery.

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Masahiro Izawa, Motohiro Hayashi, Mikhail Chernov, Koutarou Nakaya, Taku Ochiai, Noriko Murata, Yuichi Takasu, Osami Kubo, Tomokatsu Hori, and Kintomo Takakura

Object. The authors analyzed of the long-term complications that occur 2 or more years after gamma knife surgery (GKS) for intracranial arteriovenous malformations (AVMs).

Methods. Patients with previously untreated intracranial AVMs that were managed by GKS and followed for at least 2 years after treatment were selected for analysis (237 cases). Complete AVM obliteration was attained in 130 cases (54.9%), and incomplete obliteration in 107 cases (45.1%). Long-term complications were observed in 22 patients (9.3%). These complications included hemorrhage (eight cases), delayed cyst formation (eight cases), increase of seizure frequency (four cases), and middle cerebral artery stenosis and increased white matter signal intensity on T2-weighted magnetic resonance imaging (one case of each). The long-term complications were associated with larger nidus volume (p < 0.001) and a lobar location of the AVM (p < 0.01). Delayed hemorrhage was associated only with incomplete obliteration of the nidus (p < 0.05). Partial obliteration conveyed no benefit. Delayed cyst formation was associated with a higher maximal GKS dose (p < 0.001), larger nidus volume (p < 0.001), complete nidus obliteration (p < 0.01), and a lobar location of the AVM (p < 0.05).

Conclusions. Incomplete obliteration of the nidus is the most important factor associated with delayed hemorrhagic complications. Partial obliteration does not seem to reduce the risk of hemorrhage. Complete obliteration can be complicated by delayed cyst formation, especially if high maximal treatment doses have been administered.