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Marc P. Sindou and Jean-Luc Fobé

✓ Improved access to the tentorial notch can be obtained by removal of the roof of the external auditory meatus in association with a low temporal craniotomy. This approach decreases temporal lobe retraction and the risk of venous infarction. This method was perfected in the surgical laboratory on five cadavers and was successfully performed in a patient with a giant aneurysm of the posterior cerebral artery.

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Jorge E. Alvernia and Marc P. Sindou

Object. To understand the cause and prevention of postoperative ischemic and/or venous parenchymal infarcts after intracranial meningioma resection, the authors describe the value of neuroimaging in predicting the surgical plane of cleavage.

Methods. A prospective study of 100 meningiomas was performed, in which tumor size, absence or presence of peritumoral edema, tumor—parenchyma interface, and types of arterial vascularization (that is, dural—meningeal, pial—cortical, or mixed) were correlated with the type of dissection plane (extrapial, subpial, or mixed) encountered at surgery. A direct correlation was found between the tumor size identified on T1-weighted magnetic resonance (MR) imaging sequences and the degree of subpial (nonextrapial) surgical plane of cleavage (p < 0.00001). A similar correlation was found with the grade of peritumoral edema identified on preoperative computerized tomography (CT) scanning (p < 0.0001) or T2-weighted MR imaging sequences (p < 0.00001) and tumor pial vascularization as seen on angiography (p < 0.0001). Nevertheless, the tumor—parenchyma interface on preoperative T2-weighted MR imaging sequences was not predictive of the surgical plane (p > 0.5). The worst clinical outcome was found in the tumors located in eloquent areas and in which a subpial plane was encountered at surgery (p = 0.03).

Conclusions. Peritumoral edema on preoperative CT and MR studies and tumor pial vascularization as seen on selective angiography can be used to predict the surgical plane of cleavage in meningiomas. The association between tumor size and a subpial surgical plane may be explained by a more pial vascularization seen on angiography. Meningiomas with a location in eloquent cortex and a subpial dissection plane should be considered a high-risk group.

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Marc P. Sindou, Eric Blondet, Evelyne Emery and Patrick Mertens

Object. Most patients with preganglionic lesions after brachial plexus injuries suffer pain that is hard to control through medication or neuromodulation. Lesioning in the dorsal root entry zone (DREZ) is undeniably effective. Fifty-five patients who had undergone the so-called microsurgical DREZotomy (MDT) procedure were studied with the two following objectives: 1) to describe the anatomical lesions observed during MDT in correlation with sensory deficits and pain features; and 2) to analyze the results in the 44 patients who were followed for more than 1 year (mean 6 years).

Methods. The observed lesions were severe: 79.6% of ventral and 78.2% of dorsal roots from C5—T1 were impaired. Damage extended to all five roots in 42% of patients. Strong arachnoiditis was present in 38.2%, pseudomeningoceles in 31%, spinal cord distortion and/or atrophy in 49%, and abundant gliotic tissue and/or microcavitations within the dorsal horn at the avulsed segments in 36.4% of cases. Sensory deficit corresponded to the entire territory of the dorsal root lesions in 52% of patients, but was larger in 30% most certainly due to the associated extrarachidian lesions. At the last evaluation after MDT, 66% of patients showed excellent (total relief without medication) or good (total relief with medication) pain relief and 71% experienced an improvement in activity level.

Conclusions. Apart from other indications not addressed in this article, MDT can be performed to treat refractory pain due to brachial plexus avulsions. The long-term efficacy of this procedure strongly indicates that pain after brachial plexus avulsion originates from the deafferented (and gliotic) dorsal horn.

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Roberto C. Heros

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Marc P. Sindou and Jorge E. Alvernia

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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Jorge E. Alvernia, Nguyen D. Dang and Marc P. Sindou

Object

Convexity meningiomas are expected to have a low recurrence rate given their classically “easy resectability.” Nonetheless, recurrence can occur. Factors playing a role in their recurrence are analyzed here, including the extent of resection and tumor histological type, among others, with a special emphasis on the cleavage plane.

Methods

The authors reviewed 100 cases of convexity meningiomas surgically treated between 1987 and 2001 with a median follow-up of 86 months (range 2–16 years). Preoperative and postoperative functional status, Simpson resection grade, histological type, and intraoperative surgical plane with pial vessel invasion were studied and correlated with the recurrence rate.

Results

The average tumor size was 3.6 ± 0.4 cm. The pre- and postoperative Karnofsky Performance Scale scores were 92.6 ± 4.6 and 97.9 ± 2.2, respectively. Ninety-five lesions were benign (WHO Grade I) and 5 were atypical (WHO Grade II). Ninety-one and 9 tumors were subjected to Simpson Grade 1 and 3 resections (three Grade 3a and six Grade 3b), respectively. Surgical deaths did not occur. After a mean follow-up of 7.2 years, 4 meningiomas recurred; 2 (2.2%) after Simpson Grade 1 resections and 2 after Simpson Grade 3 (3a and 3b) resections (22.2%; p = 0.0034). When just the subgroup of Simpson Grade 1/WHO Grade I was studied, the recurrence rate decreased to 1.2% (1 of 86 cases). The recurrence of WHO Grade I tumors was higher in the subpial group than in the extrapial group (p = 0.025). No difference in recurrence according to the cleavage plane was seen in the WHO Grade II subgroup (p = 0.361). As for the subpial group, no difference in recurrence was noted between the WHO Grade I and II subgroups (p = 0.608). Importantly, however, the extrapial subgroup of WHO Grade II lesions had a higher recurrence rate compared with its counterpart in the WHO Grade I subgroup (p = 0.005).

Conclusions

Pial and vascular invasion affect the recurrence rate in convexity meningioma surgery. The recurrence rate of WHO Grade I tumors was higher among those with a subpial plane of dissection than among those with an extrapial one. Histological type did not determine the degree of pial invasion in WHO Grade I and II lesions.

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Jacques J. Morcos, Stephan A. Munich, Tiit Mathiesen, Marc P. Sindou and Vinko V. Dolenc