Amongst the intraspinal location, meningiomas account for 25% to 46% of primary spinal neoplasms, while the incidence of spinal meningiomas is 7.5% to 12.7% of all meningiomas
They have a peak incidence in the fifth and sixth decades. Interestingly, and unlike intracranial meningiomas, in the adult population, females are approximately ten times more commonly affected than males. In children, there does not appear to be a sex predilection.
There is an increased incidence of spinal meningiomas in patients with neurofibromatosis type 2 (NF2), and in fact in the paediatric population, meningiomas uncommonly occur outside of the setting of NF2.
Except in cases of neurofibromatosis, it is very rare for tumors of different pathological types to exist concurrently at the same spinal level, with only 9 cases reported to date, in which spinal meningioma was found with spinal schwannoma in 7 cases and with spinal neurofibroma in 2 cases 2).
Most spinal meningiomas are benign, with greater than 95% being classified as WHO grade I lesions, although clear cell meningiomas (a WHO grade II histological variant) have a predilection for the spine.
They are believed to originate from the denticulate ligaments.
The PubMed/Medline database was systematically searched to identify studies describing oncological and clinical outcomes after Simpson grade I, II, III, or IV resections of spinal meningiomas.
Thirty-two studies describing the outcomes of 896 patients were included in the analysis. Simpson grade I, grade II, and grade III/IV resections were performed in 27.5%, 64.6%, and 7.9% of cases, respectively. The risk of procedure-related complications (OR 4.75, 95% CI 1.27-17.8, p = 0.021) and new, unexpected postoperative neurological deficits (OR ∞, 95% CI NaN-∞, p = 0.009) were both significantly greater for patients undergoing Simpson grade I resections when compared with those undergoing Simpson grade II resections. Tumor recurrence was seen in 2.8%, 4.1%, and 39.4% of patients undergoing Simpson grade I, grade II, and grade III/IV resections over a mean radiographic follow-up period of 99.3 ± 46.4 months, 95.4 ± 57.1 months, and 82.4 ± 49.3 months, respectively. No significant difference was detected between the recurrence rates for Simpson grade I versus Simpson grade II resections (OR 1.43, 95% CI 0.61-3.39, p = 0.43). A meta-analysis of 7 studies directly comparing recurrence rates for Simpson grade I and II resections demonstrated a trend toward a decreased likelihood of recurrence after Simpson grade I resection when compared with Simpson grade II resection, although this trend did not reach statistical significance (OR 0.56, 95% CI 0.23-1.36, p = 0.20).
The results of this analysis suggest with a low level of confidence that the rates of complications and new, unexpected neurological deficits after Simpson grade I resection of spinal meningiomas are greater than those seen with Simpson grade II resections, and that the recurrence rates for Simpson grade I and grade II resections are equivalent, although additional, long-term studies are needed before reliable conclusions may be drawn 4).