In the period between between January 2014 and December 2020, 340 patients, matching the inclusion criteria, suffering from intracranial Meningioma underwent surgery in our departments and were retrospectively evaluated for this study.
2. Descriptive data
The final cohort consisted of 340 patients (102 males and 238 females - 70% of the population) respecting the F:M ratio reported in the literature of 2-3:1, and the average age was 60.38±13.56 years (Range 20-90), Smoke habits and Hypertension was revealed at the time of radiological diagnosis respectively in 98 patient (28,8%) and 108 patients (31,8%).
We reported the clinical debut for the population (Table 1), although only symptomatic meningiomas or meningiomas large enough to be evaluated as surgical were considered in this collection, a significant percentage of patients (14 patients, 13.2%) were incidentally diagnosed after investigations for other pathologies.
In a final division in a main subgroup A, Giant meningiomas were 117 (34,4 %) and subgroup B, Medimu/Large meningiomas were 223. All the relevant details with analysis results are included in Table 2.
The two subgroups did not present remarkable differences from the age/sex differences. Clinical debut, presence of seizure, smoke habits and hypertension were not significantly different.
Giant meningiomas did not correlate with known or likely risk factors for meningioma occurrence such as cigarette smoking (Chi-square= 1.362, dF= 1, p=0.243) or high blood pressure (Chi-square= 1.4, dF= 1, p=0.237). Specifically, we compared through contingency analysis (chi-square) whether there was a predominance of seizures at onset in either group obtaining no statistically significant results (p=0.764)
3. Histochemical and Radiological comparison analisys between the two groups
From the histochemical point of view the two subgroups in concerns to the WHO classification group A presented with a higher significant percentage of Grade II (31 patients, 26,5% versus 16 patients, 7,2%, p-value 0,001). There is evidence of a correlation between WHO grade (particularly atypical meningiomas) and tumor size and in general the diagnosis of giant meningiomas (chi-square=24.05, dF= 1, p=0.001), This difference is more evident between WHO grade I and II (in the diagnosis of atypical meningiomas, p=0.001)) than between grade II and grade III (p=0.818).
There is no correlation between the expression of progesteron on immunohistochemical analysis and the size of meningiomas in both groups, this finding is confirmed both when comparing the total volume of the lesion (p=0.847) and the largest diameter of the tumor (p=0.663). On the other hand, there is an independent correlation between ki-67 expression and total tumor volume (p=0.017, as typical for a large number of intracranial lesions ).
Interestingly, the direct proportional relationship between edema volume and tumor volume was present only in the medium/large group and was not present in the giant meningioma group with a statistically significant difference in proportionality. (t= -7.611, dF= 215, p<0.01). This finding is confirmed by similarly comparing the ratio of edema volume to lesion volume (t= 2.44, dF= 214, p=0.016). Results are obtained after Turkey and Bonferroni correction methods.
This peculiar feature suggest that giant meningiomas compared with medium and large meningiomas have a less remarkable strong relationship between the volume of the tumor mass and the edema generated around the tumor in the brain tissue. The extent of cerebral edema in relation to tumor size was evaluated. While in lesions under 5 cm there is a stable relationship between the increase in volume of the mass and the simultaneous increase in the volume of edema (Paired sample correlation test, t-student: p= 0.372) this relationship is no longer established in giant meningiomas (Paired sample correlation test, t-student: p<0.001). Analyzing the volume of edema among the different localizations of meningiomas in the whole population shows a strong variability among the different groups of meningiomas (p=0.04), with a greater prevalence of edemigenous lesions in meningiomas of the olfactory shower and sphenoidal plenum, without, however, substantial significance (p= 0.659, group 6, p>1, group 11), therefore there are no significantly edemigenous localizations compared to others. Moreover, while in medium/large meningiomas, as well as in the whole case series, there is no more edemigenous localization than another, in giant meningiomas there is a significant correlation with the site of implantation as far as tumors of the anterior basicranium (olfactory shower and sphenoidal plenum) are concerned.
4. Outcome data and Main Results
Neurological and clinical outcome as measured by KPS is affected by lesion localization, but to a different extent than recovery time. When comparing the degree of performance there is a statistically significant difference between localization and KPS immediately postoperatively (p=0.04) particularly for sphenopetroclival meningiomas (p=0.071), and partially with GIM of the olfactory groove with arterial encasement (Fig. 2).
This difference is no longer evident in the comparison at the last evaluation where the final KPS has no correlation with the location of the meningioma (p=0.318).
It is found that surgically treated giant meningiomas have a higher risk of developing complications in the postoperative phase (Chi square= 11.121, dF=1, p=0.001, Fig.3).
The most frequently encountered complications include the occurrence of ischemia (p=0.049), infection (p=0.03), and especially the occurrence of postoperative seizures.
Although there is no evidence of a greater presence of epilepsy at diagnosis of a giant meningioma compared to a medium/large meningioma (Chi-square= 0.090, dF= 1, p= 0.764), there is an increased risk of seizures in the postoperative phase (Chi-square= 8.555, dF=1, p=0.003).
On the other hand, there is no significant relationship (Chi-square= 2.189, dF=1, p=0.139) between mortality and the presence at diagnosis of a giant meningioma.
In our case series, the risk of recurrence measured at the last evaluation was superimposable between group A and group B (Chi-square = 2.581, dF = 1, p = 0.108).