In our study, the rate of postoperative death was 3.0% after large and giant PCM surgery with a severe neurological impairment in 12.8% and a severe non-neurological morbidity in 4.0%. In reported series, mortality ranged 0–10%, the incidence of cranial nerves deficits ranged 29–76%, and major complications ranged 8–45%[2, 5, 7, 11, 23, 26, 28, 31, 34, 40]. Thereby, our overall rate of severe morbidity and mortality was 15.7% after large and giant PCM surgery in accordance with the literature[2, 4, 5, 7, 11, 17, 19, 23, 26, 28, 29, 31, 34, 40].
Interestingly, Adachi et al. proposed a scoring system for predicting the extent of surgical resection and the neurological outcome for skull base meningiomas. In accordance with their results, we suggested that peri-tumoral edema on preoperative MRI increased the risk of postoperative severe neurological impairment, as previously described[1, 4, 17, 38]. The presence of peri-tumoral edema is possibly related to the pial invasion of the brainstem, which may explain difficulties during tumour dissection resulting in vascular injuries and direct injury to the brainstem. However, Adachi et al. analyzed only the postoperative severe neurological impairment but not the non-neurological morbidity, which required the preoperative assessment of the patient general conditions.
Male sex was associated with a higher rate of postoperative non-neurological morbidity, which was consistent with a previous study published by Sekhar et al., where male sex was independently associated with early postoperative KPS deterioration. We suggested that major cardiovascular morbidity increased the risk of postoperative non-neurological morbidity,
which remains a criterion found in all the scores assessing the patient general condition[9, 25, 33].
The ASA scores is a widely used grading system for preoperative health of the surgical patients, which was correlated, for neurosurgical procedures, with non-neurological morbidity[16, 24, 30, 35–37], postoperative length of stay and survival. The modified Frailty indexand the Charlson comorbidity index were also studied in the neurosurgical literature with interesting results, especially concerning their highest accuracy for predicting postoperative complications compared to the ASA score[15, 22, 43]. Youngerman et al., published a large cohort of 9149 patients who underwent oncologic neurosurgery procedures with an estimation of the modified Frailty index. They found that mortality, severe medical complications, prolonged length of stay, and unfavourable discharge increased incrementally with increasing levels of Frailty. However, all these studies were not specifically dedicated to assess skull base and PCM surgery. Here we suggested, for the first time, the importance of assessing the patient general condition in order to improve the overall risk of postoperative complications. The ASA score and the modified Frailty index are significant predictors of post-operative severe non-neurological morbidity and overall severe morbidity and mortality, respectively, and remain convenient scores that can be achieved in daily clinical practice.
In parallel, we suggested that a low neurosurgical experience was associated with a higher risk of overall postoperative morbidity and mortality. The major role of the surgical experience could be related to the assessment of the risk of neurological and non-neurological complications from an experience-based multimodal analysis. The reduction of postoperative severe neurological impairment could be associated with higher skills of the neurosurgeon and the reduction of postoperative non-neurological morbidity is possibly related to the better selection of patients eligible for surgery.
In addition to the PCM’s poor natural history[8, 10, 13, 42] -as relentlessly progressive, with frequent fatal outcomes- and with the natural increased comorbidities score linked to the aging, one may argue that the surgical indication may be proposed early in the patient PCM history. Moreover, the advancement of surgical techniques, the outcomes of PCMs are no longer as pessimistic as has been reported previously[3, 6, 20, 21, 26]. The mortality rate has decreased greatly to 3 %; however, surgical morbidity remains high[3, 12, 20, 21, 27]. For selection of the ideal treatment modality in each case, understanding of the natural history and determination of preoperative predictors -such as comorbidity score- are mandatory. A better understanding of the natural history of PCM in the elderly population may help to better wedged the surgical prognosis and the patient information, as comorbidities score appeared to be linked with poor outcomes.
Our results suggest incorporating general condition data into clinical and radiological data in order to improve the accuracy of predicting surgical risk for large and giant PCM.
These findings should be interpreted with caution, given the retrospective and monocentric design, the small numbers of patients, the rarity of the events analyzed, and the lack of an external validation set that limited the generalizability of the results. Since all patients in this study were adults, harbored a large and giant PCM surgically treated by the same senior neurosurgeon, and operated on using the same surgical approach, we thus cannot extend the results to other surgical techniques, to other location, and to patients with a recurrent large and giant PCM. In an attempt to identify predictors available before the surgery, we decided not to integrate the extent of surgical resection. In addition, for large and giant PCM, our attitude is to perform, when possible, a subtotal resection followed by Gamma-Knife radiosurgery, as previously described. Finally, the median modified Frailty Index and Charlson comorbidity index was 0, which suggests that patients who underwent surgery were already preselected by the neurosurgeon or by the referral physician.
Large and giant PCMs remain challenging surgical lesions requiring complex skull base approaches. The risk of postoperative severe neurological and non-neurological morbidity could be assessed pre-operatively following clinical examination, brain MRI analysis and by scores assessing patients' comorbidities. In this study, we propose to add scores assessing the patient general condition in daily practice to improve the selection of patients eligible for surgery. This holistic approach for surgical risk could optimize the management of patients as well as selecting those who can benefit from a surgical resection. Collaborative international multicenter studies are required to confirm these results and allow their implementation in clinical routine.