Surgical management of medium and large petroclival meningiomas: benchmark and limits

Abstract

Da Li and co-workers present a detailed sub-analysis of their series of petroclival meningiomas, which is the largest monocentric series published to date [5,6]. In the current work, they restrict the analysis to medium and large tumours of more than 2 cm in diameter-the tumours that really cause difficulties for microsurgery as well as stereotactic radiosurgery. Gross total resection was achieved in 56 % of patients; dysfunctions of the cranial nerves were the most common complication and occurred in two-thirds of the patients. Immediately following surgery, morbidity temporarily increased and the Karnovsky Performance Scale temporarily decreased on average. The case fatality rate amounted to 2 %. Permanent surgical morbidity remained in 20 % of patients during the average long-term follow-up of almost 10 years, but significantly more patients lived independently after than before surgery (61 vs 46 %). One-fourth of patients were lost to longterm follow-up, so that the numbers regarding long-term outcome must be appreciated with sound judgment.These key data focusing on medium and large petroclival meningioma are important, although difficult to compare with the smaller unselected series [1,3,[7][8][9]12]. Petroclival meningiomas smaller than 2 cm carry a much smaller surgical risk than large tumours, and in unselected series the small tumours dilute information regarding the problematic larger tumours. Numbers for the rate of gross total resection and surgical morbidities given in the published unselected series differ widely: gross total resection between one-third and twothirds, and surgical morbidity also between one-third and twothirds.Stereotactic radiosurgery is an obvious alternative for primary treatment of these tumours. There are not very many reports-a fact that reflects concerns regarding tolerance in view of the vicinity of the brainstem. The Pittsburgh group reported their experience in a series of 39 patients with a median follow-up period of 37 months. Neurological status improved in 21 %, remained stable in 66 %, and eventually worsened in 13 %. Tumour volumes decreased in 23 %, remained stable in 68 % and increased in 8 % [13]. It appears that there is some kind of consensus that radiosurgery is an adjuvant modality for larger petroclival meningiomas, which cannot be recommended as first-line therapy. However, there is little doubt that in analogy to vestibular schwannomas, stereotactic radiosurgery has evolved to an alternative for smallsized meningiomas.The substantial proportion of incomplete removal in most series and the significant rate of morbidity suggest that petroclival meningiomas remain not only difficult but basically problematic for microsurgery. Finding the balance between radicality and risk is the real challenge of managing petroclival meningiomas. The surgical risk appears to be influenced by (1) tumour size, (2) consistency and texture of the tumour and (3) the interface between tumour and arteries, brainstem and cranial nerves. In my opinion, it is hardly possible to disse...

Surgical Treatment and Clinical Outcomes of Petroclival Meningiomas: A Single-Center Experience of 107 Patients

“…In terms of the surgical approaches, the subtemporal transtentorial approach (STA) and the Kawase approach (KA) have the characteristics of short operative distance, convenient tumor base resection and less intraoperative bleeding but with the limitation for large posterior petrosal PCMS; the retrosigmoid approach (RSA) has the feature of fewer approach-related complications while the restriction to the petroclival region; the anterior sigmoid approach (ASA), also named the posterior petrosal approach (PPA), can facilitate the exposure of tumors, reduce the traction of the brainstem but perplexes the neurosurgeons for harder maneuver. Although there are many surgical approaches for PCMs and the relevant studies have repeatedly reported, the optimal choice for the operation is of extreme difficulty (2)(3)(4)(5) and no uniform standard establishing the superiority of one approach over another is acknowledged currently (6,7), due to the anatomical complexity, the multiformity of tumor invasion and the intricacy of a balance between neurofunctional preservation and tumor recurrence.…”