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|NI FEATURE: THE EDITORIAL DEBATE V-- PROS AND CONS
|Year : 2018 | Volume
| Issue : 5 | Page : 1314-1315
Large-to-giant petroclival meningiomas: The additional features in management
Department of Neurosurgery, AMRI Hospital, Kolkata, West Bengal, India
|Date of Web Publication||17-Sep-2018|
Dr. R N Bhattacharya
Department of Neurosurgery, AMRI Hospital, Dhakuria Gariahat Road, Near Dhakuria Railway Bridge, Kolkata - - 700 029, West Bengal
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Bhattacharya R N. Large-to-giant petroclival meningiomas: The additional features in management. Neurol India 2018;66:1314-5
The natural history of petroclival meningiomas demonstrates progressive growth as well as brainstem compression and displacement, eventually leading to progressive neurological deficits and an inevitable death. [1,2] Before the 1970s, these tumors were considered as being inoperable;,, even with advancements in the skull-base surgical techniques and in instrumentation, excision of these tumors is still a formidable task.
The authors of the study published in this issue of Neurology India  deserve compliments for the commendable work done by them related to the excision of large-to-giant petroclival meningiomas utilizing the middle fossa approach. The emphasis on the large number of patients recruited and their pain-staking follow up (with the mean duration of follow up being 35.77 months) is commendable. In the study, a great emphasis in the discussion has placed on comparing their data with other publications. The authors have classified petroclival meningiomas very aptly, based upon the surgical relevance, along with a historical overview, to ensure an easy understanding of the subject for the upcoming younger generation of neurosurgeons. Their comment on leaving a thin rim of tumor attached to the brainstem, and their emphasis on a serial follow-up to assess for progression, was very informative. The detailed steps of drilling of the bones of the skull base and their highlighting the inherent advantages of an easy devascularization of the tumor, if the approach is through the middle fossa or the pre-sigmoid route, is very illuminating.
There were a few short-comings of the articles too, which the surgeons dealing with these tumors should take note of; and therefore, highlighting these issues will serve to improve the management of these difficult-to-excise tumors. The actual technique recommended and pursued should be modified according to the specific situations the individual surgeons are confronted with in their own cases.
- A lot of patients come to tertiary care centers for surgical excision of petroclival meningiomas with either incompletely removed tumors or recurrent tumors. In the study, the selection criteria of whether the tumor being excised was primary or secondary has not been explained clearly. This is important as residual or recurrent tumors often lack a plane of cleavage. Furthermore, the tumor is notorious for being present in multiple subarachnoid cisterns around the brainstem and around neurovascular structures surrounding the brainstem. A lack of a proper arachnoidal plane often leads to an increased difficulty in performing complete resection and the development of additional postoperative neurological deficits.
- The causes of recurrence of the tumor have not been adequately discussed. Was the recurrence due to a histologically aggressive subtype of the tumor or was it due to an initial subtotal excision. In case it was due to the latter, why were these tumors not subjected to radiosurgery. In today's era, radiosurgery in an excellent modality for achieving recurrence-free survival in this group of tumors.
- An interesting issue was that several patients underwent a digital subtraction angiogram (DSA) to assess the displacement of major vessels by the tumor. Yet, no attempts were made to embolize the tumor which would have led to significant decrease in vascularity of the tumor and would have probably increased the ease of resection of these tumors. Failure to embolize these tumors could have been due to lack of facilities for performing interventional radiology; or, it could have been more of a philosophical issue, in that the displaced vessels are often difficult to negotiate using neurointervention, and often the distinction between a blood vessel supplying the tumor and that primarily supplying various brainstem structures may often be difficult to establish.
- Another important fact that the readers would definitely like to know is whether the staged procedures were planned preoperatively or were decided at the time of surgery, either due to a lack of plane of cleavage, or due to an existing inaccessibility in reaching the remnant tumor during surgery. An elective staged surgery either utilizing the same or a different approach would have been necessary in the event of a part of the tumor not being accessible by a single approach.
- One important drawback of the study was the loss of six patients at the follow-up evaluation. This has reduced the power of the study group and affected the significance of outcome.
- Six deaths in a series of 33 patients is a significant number but the different causes for mortality are well defined; it is also important to note that a poor preoperative grade as well as lower cranial nerve paresis and pneumonitis were the most important perioperative causes of mortality.
- In the study, in almost 31 patients, the tumor had crossed the midline in the premedullary, prepontine and interpeduncular cisterns. There was no discussion of how to prevent brainstem retraction in these patients, as this is an essential factor in achieving a better outcome for these patients. The need for the use of cerebral decongestants in the study also needs to be elaborated
- The reason for the postoperative cerebrospinal fluid (CSF) leakage has also not been elaborated. Was it due to lack of dura (due to the coagulation of tumor attachment), lack of muscle cover, or a procedural inadequacy at an earlier stage of the study. The subsequent protocol to prevent CSF leak and to address the CSF leak postoperatively should have been clearly elucidated
- The use of neuro-physiological monitoring has been mentioned once in the study. This monitoring would have been very helpful in the intraoperative preservation of cranial nerve function
- Postoperative neuro-rehabilitation should also have been discussed in view of the postoperative cranial nerve palsies encountered in the authors' series
- How was progression of venous thrombosis around the brain stem and perforator compromise reduced. This too needs clarification.
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. Surgical excision of large-to-giant petroclival meningiomas focusing on the middle fossa approaches: The lessons learnt. Neurol India 2018;66:1434-46. [Full text]