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|NI FEATURE: THE EDITORIAL DEBATE II-- PROS AND CONS
|Year : 2019 | Volume
| Issue : 1 | Page : 65-66
Foramen magnum meningiomas – Understanding the requirement and extent of condylar resection
Manas Panigrahi1, Sudhindra Vooturi2
1 Department of Neurosurgery, Krishna Institute of Medical Sciences, Minister Road, Secunderabad, Telangana, India
2 Department of Neurology, Krishna Institute of Medical Sciences, Minister Road, Secunderabad, Telangana, India
|Date of Web Publication||7-Mar-2019|
Dr. Manas Panigrahi
Department of Neurosurgery, Krishna Institute of Medical Sciences, 1-8-31/1, Minister Road, Secunderabad - 500 003, Telangana
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Panigrahi M, Vooturi S. Foramen magnum meningiomas – Understanding the requirement and extent of condylar resection. Neurol India 2019;67:65-6
Meningiomas account for nearly one-fifth of all primary intracranial neoplasms, and nearly 3% of meningiomas arise at the foramen magnum. The first successful surgical resection of foramen magnum meningiomas (FMMs) was reported by Elsberg in 1927 and comprised a suboccipital craniotomy and C1–C3 laminectomy. Despite the development of microsurgery and cranial base techniques, the most advantageous approach for surgical resection of FMM has been a subject of debate owing to the sensitivity of this region to surgical manipulation. This article intends to provide an overview of the nuances of sparing the condyles from resection during the surgical management of FMMs.
Among all FMMs, those located anterior or anterolateral to the brainstem present a significant challenge to the neurosurgeons. In recent times, the utility of systematic condylar drilling for approaching anterolateral FMMs has been formidably questioned. The anterior transoral and anterolateral transcervical approaches were proposed as alternative approaches; however, these approaches did not reach the popularity of the posterolateral approaches due to the occurrence of complications like a cerebrospinal fluid (CSF) fistula, infection, and the restriction in the ability to access the lateral field. To improve the angle of visualization, Sen and Sekhar et al., proposed the extreme lateral or the far-lateral approach in association with vertebral artery medial transposition with a total or partial condylectomy.
The extreme lateral or the far-lateral approaches with partial or total condylar drilling and the lateral or the conventional posterior approach without condylar drilling have been described to treat these lesions. On the contrary, few studies suggest that progressive growth of tumors displaces the medulla posteriorly, thus creating a space through which the tumor can be resected totally and safely through a posterolateral suboccipital craniectomy without condylar drilling. Importantly, extensive drilling of the occipital condyle, lateral mass of the Atlas More Details, and jugular tubercle may lead to injury to the hypoglossal nerve and vertebral artery and may also lead to spinal instability. These studies further suggest that in most of the cases of incomplete tumor resection, the most frequent reason is the invasion of the brainstem piamater, or the involvement of the vertebral artery or the lower cranial nerves by the tumor. In these situations, a subtotal resection is preferred. In fact, a review of literature on surgical resection of 657 patients with FMM from 29 different neurosurgical centers found that only six centers performed a condylar resection routinely. While in four centers they tailored the drilling of the condyle, and in seven other centers they never resected the condyle.
Considering the Indian perspective on surgical resection of ventrolateral intradural lesions, Sarat Chandra et al. in 2003 reported a series of 30 patients with an extramedullary tumor at the foramen magnum. Ten patients had their lesion located venterolaterally in relation to the brain stem and were resected by the extreme lateral approach. The authors reported that postoperatively, one patient succumbed to aspiration pneumonitis and one patient had CSF leak that was successfully managed using serial lumbar drainage. The authors further report that almost all the patients returned to occupation at latest follow-up. Mohammad et al., have previously reported that far-lateral route is a versatile approach for a variety of lesions located ventrolateral to the brainstem and upper cervical cord. Our experience suggests that adequate surgical removal of the tumor could be achieved without the need for partial or complete condylar resection. In addition, we also used a custom-made plug-in technique, and therefore, none of the patients in this study developed postoperative CSF fistula.
In the current issue, Srinivas et al., report their experience with surgical resection of anterior and anterolaterally situated FMM, while preserving occipital condyles, from 2005 to 2015 at a tertiary referral center in India. The study included 20 patients with an average age of 36.7 years. Encouragingly, gross total resection is reported in 80% of patients, and over the follow-up period that ranged between 6 and 140 months, new motor deficits, pseudomeningocele formation, worsening of the lower cranial nerve functions, or postoperative adhesions leading to syrinx formation were observed in 40% of the patients only. The authors conclude that “condylar preservation provides a good visualization, while helping in preserving joint stability and in avoiding instrumental stabilization” in surgical resection of FMM.
The retrocondylar approach used by the authors did not need resection of the occipital condyle nor the mobilization of the vertebral artery (VA). It has to be noted that the retrocondylar approach provides satisfactory exposure because most of the FMMs predominantly grow to one side, thus negating the need for condylar resection. Also, among FMMs, it is paradoxically easier to resect a large tumor than a small one because of the anterior space the larger tumors provides, thus lessening the need for a more lateral exposure [Table 1]. The authors report postoperative complications in eight (40.0%) of the study population, which is higher when compared with the incidence of complication reported in the existing literature and referred to by the authors. One possible assumption for the higher reported complications may be related to the fact that this study reports only one surgical approach, whereas in the existing literature complications of various surgical approaches for FMM were reported in a cumulative manner. In patients with residual tumors, who constituted nearly 20% of patients in this study, radiosurgery might be considered as an adjuvant/additional therapy to avoid recurrence.
Most of the aforementioned studies clearly demonstrated that the optimal surgical approach in the management of FMM is still unsolved. Requirement for the excision of the condyle based on the location of FMM only may be gross oversimplification. Numerous other contributing/confounding factors listed below should be considered before making a decision on the requirement and extent of condylar resection required.
Although further research is required to design a logical step-wise algorithm, it is currently important to acknowledge that the surgical trajectory for the resection of FMM should be tailor-made to the characteristics of the tumor rather than being dogmatic in approach.
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Mohammad HU, Vooturi S, Panigrahi M. Far lateral approach: Is condylar resection required? Neurol India 2016; 64:455-61.
] [Full text]
Srinivas D SP, Deora H, Beniwal M, Vikas V, Rao KVLN. “Tailored” far lateral approach to anterior foramen magnum meningiomas – The importance of condylar preservation. Neurol India 2019:67:142-8.