Cerebellopontine angle epidermoid cyst surgery
Resection is complicated by their close anatomical relation to critical neurovascular structures and their tendency to be densely adherent making complete removal a significant neurosurgical challenge 1).
The endoscope-controlled microsurgical technique enables a safe tumor removal even when parts of the lesion are not visible in a straight line in CPA epidermoids. By angled endoscopic lenses, tumor extending into adjacent cranial compartments or surgical anatomic corners can be removed through a single small craniotomy without retracting neurovascular structures 2).
The posterior cranial fossa approach was used in 27 cases in the case series of deSouza et al. Total excision of the epidermoid was the aim and was carried out in five (18%) patients but concern regarding the preservation of nearby important neurovascular structures forced partial removal in 22 patients. To minimise reformation, the residual epidermoid was carefully coagulated with the aid of the operating microscope and bipolar cautery without damaging surrounding neurovascular structures 3).
The characteristics of epidermoid cysts make them amenable to whole course neuroendoscopic resection. Use of physiologic/pathologic interspaces and neuroendoscopic angulations decreases traction on the brain, improves complete resection rates, and decreases postoperative complications 4).
Videos
This video describes the surgical management of an epidermoid cyst within the cerebellopontine angle and petroclival region with involvement of cranial nerves V through XI and the vertebrobasilar system. A retrosigmoid craniotomy was performed for gross total resection of the lesion. The key steps of the procedure are discussed, including: positioning, soft tissue dissection, craniotomy, microsurgical dissection/resection, closure. Additionally, surgical nuances with regards to the safe maximal resection of such lesions are detailed. The video can be found here: http://youtu.be/VEROVO5cYdU 5).
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Endoscopic-Assisted Keyhole Resection of a Recurrent Epidermoid Tumor: 2-Dimensional Operative Video 6).
Technique
Microsurgical Technique for Resection of a Cerebellopontine Angle Epidermoid Tumor 7).
Case series
The clinical data and outcome of 32 cases operated for CPA epidermoid between 2007 and 2015 were retrospectively analyzed. The mean follow-up period was 42.6 months, and all patients were followed up at least for a whole year. There were 15 males and 17 females. The median age was 37.6 years. Headache and cranial nerves dysfunction were the most common presenting symptoms. Surgery was performed in all patients using the standard lateral suboccipital retrosigmoid approach. In three cases, microvascular decompression of an arterial loop was performed in addition to tumor excision. Total resection was accomplished in 19 out of 32 cases (59.4%), subtotal resection in 7 cases (21.9%), and only partial excision was achieved in 6 cases (18.7%). There was no recurrence or regrowth of residual tumor during the follow-up period. We had a single postoperative mortality due to postoperative pneumonia and septic shock. New cranial nerves deficits occurred in 15.6% of cases but were transient in most of them. Conclusion The favorable outcome of total resection of CPA epidermoids should always be weighed against the critical risks that accompany it especially in the presence of tight adhesions to vital neurovascular structures. The retrosigmoid approach is suitable for the resection of these tumors even if they were large in size 8).