gms | German Medical Science

ESBS 2005: Skull Base Surgery: An Interdisciplinary Challenge
7th Congress of the European Skull Base Society held in association with
the 13th Congress of the German Society of Skull Base Surgery

18. - 21.05.2005, Fulda, Germany

Epidermoid cysts of the posterior fossa and petroclival region. Treatment and outcome

Meeting Contribution

  • Stanislaw J. Kwiek - Dept. of Neurosurgery, Medical University of Silesia, Katowice, Poland
  • Piotr Bazowski - Dept. of Neurosurgery, Medical University of Silesia, Katowice, Poland
  • Wojciech Slusarczyk - Dept. of Neurosurgery, Medical University of Silesia, Katowice, Poland
  • Wojciech Kukier - Dept. of Neurosurgery, Medical University of Silesia, Katowice, Poland
  • Jerzy Luszawski - Dept. of Neurosurgery, Medical University of Silesia, Katowice, Poland
  • Tomasz Wójcikiewicz - Dept. of Neurosurgery, Medical University of Silesia, Katowice, Poland
  • Adam Wolwender - Dept. of Neurosurgery, Medical University of Silesia, Katowice, Poland
  • Grzegorz Namyslowski - ENT Dept., Medical University of Silesia, Katowice, Poland
  • Grazyna Lisowska - ENT Dept., Medical University of Silesia, Katowice, Poland
  • Anna Zymon-Zagórska - Dept. of Radiology, Medical University of Silesia, Katowice, Poland

ESBS 2005: Skull Base Surgery: An Interdisciplinary Challenge. 7th Congress of the European Skull Base Society held in association with the 13th Congress of the German Society of Skull Base Surgery. Fulda, 18.-21.05.2005. Düsseldorf: German Medical Science GMS Publishing House; 2009. Doc05esbs43

DOI: 10.3205/05esbs43, URN: urn:nbn:de:0183-05esbs433

Published: January 27, 2009

© 2009 Kwiek et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.en). You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.


Abstract

Objectives: Surgical management of epidermoid cysts is still a challenge. One of the most important goals in epidermoids management is total tumor removal, but its tendency to adhere to cranial nerves and to the brain stem make technical problems in their complete removal. Approach to epidermal cysts of CPA and petroclival region is determined by tumor extension.

Patients and methods: Since 1988 to 2004 among 226 operations of cerebellopontine angle (CPA) tumors (retrosigmoid approach in sitting position) and 11 procedures of tumors involving petroclival region (petrosal approach) there were 26 operations of epidermal cysts and their recurrences performed in 19 patients. Continuous monitoring of selected neurophysiological functions was introduced as a routine in CPA and petroclival region surgery in 1998.

Results: There was no perioperative deaths in short postoperative period. We noticed one serious complication due to air embolism, which resulted in coma and prolonged vegetative state. In 13 patients (including 3 recurrences) we can assess procedure as completely microsurgical total resection. In long term observation facial nerve status is good (I or II H-B) after 18 procedures (70%), acceptable (III or IV H-B) after 4 procedures (15%) and not acceptable after 4 procedures (15%). In 15 out of 20 (75%) examined post operation cases measurable hearing was noticed.

Conclusions: Attempt to radical resection is proper but we shouldn’t sacrifice vital structures to reach this goal. Intraoperative multimodal monitoring of neural function is one of the important tools for success.

Keywords: epidermoid cyst, retrosigmoid approach, multimodal monitoring, petrosal approach


Text

Surgical management of epidermoid cysts (EC) is still a challenge. Tumors primary located in CPA may achieve wide extension into petroclival region or foramen magnum. The tumor grows slowly and usually penetrates to every accessible space around its origin, even through foramen of Luschka into fourth ventricle. Neurological manifestation of the tumor is caused by displacement of the cranial nerves brain stem, cerebellum or vessels. Because of slow growing and compression destruction of the petrous pyramid can occur. In advanced stages of EC growth compression and displacement of brainstem can be significant. One of the most important goals in EC surgical management is total tumor removal, but its tendency to adhere to extremely sensitive cranial nerves and to the brain stem pose technical problems in their complete removal without causing additional neurological deficits [1], [2]. Approach to EC of CPA and petroclival region is determined by tumor extension [1], [2], [3].

Patients and methods

Since 1988 to 2004 among 226 operations of cerebellopontine angle tumors (retrosigmoid approach in sitting position) and 11 procedures of tumors involving petroclival region (petrosal approach) there were 26 operations of EC and their recurrences performed in 19 patients. We attempted at total EC removal as well as the capsule but not to the point of sacrificing cranial nerves, blood or other vital structures. Continuous monitoring of selected neurophysiological functions of central and peripheral nervous system was introduced as a routine in CPA and petroclival region surgery in 1998. Since that year the patients underwent surgery having their neurophysiologic functions monitored in a continuous mode using four-channel unit Nicolet Viking IV D equipped in the special intraoperative software. Auditory evoked potentials, somatosensory evoked potentials and EMG from masseter, orbicularis oculi and trapezius muscles were registered simultaneously. Direct stimulation of cranial nerves V, VII and XI was used in order to identify and locate them using bipolar electrode. In selected cases intraoperative monitoring of cochlear function was also conducted using distortion product otoacoustic emissions (DPOAEs). Details of our methods of multimodal monitoring have been already published [4], [5]. Tumor size was defined as largest diameter and ranged from 30 to 100 mm (mediana=50). In 6 cases supratentorial extension of EC was found in radiological examination and confirmed intraoperativelly.

Results

There was no perioperative deaths in short postoperative period. We noticed one serious complication due to air embolism, which resulted in coma and prolonged vegetative state. Patient died 9 months later. In 3 cases postoperative chemical meningitis occurred. Paradoxal rhinorrhea was diagnosed in 2 patients, in both surgical intervention was required. In 13 patients (including 3 recurrences) we can assess procedure as completely microsurgical total resection. In this group up today we did not observe any recurrence. After 13 subtotal resections (50% of operations) performed in 8 patients 7 reoperations were necessary (2 patients have been operated three times). In one of them with supratentorial EC extension second excision was performed via petrosal approach. In 3 patients after subtotal procedure the remnant is stable (observation periods: 12, 12 and 10 years). One patient after subtotal procedure and intraoperative acute air embolism died on 9-nth month post surgery. Facial nerve paresis before operation was present in 9 cases (35%). In long term observation facial nerve status is good (I or II H-B) after 18 procedures (70%), acceptable (III or IV H-B) after 4 procedures (15%) and not acceptable after 4 procedures (15%). In one patient with facial palsy after first and second operation we observed recovery up to III grade after third (radical) operation. 16 procedures were conducted with intraoperative monitoring. In this group in no one case facial function is worse than III-rd grade but in 12 cases (75%) facial status is normal (I H-B). In 15 out of 20 (75%) examined post operation cases measurable hearing was noticed. Other details of neurological status are presented in Table 1 [Tab. 1].

Discussion

We agree with other authors that the approach to the EC should determined by tumor location and extension [1], [2], [3]. In our opinion for every EC located within CPA retrosigmoid avenue is optimal, but also most of EC with supratentorial extension can be totally resected by this way [1], [2], [3]. However some EC extended widely above tentorium definitely should be managed using combined approach or two-stage operation [1], [2]. The main goal of CE surgery is completely resection and in most of cases it is possible, but strong attempts to remove every bit of capsule may result in severe complications [1], [2], [3], [6], [7]. In the present series number of reoperations after not radical resection is relatively high. Most of subtotal resections were performed wen we started to deal with EC-s and can be explained by not sufficient experience, but also we advocated that introduction of intraoperative monitoring make our operations more radical. Tendency to more aggressive attempts support fact that postoperative cranial nerve dysfunction in many cases recovered during the postoperative period. Anyway we have to put into consideration that there are still impossible for total resection EC-s. Rate and range of complications and pitfalls in present group seems similar to described by other, very experienced authors [2], [7], [8], [9], [10], but we are sure that results of our procedures in last 6 years, especially facial nerve status and extension of tumor removal strongly depended on intraoperative multimodal monitoring. Chemical meningitis and hydrocephalus is common in our group, but their number is similar to other authors [2], [3]. For prevention we advocated use of extensive intraoperative Ringer’s solution rinsing and removal every left free pieces of tumor from arachnoid and skull.

Conclusions

In our opinion attempt to radical resection is proper but we shouldn’t sacrifice vital structures to reach this goal. Intraoperative multimodal monitoring of neural function is one of the important tools for success during EC surgery.


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