Epidermal cysts of the posterior fossa and petroclival region own experience'

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Epidermal cysts of the posterior fossa and
petroclival region own experience.

• Stanislaw J. Kwiek, Piotr Bazowski, Wojciech
  Slusarczyk, Wojciech Kukier, Jerzy Luszawski,
  Tomasz Wójcikiewicz, Adam Wolwender, Grzegorz
  Namyslowski, Grazyna Lisowska, Anna
  Zymon-Zagórska

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AIM

• Retrospective analysis of results epidermal cyst
  surgery in Neurosurgical Department Medical
  University of Silesia

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OBJECTIVES

• 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.
• Approach to EC of CPA and petroclival region is
  determined by tumor extension.

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MATERIAL 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.

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MATERIAL AND METHODS

• In selected cases intraoperative monitoring of
  cochlear function was also conducted using
  distortion product otoacoustic emissions
  (DPOAEs).
• Tumor size was defined as largest diameter and
  ranged from 30 to 100 mm (median50).
• In 6 cases supratentorial extension of EC was
  found in radiological examination and confirmed
  intraoperativelly.

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Ryc.1. Location of the electrodes and
stimulations.
Ryc.2. Sitting position, electrodes placement.
Ryc.3. Intraoperative multimodal monitoring of
neurophysiological modalities. Nicolet Viking
IVD.
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MATERIAL AND METHODS

• All the patients were operated on under general
  anesthesia by the same team of surgeons, in 25
  cases in a sitting position via retrosigmoid
  approach, and in one case using petrosal
  approach.

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RESULTS

• There were no perioperative deaths.
• There was one serious complication due to air
  embolism, which resulted in coma, prolonged
  vegetative state and death after 9 months.
• In 3 cases postoperative chemical meningitis
  occurred.
• Paradoxal rhinorrhea was diagnosed in 2 patients,
  in both surgical intervention was required.

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RESULTS

• 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 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.

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- Facial nerve status is significantly better in
IOM group.- 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 13
  cases (81) facial status is normal (I H-B).

cases
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In 15 out of 20 (75) examined post operation
cases measurable hearing was noticed.
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Table 1. Patients data, treatment results and
complications late outcome
Abbreviations pr - paradoxal rhinorrhea, ae -
air embolism, rd - respiratory disturbances,
CNS-inf - CNS infection, sp - spastic paresis,
d-9 mth - death after 9 months, nd no data,
np no perception
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Table 1. Patients data, treatment results and
complications late outcome
Abbreviations pr - paradoxal rhinorrhea, ae -
air embolism, rd - respiratory disturbances,
CNS-inf - CNS infection, sp - spastic paresis,
d-9 mth - death after 9 months, nd no data,
np no perception
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Patients data, treatment results and
complications late outcome
np no perception
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CONCLUSIONS

• In our opinion it is necessary to perform total
  resection, because in relatively short time after
  not radical removal reoperation was required.
• In our opinion attempt to radical resection is
  proper but we shouldnt sacrifice vital
  structures to reach this goal.
• 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. However some EC extended
  widely above tentorium definitely should be
  managed using combined approach or two-stage
  operation.
• Intraoperative multimodal monitoring of neural
  function is one of the important tools for
  success during EC surgery.
• In most cases of epidermoids hearing could be
  preserved.

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Patient K.S. MR before and after epidermal cyst
removal.
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Patient Z.D.Large epidermoid before and after
surgery.