Surgery of cerebellopontine angle epidermoid cysts: role of the widened retrolabyrinthine approach combined with endoscopy.

OBJECTIVES

To evaluate the use of the retrolabyrinthine approach (RLA) combined with endoscopy with particular reference to preservation of cranial nerve function and completeness of excision in surgery of epidermoid cysts.

METHODS

A retrospective study was performed on a series of 8 consecutive patients of whom 7 have undergone surgery. Main outcome measures Measures include audiological and neurological status preoperatively and postoperatively, size of the lesion, the surgical approach, completeness of excision, and operative morbidity.

RESULTS

The tumors were all large, ranging from 2 x 3 cm to 6 x 6 cm. Presenting symptoms were headache (75%), dysequilibrium (62%), trigeminal nerve palsy (38%), abducens nerve palsy (25%), and, rarely, auditory symptoms. Seven patients underwent surgery, 5 by the RLA, 1 by a translabyrinthine approach (TLA), and 1 by a transcochlear approach. Complete excision was achieved in 5 of the 7 patients. A transtentorial approach was combined in 2 cases (1 RLA, 1 TLA). Endoscopy was used in 3 cases. It allowed a complete tumor excision. One case of keratinous meningitis was observed. Trigeminal nerve function returned to normal in all patients. Postoperative facial nerve function was grade I in 5 cases and grade III in 2 cases. Hearing was preserved in 3 cases as class A, 1 case as class B. In the 2 cases presenting with abducens nerve palsy preoperative symptoms were initially aggravated before returning to normal function by 1 year postoperatively. The RLA with endoscopy allowed less invasive surgery and preservation of hearing in 4 of the 5 cases where it was attempted. Tumor control appeared better than with the suboccipital approach. Mortality and postoperative morbidity also appear reduced.

CONCLUSION

RLA combined with endoscopy should be considered as the standard approach for excision of epidermoid cysts. Extension of this approach into a TLA or transcochlear approach will depend on preoperative difficulties and preoperative hearing.