Dysfunctions and anatomical relationships of cranial nerves in epidermoids of the cerebellopontine angle

Abstract

To evaluate the correlation of neurological symptoms with anatomical relationships of cranial nerves, lesions and vessels in patients with epidermoids of the cerebellopontine angle. We analyzed neurological symptoms, magnetic resonance data, intraoperative findings and postoperative functional outcomes in 25 patients (14 females and 11 males aged 22-77 years) with epidermoids of the cerebellopontine angle. Cranial nerve dysfunctions were noted in 15 patients. Involvement of cochlear (n=9) and trigeminal (9 cases including 4 ones with sensory impairment and 5 patients with neuralgia) nerves was the most common. There were 10 patients with ataxia, hemiparesis and seizures without cranial nerve dysfunction. In 15 patients, epidermoids spread to supratentorial space and contralateral cerebellopontine angle. Lesion-induced brainstem compression was found in 22 cases. Cranial nerves and cerebellar arteries were partially or completely enclosed by lesion in all cases. Severe compression and dislocation of the nerve root entry/exit zone were found in all cases. One patient with trigeminal neuralgia had vascular compression of trigeminal nerve caused by superior cerebellar artery. Total resection was achieved in 16 patients. Small capsule remnants were left on vessels, nerves or brainstem in 9 patients. Postoperative complete or partial restoration of cranial nerve functions was noted in 11 cases. Deterioration of preoperative neurological deficit in 4 patients and postoperative neurological symptoms de novo in 3 patients were temporary. Cranial nerve dysfunctions are caused by compression of the nerve root entry/exit zones by epidermoids of the cerebellopontine angle. Surgical intervention is effective in alleviating symptoms of cranial neuropathy and brainstem compression. Vascular decompression should be performed in patients with trigeminal neuralgia.