Abstract

The epidermoid cyst is the third most common benign tumor of the cerebellopontine angle, accounting for 4% of lesions at this level. These tumors can remain silent for years, implying their diagnosis in advanced stages, where they manifest as headache, trigeminal neuralgia, and cochleovestibular involvement. Its treatment is resection, which is difficult in its entirety due to its growth pattern and difficult surgical access, as well as high morbidity due to the adherence of the capsule, which is generally incomplete and has sequelae.

Objectives: A 31-year-old patient who presented with trigeminal neuralgia in 2017, not controlled by medication, was diagnosed with a T1 and 2 MRI sequence of epidermoid cysts in the right cerebellopontine angle and treated with incomplete resection in 2017 without clinical improvement. He was subsequently treated with 50GY IMRT radiotherapy in 25 fractions in December 2022 with partial improvement. Four months later, due to an increase in neuralgia, he was considered a candidate for re-irradiation using radiosurgery.

Methods: After 13 months of receiving IMRT, in January 2024, radiosurgery treatment was indicated to the right trigeminal nerve at a dose of 85 Gy with a 90% isodose line at a volume of 0.034 cm3 using a linear accelerator with 6MV photons, receiving a 45 Gy (V45 Gy) 0.01 cm3 stem and V15 Gy <0.5 cm3. With the treatment, he improved at least 70% of symptoms in one month.

Results: The patient was evaluated monthly for 9 months, presenting significant improvement of up to 90% of neuralgia and vestibular neuritis, which was completely controlled with medications.

Conclusion: Radiosurgery is a first-line treatment for refractory trigeminal neuralgia. Given its success rate and low morbidity, it is possible to control pain from the beginning, and a high percentage of patients do not require medication after treatment.