Bilateral Intractable Trigeminal Neuralgia due to a Prepontine Epidermoid Tumour: An Unlikely Duo

Prepontine epidermoid is a rare congenital tumour which arises during 3rd - 5th week of embryogenesis due to incomplete separation of neuroectoderm from surface ectoderm. This is slow growing benign tumour with late presentation in adult life. The clinical symptoms depend on the location of the tumour. In this case, the patient had intractable bilateral trigeminal neuralgia. The patient was given conservative treatment for 8 weeks with carbamazipine, but it did not respond to the neuralgic pain medication. Another trial of combined neuropathic medications including carbamazepine, gabapentin, pregabalin and baclofen were given for another 8 weeks, but the symptoms continued. MRI brain showed hypodense tumour on T1 weighted image which was hyperdense on T2 weighted images. The roots of both trigeminal nerves were involved in the prepontine area, proximal to the trigeminal ganglion. Surgical resection of the tumour was carried out in a two-stage operation. After complete surgical removal, patient's symptom of pain along trigeminal nerve was relieved.