Trigeminal neuralgia secondary to epidermoid cyst and neurovascular conflict: An illustrative case with literature review

Abstract

Background: Trigeminal neuralgia (TN) is a highly disabling facial pain syndrome, historically known as the suicide disease, in which most cases can be cured with appropriate surgical treatment.

Case description: We present the case of a 43-year-old male farmer with acute, self-limiting episodes of shock-like pain on the left side of the face that started in June of 2021. He was diagnosed with TN and was treated with carbamazepine. Magnetic resonance imaging was performed, which revealed an epidermoid cyst (EC) at the prepontine cistern with an extension to the left cerebellopontine angle. The neurosurgery department at our institution was consulted, which performed surgical tumor resection and V^th cranial nerve decompression. During the resection, a neurovascular conflict (NVC) was identified at the root entry zone. After the resection around the nerve and its whole tract was completed, a microvascular decompression (MVD) was performed.

Conclusion: TN secondary to EC in association with a NVC is a rare phenomenon, due to the growth pattern of the EC. TN may remit if an appropriate treatment is carried out. In cases of NVC, an MVD is required apart from an appropriate resection to achieve pain relief.

Keywords: Epidermoid cyst; Microvascular decompression; Neurovascular conflict; Trigeminal neuralgia.

Figure 1:

Pre-surgical MRI. Compression of the pons by the EC and the immersion of the V^th CN in the tumor can be appreciated, as well as it being displaced superolaterally. (a) 3D FIESTA: The Vth CN adopted an S shape, and near the REZ, a hyperintense round figure that corresponds to the loop formed by the SCA (red arrow) can be observed. (b) T2: We appreciate a hypointense round which correspond to the SCA (red arrow) as the OV. Laterally, an oval figure that corresponds to the REZ of the V^th CN is seen. CN: Cranial nerve (orange arrow), EC: Epidermoid cyst, MRI: Magnetic resonance imaging, OV: Offending vessel, REZ: Root entry zone, SCA: Superior cerebellar artery (red arrow), 3D FIESTA: Three-dimensional fast imaging employing steady-state acquisition.

Figure 2:

Intraoperative findings. (a) PV overlying the EC. (b) Coagulated PV. (c) V^th CN immersed in the EC. (d) After tumor debulking and capsular resection from the V^th CN, the SCA was exposed and didn’t relocate far from the REZ. (e) The MVD was started by placing a Teflon piece through the ventral part of the REZ. (f) MVD was completed by placing a Teflon piece through the dorsal aspect of the REZ. CN: Cranial nerve (asterisk), EC: Epidermoid cyst (circle), MVD: Microvascular decompression (arrowhead), PV: Petrous vein (star), REZ: Root entry zone, SCA: Superior cerebellar artery (arrow).