Trigeminal schwannoma presenting with malocclusion: A case report and review of the literature

Abstract

Background: Trigeminal schwannomas are rare tumors of the trigeminal nerve. Depending on the location, from which they arise along the trigeminal nerve, these tumors can present with a variety of symptoms that include, but are not limited to, changes in facial sensation, weakness of the masticatory muscles, and facial pain.

Case description: We present a case of a 16-year-old boy with an atypical presentation of a large trigeminal schwannoma: painless malocclusion and unilateral masticatory weakness. This case is the first documented instance; to the best of our knowledge, in which a trigeminal schwannoma has led to underbite malocclusion; it is the 19^th documented case of unilateral trigeminal motor neuropathy of any etiology. We discuss this case as a unique presentation of this pathology, and the relevant anatomy implicated in clinical examination aid in further understanding trigeminal nerve pathology.

Conclusion: We believe our patient's underbite malocclusion occurred secondary to his trigeminal schwannoma, resulting in associated atrophy and weakness of the muscles innervated by the mandibular branch of the trigeminal nerve. Furthermore, understanding the trigeminal nerve anatomy is crucial in localizing lesions of the trigeminal nerve.

Keywords: Cranial neuropathy; Malocclusion; Pediatric neurosurgery; Skull base tumor; Trigeminal schwannoma.

Figure 1:

Diagnostic computed tomography maxillofacial images figure description: images a and b demonstrate axial and coronal views of a 5.2 × 6.6 × 4.3 cm intra-axial mass with compression and displacement of the brainstem. Image C demonstrates an axial view of the mandible, showing asymmetry of the left mandibular ramus and muscular hypotrophy on the left side.

Figure 2:

Diagnostic computed tomography angiogram figure description: bony erosion and remodeling of the left sphenoid and petrous temporal bones are seen, related to the mass (a and b). On contrasted imaging (c), angiography demonstrates external compression (approximately 50% narrowing) of the cavernous and petrous segment of the left internal carotid artery.

Figure 3:

Preoperative magnetic resonance imaging figure description: contrasted T1-weighted magnetic resonance imaging with axial, sagittal, and coronal views of the 5.2 × 7.8 × 5.1 cm heterogeneously extra-axial enhancing mass centered in the left mesial temporal region with involvement of the skull base and left foramen ovale, rotundum and spinosum, encasement and moderate narrowing of the left internal carotid artery, mild obstructive hydrocephalus, and marked compression of the brainstem.

Figure 4:

Mandibular and muscular atrophy figure description: contrasted T1-weighted magnetic resonance imaging demonstrates asymmetric of the mandibular rami, with left smaller than right, as well as atrophy of the muscles of mastication.

Figure 5:

Postoperative magnetic resonance imaging figure description: contrasted T1-weighted magnetic resonance imaging with axial, sagittal, and coronal views demonstrates near complete resection with a thin rim of residual tumor along the lateral dural margin of the left cavernous sinus/lesser sphenoid wing and at the floor of the left middle cranial fossa extending posteriorly to the roof of the remodeled left petrous temporal bone.