Disuse atrophy of masticatory muscles after intracranial trigeminal schwannoma resection: A case report and review of literature

Abstract

Introduction: Temporomandibular disorders (TMD) are diseases of the temporomandibular joint and masticatory muscles, and are often difficult to be diagnosed because they have various symptoms, pathological conditions and causes.

Presentation of case: Herein, we report a 78-year-old male referred to our hospital with a diagnosis of TMD and presenting with facial asymmetry, marked deviation to the right side on vertical mandibular movement and complaints of abnormal perception at the right oral and buccal region. Past medical history revealed that he had undergone a right intracranial trigeminal schwannoma resection 9 years prior. Computed tomography (CT) showed disuse atrophy of the right side of 4 masticatory muscles and 2 suprahyoid muscles controlled by the motor component of the mandibular division (V3) of the trigeminal nerve (TGN). Together with the neurosurgeon, we confirmed that there was no recurrence of the tumor and explained to the patient that the oral and maxillofacial symptoms are after-effects of the operation, and we provided oral hygiene instructions and coordinated cleaning of the inside of the oral cavity.

Discussion: Although it is difficult to compare treatment methods from case to case, we believe that in our case, the patient's understanding of the cause of his discomfort contributed significantly to the improvement of his quality of life.

Conclusion: We experienced a case of masticatory muscle disuse atrophy during long-term follow-up after resection of intracranial trigeminal schwannoma. Further studies are needed to develop the diagnostic and therapeutic protocols for disuse atrophy.

Keywords: Case report; Disuse atrophy; Masticatory muscles; Temporomandibular disorders (TMD); Trigeminal schwannoma.

Fig. 1

Extraoral photograph at first visit. Right lateral view (A), frontal view (B) and right lateral view (C) show asymmetry. Invagination was shown under the zygomatic bone.

Fig. 2

Panoramic X-ray at first visit. The right mandibular condyle situated anterior gliding, whereas the left mandibular condyle was contained in the mandibular fossa.

Fig. 3

Computed tomography (CT) of the maxillofacial regions showing atrophy of masticatory muscles of right side. A) Axial view at the level of mandibular condyle and coronoid process. B) Coronal view at the level of coronoid process. C) Axial view at the level of the mandibular foramen. D) Coronal view at the level anterior to the pterygoid plate. E) Axial view at the level of submandibular space. F) Coronal view at the level of the pterygoid plate. G) Axial view at the level of submental space. (H) Axial view showing bone defect site of intracranial tumor resection through right occipital/suboccipital craniotomy (arrowhead). TM, temporalis muscle; MM, masseter muscle; LPM, lateral pterygoid muscle; MPM, medial pterygoid muscle; TVP, tensor veli palatini muscle; MHM, mylohyoid muscle; ADM, anterior belly of the digastric muscle.