# Trigeminal Schwannanna Presenting with Masticatory Muscle Atrophy: A Rare Case Report
## 2 Case Report  
In October 2014, an 80 year-old male patient with difficulty in opening his mouth was referred by his primary dentist to the Department of Oral Surgery at [X]. His medical history included known diagnoses of sinusitis, bilateral hearing loss, reflux esophagitis, lipid metabolism disorder, benign prostatic hyperplasia, hypertension, hypertrophic pachymeningitis, and right intracranial TS. Clinical extra-oral examination revealed facial asymmetry and atrophy of the right masser muscle (Figure 1), which was first observed in December 2012 by the primary care dentist before the patient presented to our department. However, the patient did not report any disorientation, trauma, dysphagia, or dysphonia. Intra-oral examination revealed normal occlusion with restricted mouth opening (20 mm) and associated mandibular deviation to the right. There were no signs of inflammation or infection. Panoramic radiographic findings were inconclusive for the presenting clinical symptoms (Figure 2). Computed tomography (CT) showed atrophy of the right masseter muscle, temporalis muscle, and lateral and medial pterygoid muscles (Figure 3). Blood tests were normal, and the patient tested negative for antinuclear antibody and rheumatoid factors. Physiological test results revealed bilateral hearing loss and paresthesia of the right side of the face. Surface electromyography recorded no action potentials in the right masseter and temporalis muscles (Figure 4). Our consultation with the neurologist revealed that the patient had a known medical history of hypertrophic pachymeningitis and TS. In March 2013, paresthesia and dysgesua in the right trigeminal nerve innervation area were detected. In addition, the patient experienced difficulty in eating. In April 2013, he visited the Department of Neurosciences at [XX] and was hospitalized for dietary management and intensive examination and treatment. Head magnetic resonance imaging (MRI) was performed, and hypertrophic pachymeningitis and TS were suspected. No osteoarthritis change of the condyle and no articular disc displacement on both sides of the TMJ was found on multiplanar reconstructed MR images (Figure 5). Hypertrophic pachymeningitis associated with vasculitis was diagnosed based on inflammatory findings. Blood examination results revealed a high erythrocyte sedimentation rate. Myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA) was also positive. The diagnosis of hypertrophic pachymeningitis was further supported by dura mier biopsy findings. Granulomatosis with polyangitis (GPA) was also suspected due to the patient's sinusitis and hearing loss. However, no findings consistent with GPA were noted on nasal mucosal biopsy. Figure 4: Surface electromyography: Action potential was not recorded from the right masseter and temporal muscles. Left anterior temporalis (LTA), left masseter (LMM), right masseter (RMM), right anterior temporalis (RTA). \(X\)-axis: time, \(Y\)-axis: EMG activity (\(\mu\)V). Figure 5: Axial (**A**) and coronal (**B**) T2-weighted magnetic resonance imaging showing a heterogeneously enhanced mass (red arrow). Reconstructed MR images showing no abnormal structure of the TMJ components. (**C,D**) The articular disc (yellow arrow) is in a correct position. The patient required urgent treatment due to symptom progression. Steroid pulse therapy with methylprednisolone was administered at 1000 mg/day for 3 days. This was initiated at 60 mg and gradually tapered. MPO-ANCA was negative, and no inflammatory response was observed following steroid pulse therapy. However, the patient's symptoms in the trigeminal innervation region persisted. In October 2014, the patient visited our hospital because of difficulty in opening his mouth and troubled eating. We consulted his neurologist, who observed persisting lesions on MRI. Therefore, we determined that the muscle atrophy was owing to intracranial TS rather than hypertrophic pachymeningitis.