Importance of ultrasonography and magnetic resonance imaging in diagnosis of cysticercosis of temporalis muscle mimicking temporal space infection
A 35-year-old male patient reported to the Department of Oral Medicine and Radiology with the chief complaint of restricted mouth opening and heaviness on the right side of face since 1 month []. On examination, patient was moderately built and nourished and his vital signs were within the normal limit. He took a vegetarian diet and had no deleterious habits. Extraoral examination revealed a diffuse swelling present in the right infratemporal region measuring approximately 2 cm × 2 cm in size near the outer canthus of the eye []. Swelling was firm, compressible and non-tender on palpation. Overlying skin of the swelling was normal. On intraoral examination, there was grossily decayed mandibular right third molar with deep dental caries in it. It was tender, on probing percussion and palpation. Interincisal; opening was 30 mm. Based on history and clinical examination, a provisional diagnosis of masticator and predominantly temporal space infection secondary to carious mandibular right third molar was given. Radiographic examination revealed an ill-defined radiolucency in apical one-third of mandibular right third molar []. Antibiotic therapy was started, though patient responded to treatment there was a slight improvement in mouth opening, but the temporal swelling still persisted. We planned for high resolution USG on Toshiba Aplio XG USG unit (Japan) with 7.5 MHz linear array transducer probe, it revealed oval 5 mm sized cystic areas with eccentric echogenic nidus with in the right temporalis muscle []. There was mild adjacent edema, but no evidence of collection noted. Surprisingly no sign of infection in the form of cellulitis or edema were seen.\nThe right masseter muscle was normal since, ultrasound helps in detection of superficial fascial space infections. Magnetic resonance imaging (MRI), which is the gold standard for fascial space infections was done by HDe Signa 1.5-T unit with a dedicated coil and revealed 12 mm × 7 mm × 8 mm cystic lesion with hypointense nidus noted with in the belly of the right temporalis muscle with hyperintensity of muscle until mandibular insertion site on image suggestive of intramuscular parasitic cyst []. Furthermore, inflammatory changes were seen in the right masticator space prestyloid parapharyngeal space pterygomandibular fissure and right malar region subcutaneous fat suggestive of space infection []. With the help of USG and MRI, we came to final diagnosis of cysticercosis of the right temporalis muscle, which was an incidental finding. MRI also helped in diagnosing fascial space infection involving masticator, parapharyngeal and pterygomandibular spaces. Empirical antibiotic therapy was given and subsequently incision and drainage was done in masticator space region, 48 was extracted. Cysticercosis was managed conservatively. Patient was given albendazole 15 mg/kg body weight/day for 14 days. A repeat MRI was performed after 3 months, which showed no abnormality in the right temporal region [].