Medial Pterygoid Abscess Masquerading as a Temporomandibular Joint Disorder: A Case Report

Abstract

A patient presenting with a history of restricted mouth opening and deflection of the mandible after a prolonged dental procedure raises a suspicion of temporomandibular joint disorder (TMD) due to its estimated high prevalence of 29%. Muscle relaxants and routine active physiotherapy established normal range of movement and pain reduction was achieved through TENS therapy and analgesics. However, the non-subsidence of deflection prompted an initial suspicion of TMD which was overturned by MRI. The MRI evaluation revealed left side medial pterygoid abscess. It is imperative to understand that despite strong history and relevant clinical features, for the definitive diagnosis radiographic evaluation is highly contributory. Misdiagnosing TMD due to its similar presentation can have significant implications for the patient's well-being and quality of life. The clinical features of medial pterygoid abscess including restricted mouth opening and pain can be similar to that of TMD. These abscesses are most commonly caused by odontogenic infections but can also occur as a result of septic inferior alveolar nerve block techniques. Limited literature reports of pterygoid space abscess have been described, but intramuscular and medial pterygoid abscess is an absolute rarity. Causal relationship to septic inferior alveolar nerve block further makes this case report an interesting read.

Keywords: Infection; Nerve block; Temporomandibular joint disorder; Trismus.

Fig. 1

Mouth opening of 35 mm

Fig. 2

Orthopantomogram showing carious 36 tooth

Fig. 3

MRI images showing bulky left medial pterygoid muscle showing heterogeneously hyperintense signal on axial PD fat suppressed and coronal STIR images (a and d) with areas of restriction on axial diffusion weighted image (b) and heterogeneous enhancement on axial post contrast T1 weighted image (c) with small peripherally enhancing collections (arrow) suggestive of abscesses

Fig. 4

Follow up MRI images (a: axial PD fat saturated and b: coronal STIR sequences) show complete resolution of medial pterygoid muscle abscess