Risk-Stratification of Patients Undergoing Endoscopic Endonasal Approach for Lesions Involving the Infratemporal Fossa by use of Preoperative MRI Findings to Predict Development of Postoperative Trismus

Background: Trismus is a well-characterized sequela affecting more than a third of patients who undergo radiation for treatment of oral cavity and oropharyngeal primary tumors. Prospective literature shows that in this population, trismus is associated with decreased oral intake, social isolation, facial pain, poor health-related quality-of-life (HRQL) scores, and higher opioid usage. Meanwhile, it has been shown that exercise therapy can lead to improving maximal interincisal opening (MIO) by close to 1 cm. There is a deficiency in literature characterizing trismus as a post-operative finding in patients following skull base surgery and identifying means of prevention and treatment.

Objective: This study aims to utilize clinical data as well as preoperative imaging characteristics to identify which cohort of patients are at highest risk for developing trismus following resection of lesions involving the infratemporal fossa, with the aim of early intervention and prevention of long-term sequelae.

Methods: Retrospective chart review was performed on all patients aged 0 to 99 years at a single tertiary-care academic center and its affiliated children’s hospital who underwent endoscopic endonasal approach (EEA) for lesions involving the infratemporal fossa from 2006 to 2020. Patients without preoperative imaging available for review and who followed up for <1 month postoperatively were excluded. Preoperative MRIs were reviewed by two independent reviewers. Variables assessed on imaging review included lateral extent of tumor beyond the pterygoid process, involvement of the muscles of mastication, cranial nerve V, skull base foramina, and pterygoid fossa. Student’s t-tests and chi-square tests were performed for continuous and binary categorical variables, respectively.

Results: A total of 36 cases were identified of which 30 met inclusion criteria. Six (20%) patients had preoperative trismus, and nine patients (30%) patients developed new trismus postoperatively. In total, 50% (n = 15) of patients had new or persistent trismus following EEA for resection of a lesion involving the infratemporal fossa. Of the nine patients with new trismus, this presented at an average of 375 (± 598) days from surgery and followed a bimodal pattern with 5 patients developing trismus within 5 weeks from surgery and the remaining 4 developing it greater than 34 weeks after surgery. Of these patients who developed delayed trismus, 4 of 5 had undergone adjuvant radiation following surgical resection. Of the preoperative MRI characteristics assessed, development of post-operative trismus was associated with cranial nerve V involvement (p = 0.028) with an odds ratio of 5.5 [1.1, 26.4] as well as with masseter muscle involvement (p < 0.001) with an odds ratio of 17.9 [2.7, 116.8]. Involvement of the pterygoid fossa, skull base foramina, medial pterygoid muscle, lateral pterygoid muscle, and the relative lateral extension of the tumor were not associated in statistically significant way with increased risk of post-operative trismus.

Conclusion: Patients who undergo EEA for infratemporal fossa lesions have a significant risk of developing trismus and would likely benefit from prophylactic intervention including early referral to speech language pathology and/or provision of jaw mobilizing devices when safe to use. Those with masseter muscle or cranial nerve V involvement are at particularly high risk of developing trismus.

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Artikel online veröffentlicht:
07. Februar 2025