Temporalis Muscle Thickness as a Prognostic Marker in Acute Ischemic Stroke: A Systematic Review

Background: Temporalis muscle thickness (TMT) measured on routine neuroimaging has emerged as a radiological marker of sarcopenia, but its prognostic value in acute ischemic stroke is not well defined. This systematic review examined whether TMT is associated with functional status, swallowing outcomes, and mortality after acute ischemic stroke. Methods: A PRISMA-guided systematic review identified observational studies (2000-2025) reporting TMT and at least one clinical outcome in adults with acute ischemic stroke. PubMed, MEDLINE, Embase, Web of Science, and Scopus were searched. Two reviewers independently screened records and extracted data. Risk of bias was assessed using ROBINS-I and the Newcastle-Ottawa Scale, with justification relative to prognostic-factor tools. Due to heterogeneity in TMT definitions and outcome measures, findings were synthesized narratively. Results: Four cohorts, including 1361 patients, met the inclusion criteria. Mean age was 69.7 years, and 53.9% were male. Study-level mean TMT ranged from 5.2 to 6.35 mm; among the 704 patients in cohorts that reported TMT-defined sarcopenia status, prevalence was 51.8% (365/704). Across studies, lower TMT or TMT-defined sarcopenia was associated with poorer functional outcomes and higher mortality, independent of age and stroke severity. In one thrombectomy cohort, each 1-mm increase in TMT increased the odds of functional independence (adjusted OR 1.14, 95% CI 1.03-1.27). In contrast, each 1-mm increase reduced 90-day mortality (adjusted OR 0.71, 95% CI 0.54-0.93). Lower TMT also predicted prolonged nasogastric tube dependence. Conclusions: TMT is a simple CT- or MRI-based measure that is consistently associated with disability, dysphagia, and survival after acute ischemic stroke. Current evidence is observational and supports further prospective validation and measurement standardization rather than immediate routine decision-making use.