Temporal hollowing causes, classifications, and treatment options: A systematic review

Background: Recent developments in surgical techniques and grading schemas to treat temporal hollowing necessitate critically assessing their efficacy. This systematic review presents the currently available protocols for temporal hollowing, aimed toward improving the clinical approach, for the benefit of the surgeon and patient. Methods: A search was conducted in PubMed, EMBASE, and Google Scholar in September 2021 using the keywords “temporal hollowing” and “temporal augmentation.” Inclusion criteria were English-written articles published in peer-reviewed journals that reported an outcome relating to the cause, classification, or procedure used to prevent or correct hollowing in humans. Results: Of the 413, 966 publications retrieved, 24 met the study inclusion criteria. Twenty-one publications discussed the etiology of temporal hollowing, 12 discussed a classification or grading system for temporal hollowing, and 19 discussed a procedure to prevent or correct temporal hollowing. The most commonly reported etiology for temporal hollowing was iatrogenic (63%). For classifying temporal hollowing severity, visual analogue scales (25%) were most commonly used. Mesh (26%) and autologous fat grafts (26%) were the most popular procedures used to prevent or correct temporal hollowing. Discussion: We presented the spectrum of temporal hollowing grading schemas and treatment modalities currently published in the field. The use, by a majority of publications, of a grading system based on the subjective judgment of the examiner (either alone or adjunct to imaging results) suggests the need for a more standardized measurement tool. Future studies should investigate a universally applicable temporal hollowing classification system and its impact on treatment outcomes.