Introduction: Data regarding the association between thyroid dysfunction and hemifacial spasm (HFS) are limited. We conducted a single-center, retrospective study to investigate the predictive value of thyroid dysfunction in patients with HFS after microvascular decompression (MVD).

Methods: Between July 2004 and January 2015, 156 patients who were tested for thyroid hormones after MVD for HFS were enrolled in the present study. We assessed their detailed history, clinical manifestations, serum thyroid hormone levels, and surgical outcomes. The patients were classified into low and high groups based on thyroid hormone concentrations, and clinical outcomes were evaluated in each group.

Results: In a total of 156 patients with a median follow-up period of 40.9 months, the improvement rate was 87.8%. The patients were classified into low (76, 48.7%) or high (80, 51.3%) groups based on serum thyroxine (T4) levels. There was a difference between the 2 groups in terms of postoperative outcomes following MVD (p = 0.020). There were no differences in the outcomes according to serum tri-iodothyronine (T3) levels as well as other factors associated with the outcomes.

Conclusions: We found that decreased serum T4 levels are associated with poor postoperative outcomes among patients with HFS. Further studies are needed to examine the clinical benefit of thyroid hormone replacement therapy for patients with suboptimal T4 concentrations as well as active thyroid hormone screening for patients with HFS.