Surgical Management of Hirayama Disease (Monomelic Amyotrophy): Systematic Review and Meta-Analysis of Patient-Level Data

-BACKGROUND: Hirayama disease or juvenile-onset monomelic amyotrophy is a clinical syndrome that disproportionately affects young males. Standard of care revolves around conservative management, but some pa-tients experience disease progression that may benefit from surgical intervention.-METHODS: Using Preferred Reporting Items for Sys-tematic Reviews and Meta-Analyses guidelines, a sys-tematic review of previous reports of surgical treatment for Hirayama disease was performed. Studies were included if they provided individual patient-level data, described the clinical presentation and surgical intervention, and re-ported neurological improvement at last follow-up. Com-parison between those who improved and those with stable symptoms at last follow-up was performed. Decision-tree analysis was used to identify the best pre-dictors of neurological improvement by last follow-up.-RESULTS: Of 624 unique articles, 30 were included in the qualitative review and 23 in the meta-analysis. Among the 70 patients in the meta-analysis, mean age was 21.2 +/- 6.3 years, 91% were male, and mean symptom duration at presentation was 43.3 +/- 61.8 months. Fifty-nine patients (84.3%) had improvement in their neurological symptoms by last follow-up. Univariable analysis showed the only significant predictor of improvement in neurolog-ical symptoms by last follow-up was the use of stabilization-alone versus decompression with or without stabilization. Baseline clinical symptoms nor radiographic features predicted outcome. Decision-tree analysis showed surgical strategy (stabilization-alone vs. decompression +/- stabilization), age (<20 vs. double dagger 20), and surgical approach (anterior-only vs. posterior-only or anterior-posterior) predicted a higher likelihood of neuro-logical improvement by last follow-up.-CONCLUSIONS: Nearly 85% of patients experienced improvement in neurological symptoms. Improvement was best for those who underwent stabilization-alone, and decision-tree analysis suggested that the likelihood of improvement was also superior for patients under 20 years of age and those treated with an anterior versus posterior or staged approach.