Clinical characteristics, neurovascular compression, and treatment outcomes in <scp>SUNCT</scp> and <scp>SUNA</scp> : A contemporary Japanese consecutive case series

OBJECTIVE: This study aimed to characterize the contemporary clinical phenotype of short-lasting unilateral neuralgiform headache attacks (SUNHA) in Japan, evaluate the prevalence and clinical relevance of neurovascular compression (NVC), and assess real-world medical and surgical treatment outcomes. BACKGROUND: SUNHA, comprising short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing (SUNCT) and those with cranial autonomic symptoms (SUNA), is a rare trigeminal autonomic cephalalgia disorder. Although several large cohorts have been reported in Western countries, data from Asia, particularly Japan, remain limited. Moreover, the clinical significance of NVC and the role of microvascular decompression (MVD) in medically refractory cases have not been fully established, and no standardized operational definition of refractory SUNHA exists. METHODS: We conducted a retrospective consecutive case series of 28 patients with SUNHA (14 SUNCT and 14 SUNA) who were evaluated at a tertiary headache center in Japan between 2011 and 2024. Diagnoses were made according to the International Classification of Headache Disorders, 3rd edition. Clinical features, trigger factors, cranial autonomic symptoms, comorbidities, and treatment responses were systematically reviewed and analyzed. High-resolution constructive interference in steady-state (CISS) magnetic resonance imaging was used to assess the NVC. Treatment response was defined as a subjective reduction of ≥50% in the attack burden. Refractory SUNHA was operationally defined as failure of or intolerance to at least two of the three principal preventive drug classes (lamotrigine, gabapentinoids, and topiramate). Surgical outcomes following MVD were evaluated in the refractory cases. RESULTS: SUNHA accounted for 0.2% of all patients with headache evaluated in this study. The mean age at onset was 53.1 ± 20.9 years, with 17 male and 11 female patients. Right-sided pain (20/28, 71%) and ophthalmic (V1) trigeminal distribution (20/28, 71%) predominated. No statistically significant differences were detected between SUNCT and SUNA with respect to attack duration, frequency, triggers, or treatment responsiveness. NVC was identified in 17 of 27 evaluable patients (17/27, 63%; 95% confidence interval [CI]: 44.3%-78.5%) and was strongly associated with a history of TN-like pain (12/17 vs. 0/10, p < 0.001). Seven of 28 patients (7/28, 25%; 95% CI: 12.7%-43.4%) met criteria for refractory SUNHA, and all refractory cases (7/7, 100%; 95% CI: 64.6%-100%) demonstrated NVC. Five of seven refractory patients (5/7, 71%) underwent MVD and achieved complete and sustained remission. CONCLUSION: In this contemporary Japanese SUNHA cohort, no statistically significant clinical differences were detected between SUNCT and SUNA. NVC was relatively common and appeared to be associated with medical refractoriness. In carefully selected patients with refractory SUNHA and convincing NVC, MVD may provide durable clinical benefit.