High pillow and spontaneous vertebral artery dissection: A case-control study implicating "Shogun pillow syndrome".

INTRODUCTION:The underlying causes of spontaneous vertebral artery dissection (sVAD) remain insufficiently understood. This study aimed to determine whether high-pillow usage is associated with an increased risk of sVAD and evaluate the frequency of sVAD attributable to high-pillow usage. PATIENTS AND METHODS:This case-control study identified patients with sVAD and age- and sex-matched non-sVAD controls (case-to-control ratio: 1:1) treated at a certified comprehensive stroke center in Japan between 2018 and 2023. The pillow height used at the onset of the index disease was measured and classified into three categories between 12 and 15 cm boundaries. Univariable logistic regression was performed to assess the odds ratio (OR) with a 95% confidence interval (CI) of high-pillow usage for sVAD development. A subgroup of sVAD attributable to high-pillow usage was defined with the following three conditions: high-pillow usage (⩾12 or ⩾15 cm); no minor preceding trauma; and wake-up onset. RESULTS:Fifty-three patients with sVAD and 53 non-sVAD controls (42% women, median age: 49 years) were identified. High-pillow usage (⩾12 and ⩾15 cm) was more common in the sVAD group than in the non-sVAD group (34 vs 15%; OR = 2.89; 95%CI = 1.13-7.43 and 17 vs 1.9%; OR = 10.6; 95%CI = 1.30-87.3, respectively). The subgroup of sVAD attributed to high-pillow usage (⩾12 and ⩾15 cm) was found in 11.3% (95%CI = 2.7%-19.8%) and 9.4% (95%CI = 1.5%-17.3%), respectively. CONCLUSION:High-pillow usage was associated with an increased risk of sVAD and accounted for approximately 10% of all sVAD cases. This tentative subgroup of sVAD may represent a distinct spectrum of disease-Shogun pillow syndrome.