Superficial abdominal reflex in syringomyelia: Associations with Chiari I malformation

•In the largest cohort of patients studied to date with syrinx and evaluation for superficial abdominal reflex (SAR), we show that an abnormal SAR is more common in Chairi-associated syrinx, compared with idiopathic syrinx (P < 0.0001).•In our cohort of patients with idiopathic and Chiari-associated syrinx, the overall sensitivity of SAR for spinal cord syrinx was 48%.•After controlling for sex, age, syrinx size, syrinx location, scoliosis and presence of Chiari, the presence of Chiari was independently associated with an abnormal or absent SAR in patients with syrinx (OR 4.2, 95% CI 1.4–14, P < 0.01).•Patients with scoliosis were more likely to have an abnormal or absent SAR (P = 0.016).•These findings have implications for the pathophysiology of Chiari-associated and idiopathic syrinx and in the management of patients presenting with syrinx.