Trends in Incidence of Intracranial and Spinal Arteriovenous Shunts: Hospital-Based Surveillance in Okayama, Japan

Background and Purpose: To date, the incidence of intracranial and spinal arteriovenous shunts has not been thoroughly investigated. We aimed to clarify recent trends in the rates of intracranial and spinal arteriovenous shunts in Japan. Methods: We conducted multicenter hospital-based surveillance at 8 core hospitals in Okayama Prefecture between April 1, 2009 and March 31, 2019. Patients who lived in Okayama and were diagnosed with cerebral arteriovenous malformations, dural arteriovenous fistulas (DAVFs), or spinal arteriovenous shunts (SAVSs) were enrolled. The incidence and temporal trends of each disease were calculated. Results: Among a total of 393 cranial and spinal arteriovenous shunts, 201 (51.1%) cases of DAVF, 155 (39.4%) cases of cerebral arteriovenous malformation, and 34 (8.7%) cases of SAVS were identified. The crude incidence rates between 2009 and 2019 were 2.040 per 100 000 person-years for all arteriovenous shunts, 0.805 for cerebral arteriovenous malformation, 1.044 for DAVF, and 0.177 for SAVS. The incidence of all types tended to increase over the decade, with a notable increase in incidence starting in 2012. Even after adjusting for population aging, the incidence of nonaggressive DAVF increased 6.0-fold while that of SAVS increased 4.4-fold from 2010 to 2018. Conclusions: In contrast to previous studies, we found that the incidence of DAVF is higher than that of cerebral arteriovenous malformation. Even after adjusting for population aging, all of the disease types tended to increase in incidence over the last decade, with an especially prominent increase in SAVSs and nonaggressive DAVFs. Various factors including population aging may affect an increase in DAVF and SAVS.