Spinal cord arteriovenous malformations have been classified into 4 subtypes including Type I, spinal dural arteriovenous fistulas (DAVFs); Type II, intramedullary glomus malformations; Type III, extensive juvenile malformations; and Type IV, intradural perimedullary arteriovenous fistulas [1].

Spinal DAVFs, the most common type of spinal vascular malformations, are the arteriovenous shunts supplied by radiculomeningeal arteries draining into the radicular veins arterializing the coronal venous plexus around the spinal cord [2]. These fistulas have been subdivided into common type A, i.e., single feeding artery, and rare type B, i.e., multiple feeding arteries recruited from other level [3]. Spinal DAVFs affect primarily the lower thoracic and upper lumbar spine and are located within the dorsal surface of the dural root sleeve in the intervertebral foramen. The patients harboring spinal DAVFs, typically middle-aged men, commonly manifest with progressive myelopathy induced by chronic venous hypertension [4]. Hemorrhagic manifestation of spinal DAVFs is extremely rare [5].

DAVFs located at the craniocervical junction (CCJ) are rare vascular malformation and account for approximately 2 % of spinal DAVFs [6], [7], [8]. Even though these fistulas may be regarded as being in the category of spinal DAVFs, they included the element of intracranial DAVFs because of the high incidence of intracranial hemorrhage and can present with either intracranial or spinal symptoms [9], [10]. The CCJ comprises the base of the skull, the first cervical (C1), and second cervical (C2) levels. Therefore, many large series of DAVFs at the CCJ included fistulas located at the foramen magnum, C1, and C2 level [9], [10], [11], [12], [13], [14], [15]. In our opinion, DAVFs of the CCJ along C1 nerve root should be classified as distinct subgroup of lesions from the foramen magnum and C2 spinal nerve. In addition, their natural history and treatment strategy remains unclear. We reviewed patients of C1 spinal nerve DAVFs seen at our institution and analyzed the literature of patients harboring this subtype of fistulas.