Small Bone Window Surgery Completely Obliterates Rare C1 Dural Fistulas

The technique, described in a technical note in Acta Neurochirurgica, was applied to three patients treated between January 2019 and December 2024, and in every case postoperative angiography confirmed that the abnormal vessel connection had been completely eliminated.

When they arise at the C1 level they are uncommon, and the conventional microsurgical approach has required wide bony resection around the atlas to reach the lesion. The surgical team behind the new report hypothesized that a specific subgroup of these fistulas, namely those fed exclusively by dural branches of the vertebral artery, without any intradural feeders, could be obliterated through a far more limited exposure: a unilateral partial C1 hemilaminectomy, in which only part of one side of the ring-shaped atlas bone is removed.

The retrospective analysis identified five patients surgically treated for C1 DAVFs during the six-year period, of whom three met the strict inclusion criteria. To qualify, each patient’s fistula had to be symptomatic and supplied exclusively by dural branches of the vertebral artery, with no ascending pharyngeal artery contribution and no intradural feeder, as demonstrated on preoperative digital subtraction angiography.

The clinical presentations underscored why treatment could not be deferred. One patient presented with subarachnoid hemorrhage, while the other two had developed myelopathy driven by venous hypertension, the back-pressure created when arterial blood shunts directly into the venous system and engorges the delicate veins around the spinal cord. In each operation, the partial hemilaminectomy on one side of the C1 ring provided sufficient exposure to identify the arterialized draining vein, the vessel that had been transformed by the fistula into a high-pressure conduit. The surgeons coagulated and divided this fistulous connection, interrupting the shunt at its point of venous drainage.

Postoperative digital subtraction angiography confirmed complete obliteration of the fistula in all three patients, the definitive angiographic endpoint for this condition. The procedure proved remarkably well tolerated: one patient experienced transient occipital hypoesthesia that resolved within three months, and there was no permanent morbidity in the cohort. Bladder function followed a less complete trajectory, reflecting the variable capacity of the spinal cord to recover from prolonged venous congestion: neurogenic bladder improved only partially in one patient and persisted in the other. No recurrence of the fistula was observed during follow-up.

The significance of the report lies in the anatomical reasoning that makes a small opening feasible. C1 DAVFs can draw arterial supply from several sources, including the ascending pharyngeal artery and vessels that penetrate the dura into the intradural space. When those routes are absent and the fistula is fed solely by dural branches of the vertebral artery, the entire pathological target, the arterialized draining vein at the dural exit, sits within a narrow corridor that a unilateral partial hemilaminectomy can reach. Preoperative digital subtraction angiography therefore serves as the gatekeeper: it defines which patients can be offered the limited approach and which would still require conventional extensive bone resection.

The authors are careful to frame the operation as a technique for a selected subgroup rather than a universal solution for C1 fistulas. The article was published as a peer-reviewed, accepted technical report under open access, with the version released early and subject to further editorial refinement before the final Version of Record.

Even with those caveats, the report adds a concrete option to the surgical repertoire for a lesion that is both rare and dangerous. At one year, motor deficits and cord signal changes had fully resolved in both myelopathic patients, and no recurrence was observed, indicating durable obliteration in this small series.

Subject of Research: A surgical technique using a unilateral partial C1 hemilaminectomy to obliterate selected C1 dural arteriovenous fistulas supplied exclusively by vertebral artery dural branches.

Article Title: Microsurgical obliteration of C1 dural arteriovenous fistulas via a unilateral partial C1 hemilaminectomy: technical note

Article References: Lim, J., Park, K. H., & Roh, H. K. (2026). Microsurgical obliteration of C1 dural arteriovenous fistulas via a unilateral partial C1 hemilaminectomy: technical note. Acta Neurochirurgica. https://doi.org/10.1007/s00701-026-07058-0

Image Credits: AI Generated

DOI: 10.1007/s00701-026-07058-0

Keywords: dural arteriovenous fistula, C1 vertebra, hemilaminectomy, vertebral artery, microsurgery, digital subtraction angiography, Cognard type V, myelopathy, venous hypertension, spinal vascular malformation, neurosurgery, craniocervical junction