In situ disconnection of conus arteriovenous malformation: illustrative case.

BACKGROUND: Conus arteriovenous malformations (AVMs) are rare and complex surgical cases. Blood supply is entangled with eloquent conus branches associating with high surgical morbidity. While complete excision is desirable, in situ disconnection has been advocated as an alternative for AVMs located in high-risk anatomical areas. The authors describe a sequential dissection workflow for in situ disconnection of a conus AVM using a combination of intraoperative adjuncts to minimize surgical risk.

OBSERVATIONS: A 35-year-old female patient with multiple sclerosis and progressive thoracic myelopathy was diagnosed with conus AVM. The authors explored and disconnected radicular feeders and then local feeders from the "conus basket" using a cyclic disconnection workflow: 1) identification of feeders based on morphology and indocyanine green (ICG)/Doppler ultrasound, 2) interrogation with trial occlusion under neuromonitoring, 3) disconnection, and 4) reassessment of AVM perfusion and occlusion of draining vein. They achieved complete disconnection of the AVM with significant improvement of clinical symptoms sustained at 6 months of follow-up.

LESSONS: The authors illustrate a structured microsurgical workflow for safe in situ disconnection of high-risk conus AVM. Vascular architecture was anticipated on preoperative imaging, and a combination of sharp and blunt dissection techniques was used to expose AVM architecture within a cyclic workflow. Adjunct neuromonitoring, ICG, and ultrasound were used to guide safe elimination of the AVM. https://thejns.org/doi/10.3171/CASE25870.