Spinal Dural AVF In An 81-Year-Old Woman Following Horseback Riding

Introduction Spinal dural arteriovenous fistulas (SDAVFs) are rare vascular malformations involving an abnormal connection between a dural artery and a medullary vein, leading to venous hypertension and progressive myelopathy. Literature estimates an annual incidence of 5‐10 cases per million, with a strong male predominance between 50‐70 years old (∼80%), with women accounting for only 20% of cases. SDAVFs in octogenarian females are extraordinarily rare, with no current literature implicating horseback riding as a potential trigger. This case presents a patient with a proposed novel mechanism for acquired SDAVF through equestrian activity. Case Presentation An 81‐year‐old woman with hypertension and hypothyroidism presented with distal leg paresthesias progressing over three weeks to flaccid bilateral lower extremity paralysis, urinary retention, and constipation. She denied back or neuropathic pain. At baseline, she was independent with all instrumental activities of daily living and had recently taken up horseback riding. Initial lumbar spine MRI showed multilevel degenerative disc disease and foraminal narrowing. She was discharged to a skilled nursing facility with a presumed diagnosis of lumbar radiculopathy. On re‐presentation 2 weeks later, neurological exam revealed 0/5 strength in the lower extremities, areflexia, a T12‐L1 sensory level, mute plantar responses, and persistent sphincter dysfunction. Thoracic spine MRI showed long‐segment T2 hyperintensity, cord expansion, and serpentine flow voids. Digital subtraction angiography confirmed a SDAVF at the right T12 intercostal artery. She underwent Onyx‐18 embolization, with minimal motor recovery and persistent urinary retention. Due to incomplete response, she underwent T11‐L1 laminoplasty with direct surgical ligation and nBCA glue embolization of a residual extradural component. Following surgery, she regained movement in the hips, knees, and feet, though sphincter dysfunction persisted. She remains in rehabilitation with slow but measurable improvement. Discussion SDAVFs are acquired lesions often associated with dural sinus thrombosis, trauma, or prior surgery. In this patient, none of these risk factors were present. Her only recent physical change was picking up horseback riding as a new hobby in the last year, which introduced repetitive axial spinal stress. With her history of hypertension weakening the arterial walls and the introduction of axial spinal stress from horseback riding, it could have contributed to the formation of the abnormal connection between arteries and veins that characterizes a SDAVF.This may have triggered angiogenic pathways, particularly vascular endothelial growth factor (VEGF), leading to abnormal arteriovenous shunt formation. Additional mediators such as FGF and IL‐6 could have contributed to endothelial injury and neovascularization. No prior literature has linked equestrian activity with SDAVF, making this a novel etiologic consideration. The delay in diagnosis reflects the overlap of symptoms with more common conditions like lumbar stenosis. Clinicians should consider SDAVF in elderly patients with progressive myelopathy and sphincter dysfunction even if the etiology does not follow medical norms for SDAVF's. Conclusion This case raises the novel hypothesis of horseback riding as a potential mechanical trigger for angiogenesis. Early diagnosis is critical to prevent irreversible deficits. The patient's partial recovery highlights the need for a high index of suspicion and the benefits of a timely, multimodal therapeutic approach.