Supplementary Material for: Extensive Brainstem Lesion and Cervical Myelopathy: Overcoming a Grim Prognosis - Case Report

Introduction:
Cognard-type V arteriovenous fistulas are rare forms of dural arteriovenous malformations. This specific subtype is characterised by spinal venous drainage into peri-medullary veins, which presents as progressive or ascending myelopathy in 50% of cases.
Case Presentation: A 59-year-old man with three weeks of worsening quadriparesis, along with abnormal sensory findings, gait deterioration, and bowel and bladder dysfunction, was admitted to the hospital. MRI revealed extensive T2 hyperintense signal changes in the brainstem and myelopathy in the cervical spinal cord extending down to C7. The differential diagnosis for extensive myelopathy and brainstem lesions seen on MRI included a tumour, autoimmune inflammation, and suspicion of vascular malformation. The administration of corticosteroids resulted in a worsening of the patient’s neurological symptoms. Conventional angiography confirmed the presence of a dural AVF (a small arteriovenous short shunt receiving arterial supply from the middle meningeal and occipital artery) in the territory of the left external carotid artery. A minimally invasive endovascular treatment was successfully performed.
Conclusion:
We present this case considering that only 100 patients with Cognard type V fistula have been reported to date. Additionally, we aim to highlight the importance of caution when administering corticosteroids in cases of diagnostic uncertainty.