A 50-year-old previously healthy man presented with acute, non-radiating low back pain followed within 24 hours by rapidly progressive extremity weakness and respiratory failure requiring intubation. Neurological examination demonstrated marked quadriparesis with brisk reflexes, clonus, and preserved sensation. MRI revealed patchy areas of enhancement from the medulla to C2. Extensive workup—including cerebrospinal fluid (CSF) studies, autoimmune and paraneoplastic panels, and infectious disease testing—was unrevealing. The patient received high-dose corticosteroids, intravenous immunoglobulin, and plasma exchange, all with modest improvement. Repeat CSF and serum studies remained unrevealing. Digital subtraction angiography demonstrated a spinal dAVF at the cervico-medullary junction (Cognard Type V), consistent with Foix-Alajouanine syndrome, which was successfully embolized. In addition to radiographic improvement, he achieved significant motor recovery with physical therapy.

Foix-Alajouanine syndrome should be considered in patients with subacute or progressive myelopathy of unclear etiology, particularly when conventional inflammatory markers are negative. Recognition is critical as symptoms are often vague and because corticosteroid therapy—commonly initiated for presumed inflammatory disease—may precipitate clinical worsening. Diagnosis relies on MRI and spinal angiography, which reveals abnormal flow-voids and aberrant vascular connections leading to arterialization of the venous system with subsequent venous congestion and spinal cord necrosis. Definitive treatment involves surgical ligation or endovascular embolization of the fistula to restore normal venous drainage and prevent further damage. This case highlights the importance of maintaining a broad differential for acute myelopathy and the need for early vascular imaging when clinical and laboratory findings are incongruent with inflammatory or infectious causes.