History: 15-year-old girl with acute onset of numbness and weakness in both lower extremities and a T4 sensory level.
Findings: A sagittal T2-weighted MR image of the cervicothoracic region demonstrates a heterogeneous intramedullary lesion at the T3-T4 level and multiple serpentine flow voids on the surface of the cord, predominantly posteriorly. early and late frontal arterial films from a spinal arteriogram reveal an abnormal tangle of vessels projecting over the spinal canal with large, early draining veins.
Diagnosis: Spinal arteriovenous malformation
Discussion: Vascular malformations of the spinal cord have been classified according to the anatomic location of the malformation nidus or shunt. Type 1 malformations are dural arteriovenous fistulas. These typically occur in the low thoracic region in middle-aged and older men who present with progressive neurologic deterioration. Type 2 malformations are intramedullary arteriovenous malformations with a compact nidus supplied by multiple feeders from the spinal arteries. These occur in younger patients who frequently develop symptoms acutely from intramedullary hemorrhage. Type 3 arteriovenous malformations are rare lesions that extensively involve both intramedullary and extramedullary compartments with multiple feeders. Type 4 arteriovenous malformations are intradural, extramedullary arteriovenous fistulas that usually occur near the conus medullaris in middle-aged patients with progressive neurologic deficits.
Myelography usually demonstrates enlarged, tortuous vessels associated with these arteriovenous malformations, which show up as serpentine flow voids on MRI. Abnormal cord signal is also present if there has been intramedullary hemorrhage or ischemia/infarction from chronic venous congestion. Spinal arteriography is the gold standard for evaluating spinal arteriovenous malformations. Therapy consists of intravascular embolization occasionally combines with surgery.
Aunt Minnie’s Pearls
- Spinal arteriovenous malformations occur in several types that vary by location and age group involved.