Spinal arteriovenous malformations: some diagnostic difficulties with illustrative cases.

Spinal arteriovenous malformations commonly present with progressive or step-like cord and conus dysfunction. Diagnosis is achieved by demonstrating abnormal vessels on the cord by means of high-quality myelography followed by selective spinal angiography. Diagnostic difficulties arise where screening myelography is equivocal or where angiography is negative in patients with suggestive myelographic findings. Negative investigation may not exclude a spinal arteriovenous malformation in patients with very suggestive clinical presentations. Occasionally reinvestigation after a period of follow-up or surgical exploration, even in the absence of a definite diagnosis, may be indicated.