Spinal vascular malformations
Spinal vascular malformations are a rare but important cause of progressive myelopathy. Untreated, they can result in severe disability, including loss of mobility and bladder function. Treatment for spinal vascular malformations is relatively straightforward. However, the condition can go undiagnosed because early signs and symptoms often are similar to those in more common conditions such as degenerative spinal disease.
"Unfortunately, patients might have symptoms for months before a correct diagnosis is made," says Giuseppe Lanzino, M.D., a consultant in the Department of Neurologic Surgery at Mayo Clinic in Rochester, Minnesota. "After treatment, most patients with spinal vascular malformation experience improvement. But the degree and extent of improvement is strictly correlated to their condition at the time of correct diagnosis."
About 80 to 90 percent of spinal vascular malformations are spinal dural arteriovenous fistulas (SDAVFs). They present most often in patients ages 60 to 79. In a study published in the November 2010 issue of Neurosurgery, Mayo Clinic researchers reported a mean age of 63.6 years and a mean interval from symptom onset to diagnosis of 24.7 months among 154 patients who underwent surgery for SDAVF at Mayo Clinic from 1985 to 2008.
Before referral to Mayo Clinic, 31 patients in the study had undergone some form of invasive treatment for symptoms that, in retrospect, could be attributed to SDAVF. "Uniformly, patients reported worsening of symptoms after every surgical intervention not directed at obliteration of the fistula," Dr. Lanzino says.
All 154 patients in the study experienced some form of subjective and objective motor weakness. Other neurological signs and symptoms included:
- Decreased sensation in the lower extremities
- Sphincter dysfunction
On MRI, the characteristic signs of SDAVF include edema on the T2 sequence that involves the conus medullaris, and indications of the presence of an abnormally enlarged blood vessel on the sagittal T2 sequence.
Definitive diagnosis requires catheter angiography, a procedure that can be difficult for elderly patients with atherosclerosis. "It is critical that these patients are evaluated in centers where large numbers of spinal angiograms are done," Dr. Lanzino says.
Once the fistula is found, treatment consists of surgical disconnection or endovascular embolization. "Surgery is still the preferred treatment modality because it's associated with very low complication rates and is more effective in guaranteeing obliteration of the fistula," Dr. Lanzino says. In the December 2013 issue of World Neurosurgery, researchers at Mayo Clinic in Phoenix/Scottsdale, Arizona, described a minimally invasive approach for intradural ligation of SDAVF.
Less common spinal vascular lesions, such as venous malformations and cavernous malformations, often can be successfully treated with surgery. As with SDAVF, Dr. Lanzino notes, "prompt diagnosis and referral to a center with experience are key."
For more information
Saladino A, et al. Surgical treatment of spinal dural arteriovenous fistulae: A consecutive series of 154 patients. Neurosurgery. 2010;67:1350.
Patel NP, et al. Minimally invasive intradural spinal dural arteriovenous fistula ligation. World Neurosurgery. 2013;80:e267.