Daniel Korya, MD

Lee YJ, Terbrugge KG, Saliou G, and Krings T. Clinical Features and Outcomes of Spinal Cord Arteriovenous Malformations: Comparison Between Nidus and Fistulous Types. Stroke. 2014

In the 1800’s, three of the most recognized names in medicine: Virchow, Emmanuel and Luschka, described their findings on intracranial arteriovenous malformations (AVMs), for the first time. Since then, AVMs have been discovered in the spinal cord as well; however, spinal cord AVMs are more rare than intracranial AVMs, and due to their infrequent occurrence in the general population, clear guidelines about an accepted approach to diagnosis and management are lacking. 

In the 1950’s, Actor Ricardo Montalbán was diagnosed with a spinal cord AVM that became aggravated when he was thrown from his horse during the filming of the film “Across the Wide Missouri”. This caused him pain for many years, which led to an elective 9 ½ hour surgery in 1993 that left him paralyzed and wheelchair bound.
For several decades now, experts have debated the nuances of spinal cord AVMs.  As more cases were reported, two subtypes of spinal cord AVMs emerged: the nidus and fistulous type.  Accordingly, the authors of this paper first sought to describe and differentiate between the two types of spinal cord AVMs.  They observed the occurrence rates and treatment modalities for these AVMs and reported on the obliteration rates, based on their experience.
Essentially, the authors explained, fistulous AVMs are located superficially and only rarely possess intramedullary components, while the nidus AVMs are located in the spinal cord parenchyma. 
The researchers were able to gather forty-four consecutive patients with spinal cord AVMs.  There were 26 patients with a nidus-type and 18 patients with a fistulous AVM. Treatments were performed with embolization (n=23), surgery (n=13), combined embolization-surgery (n=3), or conservative management (n=5).
Overall, patients with nidus-type AVMs were younger at presentation and had a higher rate of spinal cord hemorrhage than the fistulous-type. The researchers also confirmed that complete obliteration could be achieved more often in the fistulous-type (72%) than the nidus-type (27%).
Hemodynamics and depth of the lesions seamed to be important factors affecting clinical outcome and obliteration rates. The nidus-type AVMs were less likely to have complete obliteration and had more complicated hemodynamics resulting in higher rates of morbidity.
In short, the researchers had a respectable number of cases for a rare disease, and they reported their findings in a concise and clear manner. Although their results cannot be considered universal, they are certainly a step in the right direction and provide a foundation for clinicians to build on.