Interventional procedures

Spinal AVM

Dural fistulas and intramedullary AVMs are preferably treated by endovascular methods. Following thorough angiographic mapping of the lesion, the feeders are super-selectively catheterized. In dural fistulas occlusion is usually achieved by injecting glue (bucrylate). In the ideal case, the glue should reach the proximal portion of the venous system. By this treatment, the pressure in the venous system is reduced permitting improved venous drainage from the cord. Usually the progressive myelopathy caused by the increased venous pressure can be arrested and in some favourable patients the symptoms might diminish. In intramedullary AVMs, occlusion is normally achieved by injecting small particles following super-selective catheterization of the feeders. In somecases this is combined with injection of glue. The risk of bleeding is thereby reduced and in cases with impairment of the venous drainage from the normal cord, the pressure can be lowered.

Percutaneous discectomy

Patients with contained disc herniations are candidates for treatment by percutaneous discectomy. In this technique, disc material is removed through a thin needle inserted by a dorsolateral approach. A careful preoperative investigation, preferably by high resolution MRI, is necessary to rule out free fragments, which are a contraindication for this procedure. The advantages of the technique are the following: it is minimally invasive and reduces the need for hospital admission and sick-leave. It is especially efficient for treatment of far lateral disk herniations, which are difficult to reach by conventional surgery. The formation of scar tissue is avoided, and if the procedure is unsuccessful, conventional surgery can be performed as a second step. The frequency of successful procedures is lower compared with conventional surgery, but still acceptable results are achieved in the majority of patients and there are few complications.

Chemonucleolysis

This method of treatment of disc herniations has been used for thirty years. The treatment consists of injection of chymopain through a needle introduced by posterolateral approach into the disc. The enzyme breaks down the content of the nucleus pulposus which becomes reduced in volume and the pressure in the disc diminishes. Only contained disc herniations can be treated and at some centres discography is routinely performed to disclose possible leakage of the contrast material outside the disc. The indications are the same as for percutaneous nucleotomy. The main drawback of the method is that some patients develop allergic reactions towards the enzyme.

Stig Holtås, Maximilian F. Reiser and Axel Stäbler