Abstract
By using a combination of magnetic resonance imaging (MRI) and computed tomography (CT) of the lumbar spine, it is possible to distinguish between spinal stenosis caused by bone compression and specific soft tissue epidural intraspinal lesions that cause localized spinal canal stenosis and neural compression. Examples include facet cysts and yellow ligament hypertrophy. Many of these patients are elderly with medical comorbidities that make open surgery problematic.
This is a study of patients with predominantly soft tissue stenosis being treated with targeted intraspinal radiofrequency (RF) heat ablation. This novel procedure is performed under local anesthesia in an outpatient setting using intra-operative imaging. Fine tip 20 gauge RF electrodes (Stryker® PA, USA) are precisely placed under radiologic guidance in the identified soft tissue causing the posterior compression of the lumbar spinal canal. After sensory and motor testing to make sure there is a safe distance of the needle tip from the nearby nerve roots to avoid any neural effect, multiple targeted lesions correlated by the MRI or CT scan are made in the fibrous and cystic soft tissue. Lesions are created using a focused 2 or 5 mm tip at 60 degrees centigrade (°C) for either 30 or 60 seconds. This heat causes sufficient shrinking of the targeted soft tissue resulting in relative reduction of the soft tissue component of the stenosis. This relative reduction in the stenosis of the spinal canal, similar to that measured with interspinous devices, provides long-term relief of symptoms, signs, and improvement of spinal motion in patients with lumbar stenosis. This report will review the spinal anatomy, and development and history of using RF in and around the nerve roots and epidural space, as it relates to lumbar stenosis. Examples of before and after MRI scans demonstrate the radiologic reduction in the size of the lesions. This soft tissue reduction correlates with patients' improvement in pain and clinical symptoms. Follow-up of the patients up to 30 months shows that the effect of RF heat on the soft tissue is long lasting.
In our long-term follow-up of greater than six months, 58% of RF treated patients had lasting relief of clinical symptoms, back pain, and claudication with increased spinal movement. This reduction in pain and improvement in motion allows patients to continue more aggressive physical therapy and muscle strengthening that secondarily can improve their symptoms. Post-procedure follow-up MRI scans in multiple patients have shown a clear reduction in soft tissue lesion size. Long-term follow-up demonstrated that 58% of patients treated with RF targeted ablation have not required further intervention and 22% went on to other surgical treatments for lumbar spinal stenosis.
By reducing the soft tissue component of the stenosis with RF ablation and creating relatively more epidural space, targeted intraspinal RF may be a possible minimally invasive, percutaneous non-surgical alternative to treatment in a number of patients where soft tissue lumbar stenosis is the main cause of patients' symptoms. This technique offers a simple and safe additional method to relieve symptoms of lumbar stenosis and possibly compression within the neural foramina, especially in the elderly.
