What are medial branch blocks?
Medial branch blocks are diagnostic tests used to determine if facet joints are the source of a patient’s pain, such as lumbar pain (back pain). Facet joints are small joints located at the back of the spine on each of its two sides.
Medial branch block is performed under fluoroscopic guidance. This procedure involves the local injection of anaesthetics to numb the small nerve responsible for the perception of pain. In the case of lumbar pain, a percutaneous thermo-coagulation (rhizotomy) treatment may be considered to alleviate pain.
Cervical, dorsal and lumbar facet joints can be a source of pain. The painful impulse of facet joints are transmitted by the medial branch of the posterior ramus. Posterior medial branch blocks can provide temporary relief to patients and help to pinpoint the source of pain.
Facet joints can be at the origin of pain at all levels along the spinal column. Medial branch blocks are selection tests that are essential to determine whether patients are likely to be eligible for facet denervation (rhizotomy/thermo-lesion). The selection tests come in sets of two or three. If patients respond positively to the tests, they become eligible for rhizotomy.
If the pain originates in facet joints, medial branch blocks can provide some temporary relief. The duration of relief depends on the anaesthetic product used. After the tests, patients record the intensity of their pain on a pain scale. If the pain does not originate in any facet joint, these tests will not provide relief.
During the procedure, a physiatrist will start by identifying the location of the posterior medial branch through fluoroscopy (radiography).
After disinfecting the skin and applying an anesthetic, if needed, the physiatrist will make sure that the injection needle is in the right position next to the nerve in question by injecting a small quantity of iodine colorant to pinpoint the target location. Then an anaesthetic product is injected.
At the end of the procedure, patients are taken to a resting room for about fifteen minutes to make sure that there are no allergic reactions to the injected products. They will have to complete pain scales during the next 48 hours to determine if they are relieved from the pain. They then send the pain scales to our clinic to conclude whether there is relief from pain or not. If there is relief, a second appointment is made with the patients to repeat the same test.
After the procedure, pain may increase during the first seven to ten days. Applying ice to the treated area and taking acetaminophen helps to ease discomfort.
Complications following such injections are extremely rare. Radiology devices at the cutting edge of technology and our physiatrists’ standards of practice are instrumental to lowering risks of complications.
However, there is always a very slight risk of infection or bleeding complications during injections. If you are taking blood thinning medication (anticoagulant or antiplatelet agents), you must notify us prior to the procedure.
To reduce risks of complications, certain precautions are advised :
- During pregnancy, injections performed with radiological equipment (fluoroscope) are contra-indicated.
- Patients must inform our staff of any allergies to medication or contrast agents like iodine.