Medial Branch Blocks
The anatomy of the spine
Situated in the back and neck, the facet joints are paired joints found at each vertebral level. They have surfaces of cartilage and are surrounded by synovial fluid which reduces friction when the bones rub together.
The medial branch nerve carries pain signals from the facet joints. Targeted numbing of these nerves disrupt pain signals for a variable period. These injections can be used to both diagnose and treat the symptoms which are associated with facet joint pain or strain. Diagnostic tests performed before and after this procedure will determine whether patients will proceed to have radiofrequency neurotomy three or more weeks later.
There are several different forms of medial branch blocks, depending on the location of the facet joint pain: cervical facet joints are on the side or back of the neck; thoracic facet joints are in the upper back; while lumbar facet joints are in the lower back. The pain itself can be referred and therefore located in different areas of the body, depending on which facet joints are affected.
Causes of facet joint pain
Facet joint pain can have a number of causes, including pressure overload of the joints, injury or wear and tear(aging). The joint could become strained an activity which an individual undertakes regularly, such as forms of physical exercise or manual work. It may also be consequence of a whiplash accident.
Disc degeneration can be a typical precursor to the pressure overload on the facet joints, as it causes the narrowing of the space between each vertebra, which in turn leads to a build-up of pressure on the articular cartilage surface.
Facet joint arthritis has the ability to destroy the cartilage and fluid which is used for lubrication of the joints, causing pain.
Medial Branch Blocks
Medial Branch Blocks are recognised a day case procedure. They are typically performed using fluoroscopy (live X-ray) to help guide the needle accurately and avoid any nerve injury. The procedure will take place in theatre under full aseptic conditions with the patient on his or her stomach (or on the side for the neck). A small needle in the back of your hand can be used to administer sedation or in case of an emergency. The skin is well cleaned before a small amount of local anaesthetic is applied in order to numb the injection area. The physician then directs a small needle into the medial branch nerve injecting a small mixture of steroid (anti-inflammatory medication) and anaesthetic. The physician will carry out diagnostic tests to assess the benefit gained from the blocks. Lesioning (Radiofrequency neurotomy) of the nerves at a later date will only be indicated if there is a significant reduction in the pain levels.
Patients are then monitored in a recovery area before transfer to the ward and discharge home. Patients may experience a numb feeling for a few hours. Pain and spasms at the injection site may increase for five or more days. It is advisable to rest for 24 hours and resume stretches and exercises when the pain eases. This window of pain relief should be utilised for performance of strengthening exercises and rehabilitation physiotherapy.
Complications
There is a variable response to injection treatment. It is important to discuss both the benefits and risks of the procedure with your doctor before any agreement to undergo the procedure is reached. Although the chance of any complications is generally low, as with all surgical procedures, there is an element of risk involved with medial branch blocks including failure to get benefit or pain aggravation. There may be an allergic reaction to the steroid or any of the medications, or that the injection causes an infection or bleeding. Paralysis, spinal cord or nerve damage is extremely rare.