Injury type: Chronic

Category: Medical Options

Rating: No Research

What is it?

A selective nerve root block is a procedure performed to determine if a specific spinal nerve is the source of pain and reduce inflammation around the nerve root. By reducing inflammation around the nerve root, the patient may experience a decrease in pain. This procedure is done under a local anaesthetic. The health professional locates the spinal nerve root, usually with the help of fluoroscopy (an imaging technique which obtains real time images of body structures using a fluoroscope) or more recently, ultrasound. A needle is introduced through the skin into the area adjacent to the nerve root. Medication is then injected into the area which ensures that the nerve root is immersed in medication. Traditionally, the medications injected include an anaesthetic and a steroid.

How does it work?

Injecting anaesthetic and steroids around the nerve root can help with pain relief and controlling any inflammation that may occur as a result of whiplash. Some anaesthetics, such as lidocaine, have also been shown to improve blood flow and reduce dysfunction of the neural system. Ultimately this might help in the healing of the injured nerve.

Is it effective?

There is a lack of up-to-date research evidence to support selective nerve root block as an effective treatment method for patients with whiplash. However, there are some studies conducted for patients with chronic cervical radicular pain. A randomised trial1 compared selective nerve root block to pulsed radiofrequency or a combination of both treatments for patients with persistent neck pain radiating to the posterior shoulder and arm areas. While all three groups experienced a significant pain reduction in short term, the combined therapy was more effective than each individual treatment alone at longer term follow-ups. Another two retrospective comparative studies (i.e. lower level evidence)2,3, which compared ultrasound-guided selective nerve root block with fluoroscopy-guided epidural block, suggested that ultrasound-guided selective nerve root block requires a shorter administration duration while providing similar pain relief and functional improvements, as opposed to fluoroscopy-guided epidural block.

Are there any disadvantages?

There may be increased pain after this procedure. There may also be feelings of weakness and numbness of arm(s), chest wall or leg(s). These symptoms are common after selective nerve root blocks. Other potential side effects include facial flushing, occasional low-grade fevers, hiccups, insomnia, headaches, water retention, increased appetite, increasing heart rate, abdominal cramping and bloating. These side effects occur in about 5% of people and usually resolve within 1-3 days of the injection. It is important to regularly inform health professionals regarding recovery after the nerve block.

Where do you get it?

This procedure can only be undertaken by a medical practitioner and most likely by a specialist (a radiologist) in this field.


Based on very limited available evidence, it is unclear how useful selective nerve root blocks are for treating patients with whiplash. It is likely to be reserved for people that have not responded to more conservative treatments and have chronic pain. More research is needed before concrete recommendations can be made.