Injury type: Acute

Category: Medical Options

Rating: Not effective

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). 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 very little high level, high quality evidence to support selective nerve root blocks as an effective treatment method for patients suffering from whiplash. One study used selective nerve root blocks in conjunction with physiotherapy for patients suffering from long term symptoms of whiplash. The findings indicated that while nearly half of the patients experienced short term benefit (especially in terms of pain and other symptom relief), only 14% received good and excellent outcomes. For those who benefit from nerve root blocks in the short term, there is no evidence for the effectiveness of repeated nerve root blocks (more than three). There is also no evidence that nerve root blocks reduce the incidence of surgery. Therefore, the overall quality of evidence for using selective nerve root blocks for whiplash patients is poor.

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.