Cervical nerve root injections
Over time, the intervertebral discs of the spine lose their flexibility and elasticity and the adjacent facet joints degenerate. These 2 processes can conspire to narrow the space for one of the exiting nerves in the neck. In some patients, typically the younger patients, a trapped nerve in the neck is due to a soft piece of disc which has ‘slipped’ (prolapsed, bulged or herniated- they all essentially mean the same thing). In the relatively older patients, a trapped nerve is more likely due to a gradual process of narrowing with contributions from the disc, but also the facet joint
A nerve is like an electrical wire. The motor components convey messages from your brain telling your muscles to move and the sensory components convey information such as pain, temperature, touch and pressure sensation to the brain.
If a nerve is compressed, pain which is usually severe is felt in the area of the body that the nerve spine supplies. A trapped nerve in the neck will cause pain into an arm. We term this pain brachalgia. (It is the exact equivalent of sciatica in the leg.)
Happily, many cases of brachalgia settle. Typically, 2 out of 3 people settle within 3 months.
A cervical nerve root injection may be done for a combination of diagnostic and therapeutic reasons.
The Procedure
The procedure is performed under local anaesthesia under CT guidance. The CT scanner is not as enclosed as an MRI scanner and should not cause claustrophobia.
The procedure is performed as an out-patient. Expect to be at the hospital for at least one hour. Please have someone to accompany you and you should not plan to drive home. You can eat and drink normally beforehand.
The radiologist, a doctor, will meet you beforehand to explain the procedure and to ask you to sign a consent form.
You will be taken into the CT room and positioned on your back. An initial local anaesthetic injection will be made (to numb the injection site and surrounding area) and a planning scan will be performed. A needle will then be inserted into the side of the neck and advanced so that it is placed just next to the appropriate nerve root, as it leaves the spine. Occasionally some contrast dye will be injected to help guidance. The position of the needle will be checked in the CT scan before the injection of a combination of local anaesthetic (Bupivicaine) and steroid (Triamcinolone) is made.
The procedure is not usually painful, but as the needle approaches the nerve, your typical pain may be felt down the arm.
Once the procedure is done, usually, after a cup of tea, you can go straight home and take it easy for the rest of the day.
There may be immediate benefit due to the quick acting local anaesthetic component. Sometimes the immediate benefit wears off before the steroid benefit kicks-in a few days later.
You should continue to take your usual pain relief medication until you begin to feel benefit. It is important not to stop taking certain pain relief medication suddenly, such as, morphine or neuropathic medication (gabapentin, pregabalin or amitriptyline).
The duration of benefit is variable and ranges between a few days benefit to no return of pain. For a considerable number of patients, the injections provide excellent pain relief during which time the underlying problem can resolve itself.
If the symptoms have not improved by 10 day, the injection is probably not going to help.
Typically, Mr Allibone will see you in clinic following the injection at between one to three weeks depending on the circumstances.
The Risks
Fortunately, there are very few risks associated with nerve root injections. Very uncommon risks include:
Bleeding. You must inform your consultant if you are taking tablets used to ‘thin the blood’, such as warfarin, rivaroxaban or clopidogrel. You will need to stop taking these before your injection. Mini aspirin is fine.
Infection. This is very rare
Facial flushing. Typically, this lasts a few days only but can look quite dramatic.
Interference with the menstrual cycle or post-menopausal bleeding. This can be a temporary side effect of the steroid
A rise in blood sugar levels for a few days for people who have diabetes
A needle injury to the dura (the membrane around the nerves). This can result in a small leakage of the cerebrospinal fluid (CSF), which can lead to a headache (when standing and walking) for a few days afterwards. If this does occur, you may be advised to lie down for a few days until the leakage stops. This is very unlikely with a neck injection.
Allergic reaction to the injection. Rare
Stroke. Very rare cases of stroke have been described. These cases are due to a disturbance of the blood flow to the brain, probably related to positioning of the neck and rarely due to misplacement of the needle.