Selective Transforaminal Nerve
Root Blocks are useful in
the pain relief clinic when an Epidural Injection has
failed to help for sciatica due to nerve root
irritation. They can be performed at the lumbar and
cervical levels. Indications for a block include:-
Far Lateral Disc Protrusions
Post operative epidural adhesions
The injection is performed under local anaesthesia,
intravenous sedation, with X-ray screening, whilst lying
A small diameter 3.5" needle is positioned in the
Foramen, or nerve root exit hole, at the side of the
spine. X-ray contrast medium is injected to outline the
o Lumbar Radiculogram
o Cervical Radiculogram
needle is in the correct position, and not in the
cerebrospinal fluid (CSF), a mixture containing 2%
lignocaine and triamcinolone 20 mg is injected around
the nerve root.
Commonly used steroids include:-
o Triamcinolone (Kenalog)
o Methylprednisolone (Depo-medrone)
signs monitoring is usual for a short time after the
Arm or leg weakness, numbness, and temporary loss of
use in the limb can occur in some patients, therefore an
overnight stay at
- Inability to insert the needle into the nerve root
foramen. This may be due to :-
o Obesity causing poor X-ray pictures.
o Difficulty steering the needle.
o Severe degrees of Spondylolisthesis in
the lumbar spine.
Failure to relieve the sciatic pain
o This may occur if the cause of the pain
was not due to nerve root irritation (See Non Nerve Root
Sciatica and Referred Pain).
Total Spinal Injection
o This may occur if the spinal needle
enters the CSF in the dural cuff around the nerve root.
The use of X-ray contrast should reduce the risk of this
caused by direct needle trauma.
in a very small minority of cases, cause unknown.