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What is Selective Dorsal Rhizotomy (SDR)?

J Webberly 2

SDR was first performed in the early 1900's, when complete division of all the nerve roots to the lower limbs was performed. Although this did lead to improvement in spasticity, it also caused severe muscle weakness, as well as loss of skin sensation and joint-position sense. The current technique, in which only those nerve rootlets that contribute most to the spasticity are divided, was introduced in 1978.

The current technique involves surgery in the lower back. The procedure is performed under general anaesthesia and takes around 4 to 5 hours. The technique we use is the same as that developed in St Louis in the USA, which concentrates on the lower part of the spinal cord - increasing its effectiveness and reducing risk.

A skin incision is made in the upper lumbar spine. The spinal canal is opened at only one level. An ultrasound probe is used to identify the lower end of the spinal cord. The tough tissue covering the spinal cord is opened and the lower end of the cord, with the sensory roots attached, is identified. Each of the sensory nerve roots is then subdivided into four or five rootlets. The rootlets that contribute most to the spasticity are identified by sequential stimulation and are subsequently divided. Between 66% and 75% of these nerve roots are divided during the procedure. The procedure is performed under the operating microscope. At the end of the procedure, the cover of the spinal cord is closed again, the back muscles are re-approximated and the skin is closed with absorbable sutures.

(This information can also be found within the paediatric physiotherapy SDR webpages.)