Selective Dorsal Rhizotomy
As of July 2014 NHS England has commissioned five centres to undertake Selective Dorsal Rhizotomy in the United Kingdom. A total of 100 procedures are to be performed each year under an evaluation programme. Whilst Oswestry was not selected we will continue to be activly involved in the assessment and management of children and adults with cerebral palsy. All patients who have undergone SDR in Oswestry will continue to be cared for and followed up by our team. The selected centres are:
Popularised by a South African surgeon, Warwick Peacock, the management of spasticity in the lower limbs by selective division of the dorsal roots has spreasd throughout Europe and North America. Until 1992 no selective dorsal rhizotomies had been - performed in the United Kingdom. Reports of the benefit of selective dorsal rhizotomy prompted the team in Oswestry to visit Warwick Peacock in Los Angeles, where he now works, to learn the technique and see the results first hand.
Because of the multidisciplinary nature of the services available in Oswestry and the long familiarity with multilevel surgery for cerebral palsy wewere in a good position to start using the technique for a carefully selected group of children. We concluded that in the climate of hostility towards the treatment that has existed in the United kingdom it was imperative to monitor the selection and progresso of the children treated.
A comprehensive screening programme was established with assessment by two childrens orthopaedic surgeons and a paediatric neurologist as well as full gait analysis wherever the child was able to cooperate and imaging of the nervous system, spine and hips. Over the first decade we selected 20 children out of 70 who had been referred for consideration of selective dorsal rhizotomy. Naturally, those children not deemed suitable for SDR were provided with alternative treatment packages either carried out in Oswestry or by their referring team.
Gradually our selection criteria have evolved and the limitations and benefits of the procedure have become clearer. We have had no major problems following the procedure and have observed a permanent reduction in lower limb spasticity in all the patients treated.
The multidisciplinary team involved in the programme are involved at multiple stages in the course of the treatment:
Orthopaedic surgeons x2
Gait analysis technical staff.
Paediatric recovery nurse specialist
Medical electronics support staff
Paediatric orthopaedic nursing staff
Paediatric orthopaedic physiotherapy staff
Play therapy staff
Gait analysis technical staff
Follow up to skeletal maturity
The SDR operation is aimed at reducing the strength of the reflex circuits that cause spasticity when a brian injury leads to excessive spasticity. A reflex loop exists with the spinal cord sending signals to the muscle to make it stiff and the muscle sending signals back to the spinal cord in response to any slight movement. the effect of this reflex arc is that muscles are stiff and resist movement particularly when the movement is sudden.
The rhizotomy cuts up to 50% of the nerve fibres returning to the spinal cord with the signals about muscle stretch and movement. These nerve fibres also carry sensation from the skin but a loss of 50% of the nerves does not lead to a perceptible loss of sensation. The spasticity, however, is permanently reduced.
In diplegic patients the rhizotomy is centred on the lumbar and first sacral nerves on each side. In Oswestry we do not touch the second sacral nerve as this is involved in the control of the bowels and bladder as well as sexual function and we feel that the risks involved in operating on this nerve are too great. The downside of not operating on the second lumbar nerve are that some spasticity and tightness remain in the calf muscle but this is much less than before the operation and can be managed with botulinum toxin or serial casting.
To get to the nerves the patient is anaesthetised in a kneeling position and the back of the spine is exposed. We remove the covering on the back of the spine from the sacrum to the first lumbar level and then open the tough covering (dura) surrounding the spinal cord and nerves. The spinal cord ends in children just above where the operation occurs and the operation is on the nerves that have left the spinal cord and are passing out of the dura through the vertebral foraminae and into the limb to supply stimulation to muscles and bring back sensation. The sensory nerves are at the back of the two components and are termed the dorsal rootlets. Dorsal rhizotomy simply means cutting the dorsal roots.
The selective bit comes once the nerves have been exposed. At each level the dorsal roots are teased gently apart and each bundle of fibres is tested with sophisticated electrical testing equipment to find out whether that portion of the dorsal root is causing abnormal spread of activity throughout the limb and on some occasions in the other limb and the arms. When we identify the parts of the nerve that are most out of control we divide typically 40% but occasionally we will go up to 50% if there is a great deal of spasticity in the muscle that that root supplies.
Once we have completed the testing and dviding of all the dorsal roots the bony cover to the spine is replaced and the wound closed. The procedure takes about 4 hours typically with the surgical bit lasting about 2 hours. Setting up the electrical testing equipment and getting the child safely off to sleep and waking them up again takes the rest of the time.
Without good treatment after the operation of sufficient duration and intensity the operation is far less effective in producing a good result. We consider that the treatment of the child continues after the operation at least up to the end of growth and in some of our patients into adult life as well.
For the first week after the operation the child is nursed flat in bed. This allows the wound and dura to heal. Physiotherapy stretching and splinting are used during this time to start the process of removing contractures and stretching muscles that have developed shortness due to the spasticity. By the end of the first weeek the patient then progresses to a tilt table to get them used to being upright. Usually by the second week the child has splints fitted to control their ankle posture and are mobilisaed on parallel bars. Getting muscles to work in a new range with more normal walking posture takes time and persistance,
We have a long experience of multilevel orthopaedic surgery for cerebral palsy and have found by bitter experience that leaving the rehabilitation to a remote team who are not undertaking major surgery on walking children with cerebral palsy is an haphazard business and we are insistant now on undertaking the initial training and rehabilitation ourselves. Accordingly children who have undergone selective dorsal rhizotomy stay with us for 6-8 weeks having daily physiotherapy and hydrotherapy.
Frequently asked questions:
Does SDR work for all types of cerebral palsy?
No. Only patients with the spastic form of cerebral palsy benefit from this treatment.
Does SDR cure spastic cerebral palsy?
No. Cerebral palsy is cause by a fixed injury to the brain or spinal cord. The most common cause of spastic cerebral palsy that benefits from SDR is diplegia which is generally associated with premature birth. The brain injury causes problems of control and balance and these are not altered by the operation.
What age is appropriate for selective dorsal rhizotomy?
Any age over about 4 years of age but the older the child the more problems they are likely to have as a result of growth in the presence of spasticity. We have operated on older patients but our preference is to perform the operation in the younger child.
Is SDR an alternative to bone and tendon surgery?
Depending on the degree of bony deformity present and the age of the patient at the time of the operation an SDR may allow improvement in intoeing in the younger child but is unlikely to improve skeletal deformity in the older child thus bony surgery is often needed to sort out twisting in the shin or thigh bone anf often to deal with foot deformities. The amount of tendon surgery that these children need is much reduced compared with children that have a more traditional orthopaedic surgical treatment plan.
What are the complications of SDR?
Damage to bladder or bowel control
Deformity of the spine
Dislocation of the hips
What is the incidence of these complications in the Oswestry patients?
We have had one patient that required an operation to stabilise a hip joint that became painful some years after the SDR
NICE Interventional Procedures Overview
The National Institute for clinical Excellence has recently undertaken a review of the efficacy and safety of SDR.