MedicalResearch.com Interview with:
Dr. Natasha van Zyl, MBChB (Cape Town), FRACS
FRACS Plastic and Reconstructive Surgeon
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The estimated global incidence of spinal cord injury (SCI) from all causes is 40 to 80 new cases per million population per year which means that every year between 250 000 to 500 000 people worldwide suffer SCI (1)(chap 2 p 17). In Australia the age standardised, annual incident rate of persisting traumatic SCI for Australian residents aged 15 years and above is 11.8 cases per million.(2) Just over 50% of all spinal cord injuries in Australia occur at the cervical level resulting in tetraplegia. (2)
Cervical spinal cord injury is a devastating, life-changing injury impacting almost every aspect of a person’s work, family and social life. Although compared to many other health conditions it has a relatively low incidence, it is certainly a high cost health condition, with the lifetime cost per tetraplegia incident case estimated to be AU$9.5 million.(3) For those living with tetraplegia improvement in hand function is their highest ranked goal.(4) As such, reconstruction of upper extremity function in cervical spinal cord injury is a crucial component of the surgical rehabilitation of people with mid/low cervical spinal cord injury as it has the capacity to restore critical functions such as elbow extension, wrist extension, grasp, key pinch and release. Traditionally these functions have been reconstructed using tendon transfers, which move a functioning muscle to a new insertion site to recreate the function of a paralysed muscle.(5)
The success of nerve transfers in the treatment of brachial plexus and peripheral nerve injury has inspired interest in nerve transfers for the spinal cord injured population.(6-14) Nerve transfers are an attractive surgical option as they allow direct reanimation of the muscle anatomically and biomechanically designed to perform that function. There are more donor nerves available for nerve transfer than there are donor muscles for tendon transfers and so the options for reconstruction and the number of functions that can be reconstructed is increased. Nerve transfers have the ability to re-animate more than one muscle at a time, which in contrast to tendon transfers requires one tendon to reconstruct one function. Nerve transfers require a smaller operative incision and a shorter immobilisation and/or splinting time post-surgery both of which shorten the post-surgery recovery time. Lastly, nerve transfers avoid the technical challenges of tendon transfer surgery such as intra-operative tendon tensioning and mechanical failure post-surgery such as rupture, adhesion or tendon stretch.
In 2013 when this project commenced there was very little in the published literature on nerve transfer surgery in tetraplegia with most papers presented as case reports (15). This study is the the largest prospective, consecutive case series of nerve transfers done at a single centre in the tetraplegic population to date, and examines the clinical and functional outcomes of nerve transfer surgery in detail. The use of qualitative outcome measures adds a subjective patient perspective. The unique combination of tendon and nerve transfers permits intra-individual comparison of tendon and nerve transfers for grasp and pinch and expands reconstructive options, while allowing patients to benefit functionally from the innate strengths of each technique.
Please see schematic of surgical procedure here:
MedicalResearch.com: Can you tell us a little about the nerve transfers?
Response: In a nerve transfer a functioning “donor nerve” to an expendable muscle which is supplied by the spinal cord above the level of the spinal cord injury is cut at transferred to a “recipient” nerve supplying a paralysed muscle. Nerve fibres form the donor nerve then need to grow down the “scaffold” of the recipient nerve an make contact with the muscle and re-animate it . Nerve fibres grow at a rate of about 1mm per day with a 30 day delay at the start. Depending on the nerve transfer used, nerves take between 3-9 months to reach their target muscle. The nerve transfers in this study were chosen to re-animate elbow extension, grasp, pinch and hand opening.
MedicalResearch.com: What are the main findings?
Response: Nerve transfer surgery is a safe and effective addition to the surgical techniques available for upper limb reanimation in tetraplegia. This study has demonstrated an overall improvement in all clinical and functional outcomes tested, which are similar to outcomes reported in the literature for tendon transfers. Enhanced patient selection based on the learnings from this project may improve results further. It remains to be seen if function and power in nerve transfer reanimated muscles continue to improve beyond 24 months. No patient permanently lost function or deteriorated and adverse events were minimal. Patients were satisfied with outcomes, would have the surgery again and would recommend it to others. The advent of nerve transfer surgery for this patient group has put the spotlight on the wider topic of surgical rehabilitation in spinal cord injury. As a consequence of our work and that of others, many more rehabilitation physicians, therapists and spinal cord injury consumers are aware of the surgical options available to improve arm and hand function. Close collaboration and open communication between all stakeholders, along with a willingness to consider and combine the different interventions available in an individualised way, will maximise outcomes for people living with tetraplegia. This in turn will reduce carer burden and enhance independence, quality of life and the ability to contribute to family, community and vocation.
MedicalResearch.com: What should readers take away from your report?
Response: The option for the reconstruction of function in the arm and hand exist for C5 and below spinal cord injury. People with cervical spinal cord injury should have timely access to a surgeon working in this field to discuss their options and make an informed choice about whether surgery is something they would like to consider.
MedicalResearch.com: What recommendations do you have for future research as a result of this work?
Response: Correlations between clinical and spinal cord injury variables, and outcomes need to be made in order to optimise patient selection for nerve transfer surgery. Surgical algorithms combining nerve and tendon transfers need to be established for the different spinal cord injury levels. A project examining the histological morphology of the donor and recipient nerves of participants in this study is underway, this will provide valuable information on the changes seen in the peripheral nerve system after spinal cord injury. A study describing a small sample of these nerves has already been published by the authors (16).
MedicalResearch.com: Is there anything else you would like to add?
Response: This project was founded by ISCRR (Institute for Safety, Compensation and Recovery Research)
- International Perspective on Spinal Cord Injury. Bickenbach, JE ed: World Health Organization; 2013.
- AHIHW: Tovell A. Spinal cord injury Australia, 2014-15. Injury stastistics and stastistics series no. 113. Cat. No. INJCAT 193.; 2018.
- Collie A. The economic cost of spianl cord injury and traumatic brain injury in Asutralia. The Victorian Neurotramua Initiative; 2009.
- Anderson K. Targeting Recovery – priorities of the SCI population. Journal of Neurotrama. 2004;21(10):1371-3.
- Hentz VR, Leclercq C. Surgical Rehabilitation of the Upper Limb in Tetraplegia. New York: WB saunders; 2002.
- Bertelli JA, Tacca CP, Ghizoni MF, Kechele PR, Santos MA. Transfer of supinator motor branches to the posterior interosseous nerve to reconstruct thumb and finger extension in tetraplegia: case report. J Hand Surg Am. 2010;35(10):1647-51.
- Bertelli JA, Mendes Lehm VL, Tacca CP, Winkelmann Duarte EC, Ghizoni MF, Duarte H. Transfer of the Distal Terminal Motor Branch of the Extensor Carpi Radialis Brevis to the Nerve of the Flexor Pollicis Longus. Neurosurgery. 2012;70(4):1011-6.
- Bertelli JA, Ghizoni MF, Tacca CP. Transfer of the teres minor motor branch for triceps reinnervation in tetraplegia. J Neurosurg. 2011;114(5):1457-60.
- Fridén J, Gohritz A. Brachialis-to-Extensor Carpi Radialis Longus Selective Nerve Transfer to Restore Wrist Extension in Tetraplegia: Case Report. The Journal of hand surgery. 2012;37(8):1606-8.
- Brown JM. Nerve transfers in tetraplegia I: Background and technique. Surgical neurology international. 2011;2:121.
- Mackinnon SE, Yee A, Ray WZ. Nerve transfers for the restoration of hand function after spinal cord injury. J Neurosurg. 2012;117:176-85.
- Krasuski M, Kiwerski J. An analysis of the results of transferring the musculocutaneous nerve onto the median nerve in tetraplegics. Archives of Orthopaedic & Trauma Surgery. 1991;111(1):32-3.
- Bertelli JA, Ghizoni MF. Single-stage surgery combining nerve and tendonntransfers for bilateral upper limb reconstruction in a tetraplegic patient; case report. The Journal of hand surgery. 2013;38(7):1366-9.
- Bertelli JA, Ghizoni MF. Transfer of nerve to brachialis to reconstruct elbow extension in incomplete tetraplegia: case report. Journal of Hand Surgery (Am). 2012;37(10):1990-3.
- Cain SA, Gohritz A, Friden J, Van Zyl N. Review of upper extremity nerve transfer in cervical spinal cord injury. J Brachial Plex Peripher Nerve Inj. 2015;10(1):e34-e42.
16 . Messina A, Van Zyl N, Weymouth M, Flood S, Nunn A, Cooper C, et al. Morphology of Donor and Recipient Nerves Utilised in Nerve Transfers to Restore Upper Limb Function in Cervical Spinal Cord Injury. Brain Sciences. 2016;6:42.
Natasha van Zyl, Bridget Hill, Catherine Cooper, Jodie Hahn, Mary P Galea. Expanding traditional tendon-based techniques with nerve transfers for the restoration of upper limb function in tetraplegia: a prospective case series. The Lancet, 2019; DOI: 10.1016/S0140-6736(19)31143-2
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