Spinal Muscular Atrophy (SMA) is a congenital motor neuron degenerative disorder resulting in weakness, low tone, and when presenting in early life, death.1 Though some investigators have seen evidence of sensory nerve death,2 SMA is typically considered to be a motor disease without a significant a sensory neuropathy component because the neurodegeneration in SMA is confined to motor neurons in the anterior horn of the spinal cord.3
Despite a lack of sensory nerve involvement, over 70% of adolescent patients with SMA in a published study reported experiencing chronic pain, especially localized to the neck and legs.4 The most commonly reported causes of pain in association with SMA are immobility4 and scoliosis, a common longitudinal consequence of SMA.5 The pain that patients with SMA report persists despite surgical correction of orthopedic issues, and the pain can be worsened by activities such as transferring from bed to wheelchair.4
Managing pain in patients with SMA begins with the recognition that there are predictable etiologies yielding pain in SMA and inquiring about them at every medical appointment.6 Patients with SMA may report pain from any of the following treatable secondary conditions:
- Gastrointestinal (gastroesophageal reflux disease, erosive esophagitis, constipation)6
- Orthopedic (hip dislocation, osteoporosis with spinal compression fractures, scoliosis, tendon retractions, weight-bearing pain)4,6
- Neurological (acute or chronic post-surgical pain)4,6
- Urological (catheterization trauma)7
- Respiratory (bronchiolitis, hypoxia)6,7
In terms of prevention, a consensus recommendation from a panel of international experts in SMA advises an individualized multidisciplinary approach to specialty care for patients with SMA.8 Early, even anticipatory, referral for orthopedic, gastrointestinal, respiratory and pain/palliative specialty care may improve outcomes.5 Surgical correction of orthopedic complications of SMA may reduce, but not eliminate, pain; surgery may not be indicated for most hip dislocations.4,6 Pain due to compression fractures associated with osteoporosis can be prevented through ergocalciferol and calcium supplementation and treated with bisphosphonates when fractures are evident.6 Acute or immediate post-surgical pain can be treated with any number of available anesthetics, opioids, or benzodiazepines with caution advised because SMA compromises respiratory muscle function; chronic pain can be addressed with opioids or if chronic pain has a clear neuropathic etiology alternative approved therapies like gabapentin may be used.6,7 Benzodiazepines or morphine (including inhaled morphine) can be used for the agitation caused by respiratory distress, especially at end of life, or associated with repeated catheter use.6,7
1. Kolb SJ, Kissel JT. Spinal Muscular Atrophy. Neurologic clinics. 2015;33(4):831-846.
2. Yonekawa T, Komaki H, Saito Y, Sugai K, Sasaki M. Peripheral nerve abnormalities in pediatric patients with spinal muscular atrophy. Brain Dev. 2013;35(2):165-171.
3. Wong PC, Rothstein JD, Price DL. The genetic and molecular mechanisms of motor neuron disease. Current opinion in neurobiology. 1998;8(6):791-799.
4. Lager C, Kroksmark AK. Pain in adolescents with spinal muscular atrophy and Duchenne and Becker muscular dystrophy. Eur J Paediatr Neurol. 2015;19(5):537-546.
5. Roper H, Quinlivan R. Implementation of “the consensus statement for the standard of care in spinal muscular atrophy” when applied to infants with severe type 1 SMA in the UK. Archives of Disease in Childhood. 2010;95(10):845-849.
6. Cuisset JM, Estournet B. Recommendations for the diagnosis and management of typical childhood spinal muscular atrophy. Revue neurologique. 2012;168(12):902-909.
7. Di Pede C, Agosto C, De Tommasi V, De Gregorio A, Benini F. Symptom management and psychological support for families are the cornerstones of end-of-life care for children with spinal muscular atrophy type 1. Acta Paediatr. 2018;107(1):140-144.
8. Wang CH, Finkel RS, Bertini ES, et al. Consensus statement for standard of care in spinal muscular atrophy. J Child Neurol. 2007;22(8):1027-1049.