Scoliosis Surgery Significantly Impacts Motor Abilities in Higher-functioning Individuals with Spinal Muscular Atrophy¹

Article type: Research Article

Authors: Dunaway Young, Sally^{a; b; c; *} | Montes, Jacqueline^{a; b} | Salazar, Rachel^a | Glanzman, Allan M.^d | Pasternak, Amy^{e; f} | Mirek, Elizabeth^{e; f} | Martens, William^g | Finkel, Richard S.^h | Darras, Basil T.^e | De Vivo, Darryl C.^a

Affiliations: [a] Department of Neurology, Columbia University Irving Medical Center, New York, NY, USA | [b] Department of Rehabilitation and Regenerative Medicine, Columbia University Irving Medical Center, New York, NY, USA | [c] Department of Neurology, Stanford University School of Medicine, Stanford, CA, USA | [d] Department of Physical Therapy, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA | [e] Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA | [f] Department of Physical Therapy and Occupational Therapy, Boston Children’s Hospital, Boston, MA, USA | [g] Department of Neurology, University of Rochester, Rochester, NY, USA | [h] Department of Pediatrics, Division of Neurology, Nemours Children’s Hospital, Orlando, FL, USA

Correspondence: [*] Correspondence to: Sally Dunaway Young, Completed work while at Columbia University and is now employed at Stanford University. Address: 2652 East Bayshore Road MC 5267 Palo Alto, CA 94303, USA. Tel.: +1 650 497 0075; Fax: +1 650 736 6603; E-mail: sdy@stanford.edu.

Note: [1] Publication History: This abstract was previously published in Neurology Supplement April 05, 2016; 86 (16 Supplement): https://n.neurology.org/content/86/16_Supplement/P5.006 and in Neuromuscular Disorders Supplement Volume 26, Supplement 2, October 2016, Page S104: https://www.sciencedirect.com/science/article/pii/S0960896616303637

Abstract: Background:Weakness affects motor performance and causes skeletal deformities in spinal muscular atrophy (SMA). Scoliosis surgery decision-making is based on curve progression, pulmonary function, and skeletal maturity. Benefits include quality of life, sitting balance, and endurance. Post-operative functional decline has not been formally assessed. Objective:To assess the impact of scoliosis surgery on motor function in SMA types 2 and 3. Methods:Prospective data were acquired during a multicenter natural history study. Seventeen participants (12 type 2, 5 type 3 with 4 of the 5 having lost the ability to ambulate) had motor function assessed using the Hammersmith Functional Motor Scale Expanded (HFMSE) performed pre-operatively and at least 3 months post-operatively. Independent t-tests determined group differences based on post-operative HFMSE changes, age, and baseline HFMSE scores. Results:Three participants had minimal HFMSE changes (±2 points) representing stability (mean change = –0.7). Fourteen participants lost >3 points, representing a clinically meaningful progressive change (mean change = –12.1, SD = 8.9). No participant improved >2 points. There were no age differences between stable and progressive groups (p = 0.278), but there were significant differences between baseline HFMSE (p = 0.006) and change scores (p = 0.001). Post-operative changes were permanent over time. Conclusions:Scoliosis surgery has an immediate impact on function. Baseline HFMSE scores anticipate post-operative loss as higher motor function scores were associated with worse decline. Instrumentation that includes fixation to the pelvis reduces flexibility, limiting the ability for compensatory maneuvers. These observations provide information to alert clinicians regarding surgical risk and to counsel families.

Keywords: Spinal muscular atrophy, scoliosis, surgery, motor function

DOI: 10.3233/JND-190462

Journal: Journal of Neuromuscular Diseases, vol. 7, no. 2, pp. 183-192, 2020