{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,27]],"date-time":"2026-09-27T13:42:33Z","timestamp":1790516553650,"version":"4.1.0"},"reference-count":41,"publisher":"BMJ","issue":"1","license":[{"start":{"date-parts":[[2020,10,26]],"date-time":"2020-10-26T00:00:00Z","timestamp":1603670400000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["J Neurol Neurosurg Psychiatry"],"published-print":{"date-parts":[[2021,1]]},"abstract":"<jats:sec><jats:title>Objectives<\/jats:title><jats:p>To elucidate the motor unit response to intrathecal nusinersen in children with symptomatic spinal muscular atrophy (SMA) using a novel motor unit number estimation technique.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>MScanFit MUNE studies were sequentially undertaken from the abductor pollicis brevis muscle after stimulation of the median nerve in a prospective cohort of symptomatic children with SMA, undergoing intrathecal treatment with nusinersen at a single neuromuscular centre from June 2017 to August 2019. Electrophysiological measures included compound muscle action potential (CMAP), motor unit number estimation (MUNE), motor unit number contributing to 50%\u2013100% of CMAP (N50) and measures of collateral reinnervation including largest single motor unit potential (LSMUP) and amplitude of the smallest unit contributing to N50 (A50).<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Twenty children (median age 99 months, range 4\u2013193) were followed for a median of 13.8 (4\u201333.5) months. Therapeutic intervention was an independent and significant contributor to an increase in CMAP (p = 0.005), MUNE (p = 0.001) and N50 (p = 0.04). The magnitude of this electrophysiological response was increased in children with shorter disease durations (p&lt;0.05). Electrophysiological changes delineated children who were functionally stable from those who attained clinically significant gains in motor function.<\/jats:p><\/jats:sec><jats:sec><jats:title>Interpretation<\/jats:title><jats:p>Nusinersen therapy facilitated functional innervation in SMA through recovery of smaller motor units. Delineation of biomechanisms of therapeutic response may be the first step in identifying potential novel targets for disease modification in this and other motor neuropathies. MScanFit MUNE techniques may have a broader role in establishing biomarkers of therapeutic response in similar adult-onset diseases.<\/jats:p><\/jats:sec>","DOI":"10.1136\/jnnp-2020-324254","type":"journal-article","created":{"date-parts":[[2020,10,26]],"date-time":"2020-10-26T21:26:27Z","timestamp":1603747587000},"page":"78-85","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":57,"title":["Motor unit changes in children with symptomatic spinal muscular atrophy treated with nusinersen"],"prefix":"10.1136","volume":"92","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4176-4010","authenticated-orcid":false,"given":"Didu","family":"Kariyawasam","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arlene","family":"D'Silva","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"James","family":"Howells","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karen","family":"Herbert","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Peter","family":"Geelan-Small","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cindy Shin-Yi","family":"Lin","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4472-0902","authenticated-orcid":false,"given":"Michelle Anne","family":"Farrar","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2020,10,26]]},"reference":[{"key":"2021022403000726000_92.1.78.1","doi-asserted-by":"crossref","first-page":"786","DOI":"10.1007\/s13311-014-0293-y","article-title":"Spinal muscular atrophy: journeying from bench to bedside","volume":"11","author":"Awano","year":"2014","journal-title":"Neurotherapeutics"},{"key":"2021022403000726000_92.1.78.2","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/j.nmd.2008.10.004","article-title":"Ramblings in the history of spinal muscular atrophy","volume":"19","author":"Dubowitz","year":"2009","journal-title":"Neuromuscul Disord"},{"key":"2021022403000726000_92.1.78.3","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1016\/0092-8674(95)90460-3","article-title":"Identification and characterization of a spinal muscular atrophy-determining gene","volume":"80","author":"Lefebvre","year":"1995","journal-title":"Cell"},{"key":"2021022403000726000_92.1.78.4","doi-asserted-by":"crossref","DOI":"10.1177\/1756286418776932","article-title":"Antisense oligonucleotides in neurological disorders","volume":"11","author":"Wurster","year":"2018","journal-title":"Ther Adv Neurol Disord"},{"key":"2021022403000726000_92.1.78.5","doi-asserted-by":"crossref","first-page":"625","DOI":"10.1056\/NEJMoa1710504","article-title":"Nusinersen versus sham control in Later-Onset spinal muscular atrophy","volume":"378","author":"Mercuri","year":"2018","journal-title":"N Engl J Med"},{"key":"2021022403000726000_92.1.78.6","doi-asserted-by":"crossref","DOI":"10.3389\/fneur.2019.00898","article-title":"Biomarkers and the development of a personalized medicine approach in spinal muscular atrophy","volume":"10","author":"Kariyawasam","year":"2019","journal-title":"Front Neurol"},{"key":"2021022403000726000_92.1.78.7","doi-asserted-by":"publisher","DOI":"10.1136\/jnnp-2019-322327"},{"key":"2021022403000726000_92.1.78.8","doi-asserted-by":"crossref","first-page":"391","DOI":"10.1016\/S1050-6411(98)00020-0","article-title":"1998 ISEK Congress Keynote Lecture: motor units: how many, how large, what kind? 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