Paeds Cases · neurology-neurodisability-and-neuromuscular
Spinal muscular atrophy: Case
Clinical case of a 4-month-old infant with type 1 spinal muscular atrophy presenting with progressive floppiness, covering the bright-and-floppy pattern of symmetric proximal weakness with absent reflexes and tongue fasciculations and spared intellect, the genetic diagnosis by homozygous SMN1 deletion with SMN2 copy number, the respiratory resuscitation for neuromuscular ventilatory failure, the urgent disease-modifying therapy choice between nusinersen risdiplam and onasemnogene abeparvovec using the ENDEAR FIREFISH and STR1VE evidence, the multidisciplinary respiratory nutritional and orthopaedic care, and the prognosis and family counselling with the one in four recurrence risk.
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Summary and immediate impression
This infant presents a textbook case of type 1 spinal muscular atrophy, or Werdnig-Hoffmann disease. The reduced fetal movements, the severe symmetric proximal weakness worse in the legs, the absent deep tendon reflexes, the tongue fasciculations, and the paradoxical breathing with a bell-shaped chest, all in a bright and socially engaged child whose intellect is spared, are the signature picture. The contrast between the alert face and the limp body is the single most valuable bedside clue, and the diagnosis is the homozygous SMN1 deletion test. [1]
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- [1]Mercuri E, Finkel RS, Muntoni F, et al Diagnosis and management of spinal muscular atrophy: Part 1: Recommendations for diagnosis, rehabilitation, orthopedic and nutritional care. Neuromuscul Disord, 2018.PMID 29290580
- [2]Finkel RS, Mercuri E, Meyer OH, et al Diagnosis and management of spinal muscular atrophy: Part 2: Pulmonary and acute care; medications, supplements and immunizations; other organ systems; and ethics. Neuromuscul Disord, 2018.PMID 29305137
- [4]Finkel RS, Mercuri E, Darras BT, et al. Nusinersen versus Sham Control in Infantile-Onset Spinal Muscular Atrophy. N Engl J Med, 2017.PMID 29091570
- [6]Mendell JR, Al-Zaidy S, Shell R, et al Single-Dose Gene-Replacement Therapy for Spinal Muscular Atrophy. N Engl J Med, 2017.PMID 29091557
- [8]Baranello G, Darras BT, Day JW, et al. Risdiplam in Type 1 Spinal Muscular Atrophy. N Engl J Med, 2021.PMID 33626251
- [9]De Vivo DC, Bertini E, Swoboda KJ, et al. Nusinersen initiated in infants during the presymptomatic stage of spinal muscular atrophy: Interim efficacy and safety results from the Phase 2 NURTURE study. Neuromuscul Disord, 2019.PMID 31704158
- [11]Cooper K, Nalbant G, Sutton A, et al. Systematic Review of Presymptomatic Treatment for Spinal Muscular Atrophy. Int J Neonatal Screen, 2024.PMID 39189228