Tongue Fasciculations and Electrocardiographic Tremors in Spinal Muscular Atrophy

A 6-year-old girl, born out of a nonconsanguineous union, presented with delayed motor milestones. On examination, she had a normal head size; normal cognitive, social, and language function, tongue fasciculations (Video; available at www.jpeds.com), generalized hypotonia, proximal muscle weakness involving lower limbs more than upper limbs, and areflexia. The examinations of other systems were unremarkable. Her nerve conduction studies and echocardiography were normal. A 12-lead electrocardiogram (ECG) showed muscle fasciculations (Figure). We did not perform electromyography as ECG showed fasciculations. A genetic study (polymerase chain reaction) revealed a homozygous deletion in SMN1 gene in the child. Parents were heterozygous carriers of the same mutation. ECG tremors are present in 50%-60% patients with spinal muscular atrophy.1Dawood A.A. Moosa A. Hand and ECG tremor in spinal muscular atrophy.Arch Dis Child. 1983; 58: 376-378Crossref PubMed Scopus (14) Google Scholar Chronic re-innervation of alpha motor neurons produces somatic muscle fasciculations that manifest as tremors during ECG tracing.2Coletta C. Carboni P. Carunchio A. Porro G. Bacci V. Electrocardiographic abnormalities in childhood spinal muscular atrophy.Int J Cardiol. 1989; 24: 283-288Abstract Full Text PDF PubMed Scopus (12) Google Scholar These tremors may also be seen in other anterior horn cell diseases, like poliomyelitis. In the relevant clinical context, the presence of ECG tremors, coupled with tongue fasciculations suggests the diagnosis of spinal muscular atrophy. eyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiI0NjE4MjI2ZWEyMjk0YzcyN2U0ZGFkNWZjNWFhMWM3YiIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjMxODExMTQyfQ.IBImbkQdvGxqm5FjuZrEWiVye0iPc1b9tN3HpJimgSp0Bm61BWVRxRhZMRDhCmV-Z-AUb1KhNINIJ1Rd2nHsK_i3TigbRpBLaIomjpFnxJG32RfqYdG6tvjF4urqAzEEZyEF51ZHFTHu5WzgOKJ24wh-uEIl22_FKc8sKQxHy7lzK4nEwACUjhpVpqDgyypuh_0k5xYA6lo4T3Xd1OuKPobJtPsUdBpUNYMg1MKRI-A4VHKYoYAh4ZP2CMJr_w-WDM_MXTqOpiYiN8EOKUYITavoqAgRKvOT8fCpT1YE2wWOSA24nUmm5xg-Srll0A1baELJJqkp-PMXcgTYUCkLyQ Download .mp4 (1.55 MB) Help with .mp4 files VideoNote the continuous, involuntary undulating tongue fasciculations in this child with spinal muscular atrophy.