Introduction: Hypotonia is a common presentation that child neurologists encounter daily. The hypotonic neonate represents a diagnostic challenge as a lesion at any level in the neuro-axis may cause hypotonia. In this paper, we study the diagnostic yield of investigations commonly used as part of a hypotonia work-up.
Methods: A 12-year retrospective cohort study was conducted at a tertiary care center in Saudi Arabia from 2007 to 2018. Final diagnoses, clinical presentations, laboratory tests, imaging and genetic studies were reviewed from the patient's electronic health records.
Results: 164 patients were identified as fitting the inclusion criteria of the study. 50% had central hypotonia, 18% peripheral hypotonia and 32% mixed hypotonia. Molecular testing was performed for 82% (74) of patients. 65 Microarray studies were done; 27% abnormal and 9% diagnostic. 55 gene panels were done; 58% abnormal and 30% diagnostic. 53 single-gene tests were done; 57% abnormal and 40% diagnostic. 61 whole exome sequences were done; 72% positive and 59% diagnostic. 126 MRIs were reviewed; 56% abnormal and 33% contributed to the diagnosis.
Conclusion: Molecular genetic testing is our recommended next step in the diagnosis of patients with hypotonia after careful phenotyping. Neuroimaging is helpful to guide further costly workup of patients with hypotonia.
Keywords: CH, Central Hypotonia; CK, Creatine Kinase; CNS, Central Nervous System; Central hypotonia; EEG, Electroencephalography; EMG, Electromyography; MH, Mixed Hypotonia; MRI brain; MRI, Magnetic resonance imaging; Mixed hypotonia; Molecular genetics; NCS, Nerve Conduction Studies; PH, Peripheral Hypotonia; Peripheral hypotonia; RNS, Repetitive Nerve Stimulation; VLCFA, Very-Long-Chain Fatty Acids; WES, Whole-Exome Sequencing; Whole exome sequencing; aCGH, Microarray-based Comparative Genomic Hybridization.
© 2020 The Authors.