Suspecting of neuromuscular disease in newborns: Clinical variables more suggestive of the diagnosis in 20 years of experience

Abstract

Introduction: The suspicion of neuromuscular disease (NMD) in newborns admitted to the Neonatal Intensive Care Unit (NICU) is based on several clinical aspects. It is important to know which variables are most frequently associated with the diagnosis. Objectives: To assess the prevalence of NMD in a population of newborns with this suspicion and to quantify (sensitivity [S], specificity [E], positive predictive value [PPV], and negative predictive value [NPV]) the contribution of the main clinical variables associated to the diagnosis. Methods: This is a retrospective study, based on the consultation of the NICU files, from 1995 to 2015, using the following keywords: “neuromuscular”, “muscular”, “hypotonia”, “arthrogryposis”, “malformation” and “paresis”. Of the cases identified, data were collected on obstetric history and neurological signs/symptoms identified in the early neonatal period. Results: Sixteen cases of suspected NMD were identified, 9 of which were female (56%). Eight cases (50%) were diagnosed with NMD: 5 myotonic dystrophies (62.5%), 1 unspecified muscular dystrophy (12.5%) and 2 type 1 spinal muscular atrophies (25%). There were 10 deaths (autopsies were performed in 5) among the cases studied, of which 6 (60%) occurred in newborns with NMD. The clinical variables that were significantly associated with the diagnosis of NMD were: perception of decreased fetal movements (p = 0.021), hypotonia (p = 0.001), facial dysmorphism (p = 0.001), respiratory distress (p = 0.001) and need for invasive ventilation (p = 0.004). For each of these variables, the following properties were obtained: perception of decreased fetal movements (S > 99.0%, E = 37.5%, PPV = 61.5%, NPV > 99.0%); hypotonia (S > 99.0%, E = 12.5%, PPV = 53.3%, NPV > 99.0%); facial dysmorphism (S > 99.0%, E = 12.5%, PPV = 53.3%, NPV > 99.0%); respiratory distress (S > 99.0%, E = 12.5%, PPV = 53.3%, NPV > 99.0%) and need for invasive ventilation (S = 87.5%, E = 12.5%, PPV = 50.0%, NPV = 50.0%). Conclusion: In the NICU, a hypotonic newborn with facial dysmorphism, respiratory distress and need for invasive ventilation, with a previous history of decreased fetal movements, may raise the suspicion of having a NMD.