frequency and causes of hypotonia in neonatal period with the gestational age of more than 36 weeks in nicu of mofid children hospital during 2012-2014

abstract hypotonia is a serious neurologic problem in neonatal period. although hypotonia is a nonspecific clinical finding but it is the most common motor disorder in the newborn. the objective of this study was to determine the frequency of neonatal hypotonia then to ascertain of the most common causes methods this cross –sectional prospective study was carried out on the 3281 term infants hospitalized in conventional and nicu of mofid children ,s hospital during 2012-2014 .diagnosis was made by history, physical & neurological examination and accessible diagnostic tests. results  fifty nine hypotonic neonates were identified , forty seven(79.6%) had central hypotonia ( hypoxic ischemic encephalopathy(n= 2),other encephalopathies( n= 2) , intracranial hemorrhage(n= 4), cns abnormalities (n= 7), chromosomal disorders(n= 4), syndromic –nonsyndromic(n= 8), and metabolic diseases(n= 8 ). peripheral hypotonia recognized in 6infants (10.7%); spinal muscular atrophy (n= 1), and congenital muscular hypotonia (n= 5) .and 6 cases (10.7%) remained unclassified. twelve infants had transient hypotonia. in final study 18 of 59 infants (30%) died, nearly 90% before one year of age .28(47%) infants found developmental disorders and only 13(22%) infants achieved normal development in their follow up . conclusion neonatal hypotonia is a common event in neonatal period. a majority of diagnosis obtained by history and physical examination .neuroimaging, genetic and metabolic tests were also important in diagnosis. this study demonstrated that genetic, syndromic –non syndromic, and metabolic disorders were the most causes of neonatal hypotonia.