The floppy infant: evaluation of hypotonia

Pediatr Rev. 2009 Sep;30(9):e66-76. doi: 10.1542/pir.30-9-e66.

Abstract

Hypotonia is characterized by reduced resistance to passive range of motion in joints versus weakness, which is a reduction in the maximum muscle power that can be generated. (Dubowitz, 1985; Crawford, 1992; Martin, 2005) Based on strong research evidence, central hypotonia accounts for 60% to 80% of cases of hypotonia, whereas peripheral hypotonia is the cause in about 15% to 30% of cases. Disorders causing hypotonia often are associated with a depressed level of consciousness, predominantly axial weakness, normal strength accompanying the hypotonia, and hyperactive or normal reflexes. (Martin, 2005; Igarashi, 2004; Richer, 2001; Miller, 1992; Crawford, 1992; Bergen, 1985; Dubowitz, 1985) Based on some research evidence, 50% of patients who have hypotonia are diagnosed by history and physical examination alone. (Paro-Panjan, 2004) Based on some research evidence, an appropriate medical and genetic evaluation of hypotonia in infants includes a karyotype, DNA-based diagnostic tests, and cranial imaging. (Battaglia, 2008; Laugel, 2008; Birdi, 2005; Paro-Panjan, 2004; Prasad, 2003; Richer, 2001; Dimario, 1989) Based on strong research evidence, infant botulism should be suspected in an acute or subacute presentation of hypotonia in an infant younger than 6 months of age who has signs and symptoms such as constipation, listlessness, poor feeding, weak cry, and a decreased gag reflex. (Francisco, 2007; Muensterer, 2000)

MeSH terms

  • Brain / physiopathology
  • Cerebral Cortex / physiopathology
  • Child, Preschool
  • Constipation / etiology
  • Fasciculation / etiology
  • Female
  • Humans
  • Infant
  • Infant, Newborn
  • Joints / physiopathology
  • Male
  • Muscle Hypotonia / genetics*
  • Muscle Hypotonia / physiopathology*
  • Muscle, Skeletal / physiopathology
  • Neuromuscular Junction / physiopathology
  • Posture
  • Trisomy / genetics