The floppy infant: evaluation of hypotonia.
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)
Peredo
Dawn E
DE
Madigan Army Medical Center, Tacoma, Wash., USA.
Hannibal
Mark C
MC
D001921:Brain / Q000503:physiopathology; D002540:Cerebral Cortex / Q000503:physiopathology; D002675:Child, Preschool; D003248:Constipation / Q000209:etiology; D005207:Fasciculation / Q000209:etiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007596:Joints / Q000503:physiopathology; D008297:Male; D009123:Muscle Hypotonia / Q000235:genetics* / Q000503:physiopathology*; D018482:Muscle, Skeletal / Q000503:physiopathology; D009469:Neuromuscular Junction / Q000503:physiopathology; D011187:Posture; D014314:Trisomy / Q000235:genetics