Paro-Panjan and Neubauer reviewed the diagnostic process for evaluating a neonate with hypotonia. The authors are from University Children's Hospital in Slovenia.
Patient selection: neonate with hypotonia
Causes of central hypotonia identified in their series:
(1) hypoxic ischemic encephalopathy
(2) other encephalopathy
(3) intracranial hemorrahge
(4) cerebral palsy
(5) brain abnormality
(6) chromosomal disorder (Trisomy 21, Trisomy 18, other)
(7) Prader-Will syndrome
(8) other dysmorphic syndromes
(9) joint hyperlaxity
(10) metabolic disorder (congenital defect in glycosylation, Zellweger syndrome, PKU, propionic aciduria, galactosemia)
Causes of peripheral hypotonia identified in their series:
(1) spinal muscular atrophy
(2) neuropathy
(3) neuromuscular junction disorder
(4) congenital myotonic dystrophy
(5) myotubular myopathy
(6) Duchenne muscular dystrophy
(7) benign myopathy
(8) severe myopathy
Most common causes:
(1) hypoxic ischemic encephalopathy
(2) intracranial hemorrhage
(3) trisomy
(4) dysmorphic syndromes
Clinical pathway for working up a neonate with hypotonia (80% of cases identified within the first 4 steps):
(1) clinical assessment (family history, review of pregnancy and delivery, clinical exam)
(2) imaging of the CNS
(3) evaluation for a dysmorphic syndrome
(4) karyotype
(5) biochemical tests for a metabolic disorder
(6) muscle and nerve investigations (EMG, muscle biopsy, etc)
(7) further testing
