Fractures due to non-accidental injury should always be considered, however differentials such as osteogenesis imperfecta and rare neuropathies are additional possibilities.
This case study presents a 2 year-old boy admitted via A&E with unexplained fractures to his right tibia and fibula. The injuries and additional concerns regarding late presentation resulted in child protection proceedings being initiated. He and his younger sister were initially placed by social care with a family friend under a working agreement. Two months post-discharge he was readmitted due to concerns regarding worsening of the same fracture.
He was born at term via caesarean section for breech delivery to consanguineous Pakistani parents. A systematic examination identified eczema and bites to tongue and fingers resulting in a deep cut to the tongue – requiring surgery. He was fully mobile but displayed challenging behaviour and developmental delay; no neurological abnormalities were identified on examination. Parents noted he did not appear to feel pain, this was confirmed by healthcare professionals during vaccinations. Though family were considered vulnerable no concerns had been raised by primary care and outpatient appointments (maxillofacial, dental, paediatric) had been attended.
Standard investigations (Table 1) undertaken on each admission detected a raised alkaline phosphatase and displaced transverse fractures through the right mid-diaphysis of both tibia and fibula with anterior soft tissue swelling (Figure 1) only. He had normal nerve conduction studies however molecular investigations for Hereditary Sensory and Autonomic Neuropathy (HSANs) showed homozygous mutation of the NTRK1 gene confirming HSAN IV or Congenital Insensitivity to Pain Syndrome (CIPA), one of five recognised HSAN subtypes.
This extremely rare autosomal recessive condition is characterised by the absence of pain and temperature sensation, anhidrosis and mental retardation. Patients also suffer from oral mutilation, fractures, bruises and lacerations of extremities secondary to pain insensitivity due to abnormalities in peripheral nerves.
This case illustrates the difficulty in differentiating non-accidental injury from CIPA. Whilst child abuse should always be considered practitioners should be mindful of rarer disorders such as CIPA. It should also be acknowledged that children with CIPA can also be victims of child abuse.
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