Type IV Hereditary Sensory and Autonomic Neuropathy: Challenges and Functional Outcomes.

BACKGROUND

Type IV Hereditary Sensory and Autonomic Neuropathy (HSAN IV) is an exceedingly rare autosomal recessive disease classically characterized by generalized loss of temperature/pain sensation, intellectual disability, and anhidrosis. HSAN IV patients are subject to repeated orthopaedic injuries and complications. There is some data on the clinical presentation, but limited data on the diagnostic and treatment challenges, and functional outcomes with HSAN IV.

METHODS

This is a retrospective case series of 4 siblings with HSAN IV. Medical records were reviewed for data regarding presentation, diagnosis, and management. Functional outcomes were assessed using the Pediatric Outcomes Data Collection Instrument, with historical normative data used as a control. The 2 populations were evaluated with a Welch-modified 2-sample t test to explore the alternative hypothesis that HSAN IV patients are significantly functionally impaired.

RESULTS

Our study included 4 siblings, 2 males and 2 females, aged 3, 8, 12, and 21 years, respectively. The average time to diagnosis was 53 months, and each diagnosis was confirmed through whole-exome sequencing. The challenges faced included delayed diagnosis, diverse clinical presentations, unestablished treatment guidelines, and unnecessary healthcare utilization before definitive diagnosis. The comparison of means between the normative population and the HSAN IV patients revealed a significant difference in sports/play ( T -score =-4.14, P =0.025) and global function ( T -score =-3.19, P =0.049) but no significant difference in upper extremity function ( P =0.216), transfer mobility ( P =0.164), pain/comfort ( P =0.955), and happiness ( P =0.995).

CONCLUSIONS

HSAN IV is a rare genetic condition with protean clinical manifestations that can result in significant deficits in play and global function. The clinical manifestations are varied, including multiple fractures, delayed/abnormal fracture healing, bone deformity, osteomyelitis, and various other non-orthopaedic manifestations. Whole-exome sequencing is a useful tool that, when combined with a high index of clinical suspicion, can expedite the diagnostic process for HSAN IV. Patients can benefit from earlier diagnosis and earlier access to education to prevent functional deterioration and repeat medical interventions.

LEVEL OF EVIDENCE: IV-case series.