Diagnostic difficulties in the floppy neonate

Abstract

<h3>Background</h3> A term baby with no significant maternal, family or antenatal history was born in poor condition necessitating resuscitation which included intubation, cardiac compressions and subsequent admission to our NICU. On admission, he was noted to be markedly hypotonic, with absent gag and suck reflexes and displayed minimal spontaneous movements. Initially felt to be hypoxic ischaemic encephalopathy, he had a normal cranial ultrasound and normal EEG/CFM findings. <h3>Progress and management</h3> Invasive ventilation continued for 7 days, before extubation to BiPAP and later CPAP. He had frequent apnoeic and bradycardic episodes, including 2 respiratory arrests requiring resuscitation. A total of 76 days of respiratory support was needed. Full examination found a large, dolichocephalic head, adducted thumbs, cryptorchidism and a heart murmur (ECHO revealed a VSD, PDA and pericardial effusion). Neurological signs persisted, with hypotonia noted to be more significant in the upper versus lower limbs. Numerous sub-speciality reviews were undertaken, including genetics, neurology and metabolic. An abundance of investigations were performed which included MRI (structurally normal, immature brain), barium swallow, renal imaging, metabolic screen, karyotyping and EMG. No specific abnormalities were identified, and conditions such as Prader-willi, Soto9s, SMA and myotonic dystrophy were excluded. <h3>Outcome and issues</h3> He was eventually discharged from NICU at 100 days old, with NG feeds as he was felt to have an unsafe swallow, and with no formal diagnosis being made. Unfortunately, he was readmitted to hospital 3 weeks after discharge, with increased work of breathing and decreased oxygen saturations, with investigations revealing a rhinovirus and parainfluenza virus positive pneumonia. This episode required PICU admission for ventilation and ultimate tracheostomy placement. In view of continued hypotonia without diagnosis, a decision was made to perform a muscle biopsy. This revealed a diagnosis of myotubular myopathy. Our patient was eventually discharged home being non-invasive positive pressure ventilation dependant and with palliative care input. This case highlights the complexities of ascertaining a diagnosis in the hypotonic neonate, and the need for involvement of multiple members of the paediatric and sub-speciality teams.