Optic nerve sheath diameter measurement for the paediatric patient with an acute deterioration in consciousness

Ocular Point of Care Ultrasound (PoCUS) is emerging as a valuable utility within emergency medicine. Optic nerve sheath diameter (ONSD) has been demonstrated to correlate closely with intracranial pressure (ICP) and an elevated measurement can detect raised ICP readily, where fundoscopy may not, owing to both technical challenges and insufficient clinical skills. A previously fit and well 10-year-old girl presented to the paediatric emergency department with worsening headache, fever and lethargy. On examination, her left pupil was large, and not reactive to light. Initially, her GCS was 15 but suddenly dropped to 8/15. Her blood tests showed raised inflammatory markers. A CT head was reported as possible pansinusitis and MRI of her brain was initially reported as showing evidence of meningeal irritation only. Due to her drop in GCS PoCUS of optic nerve sheath was conducted which showed evidence of increased ICP with increased optic nerve sheath diameter of 6.8mm. This led to a reassessment of the MRI imaging by the neurosurgical team who felt there was evidence of subdural empyema. The patient was transferred to the tertiary neurosurgical centre, where an emergency evacuation of subdural empyema was carried out. Staphylococcus aureus and Streptococcus pyogenes were grown from pus samples. Early detection of raised ICP is of paramount importance in terms of being able to instigate neuroprotective measures and prevent adverse neurological outcomes. PoCUS is a readily available, non-irradiating, easily repeatable, well-tolerated and readily teachable ultrasound modality and a useful tool which should be employed in paediatric and adult emergency departments.