Recognition of Intracranial Hypertension in Children using Handheld Optical Coherence Tomography

Paediatric intracranial hypertension remains an area of major importance amongst the medical community. If undetected, intracranial hypertension can cause blindness, disability and death. The gold standard method for measuring intracranial pressure involves inserting a monitor into the brain under general anaesthesia and admitting the patient into hospital, which is invasive and carries risks. Intracranial hypertension causes the optic nerve head to swell, termed papilloedema. Optical coherence tomography (OCT) may represent a valuable, non-invasive surveillance tool in this role, providing three-dimensional images of the optic nerve head in amazingly minute detail within seconds. Conventional, table-mounted OCT devices are not designed for children, but handheld OCT is child-friendly and feasible in a wide variety of paediatric conditions. This thesis addresses the Past, Present and Future of ophthalmological monitoring in paediatric intracranial hypertension.

The Past is addressed by a systematic review of OCT in paediatric intracranial hypertension. This review identified significant knowledge gaps, with no level 1 evidence for OCT in this role and no study using handheld OCT in craniosynostosis (premature fusion of the cranial sutures) – a major patient group at risk of intracranial hypertension.

The Present is addressed by a retrospective diagnostic accuracy study of visual evoked potentials (VEPs) and fundoscopy in detecting intracranial hypertension in craniosynostosis. These ophthalmological monitoring methods are currently used at Great Ormond Street Hospital (GOSH), London, and other specialist centres. Papilloedema present on fundoscopy reliably indicated intracranial hypertension in this cohort, but due to poor sensitivity, its absence did not exclude intracranial hypertension. Isolated VEPs demonstrated fair sensitivity, which was boosted by longitudinal testing at the expense of specificity.

The Future is addressed by studies using handheld OCT in paediatric intracranial hypertension. These studies found that handheld OCT is feasible and repeatable in children with craniosynostosis, and even feasible in extraordinarily rare craniopagus twins conjoined at the skull. Important optic nerve head differences were identified in craniosynostosis (especially FGFR1/2-associated syndromes) versus healthy controls. Initial findings of the diagnostic accuracy study demonstrated promise for handheld OCT in the recognition of paediatric intracranial hypertension (n=30 children, sensitivity=87.5%; specificity=64.3%).

Future research directions include a larger cohort for the diagnostic accuracy study with subgroup analysis by diagnosis, quantitative ICP analysis, longitudinal OCT analysis and foveal analysis. This work could inform guidelines for the management of paediatric intracranial hypertension. 

Children with craniosynostosis have important morphological differences in the optic nerve head requiring special consideration when assessing for intracranial hypertension. Handheld OCT may strengthen, but not entirely replace, existing evidence-based surveillance methods for paediatric intracranial hypertension. Handheld OCT removes barriers to imaging the eyes of infants and young children at risk of intracranial hypertension.