Quantitative Pupillometry in Brain Injury Children : Variation After Osmotherapy

Quantitative Pupillometry in Brain Injury Children : Variation After Osmotherapy

Intracranial hypertension (ICH) is a common and serious complication in children admitted to pediatric intensive care units. It is primarily caused by traumatic brain injury but can also result from brain malformations, brain tumors, or neuro-meningeal infections. Rapid identification of ICH in acute settings is crucial to ensure prompt management and mitigate potential consequences, such as severe neurological sequelae or death.

The assessment of the pupillary light reflex is one of the key clinical parameters used to identify ICH in children with neurological injuries. This clinical sign is correlated with neurological prognosis. During an episode of ICH, regardless of the underlying cause, the oculomotor nerve becomes compressed between the midbrain and the temporal lobe, leading to anisocoria (unequal pupil sizes) and loss of pupillary reactivity. Other factors, such as episodes of ischemia or hypoperfusion in the midbrain, can also contribute to decreased pupillary reactivity.

Traditionally, the pupillary light reflex is assessed using a simple light source, with subjective evaluation by a healthcare professional. However, this method has significant inter- and intra-individual variability. Quantitative pupillometry offers a more objective and reproducible way to evaluate pupillary reactivity. In adults, some parameters are well-known indicators of ICH, such as a constriction velocity of less than 0.6 mm/sec and a constriction percentage below 10%. The constriction percentage can be simplified with the Neurological Pupil index (NPI), which ranges from 0 to 5. An NPI of 4 or 5 is considered to indicate good pupillary reactivity. The two quantitative pupillometers currently on the market (Neurolight, Neuroptics) appear to provide similar data for most variables assessed. However, there are few studies evaluating this tool in pediatric patients with neurological injuries.

One study on quantitative pupillometry found that children with neurological injuries and an intracranial pressure (ICP) above 20 mmHg had significantly lower pupillary reactivity, NPI, constriction percentage, and dilation and constriction velocities compared to children without ICH.

Osmotherapy is a commonly used pharmacological intervention in pediatrics to lower intracranial pressure and improve cerebral perfusion pressure. Based on the work of Freeman et al., we hypothesize that the pupillary constriction percentage improves after osmotherapy in children with neurological injuries.

Inclusion Criteria:

• Hospitalized in a pediatric intensive care unit or neurosurgical intensive care unit
• Inclusion within 24 hours of ICU admission
• with clinically suspected HTIC (disorders of consciousness with transcranial Doppler abnormality, symptoms of involvement, poor cerebral perfusion pressure) for which osmotherapy is prescribed

Exclusion Criteria:

• Presence of eye damage (or antecedent)
• Refusal by parents and/or child Opposition by child or parental guardians.
• Persons not affiliated to the social security system.
• Protected persons (under guardianship, curatorship, pregnant or breast- feeding women, persons deprived of their liberty, persons not subject to a psychiatric measure