(827) Transient Anisocoria due to Subcutaneous Emphysema in a Child With Status Asthmaticus

Introduction: Extra-pulmonary extravasation of air with asthma is well described, however pupillary manifestations from subcutaneous (SQ) emphysema or pneumomediastinum have not been described in the pediatric literature. Rare pneumomediastinum induced anisocoria has been noted in adults. We report the first pediatric case of unilateral mydriasis presumed due to cervical nerve stimulation from severe emphysema.

Description: An obtunded 13-year-old male with status asthmaticus was intubated and transferred to our PICU in extremis with a pH of 6.8 and a PCO2 of 165 mmHg. On arrival, pupillary exam and head CT were normal. Emphysema rapidly developed in the chest, neck, facial and orbital regions, right greater than left, along with a large pneumomediastinum. Despite various ventilation strategies and maximal medical management with continuous albuterol, steroids, aminophylline, magnesium, ketamine, epinephrine and sevoflurane, the decision was made to provide VV ECMO support due to continued hypercarbia and rising lactate. While preparing for ECMO the right pupil acutely dilated (5.7 mm) as compared to the left (2.4 mm) and was minimally responsive. A complete review did not reveal any parasympathetic agent (i.e. ipratropium bromide) at the outside hospital that could have inadvertently affected pupillary exam. Although sedated, the patient was not paralyzed, and his neuro exam had no focal findings. An urgent brain MRI showed no acute process. Femoral VV ECMO commenced within 3 hours of arrival and ventilator settings were then markedly reduced. The following morning, his SQ emphysema was nearly resolved, and pupils were equal and reactive. He required ECMO support for 3 days and discharged 2 weeks later completely neurologically intact. A follow up brain MRI was normal.

Discussion: Transient anisocoria can occur after a cholinergic or alpha-adrenergic drug has inadvertent contact with the patient’s eye. Careful review supported that this was not the etiology in our asthmatic patient. Trauma, inflammation or irritation to neck and lung apex area including pneumomediastinum have been reported to cause anisocoria due to proximity of the superior cervical ganglion. We believe the most likely cause of unilateral mydriasis was severe emphysema in the cervical region and/or mediastinum.