Horner`s Syndrome after internal jugular vein catheterization: a case report.

Context: Central venous catheterization of the internal jugular vein is a common procedure that can be complicated with Horner`s Syndrome, caused by a direct lesion of cervical sympathetic pathways, pneumothorax compression, or carotid dissection. This entity should be considered when assessing new anisocoria in intensive care scenarios. Case Report: We report the case of a 64-year-old woman, who presented anisocoria during an intensive care unit hospitalization. She had been admitted with severe COVID-19 and need for mechanical ventilation. Her anisocoria was more evident in the dark, with right miosis, ipsilateral semi-ptosis, and preserved photoreaction reflexes. Before the anisocoria, she had a venous catheter inserted in her right jugular vein. Further evaluation showed a right pneumothorax, which was promptly drained after the mispuncture. The cervical arterial angiotomography showed no signs of carotid dissection. Conclusion: New anisocoria in critical patients is usually associated with impairment of the parasympathetic tonus, either by the use of topic or inhalatory anticholinergic drugs or cerebral herniation syndrome. However, in these situations, the anisocoria is more appreciable in light, with disruption of photoreaction in the greater pupil and ipsilateral ptosis. Therefore, we believe our patient developed an iatrogenic Horner`s Syndrome, secondary to a catheterization mispuncture, leading to a direct lesion of sympathetic pathways and their compression by the pneumothorax. Beyond parasympathetic pharmacologic blockade or cerebral herniation, Horner`s Syndrome constitutes a valuable differential diagnosis when evaluating patients with new anisocoria in the ICU.