Horner syndrome due to right subclavian artery dissection: Case report

This is a novel case of spontaneous subclavian artery dissection presenting with an asymptomatic right Horner Syndrome, highlighting both the importance of carefully evaluating the pupils on comprehensive exam, and also the subclavian arteries when assessing for the cause of Horner Syndrome. This original case serves as a caution for practitioners not to overlook the subclavian arteries in the search for the cause of Horner Syndrome. While rare, spontaneous subclavian artery dissection can occur, and carries a risk of morbidity and mortality that must be mitigated. We present a case of asymptomatic, atraumatic right Horner Syndrome where a spontaneous right subclavian artery dissection was found to be the source. It was managed with aspirin therapy and the patient has not suffered any subsequent cardiovascular events related to the dissection. Careful angiographic evaluation of the subclavian arteries should be included in the workup for Horner Syndrome to assess for subclavian artery dissection.