A large proportion of patients with Horner syndrome (HS) has no identifiable cause of the sympathetic deficit. This study examines the long-term evolution of such patients having idiopathic HS .
Patients diagnosed with a unilateral HS at a university-based hospital between 1995 and 2017 were identified. All patients had negative imaging studies. A paper-based questionnaire was used to update their medical status.
Twenty-seven patients completed the questionnaire. Follow-up from diagnosis was 3 to 20 years. At diagnosis, all patients had an anisocoria, 85% had ptosis and 3 patients reported sudomotor and/or vasomotor symptoms. After diagnosis, three patients underwent surgical correction of ptosis. Of the remaining patients, ptosis was unchanged in 50%, 20% reported spontaneous resolution and 10% improved. In 20% of patients, ptosis had worsened. The vasomotor and sudomotor manifestations were unchanged. No patient developed a contralateral HS. The prevalence of other medical conditions that developed after Horner diagnosis was similar to that of the general population.
The prognosis of idiopathic unilateral HS is benign. About one-third of patients have spontaneous improvement or resolution of Horner-associated ptosis. There was no increased risk of developing any specific medical disorder, suggesting that long-term follow-up is not needed in these patients.