Background and Purpose Trochlear palsy is the most common cause of vertical diplopia. The etiologies of trochlear palsy have shown a large discrepancy among studies. This study aimed to establish the clinical features and underlying etiologies of isolated trochlear palsy by recruiting the patients from all departments in a referral‐based university hospital. Methods We reviewed the medical records of 1258 patients who had a confirmed diagnosis of isolated trochlear palsy at all departments of Seoul National University Bundang Hospital, Seongnam, South Korea, from 2003 to 2020. We also compared the proportion of etiologies with that of the patients pooled from previous studies. Results The most common etiology was congenital (n = 330, 32.4%), followed by idiopathic (n = 256, 25.1%), microvascular (n = 212, 20.8%), and traumatic (n = 145, 14.2%). These four etiologies explained 92.5% of isolated trochlear palsy. Patients were mostly managed by ophthalmologists (n = 841, 82.5%), followed by neurologists (n = 380, 37.3%), emergency physicians (n = 197, 19.3%), neurosurgeons (n = 75, 7.4%), and others (n = 18, 1.8%). The etiologic distribution of isolated trochlear palsy in the current study did not differ from that of 2664 patients pooled from the previous studies. Conclusions The proportion of etiologies of isolated trochlear palsy differs according to the age ranges of the patients and specialties involved in the management. The etiologic distribution of isolated trochlear palsy in the current study was comparable to the pooled result of previous reports.

Background and Purpose The etiologies of abducens nerve palsy have shown a large variability among studies. This study aimed to establish the clinical features and underlying etiologies of isolated abducens nerve palsy by recruiting patients from all departments in a referral‐based university hospital. Methods We reviewed the medical records of 807 patients with a confirmed diagnosis of isolated abducens nerve palsy at all departments of Seoul National University Bundang Hospital, Seongnam, Republic of Korea, from 2003 to 2020. We also compared the proportion of etiology with that of the patients pooled from the previous studies. Results The most common etiology was microvascular (n = 296, 36.7%), followed by idiopathic (n = 143, 17.7%), neoplastic (n = 115, 14.3%), vascular anomalies (n = 82, 10.2%), inflammatory (n = 76, 9.4%), and traumatic (n = 35, 4.3%). Patients were mostly managed by ophthalmologists (n = 576, 71.4%), followed by neurologists (n = 479, 59.4%), emergency physicians (n = 278, 34.4%), neurosurgeons (n = 191, 23.7%), and others (n = 72, 8.9%). The proportion of etiology significantly differed according to the age and sex of the patients and the specialties involved in the management (p < 0.001). Compared to the pooled data from the previous reports, the current study showed a higher prevalence of microvascular cause but a lower occurrence of traumatic and neoplastic causes. Conclusions The results of previous studies on etiologic distribution of isolated abducens nerve palsy should be interpreted with consideration of the demographic features of patients recruited and the specialties involved.