Etiologic distribution of isolated trochlear palsy: Analysis of 1020 patients and literature review

Abstract

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.

Etiologic distribution of isolated abducens nerve palsy: Analysis of 807 patients and literature review

“…Compared to our previous study on isolated trochlear palsy [30], patients with abducens nerve palsy more frequently visited the emergency department first (30.1% vs. 17.8%, p < 0.001). This may be explained by a higher proportion of etiologies causing the acute or subacute onset of diplopia such as microvascular (36.7% vs. 20.8%), vascular anomalies (10.2% vs. 1.3%), and inflammatory (9.4% vs. 1.5%), and a lower proportion of congenital etiology (1.2% vs. 32.4%) in isolated abducens nerve palsy than in isolated trochlear palsy.…”

“…In this study, the specialties involved in the management of isolated abducens nerve palsy differed markedly depending on the etiology. Even though the ophthalmologists were mostly involved in the management of isolated abducens nerve palsy, the proportion of involvement was lower than in isolated trochlear palsy observed in our previous study on isolated trochlear palsy (82.5% vs. 71.4%, p < 0.001) [30]. This discrepancy seems to be also related to the difference in the proportion of etiology between isolated abducens and trochlear palsies, with a lower portion of congenital etiology in isolated abducens nerve palsy (1.2% vs. 32.4%, p < 0.001).…”

“…We compared the results of this study with those of our previous report on isolated trochlear palsy, which was performed in the same institution with the same methods during the same period [30].…”

“…Previous studies were primarily performed in referral‐based neuro‐ophthalmologic clinics run exclusively by ophthalmologists or neurologists, which would have introduced a referral or inclusion bias. Although our hospital has neuro‐ophthalmologic clinics run by ophthalmologists and neurologists independently but in close cooperation and consultation, our preliminary analyses showed that only 37.9% of the patients with binocular diplopia as the primary symptom and only 20.1% of the patients with isolated trochlear palsy were managed by both neurologists and ophthalmologists in our institution [30, 31]. Furthermore, the etiologic proportion of trochlear palsy differed significantly between the clinics [30].…”

Etiological distribution of isolated oculomotor nerve palsy: analysis of 633 patients and literature review

“…This finding is similar to that observed in our previous studies on isolated trochlear and abducens palsies [18,19]. However, the proportion of involved specialists differed markedly amongst the isolated ocular motor nerve palsies (Figure 6c).…”