Clinical Course and Prognostic Factors of Acquired Third, Fourth, and Sixth Cranial Nerve Palsy in Korean Patients

Abstract

PurposeThis study aimed to evaluate the clinical course and prognostic factors of acquired third, fourth, and sixth cranial nerve (CN) palsy grouped according to etiology.MethodsThis study involved a retrospective review of the medical records of 153 patients who were diagnosed with acquired paralytic strabismus from January 2004 to July 2015. Outcomes, recovery rates, and time to recovery were investigated according to the affected CN: CN3, CN4, and CN6 palsies. The patients were classified into four groups based on etiology: idiopathic, traumatic, neoplastic, and vascular.ResultsThe mean age of the patients was 59.8 ± 14.5 years and the mean follow-up period was 10.8 months. Out of the 153 patients, 63 (41.2%) had CN3 palsy, 35 (22.9%) had CN4 palsy, and 55 (35.9%) had CN6 palsy. The most common causes were vascular related (54.9%), followed by idiopathic (28.1%), trauma (8.5%), and neoplasm (5.88%). About 50% of the patients recovered within six months. Among the four etiologic groups, the idiopathic group showed the best prognosis because about 50% of the patients in this group recovered within three months. This was followed by the vascular, traumatic, and neoplastic groups. Cox proportional hazard analysis revealed a significant association between the baseline prism diopter and recovery rate.ConclusionsThe prognosis and natural history of paralytic strabismus vary depending on its cause. The vascular group had the best recovery rate and shortest recovery time, whereas the neoplastic group required the longest time to recover.

The incidence and etiology of sixth cranial nerve palsy in Koreans: A 10-year nationwide cohort study

“…Studies on the etiology of CN6 palsy have reported high frequencies of microvascular disease (28–46%) 3,5,18 or unknown origin (24–31%) 3–5,10,13,18 . It is widely reported that microvascular diseases are a common cause of isolated unilateral CN6 palsy in patients over 50 years of age 1 .…”

“…Recovery rates of CN6 palsy have been reported as high as 60.0 to 87.3% 3,10,24 . Vascular and idiopathic etiologies were associated with higher natural recovery rates than other etiologies of ocular motor nerve palsies 3,4,9,22 .…”

“…Thus far, the clinical features of CN6 palsy have mostly been investigated in institution-based studies focused mainly on its causes and prognosis 3,6–10 . Studies on the epidemiology of CN6 palsy using a population-based method are limited 5 .…”

Aetiology, clinical features and surgical outcomes of isolated medial rectus palsy

“…In extraocular muscle palsy, CN VI represents the most common type of paralytic strabismus, accounting for 33% to 63% of cases, followed by CN III palsy (22%-41.2%) and CN IV palsy (11%-36%). [1][2][3][4] Isolated medial rectus palsy (MRP) is extremely rare in clinical practice, with only 59 cases being reported in the English literature, often involving single case presentations. [5][6][7][8][9][10][11][12][13][14] Possible aetiologies may include damage of the medial rectus nucleus or terminal branches of the oculomotor nerve serving only the medial rectus, or direct medial rectus muscle injury, such as orbital trauma or surgical complications of endoscopic sinus surgery.…”

“…In extraocular muscle palsy, CN VI represents the most common type of paralytic strabismus, accounting for 33% to 63% of cases, followed by CN III palsy (22%‐41.2%) and CN IV palsy (11%‐36%) 1‐4 . Isolated medial rectus palsy (MRP) is extremely rare in clinical practice, with only 59 cases being reported in the English literature, often involving single case presentations 5‐14 .…”