| Fourth nerve palsy | |
|---|---|
| Classification and external resources | |
Trochlear nerve |
|
| ICD-10 | H49.1 |
| ICD-9 | 378.53 |
| eMedicine | oph/697 |
| MeSH | D020432 |
Fourth nerve palsy is a condition caused by weakness or paralysis of the superior oblique muscle. This condition often causes double vision as the weakened muscle prevents the eyes from moving in the same direction.
When present at birth, it is known as congenital fourth nerve palsy.