Fourth cranial nerve palsy or trochlear nerve palsy, is a condition affecting cranial nerve 4 (IV),
the
trochlear nerve, which is one of the
cranial nerves. It causes weakness or paralysis of the
superior oblique muscle that it innervates. This condition often causes vertical or near vertical double vision as the weakened muscle prevents the eyes from moving in the same direction together.
Because the trochlear nerve is the thinnest and has the longest intracranial course of the cranial nerves, it is particularly vulnerable to traumatic injury.
To compensate for the double-vision resulting from the weakness of the superior oblique, patients characteristically tilt their head down and to the side opposite the affected muscle.
When present at birth, it is known as
congenital fourth nerve palsy
Congenital fourth nerve palsy is a condition present at birth characterized by a vertical misalignment of the eyes due to a weakness or paralysis of the superior oblique muscle.
Other names for fourth nerve palsy include superior oblique palsy and ...
.
See also
*
Harada–Ito procedure
References
External links
{{DEFAULTSORT:Fourth Nerve Palsy
Disorders of ocular muscles, binocular movement, accommodation and refraction