J Neurol Surg B Skull Base 2015; 76 - P047
DOI: 10.1055/s-0035-1546675

Trochlear Nerve Palsy Associated with Pineal Cyst

T. Benton Ableman 1, Steven A. Newman 1
  • 1University of Virginia, Virginia, United States

Introduction: Skull base lesions often present with cranial nerve palsies producing diplopia. Most of these involve the area of the cavernous sinus. Lesions affecting the dorsal midbrain can also affect the IV nerve producing hypertropia and double vision.

Materials and Methods: Two patients presenting with diplopia were found to have IV nerve palsies associated with a pineal cysts. They were further characterized by MRI scans to analyze the superior oblique muscle.

Results: Hess screen and Maddox rod testing clearly indicated unilateral ophthalmoplegia with no evidence of aqueductal obstruction on imaging.

Discussion: Fourth nerve palsies are usually divided into those related to decompensation of congenital trochlear dysfunction and those that are acquired. Most acquired IV nerve palsies are related to trauma or microvascular disease, but they can also be seen with skull base pathology. Recent literature suggests that along with increased fusional amplitudes and head tilt, long-standing congenital IV nerve palsies are associated with atrophy of the superior oblique muscle which can be identified on MRI scanning. Absence of atrophy in our cases suggests that these are acquired, and most likely related to the pineal cyst.

Conclusions: (1) Pineal cysts and other lesions in the area of the dorsal midbrain may be associated with IV nerve dysfunction. (2) MRI scanning may help distinguish long-standing unrelated IV nerve palsies in the setting of a pineal cyst. (3) With the absence of involvement of the aqueduct producing CSF outflow problems or more impressive evidence of dorsal midbrain dysfunction, diplopia can be managed with eye muscle surgery without intracranial intervention. (4) Evidence of pineal cyst and IV nerve dysfunction is not necessarily an indication for intracranial surgery.