J Korean Ophthalmol Soc.  2016 Nov;57(11):1812-1816. 10.3341/jkos.2016.57.11.1812.

A Case of Trochlear Nerve Schwannoma Presenting with Binocular Diplopia

• Kee HJ
• Yoo YJ
• Kim JH
• Yang HK

• KMID: 2357742
• DOI: http://doi.org/10.3341/jkos.2016.57.11.1812

Abstract

PURPOSE
To report a case of unilateral trochlear nerve schwannoma in a patient without neurofibromatosis.
CASE SUMMARY
A 58-year-old male presented with acute onset of diplopia which developed 10 days prior. Alternate prism cover test, ductions and versions and Bielschowsky three-step test were compatible with left superior oblique muscle palsy. High-resolution magnetic resonance imaging showed a 6-mm-sized lobulated mass in the cisternal segment of the left trochlear nerve passing lateral to the brainstem. An additional thin-section gadolinium-enhanced orbit magnetic resonance imaging showed definite enhancement in the entire portion of the lobulated mass, compatible with a trochlear nerve schwannoma. Diplopia was managed conservatively with prism glasses and regular follow-up examinations were recommended without further treatment.
CONCLUSIONS
A trochlear nerve tumor should be considered in adults who develop diplopia associated with acquired superior oblique muscle palsy.

Keyword

Acquired superior oblique muscle palsy; Trochlear nerve schwannoma; Trochlear nerve tumor

MeSH Terms

Adult
Brain Stem
Diplopia*
Eyeglasses
Follow-Up Studies
Glass
Humans
Magnetic Resonance Imaging
Male
Middle Aged
Neurilemmoma*
Neurofibromatoses
Orbit
Paralysis
Telescopes*
Trochlear Nerve*

Figure

• 

  Figure 1. Photographs of the nine cardinal positions of gaze. The left superior oblique muscle shows underaction, without definite overaction of the left inferior oblique muscle.

• 

  Figure 2. High-resolution magnetic resonance imaging of the trochlear nerve. (A, B) Axial T2-weighted images at the lower midbrain and upper pons reveal a 6 mm-sized lobulated trochlear nerve mass with low signal intensity (arrows). Sagittal (C) and axial (D) planes of gadolinium-enhanced T1-weighted images show a well circumscribed, homogeneously enhancing lesion (arrows) originating from the trochlear nerve in the left ambient cistern.

Reference

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