Korean J Neurotrauma.  2018 Oct;14(2):129-133. 10.13004/kjnt.2018.14.2.129.

Delayed Trochlear Nerve Palsy Following Traumatic Subarachnoid Hemorrhage: Usefulness of High-Resolution Three Dimensional Magnetic Resonance Imaging and Unusual Course of the Nerve

• Ko YS
• Yang HJ
• Son YJ
• Park SB
• Lee SH
• Chung YS

• KMID: 2424325
• DOI: http://doi.org/10.13004/kjnt.2018.14.2.129

Abstract

Cranial nerve palsies are relatively common after trauma, but trochlear nerve palsy is relatively uncommon. Although traumatic trochlear nerve palsy is easy to diagnose clinically because of extraocular movement disturbances, radiologic evaluations of this condition are difficult to perform because of the nerve's small size. Here, we report the case of a patient with delayed traumatic trochlear nerve palsy associated with a traumatic subarachnoid hemorrhage (SAH) and the related radiological findings, as obtained with high-resolution three-dimensional (3D) magnetic resonance imaging (MRI). A 63-year-old woman was brought to the emergency room after a minor head trauma. Neurologic examinations did not reveal any focal neurologic deficits. Brain computed tomography showed a traumatic SAH at the left ambient cistern. The patient complained of vertical diplopia at 3 days post-trauma. Ophthalmologic evaluations revealed trochlear nerve palsy on the left side. High-resolution 3D MRI, performed 20 days post-trauma, revealed continuity of the trochlear nerve and its abutted course by the posterior cerebral artery branch at the brain stem. Chemical irritation due to the SAH and the abutting nerve course were considered causative factors. The trochlear nerve palsy completely resolved during follow-up. This case shows the usefulness of high-resolution 3D MRI for evaluating trochlear nerve palsy.

Keyword

Imaging, three-dimensional; Magnetic resonance imaging; Subarachnoid hemorrhage, traumatic; Trochlear nerve diseases

MeSH Terms

Brain
Brain Stem
Cranial Nerve Diseases
Craniocerebral Trauma
Diplopia
Emergency Service, Hospital
Female
Follow-Up Studies
Humans
Imaging, Three-Dimensional
Magnetic Resonance Imaging*
Middle Aged
Neurologic Examination
Neurologic Manifestations
Posterior Cerebral Artery
Subarachnoid Hemorrhage, Traumatic*
Trochlear Nerve Diseases*
Trochlear Nerve*

Figure

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  FIGURE 1 Initial computed tomography (CT). (A) The subarachnoid hemorrhage (SAH) at the left ambient cistern (arrow). (B) A follow-up CT taken 6 days later that shows resolution of the SAH.

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  FIGURE 2 Nine-gaze photograph taken 1 week after injury that shows underaction of the left superior oblique muscle and mild overaction of the left inferior oblique muscle. The deviation is greatest when the patient was looking up and to the right (arrow 1), left hypertropia in primary position (arrow 2), overelevation in adduction (arrow 3), and limitation of depression when looking down and to the right (arrow 4).

• 

  FIGURE 3 (A–F) High-resolution three dimensional magnetic resonance imaging, taken 20 days after trauma, shows continuity of the left trochlear nerve (white arrows) without any change in contour. It was abutted by the posterior cerebral artery branch (black arrow head) at the brain stem. (D–F) are magnified views of (A–C) for clearer demonstration of details (volume isotropic turbo-spinecho acquisition technique, repetition time 10.5, echo time 5.3, 0.3 mm thickness).

• 

  FIGURE 4 Nine-gaze photograph taken 6 months after injury, showing improvement of superior oblique muscle dysfunction.

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