From the Guidelines
Mid orbital gaze divergence on a CT head scan is a significant finding that requires prompt further evaluation by a neuroradiologist or ophthalmologist to determine the underlying cause, which may include cranial nerve dysfunction, orbital pathology, or neurological issues. This finding may be caused by conditions such as cranial nerve palsies (particularly CN III, IV, or VI), orbital fractures, thyroid eye disease, orbital tumors, or intracranial processes affecting eye movement control centers 1. A complete ophthalmologic examination including visual acuity testing, extraocular movement assessment, and possibly additional imaging such as MRI with thin cuts through the orbits and brainstem would be recommended.
Key Considerations
- The American College of Radiology recommends that orbital trauma be assessed with a noncontrast orbit CT and/or noncontrast CT of the head, which are often complementary 1.
- For evaluation of visual loss localized to the orbit or disease process involving the pre-chiasmatic optic nerve, targeted contrast-enhanced MRI of the orbits or contrast-enhanced CT of the orbits are recommended, which are complementary 1.
- In patients with proptosis or if a mass lesion is suspected within the globe, optic nerve, within the adjacent orbital soft tissues, or within the adjacent skull base, an MRI of the orbits without and with contrast is the optimal imaging modality used to localize and characterize the primary lesion 1.
Next Steps
- Laboratory tests may be indicated depending on clinical suspicion, particularly thyroid function tests if thyroid ophthalmopathy is suspected.
- Treatment depends on the underlying cause and may range from observation to medical management (such as corticosteroids for inflammatory conditions) to surgical intervention for structural abnormalities.
- The finding of gaze divergence on CT is significant because eye alignment is controlled by precise coordination of multiple cranial nerves and extraocular muscles, and disruption can indicate important neurological or orbital pathology requiring prompt attention.
From the Research
Mid Orbital Gaze Divergence on CT Head
- Mid orbital gaze divergence on CT head can be an indicator of various neurological conditions, including ischemic stroke and intracranial aneurysms 2.
- The visual criterion for horizontal gaze deviation (HGD) on computed tomography (CT) is defined as a deviation angle of ≥ 14° in unidirectionally deviated eyes 2.
- HGD frequency is significantly increased in most stroke subgroups, particularly in middle cerebral artery (MCA) cardioaortic embolism and posterior inferior cerebellar artery (PICA) stroke 2.
- In MCA stroke, ipsilesional HGD probability decreases daily and increases with cardioaortic embolism and lenticular nucleus lesions 2.
Intracranial Aneurysms
- Intracranial aneurysms can cause isolated third cranial nerve palsies, particularly those located at the junction of the internal carotid and posterior communicating arteries or at the apex of the basilar artery 3, 4.
- The treatment of third nerve palsy associated with intracranial aneurysms remains controversial, but endovascular coiling is a viable treatment modality 4.
- The natural history and treatment outcomes of cerebral aneurysms have significantly increased over the last few decades, and choosing the optimal management for each patient requires careful consideration of numerous medical, clinical, and anatomic factors 5.
Cranial Nerve Neuritis
- Idiopathic third and sixth cranial nerve neuritis can present with mid orbital gaze divergence on CT head, and patients tend to respond well to steroid treatment and have good prognoses 6.
- High-resolution MRI with three-dimensional sequences can help visualize cranial nerves and identify patients with cranial nerve enhancement, which is essential for diagnosing cranial nerve neuritis 6.