From the Guidelines
For a patient with unilateral visual changes and hearing issues on the same side, a CTA (Computed Tomography Angiography) would be the recommended initial CT scan. This imaging modality provides detailed visualization of the blood vessels while also showing surrounding structures. The combination of unilateral visual and auditory symptoms suggests a possible vascular etiology affecting the cerebellopontine angle or cavernous sinus region, such as an aneurysm, arteriovenous malformation, or vascular compression. A CTA requires intravenous contrast administration and will show arterial structures in detail, which is particularly important for identifying vascular abnormalities that might be compressing cranial nerves II (optic) and VIII (vestibulocochlear) 1.
Some key points to consider when ordering a CTA include:
- The use of modern CT equipment, which has been shown to have accuracy comparable to catheter angiography for the diagnosis of vascular injury 1.
- The ability of CTA to detect a wide range of pathologies, including dural arteriovenous fistulas, arterial dissections, and sigmoid sinus wall diverticulum or anomalies 1.
- The importance of considering the clinical context and suspected underlying pathology when selecting the initial imaging modality, with CTA being a reasonable choice for patients with suspected vascular etiologies 1.
If the CTA is negative but clinical suspicion remains high, an MRI with contrast would be the next appropriate step as it provides superior soft tissue resolution for evaluating the cranial nerves and brain parenchyma. In some cases, if venous pathology is specifically suspected after initial evaluation, a CT venogram might be subsequently ordered to evaluate the venous structures, but CTA would typically be the first-line imaging study given the presenting symptoms 1.
From the Research
Recommended CT Scan for Unilateral Visual Changes and Hearing Issues
For a patient presenting with unilateral visual changes and hearing issues on the same side, the recommended CT scan is a Computed Tomography Angiography (CTA).
- CTA offers a rapid means of evaluating the vasculature of the head and neck in patients presenting with acute onset of neurologic symptoms 2.
- It is noninvasive, easy to acquire, and offers excellent detail in identifying the site and nature of the lesion 2.
- CTA is particularly useful for evaluating neurovascular disease, including dissection, trauma, intracranial stenosis, thrombosis, and aneurysms 3.
- It has several key advantages over other imaging modalities, including magnetic resonance angiography (MRA), and is highly accurate for diagnosing vascular pathologies 3, 4.
Comparison with Venogram
A venogram is not typically recommended for evaluating unilateral visual changes and hearing issues on the same side, as it is more focused on evaluating the venous system rather than the arterial system.
- CTA is more suitable for evaluating the arterial system and identifying potential causes of unilateral visual changes and hearing issues, such as vascular stenosis or aneurysms 3, 4.
- While a venogram may be useful in certain cases, such as evaluating cerebral venous sinus thrombosis, it is not the primary imaging modality for evaluating unilateral visual changes and hearing issues 5, 6.