Can Acoustic Neuroma Affect Vision & Will Brain MRI Show Acoustic Neuroma?

Can Acoustic Neuroma Affect Vision?

The acoustic neuroma lesions are commonly located in the internal auditory canal which is closer to the brainstem. The sensory information regarding visual images is carried by the ophthalmic nerve and its pathway does not cross with the pathway of the vestibulocochlear nerve which is the nerve acoustic neuroma lesion that arises. The motor component to control the eye muscle movements are carried by the oculomotor, trochlear and abducent nerves and these nerves can sometimes be affected from the growing acoustic neuroma tumor which is large enough to compress the adjacent structures. Compression and irritation of these nerves can cause double vision, blurred vision, eye twitching, excess tearing or dry eyes. These can affect the vision as this can cause difficulty in clear vision. Most of these symptoms occur when the tumor is very large, usually, small tumors do not cause any compression or irritation of the oculomotor, trochlear and abducent nerves. But the ophthalmic nerve is not usually directly involved from the compression or irritation of the acoustic neuroma tumor. ⁽¹⁾

Can Acoustic Neuroma Affect Vision?

Does Brain MRI Show Acoustic Neuroma?

Magnetic resonance imaging (MRI) is quite accurate in diagnosing acoustic neuroma lesions. Information provided by contrast-CT scan and CT cisternography is provided by the MRI scan as well. Similar to the CT scan MRI also shows an acoustic neuroma tumor as a homogenous enhancement. MRI uses magnetic fields and radio waves to create a 3D view of the brain therefore, there is no exposure to radiation in the process of MRI scans. Sometimes contrast such as gadolinium might be needed to identify a tumor especially if it is small and hidden under the bones of the internal acoustic canal. The tumor absorbs more dye than the normal brain tissue and it will appear clearly. The MR has a 100% accuracy with the use of gadolinium in diagnosing acoustic neuroma tumor even the very small ones. Overall MRI is better in diagnosing acoustic neuroma tumors than a CT scan or contrasts CT scan as the lesions are seen clearly, the characteristics of the tumor are clear and the risks are less too. MRI scan is commonly performed to diagnose acoustic neuroma lesion.

Computed tomography (CT) scan is useful in diagnosing acoustic neuroma but small acoustic neuroma tumors might not be visible clearly from a CT scan. A large acoustic neuroma tumor is seen as a homogenous enhancement and can be seen well from a CT scan. The contrast-enhanced CT scan is more accurate in detecting acoustic neuroma tumors than the normal CT scan however, tumors less than 1 cm are difficult to visualize even with contrast CT scans. Some patients cannot undergo an MRI scan if they have metal implants or metal shrapnel, in that case, a CT can be done. On the other hand, a CT scan of the head is done to assess what is the best way to approach the tumor surgically to remove it. ^{(2) (3) (4)}

Conclusion

Compression and irritation of the oculomotor, trochlear and abducent nerve can cause double vision, blurred vision, eye twitching, excess tearing or dry eyes. These can affect the vision as this can cause difficulty in clear vision. Most of these symptoms occur when the tumor is very large. But the ophthalmic nerve is not usually directly involved from the compression or irritation of the acoustic neuroma tumor. Magnetic resonance imaging (MRI) is quite accurate in diagnosing acoustic neuroma lesions. MRI shows an acoustic neuroma tumor as a homogenous enhancement. Sometimes contrast such as gadolinium might be needed to identify a tumor clearly. The MR has a 100% accuracy with the use of gadolinium in diagnosing acoustic neuroma tumors even the very small ones.

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Can Acoustic Neuroma Affect Vision & Will Brain MRI Show Acoustic Neuroma?