Getting an MRI for facial pain diagnosis

An MRI (magnetic resonance imaging) scan is a primary diagnostic tool for facial pain diagnosis. MRI uses a large magnet, pulsed radiofrequency waves (RF), and an analyzing computer to create an image of the brain. The scanner itself is a tube with a table in the middle, into which the patient slides for a 45-minute session. If the tube feels claustrophobic for you, it is possible for a physician to prescribe a calming medication, such as valium before proceeding with the scan. MRI scans differ from CT (computed tomography) scans because MRI does not use radiation. Radiation has the potential of being harmful. Magnetism does no harm at all.

Do I need an MRI to diagnose my facial pain?

Your MRI is not done to diagnose the nature of your pain. It is used to determine if the cause of your pain is from vascular compression. In one percent of cases there can be a tumor or vascular malformation associated with the pain which would be detected by the MRI. Multiple sclerosis can cause facial pain and the MRI will help to detect this also. The data from your MRI helps your doctor to know how best to treat your neuropathic pain.

What type of MRI do I need to diagnose my facial pain? 

There are three software programs that enhance the ability to distinguish between nerves and brain tissue, spinal fluid, and vessels. These are referred to by their acronyms, FIESTA, CISS or VIBE. Your MRI needs to be done using one of these techniques.

A “routine” MRI evaluates the brain at three-millimeter intervals and may miss an area of vascular association or even the trigeminal nerve completely. Thinner cuts are required. A negative routine MRI does not necessarily mean that there is no vascular association present. It simply was not seen either because the “cuts” were too far apart or because the radiologist reviewing the study did not know how to interpret it adequately.

Who will read my MRI?

An experienced neuro radiologist or neurosurgeon should read the images. He or she will look for the presence of any vessel-either a vein or an artery-in contact with the trigeminal nerve at any point between the brainstem and the base of the skull. Neurosurgeons must be familiar with interpreting these studies and must review the images themselves. A report from a radiologist is not enough. Be sure the full set of images are sent to your neurosurgeon, not just the radiologist’s report.

A neuroradiologist not familiar with the treatment of trigeminal neuropathic pain may report that an MRI scan is “normal.” While that finding is “anatomically” true, the radiologist has no insight into the physiology of the nerve. You are having pain, so by definition it is not physiologically “normal.”

Providers experienced in treating neuropathic facial pain will send you to an imaging center that will conduct the right kind of MRI. Appropriately done MRI scans specific to trigeminal neuropathic pain will ensure that your neurosurgeon will know exactly what to look for during surgery and where along the nerve to look for a compressing vessel.

What do I need to know about contrast dye in MRI?

Do you need to have intravenous contrast injected? Gadolinium-based contrast agents (GBCAs) provide doctors and radiologists with sharper, more accurate MRI images. During MRI scans with contrast, healthcare providers inject patients with the GBCA. The active ingredient in GBCAs is a rare, silvery-white earth metal called gadolinium. It reacts with atoms and molecules in the body to make them easier to see in imaging scans. Alone, gadolinium is toxic to humans. But gadolinium in GBCAs goes through a process called chelation, which makes it safer for use in the body.

The most recent version of gadolinium chelation that is used (Gadovist) uses a form of chelation that surrounds the gadolinium molecule and makes it easier for the kidneys to flush it out. Can particles of the element be deposited in the brain and remain there? Maybe, but the evidence is that it remains within small blood vessel walls rather than brain tissue, and there is no research evidence that any damage is done to the brain tissue itself. Is there scientific evidence that gadolinium left in the brain can cause injury? No.

If you have a diagnosis of neuropathic facial pain, your MRI is important to determine the cause of your pain. Get the best imaging possible. It will reduce or eliminate the need to “explore” for vessels during surgery. This should speed the operation and reduce the length of surgery and the risks of complications.