What is the recommended imaging protocol for an older adult patient, likely over 50 years old, with a history of chronic pain and possible multiple sclerosis or hypertension, presenting with symptoms of trigeminal neuralgia?

Imaging for Trigeminal Neuralgia

MRI with contrast of the trigeminal ganglion is the gold-standard imaging modality and should be performed in all patients with trigeminal neuralgia to identify underlying causes, assess for neurovascular compression, and exclude secondary etiologies such as multiple sclerosis or tumors. 1, 2

Recommended MRI Protocol

The optimal imaging protocol must include specific high-resolution sequences covering the entire course of the trigeminal nerve from brainstem to peripheral branches 3, 1:

• 3-D heavily T2-weighted MRI sequences are essential for optimal nerve visualization 1, 2
• MR angiography (MRA) combined with anatomic MRI achieves 97-100% sensitivity and 100% specificity for detecting neurovascular compression 2
• Pre- and post-contrast imaging provides the best characterization of the trigeminal nerve and potential pathology 1, 2
• Thin-cut high-resolution techniques through the entire trigeminal nerve course are necessary for accurate assessment 1, 2

Critical Coverage Requirements

Imaging must extend from the brainstem through all peripheral branches, as the trigeminal nerve can be affected anywhere along its course 3:

• Brainstem imaging is mandatory to evaluate for demyelinating disease (particularly multiple sclerosis), infarction, hemorrhage, vascular lesions, inflammatory conditions, and tumors 3
• Standard brain MRI coverage is insufficient and will miss extracranial pathology 2
• Coverage must include the cisternal segment, Meckel cave, cavernous sinus, skull base foramina, pterygopalatine fossa, orbit, and masticator space 3

Special Considerations for Older Adults with Comorbidities

In your patient population (older adults with chronic pain, possible MS or hypertension), several factors warrant emphasis:

• Multiple sclerosis can cause trigeminal neuralgia, making brainstem imaging particularly critical to identify demyelinating plaques 3, 4
• Younger patients and those with pain in multiple trigeminal branches have higher rates of secondary causes (tumors or MS), but older patients still require comprehensive imaging 5
• 3T MRI offers superior resolution compared to 1.5T, particularly for detecting smaller vessel compression 2

Role of CT Imaging

CT has a limited but complementary role 3:

• CT is useful only for evaluating osseous integrity of the skull base and neural foramina 3
• Standard CT head coverage is insufficient to evaluate the full trigeminal nerve 3
• MRI offers superior detection of perineural tumor spread compared to CT (which has 88% sensitivity and 89% specificity) 3
• CT without contrast is adequate for bone assessment; combined pre- and post-contrast CT is not supported by evidence 3

Interpretation Caveats

Critical pitfall: MRI findings must be interpreted in the context of clinical presentation 2:

• Both false-positive and false-negative studies occur when assessing neurovascular contact 2
• Imaging evidence of compression must be ipsilateral to the patient's pain symptoms 2
• Congruence rates between MRI and intraoperative findings range from 83-100% 2
• MRI is supportive rather than diagnostic—the diagnosis is made primarily on clinical history 2

Advanced Imaging Techniques

For complex cases, emerging modalities may provide additional information 1:

• Diffusion tensor imaging (DTI) can detect microstructural tissue changes in symptomatic nerves 1
• MR neurography is useful for characterizing peripheral trigeminal neuropathy 1
• These advanced techniques have detected structural alterations in gray and white matter in patients with trigeminal neuralgia 1