Is contrast needed for MRI in patients with persistent dizziness after a concussion?

From the Guidelines

Contrast is not routinely needed for MRI in patients with persistent dizziness after a concussion. A standard non-contrast MRI brain protocol is typically sufficient to evaluate post-concussive dizziness, as it can detect structural abnormalities, small hemorrhages, white matter changes, and other potential causes of persistent symptoms 1. According to the most recent guidelines, noncontrast MRI head is usually appropriate for the initial imaging of patients with subacute or chronic head trauma and unexplained cognitive or neurologic deficit(s), which includes dizziness 1.

The diagnostic yield of noncontrast MRI head in patients presenting with isolated dizziness is low, with ischemic stroke being the most common abnormality seen in nearly 70% of cases with positive findings 1. The use of contrast (gadolinium-based agents) should be individualized and reserved for cases where there is clinical suspicion for conditions that specifically require contrast enhancement for diagnosis, such as tumors, infections, inflammatory processes, or vascular abnormalities that aren't apparent on non-contrast imaging.

If the standard MRI is normal but symptoms persist, additional specialized imaging like fMRI, DTI (diffusion tensor imaging), or vestibular-specific protocols might be more appropriate than simply adding contrast 1. This approach minimizes unnecessary exposure to gadolinium-based contrast agents, which carry small risks including allergic reactions and potential gadolinium deposition in tissues, while still providing comprehensive diagnostic information for most post-concussion dizziness cases.

Key points to consider:

• Noncontrast MRI is usually sufficient for initial evaluation of post-concussive dizziness
• Contrast should be used judiciously based on clinical suspicion for specific conditions
• Additional specialized imaging may be more appropriate than contrast for persistent symptoms after a normal standard MRI
• Minimizing unnecessary contrast use reduces risks associated with gadolinium-based agents 1.

From the FDA Drug Label

In both studies, patients underwent a baseline, pre-contrast MRI prior to administration of gadobutrol injection at a dose of 0. 1 mmol/kg, followed by a post-contrast MRI. The studies were designed to demonstrate superiority of gadobutrol injection MRI to non-contrast MRI for lesion visualization Gadobutrol injection provided a statistically significant improvement for each of the three lesion visualization parameters when averaged across three independent readers for each study.

The use of contrast is needed for MRI in patients to improve lesion visualization, as it provides a statistically significant improvement in contrast enhancement, border delineation, and internal morphology compared to non-contrast MRI 2 2.

From the Research

Contrast Needed for MRI in Patients with Persistent Dizziness after a Concussion

• The provided studies do not directly address the need for contrast in MRI scans for patients with persistent dizziness after a concussion 3, 4, 5, 6, 7.
• However, the studies suggest that vestibular rehabilitation therapy (VRT) can be an effective treatment for patients with postconcussion syndrome experiencing prolonged dizziness 3, 6.
• The diagnosis of post-concussive dizziness (PCD) can be divided into non-vestibular, central vestibular, and peripheral vestibular causes, and symptoms may be due to peripheral dysfunction 4.
• Management of concussion and persistent post-concussive symptoms relies on identifying underlying symptom generators, and treatment options include sub-symptom threshold aerobic exercise, cervical physical therapy, vestibular therapy, and pharmacological management 5.
• Vestibular rehabilitation following mild traumatic brain injury utilizes similar tools and techniques employed when treating those solely with peripheral pathology, and the clinician must consider co-morbidities such as cognitive and behavioral issues, visual-perceptual dysfunction, and autonomic dysfunction 6.

Diagnostic Approaches

• The studies highlight the importance of a thorough evaluation to identify the underlying causes of persistent dizziness after a concussion, including peripheral vestibular disorders and central nervous system trauma 4, 7.
• Diagnostic categories for post-concussive dizziness include central vestibular disorders, benign paroxysmal positional vertigo (BPPV), labyrinthine dehiscence/perilymph fistula syndrome, and temporal bone fracture 4.
• The use of MRI scans may be considered as part of a comprehensive diagnostic approach, but the need for contrast is not explicitly addressed in the provided studies 3, 4, 5, 6, 7.