Should I consider an MRI (Magnetic Resonance Imaging) of the brain if the CT (Computed Tomography) scan is clear and the patient is delirious with seizure-like activity?

From the Guidelines

Yes, you should consider an MRI of the brain even if the CT scan is clear in a patient with delirium and seizure-like activity. This recommendation is based on the most recent and highest quality study, which suggests that MRI may prove useful in the setting of altered mental status (AMS) as a second-line test when occult pathology is suspected and initial head CTs are unrevealing, due to MRI’s higher sensitivity in detecting ischemia, encephalitis, or subtle cases of subarachnoid hemorrhage 1.

The patient's presentation with delirium and seizure-like activity warrants further investigation, as the underlying causes can include conditions that are not readily apparent on CT, such as small ischemic changes, early encephalitis, autoimmune encephalitis, certain tumors, cortical dysplasias, and demyelinating diseases. MRI provides superior soft tissue contrast and can detect these subtle abnormalities, which can significantly impact treatment decisions and patient outcomes.

Key points to consider:

• MRI is particularly valuable in detecting occult pathology in patients with AMS and normal CT scans 1
• The yield of brain MRI is higher than CT in detecting lesions in focal epilepsies, with a success rate of more than 30% for MRI compared to CT 1
• Early detection of underlying conditions through MRI can significantly impact treatment decisions and patient outcomes, including revised diagnoses, revised levels of care, improved diagnostic confidence, and improved prognostications 1
• An electroencephalogram (EEG) should also be performed to detect abnormal electrical activity in the brain, and immediate seizure management may be necessary, with options including administering benzodiazepines such as lorazepam 2-4mg IV or diazepam 5-10mg IV while arranging neuroimaging.

In summary, considering an MRI of the brain is crucial in patients with delirium and seizure-like activity, even with a clear CT scan, to detect potential underlying conditions that may not be apparent on CT, and to guide treatment decisions and improve patient outcomes, as supported by the most recent and highest quality study 1.

From the Research

Consideration of MRI Brain in Delirious Patients with Seizure-Like Activity

• When a patient presents with delirium and seizure-like activity, and the CT scan is clear, it is essential to consider further diagnostic tests to determine the underlying cause of the symptoms.
• According to the study by 2, brain imaging with CT or MRI should be considered as part of the routine neurodiagnostic evaluation of adults presenting with an apparent unprovoked first seizure.
• The study by 3 suggests that MRI examination can demonstrate small abnormalities correlating with the location of the epileptogenic focus in the EEG, even in patients with normal CT scans.
• Additionally, the study by 4 highlights the importance of MRI in diagnosing and localizing the seizure focus in patients with status epilepticus.

Indications for MRI Brain

• The following are suggested as sound indications for ordering CT or MR brain imaging among patients with seizure-like activity:
  • Positive history of head injury, stroke, or other neurologic disease
  • Presence of abnormal neurologic signs or organic mental signs, such as confusion or cognitive decline
  • A first psychotic break or personality change after the age of 50 years
  • Delirium with seizure-like activity, as seen in the patient in question
• As stated in the study by 5, when a history of neurologic disorder and/or the presence of abnormal neurologic/organic mental signs is positive, scans are abnormal in 74% of cases.

Diagnostic Value of MRI Brain

• The study by 6 found that CT scans can identify structural lesions in 37% of patients with their first seizure, and MRI can provide additional information on the location and extent of the lesion.
• The study by 3 demonstrated that MRI can show small abnormalities that are not visible on CT scans, highlighting the importance of using both imaging modalities in the diagnostic workup of patients with seizure-like activity.
• As noted in the study by 4, MRI changes in status epilepticus can include diffusion-weighted imaging (DWI) changes, T2-weighted, and T2-Fluid-Attenuated Inversion Recovery (FLAIR) sequences, which can help in diagnosing and localizing the seizure focus.