From the Guidelines
To differentiate an acute cerebral injury in a person who is speaking well, a non-contrast CT scan of the brain should be the initial test of choice, followed by MRI with diffusion-weighted imaging if necessary, as recommended by the American College of Radiology Appropriateness Criteria 1. The most effective diagnostic approach combines neuroimaging and clinical assessment.
- Non-contrast CT scan of the brain is the initial test of choice due to its rapid availability, ability to detect hemorrhage, and utility in emergency settings.
- This should be followed by MRI with diffusion-weighted imaging, which offers superior sensitivity for detecting early ischemic changes, small lesions, and posterior fossa abnormalities, as noted in the study by 1. Clinical evaluation using standardized neurological assessment tools like the National Institutes of Health Stroke Scale (NIHSS) is essential even when speech is preserved, as subtle deficits may be present.
- Laboratory tests including complete blood count, coagulation studies, and metabolic panel help rule out non-neurological causes of symptoms. In cases where vascular pathology is suspected, CT angiography or MR angiography should be performed to evaluate cerebral vasculature, as suggested by 1. EEG may be valuable if seizure activity is suspected despite normal speech. This comprehensive approach is necessary because preserved speech doesn't exclude significant cerebral injury, as language function is localized and many brain regions can be damaged while speech remains intact.
From the Research
Imaging Modalities for Acute Cerebral Injury
The following imaging modalities can be used to differentiate an acute cerebral injury in a person who is speaking well:
- Computed Tomography (CT) scan: CT allows for rapid assessment of brain pathology and is crucial in assessing the outcome of surgical intervention 2, 3
- Magnetic Resonance Imaging (MRI): MRI provides greater spatial resolution and is more accurate than CT in identifying and characterizing most forms of traumatic cerebral pathology 3, 4
- CT perfusion: CT perfusion can be implemented easily in most hospital centers and provides quantitative perfusion data in addition to structural images 2
- MR angiography: MR angiography can be used to evaluate patients with suspected acute cerebral infarction 5
- Diffusion-weighted MR imaging: Diffusion-weighted MR imaging can be used to evaluate patients with suspected acute cerebral infarction 5
- Cerebral perfusion studies: Cerebral perfusion studies can be used to evaluate patients with suspected acute cerebral infarction 5
Comparison of Imaging Modalities
Studies have compared the effectiveness of different imaging modalities in detecting acute cerebral injury:
- A study found that MRI may be as sensitive as CT scanning in the detection of traumatic head injury, diffuse axonal injury, and intracranial hemorrhage, but missed skull fractures in 5 of 13 patients 4
- Another study found that MRI-based selection for acute ischemic stroke patients is accomplished within a timeframe similar to CT-based selection, without delaying treatment or impacting functional outcome 6
Considerations for Imaging Modalities
When choosing an imaging modality, the following factors should be considered:
- Availability: CT scans are widely available, while MRI may not be as readily available in all hospitals 2, 3
- Time: CT scans are generally faster than MRI scans 6
- Accuracy: MRI is more accurate than CT in identifying and characterizing most forms of traumatic cerebral pathology 3, 4
- Radiation exposure: CT scans involve radiation exposure, while MRI does not 4