What is the interpretation of a 1.2 cm extra-axial lesion, likely a meningioma, found on a CT (Computed Tomography) head scan in a patient with declining cognitive function?

Interpretation of CT Head Findings: Likely Meningioma with Cognitive Decline

This 1.2 cm parafalcine meningioma with mild vasogenic edema is unlikely to be the primary cause of the patient's declining cognitive function, hemineglect, and behavioral symptoms—the small vessel ischemic changes and potential undetected pathology are more probable culprits, necessitating contrast-enhanced MRI for definitive evaluation. 1

Key Radiological Findings and Their Clinical Significance

The Meningioma

• The 1.2 cm extra-axial lesion with calcification at the left vertex is characteristic of a WHO grade 1 meningioma, which represents 90% of all meningiomas and typically follows a benign course 2
• The presence of calcification is common, occurring in up to 50% of meningiomas, and does not indicate aggressive behavior 3
• The mild vasogenic edema in the underlying left frontal juxtacortical white matter is a typical finding with meningiomas due to their vascular nature 3

Size and Symptom Correlation

• At 1.2 cm, this meningioma is considered small (<30 mm) and would typically be asymptomatic 3
• The patient's constellation of symptoms—hemineglect, getting lost, leaving the stove on, and declining cognitive function—suggests diffuse cortical dysfunction rather than a focal mass effect from a small meningioma 1
• The small vessel ischemic changes noted in the white matter are more consistent with the patient's cognitive and behavioral symptoms 1

Critical Next Steps: Why Contrast MRI is Essential

Inadequacy of Non-Contrast CT

• CT without contrast has limited sensitivity for detecting subtle parenchymal lesions, early ischemia, and inflammatory processes that could explain the patient's symptoms 1, 4
• MRI is superior to CT for all post-traumatic and degenerative lesions except skull fractures and subarachnoid hemorrhage 4
• The ACR recommends MRI brain without and with contrast when initial CT is unrevealing but clinical symptoms persist 1

What Contrast MRI Will Reveal

• Definitive characterization of the meningioma including homogeneous dural-based enhancement, dural tail sign, and CSF cleft—confirming the diagnosis 3
• Detection of additional pathology that may explain cognitive decline: early infarcts, inflammatory lesions (such as demyelinating disease), or other mass lesions not visible on non-contrast CT 1
• Assessment of the extent of small vessel disease and white matter changes that correlate with cognitive impairment 1
• Evaluation for leptomeningeal disease or other processes that could cause hemineglect 5

Management Algorithm for This Patient

Immediate Actions

1. Order MRI brain without and with IV contrast as the radiologist recommended—this is the gold standard for evaluating both the meningioma and unexplained neurological symptoms 3, 1
2. Perform detailed neurological examination specifically assessing for focal deficits, visual field cuts, and signs of increased intracranial pressure 1
3. Obtain comprehensive metabolic panel to exclude metabolic causes of altered mental status (hyponatremia, hypercalcemia, renal failure) 1

Meningioma-Specific Management

• For this asymptomatic small meningioma (<30 mm), observation is the appropriate initial management 3
• If the meningioma proves to be the cause of symptoms (unlikely given size), surgical resection would be considered only if accessible with acceptable risk 3
• Establish baseline MRI surveillance: For WHO grade 1 meningiomas, follow-up MRI every 6-12 months initially, with potential to extend intervals after demonstrating stability 5

Addressing the Cognitive Decline

• The cognitive symptoms warrant investigation beyond the meningioma: Consider neurodegenerative workup, vascular dementia evaluation, and assessment for reversible causes 1
• The small vessel ischemic changes may represent chronic microvascular disease contributing to cognitive impairment 1
• Risk stratification for stroke prevention should be initiated given the white matter changes 1

Common Pitfalls to Avoid

Diagnostic Errors

• Do not attribute all symptoms to the incidental meningioma—the size and location make it an unlikely primary cause of diffuse cognitive symptoms 3
• Do not rely solely on non-contrast CT when symptoms are unexplained, as MRI detects 70% of missed ischemic strokes that present with altered mental status 1
• Do not assume calcification indicates malignancy—calcifications are common in benign meningiomas 3

Management Missteps

• Do not rush to surgery for small asymptomatic meningiomas; observation is standard of care 3
• Do not delay contrast MRI thinking the CT is sufficient—the radiologist's recommendation for follow-up contrast study is appropriate and necessary 1
• Do not overlook the small vessel disease as a contributor to cognitive decline—this may be the primary pathology requiring intervention 1

Surveillance Considerations

• Do not discharge without establishing follow-up imaging plan—even benign meningiomas require long-term surveillance as recurrence can occur up to 20% within 25 years 3
• Do not use CT for surveillance—MRI without and with contrast is the appropriate modality for meningioma follow-up 5

Special Considerations for This Patient

The Hemineglect Finding

• Left-sided lesions (as in this case) typically cause right-sided neglect, but the patient presents with hemineglect 1
• This symptom strongly suggests additional pathology beyond the small meningioma, possibly involving the right parietal lobe or bilateral disease 1
• Contrast MRI is critical to identify the anatomical substrate for this specific symptom 1

Age-Related Factors

• The "within normal limits for age" ventricular size suggests the patient is older, making vascular cognitive impairment and mixed dementia more likely than mass effect from a small meningioma 1
• Older patients with new cognitive symptoms and normal non-contrast CT still benefit from MRI to detect subtle ischemia and other age-related pathology 1