What is the management approach for a child or young adult with a history of seizures or epilepsy, presenting with cortical flair hyperintensity without perfusion change on imaging studies?

Management of Cortical FLAIR Hyperintensity Without Perfusion Change in Children/Young Adults with Seizures

Primary Recommendation

In a child or young adult with seizures presenting with cortical FLAIR hyperintensity without perfusion change, the most likely diagnosis is focal cortical dysplasia (FCD), and management should prioritize complete epilepsy protocol MRI evaluation followed by medical optimization with antiepileptic drugs, with early consideration of surgical resection if seizures prove medically refractory. 1, 2

Diagnostic Interpretation

Understanding the Imaging Pattern

• Cortical FLAIR hyperintensity without perfusion change strongly suggests focal cortical dysplasia (FCD), the most common cause of medically refractory focal epilepsy in children and the most frequent malformation of cortical development subtype. 1

• The absence of perfusion change distinguishes this from acute seizure-related changes (which show hyperperfusion ictally) or post-ictal changes, making a structural developmental abnormality the primary consideration. 3

• FLAIR hyperintensity in FCD typically predominates in the bottom part of the sulcus, representing the malformation's characteristic bottom-of-sulcus-rooted distribution pattern. 4

Critical Imaging Optimization

• Immediate action: Obtain a dedicated epilepsy protocol MRI with 3T scanner if not already performed, as standard MRI protocols miss up to 30% of cortical dysplasias. 2, 5

• The dedicated protocol must include: coronal T1-weighted imaging (3mm) perpendicular to hippocampal long axis, high-resolution 3D T1-weighted gradient echo with 1mm isotropic voxels, coronal T2-weighted sequences, and coronal/axial 3D FLAIR sequences. 2

• 3D FLAIR sequences are superior to conventional 2D FLAIR for detecting and delineating FCD extent, with significantly better assessment of cortical thickness, cortical signal intensity, adjacent white matter abnormalities, and gray-white matter junction. 5

Medical Management Algorithm

Initial Antiepileptic Drug Therapy

• Begin appropriate antiepileptic drug (AED) therapy based on seizure type, following standard clinical practice guidelines for the specific seizure semiology. 3

• Use a "start low, go slow" approach to medication dosing, particularly important in patients with developmental brain abnormalities who may have altered seizure thresholds. 3

• Document seizure frequency, characteristics, and response to each medication trial meticulously, as this information becomes critical for surgical candidacy assessment. 6

Defining Medical Refractoriness

• The standard observation period is 2 years of appropriate medical management before considering surgery, though earlier surgical intervention may be warranted when multiple appropriate AEDs fail to establish control. 6

• Medical refractoriness is defined as failure of adequate trials of at least two appropriately chosen and tolerated AED regimens to achieve sustained seizure freedom. 1

Surgical Evaluation Pathway

When to Initiate Presurgical Workup

• Begin presurgical evaluation when seizures remain uncontrolled despite trials of 2-3 appropriate AEDs, rather than waiting the full 2-year period if clear medication failure is evident. 6

• Earlier surgical referral is particularly justified in children, as prolonged uncontrolled seizures negatively impact neurodevelopment and quality of life. 1

Advanced Functional Imaging

• FDG-PET should be obtained as complementary imaging, showing glucose hypometabolism in the region of FCD with sensitivity of 87-90% for temporal lobe lesions and 38-55% for extra-temporal lesions. 2, 6

• Ictal SPECT with SISCOM (subtraction ictal SPECT co-registered to MRI) improves sensitivity and specificity for identifying the epileptogenic zone, demonstrating hyperperfusion during seizures with localization sensitivity >90% in temporal lobe epilepsy and 70% in extra-temporal epilepsy. 3, 2

• Concordance between MRI, EEG, PET, and SPECT findings significantly improves surgical outcome prediction. 6

Surgical Decision-Making

• Complete surgical resection of the epileptogenic region is the treatment of choice for medically refractory FCD, with extended resection showing higher success rates and low morbidity compared to lesionectomy alone. 6

• The critical factor for optimal seizure control is complete removal of the epileptogenic zone—incomplete resection significantly increases seizure recurrence risk and need for reoperation. 6

Critical Pitfalls to Avoid

Imaging Interpretation Errors

• Do not assume the visible FLAIR hyperintensity represents the complete extent of the dysplasia—FCD often extends beyond MRI-visible abnormalities, requiring functional imaging and electrophysiological correlation. 5, 7

• Do not mistake periictal/postictal changes for FCD—seizure-related FLAIR hyperintensity typically shows associated perfusion changes (hyperperfusion ictally, hypoperfusion postictally) and may be reversible on follow-up imaging. 8

• Recognize that approximately 30% of FCD cases may appear normal on routine MRI protocols, necessitating specialized sequences. 1, 5

Management Timing Errors

• Do not delay surgical evaluation for the arbitrary 2-year period if clear medical refractoriness is evident—prolonged uncontrolled seizures in children cause cumulative neurodevelopmental harm. 6

• Do not proceed with lesionectomy alone—extended resection based on electrophysiological and functional imaging data yields superior outcomes compared to resecting only the MRI-visible lesion. 6

Diagnostic Workup Gaps

• Do not rely solely on structural imaging—functional imaging (PET/SPECT) and comprehensive video-EEG monitoring are essential for defining the epileptogenic zone boundaries. 3, 2, 6

• Ensure evaluation includes assessment for extracerebral abnormalities, as cranial nerve enlargement or other anomalies may occasionally accompany FCD. 7

Monitoring and Follow-Up

• Serial neurological examinations should assess for focal deficits that may indicate lesion progression or seizure-related injury. 1

• Follow-up MRI is indicated if seizure pattern changes, new neurological deficits develop, or to assess for seizure-induced long-term injuries such as focal brain atrophy, cortical laminar necrosis, or mesial temporal sclerosis. 8

• Patients with periodic epileptiform discharges on EEG have higher possibilities of widespread MRI abnormalities and poorer long-term prognosis, warranting closer monitoring. 8