ILAE recommendation

  • Compared to patients in whom the cause is unknown, the rate of seizure recurrence increases twofold in those with a lesion on MRI, from 10% to 26% at 1 year and from 29% to 48% at 5 years.
  • The identification of a structural lesion in recent onset epilepsy is a strong indicator of drug resistance.
  • Once a lesion is discovered on MRI, a patient should be referred to a specialized epilepsy surgery center to evaluate surgical candidacy.
  • ILAE recommends the use of the Harmonized Neuroimaging of Epilepsy Structural Sequences (HARNESS‐MRI) protocol, containing at minimum the following sequence types:
    • High resolution 3D T1-weigted gradient echo (MPRAGE or equivalent)
    • High resolution 3D T2-weighted fluid‐attenuated inversion recovery (FLAIR)
    • High in‐plane resolution 2D coronal T2‐weighted MRI
    • If a tumor is discovered the study should be complemented with post-gadolinium T1-weighted images and a T2*-weighted or susceptibility-weighted sequence
  • The patient should be imaged using the HARNESS-MRI protocoll soon after the first seizure.
  • The MRI should be repeated using the HARNESS‐MRI protocol if images from a previous examination are not available or the type and quality of previous acquisitions are suboptimal.

Indications for MRI imaging in epilepsy

  • Abnormal neurologic examination.
  • Worsening or crescendo seizures.
  • Treatment resistant epilepsy.
  • Non-idiopathic epilepsy.
  • Evidence of partial seizure onset on EEG or history.
  • Patient evaluation for epilepsy surgery (MRI, fMRI, PET, SPECT).

Epileptogenic lesions discoverable by MRI

  • Tumors, including metastases
  • Trauma
  • Infection (eg. meningoencephalitis, brain abscess, CJD)
  • Toxic/metabolic encefalopathies
  • Focal cortical dysplasias
  • Hippocampal sclerosis
  • Cavernous, arteriovenous, and other vascular malformations
  • Developmental anomalies (eg. lisencephaly, porencephaly, schizencephaly, megalencephaly)
  • Disorders of neuronal migration (eg. heterotopia) or cortical organization (eg. polymicrogyria)
  • Lesions associated with specific syndromes (eg. Tuberus sclerosis, Sturge-Webber, etc.)



References

  • Recommendations for the use of structural magnetic resonance imaging in the care of patients with epilepsy: A consensus report from the International League Against Epilepsy Neuroimaging Task Force Epilepsia. 2019 Jun;60(6):1054-1068. doi: 10.1111/epi.15612