A distinct clinicopathological variant of focal cortical dysplasia IIId characterized by loss of layer 4 in the occipital lobe in 12 children with remote hypoxic–ischemic injury

Abstract

Prominent disorganization of cortical layering and lack of any other microscopically visible principle lesion in the surgical specimen would result in this neuropathological pattern hitherto being classified as FCD ILAE type Ib. However, perinatal hypoxia with distinctive MRI changes suggested primarily a hypoxemic lesion and acquired pathomechanism of neuronal cell loss in the occipital lobe of our patient series. We propose, therefore, classifying this distinctive clinicopathological pattern as a separate variant of FCD ILAE type IIId.

Review: The international consensus classification of Focal Cortical Dysplasia – a critical update 2018

“…The reason for radial micro‐columnar cortical architecture adjacent to a foetal infarct or porencephalic cyst that occurred at mid‐gestation is maturational arrest of an ischemic zone that was not quite severe enough to be included in the frank infarct. Foetal ischemia after mid‐gestation or perinatal ischemia may produce a laminar lesion that in later life is epileptogenic and this new sub‐type IIId of ischemic lesions might be a better classification than the earlier FCD Ib. FCD adjacent to postnatally acquired infarcts presents the same problem of pathogenesis with non‐developmental lesions already mentioned.…”

“…Indeed, panel C of figure from the original ILAE publication in 2011 showed an example of FCD Ib, which will need revision and reclassification as FCD IIId. A recent report showed evidence that loss of layer 4 neurons results from early (perinatal) hypoxic‐ischemic injury in the occipital lobe . Histopathology of FCD Ic was never described before the ILAE classification in 2011 as FCD.…”

Clinical Value of Hybrid TOF-PET/MR Imaging–Based Multiparametric Imaging in Localizing Seizure Focus in Patients with MRI-Negative Temporal Lobe Epilepsy

“…The laboratory protocols used for specimen preparation were similar in all samples as described previously. 24 Tissue sections were fixed overnight in 10% buffered formalin and then orientated and cut perpendicularly to the cortical surface. Following routine paraffin embedding, 4-or 8-m-thick sections were stained with hematoxylin-eosin and Luxol fast blue.…”

Toward a refined genotype–phenotype classification scheme for the international consensus classification of Focal Cortical Dysplasia

“…This pattern contrasts any traumatic brain injuries occurring at later ages and which do not change the architectural matrix of the neocortex. A distinct clinico‐pathological variant of FCD Type 3D has recently been described in 12 children with remote hypoxic–ischemic injury, histologically showing vertical dyslamination characterized by loss of layer 4 in the occipital neocortex (51), similar to the picture shown in the 2011 ILAE classification as one example of FCD Type 1B. The case published in 2011 was re‐reviewed and re‐assigned to FCD Type 3D (Figure 1C).…”

“…(C) Loss of layer 4 was observed in a 6‐year‐old boy with remote hypoxemic brain injury. This pattern should be classified as associated FCD 3D (51). (D) Another characteristic pattern of FCD 3D was detected in a patient with perinatal brain injury, demonstrating horizontal and vertical layering abnormalities (arrow).…”