Prosopagnosia seizure semiology in a 10-year-old boy: a functional neuroimaging study

Abstract

We illustrate a case of post-traumatic recurrent transient prosopagnosia in a paediatric patient with a right posterior inferior temporal gyrus haemorrhage seen on imaging and interictal electroencephalogram abnormalities in the right posterior quadrant. Face recognition area mapping with magnetoencephalography (MEG) and functional MRI (fMRI) was performed to clarify the relationship between the lesion and his prosopagnosia, which showed activation of the right fusiform gyrus that colocalised with the lesion. Lesions adjacent to the right fusiform gyrus can result in seizures presenting as transient prosopagnosia. MEG and fMRI can help to attribute this unique semiology to the lesion.

Keywords: epilepsy and seizures; neuroimaging; neurosurgery; paediatric surgery.

Figure 1

Preoperative MRI and positron emission tomography (PET), face recognition area mapping with magnetoencephalography (MEG) and functional MRI (fMRI), and preoperative and postoperative MRI with MEG-localised face recognition area overlay. A right posterior-inferior temporal focal lesion involving the cortex and subcortical white matter of the inferior temporal gyrus is seen on T2 fluid-attenuated inversion recovery (FLAIR) (A) and susceptibility-weighted imaging (SWI) (B) obtained 3 months after initial presentation. A susceptibility blooming artefact can be seen on SWI, in keeping with a remote bleed and hemosiderin deposition. Another axial cut of the T2 FLAIR (C) more inferior to the previous images shows the location of a small area of T2 FLAIR hyperintensity (arrow) co-localised with fluorodeoxyglucose PET hypometabolism (arrow) (D) at the crown of sulcus anterior-inferior to the hemosiderin staining. For face recognition area mapping, MEG results were displayed as maximal intensity projections while fMRI results were displayed on the patient’s T1 (E–H). Bilateral fusiform activation was seen in both MEG and fMRI in the faces condition (E), with greater activation on the right versus the left. For the houses condition, fusiform activation was greatly decreased with MEG and absent with fMRI (F), while activation was greatest in the primary and secondary visual cortices in MEG and fMRI, respectively. There was left fusiform activation with MEG in the unknown faces condition, but none for fMRI (G). Both modalities showed bilateral fusiform activation for the famous faces conditions with an overall higher amplitude event-related field compared with the unknown faces condition on MEG (H). MEG additionally showed activation of the right fusiform gyrus more anteriorly. The MEG activation map from (H) was overlaid onto the preoperative T2 FLAIR and postoperative T1 MRIs (I, J), demonstrating the adjacency of the MEG-localised face recognition area with the lesion and resection cavity.