PMC4350194_01
(a) Inter-ictal EEG shows right occipital discharges with normal symmetrical background activity and posterior dominant alpha waves; (b) Ictal onset was in the right occipital region; (c) IGEA noted during the seizure the mean amplitude was 62.40 +- 15.1 muV. During this period the ECG was normal but with decreased chest excursions
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F1
Inter-ictally, there were frequent spike and sharp wave discharges from right posterior quadrant (T6-O2) [Figure 1a]. Prior to clinical seizure, there was build-up of spikes and sharp waves in the right temporo-occipital leads (T6, O2) [Figure 1b] which lasted for a very long period, later spreading to the right hemisphere before becoming generalized. During the apparent periods of hypopnea there was cessation of the clinical seizure, and EEG showed absence of epileptiform activity and generalized attenuation of the cerebral electrical activity (right > left) [Figure 1c] lasting for 260-4682 msec with mean amplitude of 20 +- 10 muV, compared to the average background amplitude of 175.55 +- 19.11muV. IGEA would be followed by either generalized seizure activity or seizure onset building up again in the right occipital region [Figure 1g]. Ictal tachycardia was noted (125-135 bpm).
PMC4350194_02
(A): 3TMRI Brain FLAIR-axial sequence showing subtle cortical hyperintensity of the right lateral superior (temporo) occipital gyrus with poor grey white matter differentiation; (b) Interictal FDG - PET with CT axial, showed hypometabolism in the right posterior quadrant, predominantly the occipital and posterior temporal regions; (c,d) MEG showing spikes and dipole clusters predominantly from the right occipital regions propagating anteriorly; E-G: Histopathological examination of the occipital lobe revealed focal widening of the cortical ribbon (Figure 1e, arrows) highlighted on Luxol Fast Blue stain (Figure 1e, bracket) and NeuNimmuno labeling compared to adjacent cortex of normal thickness (Figure 1e, asterix). Radial dyslamination and microcolumnar organization of neurons is seen on NeuNimmunolabeling in these zones [Figure 1f, g) corresponding to focal cortical dysplasia type 1a. [e: LFBx8, f,g: neuNimmunostaining; magnification=scale bar]
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F2
A 3-Tesla brain MRI revealed focal loss of grey-white matter differentiation on T2W imaging with subtle cortical hyperintensity on 3D-Flair involving the right lateral superior temporo-occipital gyrus, suggesting cortical dysplasia [Figure 2a]. Inter-ictal positron emission tomography (PET) scan revealed right temporo-occipital hypometabolism [Figure 2b]. Magnetoencephalography (MEG) revealed dipole clusters from the right occipital region [Figure 2c,d]. Histo-pathological examination revealed focal widening of the cortical ribbon [Figure 2e]. NeuNimmuno labeling revealed radial dyslamination in these zones with micro-columnar organization of neurons [Figure 2f,g] corresponding to focal cortical dysplasia type 1a in the occipital neocortex.