Quantitative magnetic resonance imaging evidence for altered structural remodeling of the temporal lobe in West syndrome

Abstract

SummaryObjectiveTo explore the structure–function relation of the temporal lobe in newly diagnosed West syndrome of unknown cause (uWS).MethodsQuantitative magnetic resonance imaging (three‐dimensional [3D] structural MRI and diffusion tensor imaging [DTI]) was analyzed using voxel‐based morphometry (VBM) and tract‐based spatial statistics (TBSS) in 22 patients and healthy age‐matched controls. The electrophysiologic responsiveness of the temporal lobe was measured using the N100 auditory event‐related potential (aERP) to a repeated 1,000 Hz tone. Neurocognitive function was assessed using the Bayley Scales of Infant Development, Second Edition (BSID‐II). Tests followed first‐line treatment with vigabatrin (17 patients) or high‐dose oral prednisolone (5 patients).ResultsTotal temporal lobe volume was similar in patients and controls. Patients had a smaller temporal stem (TS) (p < 0.0001) and planum temporale (PT) (p = 0.029) bilaterally. TS width asymmetry with a larger right‐sided width in controls was absent in patients (p = 0.033). PT asymmetry was present in both groups, being larger on the right (p = 0.048). VBM gray matter volume was increased at the left temporal lobe (superior and middle temporal gyri, the peri‐rhinal cortex, and medial temporal lobe) (p < 0.005, family wise error‐corrected). VBM gray matter volume correlated with the duration of infantile spasms (Pearson's r = −0.630, p = 0.009). DTI metrics did not differ between patients and controls on TBSS. Mean BSID‐II scores were lower (p < 0.001) and auditory N100 ERP attenuated less in patients than in controls (p = 0.002).SignificanceThe functional networking and white matter development of the temporal lobe are impaired following infantile spasms. Treatment may promote structural plasticity within the temporal lobe following infantile spasms, manifest as increased gray matter volume on VBM. It remains to be investigated further whether this predicts patients' long‐term cognitive difficulties.

Auditory processing following infantile spasms: An event‐related potential study

“…The uWS patients (n = 22; 12 female) had onset of infantile spasms (IS) at a median age of 5 months (range 4–7 months). The cognitive profile of the patient group has been reported elsewhere, with all having a history of normal development followed by regression with the onset of IS. Median lag to treatment was 4 weeks (range 2–20 weeks) (Table ).…”

“…Early onset childhood epilepsies show neurologic comorbidities (psychiatric, sensory‐perceptual, linguistic, motor, and intellectual), the substrates of which are beginning to be specified . Language is particularly impaired, even following seizure remission, and provides a paradigm for functional connection between the temporal and frontal lobes .…”

Cytotoxic edema at onset in West syndrome of unknown etiology: A longitudinal diffusion tensor imaging study

“…A similar study of patients with WS of unknown etiology by Fosi et al 35 showed no differences in FA and MD between patients and controls on TBSS analysis at onset. In that study, treatment using vigabatrin or high-dose oral prednisolone was initiated prior to MRI, and epileptiform activity had probably been reduced at that time in some patients.…”

“…The higher resolution of MRI might have contributed to the detection of more subtle microstructural changes of the white matter in our study. Furthermore, additional differences may arise from the different control group compared with that used by Fosi et al 35 Considerable evidence suggests that the brainstem plays important roles in the generation of epileptic spasms and hypsarrhythmia in WS. 1 Abnormal function of serotonergic neurons in the dorsal brainstem raphe nuclei, which project to the cerebellum, cerebral cortex, and basal ganglia, are considered likely to cause the hypsarrhythmic EEG pattern.…”

White Matter Abnormality Correlates with Developmental and Seizure Outcomes in West Syndrome of Unknown Etiology

“…This is the first report revealing abnormal findings on DTI in patients with WS of unknown etiology. A recently published study by Fosi et al 14 did not show a significant difference between patients with WS and controls on TBSS analysis of DTI. The timing of MR imaging scans in their study was not clearly described and seems to be variable.…”