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

Abstract

Objective: To explore the structure-function relation of the temporal lobe in newly diagnosed West syndrome of unknown cause (uWS).

Methods: Quantitative 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).

Results: Total 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).

Significance: The 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.

Keywords: Auditory event-related potential; Quantitative magnetic resonance imaging; Temporal lobe; West syndrome.