Abstracts

Rationale: Cryptogenic West syndrome (WS) has normal development before the onset, and no structural abnormalities are observed on conventional MRI. However, seizure and psychomotor outcome is very diverse. Diffusion tensor imaging (DTI) is an MRI technique that can provide information about white matter fiber orientation and integrity. We prospectively performed DTI to assess white matter abnormalities in patients with cryptogenic WS. Images were analyzed with tract-based spatial statistics (TBSS). Methods: We studied 9 consecutive patients with cryptogenic WS. Age at the onset of spasms was from 3 to 10 months. Developmental quotient at 1 year of age was from 53 to 100. DTI was acquired using 3T MRI (3.0T Trio, Siemens) at the onset and 1 year of age, and fractional anisotropy (FA) images are constructed. Images scanned at 1 year of age were used for analysis. FA images in patients were compared with those of 9 controls whose mean age at the scan was 12 months. Statistical analysis of FA images was carried out using TBSS implemented in FSL (The Oxford FMRIB Software Library). TBSS projects all subjects FA data onto a mean FA tract skeleton, before applying voxelwise cross-subject statistics. Individual FA data were then projected onto the skeleton, and then correction for multiple comparisons was performed. Regions with significant differences were identified with threshold: p<0.05. Results: The patients with cryptogenic WS, as compared to controls, showed clusters of significantly decreased FA. Decreased FA was observed in anterior corpus callosum, bilateral deep white matters, and right temporal lobes. On the other hand, no areas of increased FA were observed in patients. Conclusions: Decreased FA on TBSS may reflect delayed myelination or micro-structural abnormalities, such as microdysgenesis. TBSS is useful to detect latent white matter abnormalities in cryptogenic WS. Decreased white matter integrity may be correlated with developmental outcome in cryptogenic WS.