SPAST and hereditary spastic paraplegia: The broad alterations in pure HSP found in our study confirm findings of previous studies analyzing multiple genotypes of pure and complicated HSP (e.g., SPG3a, 4, 5, 7, 10, 11, 15, 31, 35) [14,33] and studies concentrating on SPG4 [18,20] showing a widespread impairment of commissure, association and projection fibers dominated by the corpus callosum and the CST as well.