Human transmissible spongiform encephalopathies (TSEs) or prion diseases are neurodegenerative disorders of infectious, inherited or sporadic origin and include Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker disease (GSS), kuru and fatal familial insomnia (FFI). Clinicopathologic features of FFI differ markedly from other human TSEs. Previous studies demonstrated selective neuronal vulnerability of parvalbumin positive (PV+) GABAergic inhibitory interneurons in sporadic CJD and experimental TSEs. In this report we show uniform severe loss of PV+ neurons also in other TSEs such as GSS, kuru, new variant and familial CJD. In contrast, these neurons are mostly well preserved, or only moderately reduced, in FFI. Only PV+ neurons surrounded by isolectin-B4 positive perineuronal nets were severely affected in TSEs, suggesting a factor residing in this type of extracellular matrix around PV+ neurons as modulator for the selective neuronal vulnerability.