Gait Disorders in Fatal Familial Insomnia

BackgroundFatal familial insomnia (FFI) is a hereditary autosomal-dominant prion disease linked to a mutation of the prion protein gene and characterized by sleep and autonomic abnormalities at onset followed by motor disturbances. We describe gait abnormalities in 13 FFI cases with different disease durations. MethodsClinical records and corresponding videos of 13 FFI cases were regularly monitored from disease onset to death. ResultsGait disturbances appeared in all FFI subjects 52 months after disease onset following a distinct progression for the 2 genetic FFI variants. Homozygous patients developed only a cautious gait with some difficulties in turning and in tandem gait; heterozygous patients showed a clear progressive worsening of equilibrium with latero/retropulsion ultimately preventing standing and walking unaided. ConclusionsThe severity and features of gait dysfunction in FFI are related to the duration of the disease, which in turn is a result of the genotype. The evolving gait dysfunction in the disease course may mirror the spread of neuronal degeneration from the thalamus to other brain areas involved in the control of gait or may be the functional effect of a disturbed neuronal network in which the thalamus is a crucial relay. (c) 2013 International Parkinson and Movement Disorder Society