All in the blink of an eye: new insight into cerebellar and brainstem function in DYT1 and DYT6 dystonia.

BACKGROUND AND PURPOSE: Traditionally dystonia has been considered a disorder of basal ganglia dysfunction. However, recent research has advocated a more complex neuroanatomical network. In particular, there is increasing interest in the pathophysiological role of the cerebellum. Patients with cervical and focal hand dystonia have impaired cerebellar associative learning using the paradigm eyeblink conditioning. This is perhaps the most direct evidence to date that the cerebellum is implicated in patients. METHODS: Eleven patients with DYT1 dystonia and five patients with DYT6 dystonia were examined and rates of eyeblink conditioning were compared with age-matched controls. A marker of brainstem excitability, the blink reflex recovery, was also studied in the same groups. RESULTS: Patients with DYT1 and DYT6 dystonia have a normal ability to acquire conditioned responses. Blink reflex recovery was enhanced in DYT1 but this effect was not seen in DYT6. CONCLUSIONS: If the cerebellum is an important driver in DYT1 and DYT6 dystonia our data suggest that there is specific cerebellar dysfunction such that the circuits essential for conditioning function normally. Our data are contrary to observations in focal dystonia and suggest that the cerebellum may have a distinct role in different subsets of dystonia. Evidence of enhanced blink reflex recovery in all patients with dystonia was not found and recent studies calling for the blink recovery reflex to be used as a diagnostic test for dystonic tremor may require further corroboration.

Anticardiolipin antibodies are associated with cognitive dysfunction in stroke-free individuals.

BACKGROUND AND PURPOSE: The presence of anticardiolipin antibodies (aCLs) has been associated with vascular occlusive events. The role of aCLs as a risk factor for stroke has been a matter of debate, and scarce information exists on the relationship between aCLs and other cerebral disorders. Reports exist for seizures, chorea and subtle cognitive dysfunction. The association between aCLs and cognition was further explored and the relationship between aCL titres and brain magnetic resonance imaging (MRI) findings was evaluated in a large cohort of community-dwelling individuals. METHODS: The study cohort was drawn from the Austrian Stroke Prevention Study. A total of 1895 subjects had a complete risk factor assessment and measurement of aCL titres in serum. Participants were classified as aCL positive if either the immunoglobulin G (IgG) or IgM aCL titres were elevated (IgG > 21 U/ml, IgM > 12 U/ml). All subjects were also categorized based on the quartile distribution of IgG and IgM isotype titres. All underwent cognitive testing by the Mini Mental State Examination (MMSE) and a random sample of 947 participants also underwent brain MRI. RESULTS: aCL positive participants performed worse on the MMSE. IgG but not IgM isotype titres related to worse performance on the MMSE. No significant association existed with vascular brain abnormalities including lacunes, cortical infarcts and white matter lesions. CONCLUSIONS: These data support the view that in normal elderly persons increasing IgG aCL titres relate to global cognitive dysfunction. It is unlikely that structural brain lesions are responsible for this finding.