The ‘risus sardonicus’ of multiple system atrophy
2003; Wiley; Volume: 18; Issue: 10 Linguagem: Inglês
10.1002/mds.10499
ISSN1531-8257
AutoresGregor K. Wenning, Felix Geser, Werner Poewe,
Tópico(s)Neurological disorders and treatments
ResumoThe clinical diagnosis of multiple system atrophy (MSA) is fraught with difficulty and there are no pathognomonic features to discriminate the common (80% of cases) parkinsonian variant (MSA-P) from Parkinson's disease (PD). A number of early warning signs have been proposed as 'red flags' of MSA; they include disproportionate antecollis, myoclonic postural and action tremor, REM sleep behavior disorder, respiratory stridor, and the 'cold hand sign'. Many of our MSA patients, particularly (but not exclusively) of the MSA-P subtype, exhibit distinctive spontaneous dystonia of orofacial and platysma musculature (Fig. 1). In our experience, cranial dystonia of MSA often results in a characteristic facial distortion reminiscent of the well-known risus sardonicus (RS) of cephalic tetanus that is thought to be mediated by tetanospasmin-induced disinhibition of anterior horn cells. We have observed this 'dystonic RS of MSA' both in levodopa (L-dopa)-naive patients as well as a type of L-dopa–induced facial dystonia.1, 2 The RS sign, however, has failed to gain wider recognition as a useful red flag of MSA. We propose that the RS of MSA reflects selective sparing of orofacial ventral striatopallidal circuitry as has been shown to occur in post mortem proven striatonigral degeneration, the neuropathological substrate of MSA associated parkinsonism.3, 4 Interestingly, there is strong evidence that stimulation of ventral striatal dopamine release induces orofacial choreodystonia in rats.5 Future prospective natural history studies are required to determine the true diagnostic value of dystonic RS in MSA. Risus sardonicus (RS) of a patient with multiple system atrophy–parkinsonian type. Gregor K. Wenning MD, PhD*, Felix Geser MD*, Werner Poewe MD*, * Department of Neurology, University Hospital, Innsbruck, Austria.
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