Somatosensory temporal discrimination in patients with primary focal dystonia

Department of Neurological Sciences, Sapienza, University of Rome, Rome, Italy.
Journal of neurology, neurosurgery, and psychiatry (Impact Factor: 6.81). 07/2009; 80(12):1315-9. DOI: 10.1136/jnnp.2009.178236
Source: PubMed


To determine whether somatosensory temporal discrimination will reliably detect subclinical sensory impairment in patients with various forms of primary focal dystonia.
The somatosensory temporal discrimination threshold (STDT) was tested in 82 outpatients affected by cranial, cervical, laryngeal and hand dystonia. Results were compared with those for 61 healthy subjects and 26 patients with hemifacial spasm, a non-dystonic disorder. STDT was tested by delivering paired stimuli starting with an interstimulus interval of 0 ms followed by a progressively increasing interstimulus interval.
STDT was abnormal in all the different forms of primary focal dystonias in all three body regions (eye, hand and neck), regardless of the distribution and severity of motor symptoms. Receiver operating characteristic curve analysis calculated in the three body regions yielded high diagnostic sensitivity and specificity for STDT abnormalities.
These results provide definitive evidence that STDT abnormalities are a generalised feature of patients with primary focal dystonias and are a valid tool for screening subclinical sensory abnormalities.

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    • "- onset dystonia patients TDT does not improve with botulinum toxin or with pallidal stimulation Aglioti et al., 2003 Bara - Jimenez , Shelton , et al., 2000 Bradley et al . , 2009 ; 2012 Fiorio et al . , 2003 Fiorio , Gambarin , et al . , 2007 Fiorio , Tinazzi , et al . , 2008 Kimmich et al . , 2014 Sadnicka , et al . , 2013 Sanger et al . , 2001 Scontrini , et al . , 2009 ; 2011 Tinazzi et al . , 1999 ; 2002 ; 2004 Aristotle ' s illusion"
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    ABSTRACT: Traditional definitions of focal dystonia point to its motor component, mainly affecting planning and execution of voluntary movements. However, focal dystonia is tightly linked also to sensory dysfunction. Accurate motor control requires an optimal processing of afferent inputs from different sensory systems, in particular visual and somatosensory (e.g., touch and proprioception). Several experimental studies indicate that sensory-motor integration -the process through which sensory information is used to plan, execute, and monitor movements- is impaired in focal dystonia. The neural degenerations associated with these alterations affect not only the basal ganglia-thalamic-frontal cortex loop, but also the parietal cortex and cerebellum. The present review outlines the experimental studies describing impaired sensory-motor integration in focal dystonia, establishes their relationship with changes in specific neural mechanisms, and provides new insight towards the implementation of novel intervention protocols. Based on the reviewed state-of-the-art evidence, the theoretical framework summarized in the present article will not only result in a better understanding of the pathophysiology of dystonia, but it will also lead to the development of new rehabilitation strategies. Copyright © 2015. Published by Elsevier Ltd.
    Full-text · Article · Jul 2015 · Neuropsychologia
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    • "However, we believe that the impairment of the tactile and proprioceptive temporal discrimination seen in FT patients represents an intrinsic feature of FT. First, we tried to minimize the bias due to possible changes in attention by delivering catch trials (3 for each series) with 0 msec interstimulus interval, as already described in previous studies;[11], [15], [21] second, FT patients performed similarly on repeated tests, while we should have found a marked variability if these results would have been caused by attention deficits; third, we found a consistent bilateral pattern of impairment also in patients with unilateral symptoms; finally, abnormal temporal processing of somatosensory input in FT is in line with the abnormal TDT we reported in patients with functional dystonia,[9] although in that study we did not test the TDMT. "
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    ABSTRACT: Background and Methods In order to obtain further information on the pathophysiology of functional tremor, we assessed tactile discrimination threshold and proprioceptive temporal discrimination motor threshold values in 11 patients with functional tremor, 11 age- and sex-matched patients with essential tremor and 13 healthy controls. Results Tactile discrimination threshold in both the right and left side was significantly higher in patients with functional tremor than in the other groups. Proprioceptive temporal discrimination threshold for both right and left side was significantly higher in patients with functional and essential tremor than in healthy controls. No significant correlation between discrimination thresholds and duration or severity of tremor was found. Conclusions Temporal processing of tactile and proprioceptive stimuli is impaired in patients with functional tremor. The mechanisms underlying this impaired somatosensory processing and possible ways to apply these findings clinically merit further research.
    Full-text · Article · Jul 2014 · PLoS ONE
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    • "These abnormalities are not restricted to a specific type of dystonia; they can also emerge in patients with blepharospasm, focal hand, cervical, and generalized dystonia. Moreover, sensory deficits in dystonia are not strictly related to the affected limb but can also occur in body parts remote from dystonic symptoms [19], [24], [31], [33]. This evidence challenges the notion of specificity of sensory abnormalities to the pathophysiology of different movement disorders [23]. "
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    ABSTRACT: Sensory alterations, a common feature of such movement disorders as Parkinson's disease (PD) and dystonia, could emerge as epiphenomena of basal ganglia dysfunction. Recently, we found a selective reduction of tactile perception (Aristotle's illusion, the illusory doubling sensation of one object when touched with crossed fingers) in the affected hand of patients with focal hand dystonia. This suggests that reduced tactile illusion might be a specific feature of this type of dystonia and could be due to abnormal somatosensory cortical activation. The aim of the current study was to investigate whether Aristotle's illusion is reduced in the affected hand of patients with PD. We tested 15 PD patients, in whom motor symptoms were mainly localised to one side of the body, and 15 healthy controls. Three pairs of fingers were tested in crossed (evoking the illusion) or parallel position (not evoking the illusion). A sphere was placed in the contact point between the two fingers and the blindfolded participants had to say whether they felt one or two stimuli. Stimuli were applied on the affected and less or unaffected side of the PD patients. We found no difference in illusory perception between the PD patients and the controls, nor between the more affected and less/unaffected side, suggesting that Aristotle's illusion is preserved in PD. The retained tactile illusion in PD and its reduction in focal hand dystonia suggest that the basal ganglia, which are dysfunctional in both PD and dystonia, may not be causally involved in this function. Instead, the level of activation between digits in the somatosensory cortex may be more directly involved. Finally, the similar percentage of illusion in the more affected and less or unaffected body sides indicates that the illusory perception is not influenced by the presence or amount of motor symptoms.
    Full-text · Article · Feb 2014 · PLoS ONE
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