Digit‐specific aberrations in the primary somatosensory cortex in Writer's cramp

Abstract

Therapeutic regimes aimed at facilitating inter-digit separation of digits 1, 2 and 3 may promote beneficial plasticity in WC patients.

Imaging insights into basal ganglia function, Parkinson's disease, and dystonia

“…65 Tasks that induced dystonia were frequently associated with increased activation in motor regions and associated areas, whereas tasks that did not induce dystonia, probably showing primary changes in the brain or longstanding consequences of dystonia, were associated with more variable activation changes. Abnormalities in movement imagination and in sensory representation in dystonias have also been reported, 66 supporting the view that afferent inputs are inadequately processed at several levels of the CNS, as shown with electrophysiological techniques. 67 Signal changes on MRI might be recorded with extensive practice and overtraining-a finding that might be highly relevant to dystonia, in which overuse of the affected body part is a common finding.…”

Dystonia Pathophysiology: A Critical Review

“…Kinesthesia is also impaired (101)(102)(103) and abnormal somatotopy was demonstrated by somatosensory evoked potential mapping based on EEG (94), MEG (94,104,105) and fMRI (106)(107)(108). As for motor control, a loss of lateral inhibition in sensory processing in space and time was reported (109)(110)(111).…”

“…In the cortex, activation level was variably altered, depending on the task, the type of dystonia, and whether patients expressed dystonia during task performance or not. The primary sensory cortex was activated frequently (165-167) but not always (107,166,168).…”

“…However, reduced sensorimotor activation also may occur during dystonic movements (165,166). The abnormal fMRI signals for representation of digits in the primary sensory cortex (107,108) or other body parts in the basal ganglia (171) have been interpreted as a loss of neuronal selectivity. It is noteworthy that although fMRI presumably monitors neuronal activation, results only partially correlate with PET studies of blood flow.…”

Dystonia – a disorder of dynamics of brain plasticity modulation?

“…These results are very much in keeping with magnetoencephalography (MEG) findings of aberrant cortical sensory maps of the dystonic hand fingers in patients with writer's cramp. Similarly to the motor maps, the sensory maps overlapped significantly, particularly for the fingers I, II and III, the ones which are affected the most by dystonic movements (Bara-Jimenez et al 1998, Nelson et al 2009). The feature, however, seems not to be restricted to the dystonic hand, but could be seen for asymptomatic hand as well (Meunier et al 2001).…”