Objective: This study investigates the patterns of brain functional MRI (fMRI) during resting-state (RS) with and without sensory trick (ST) and during the ST imagination in subjects with cervical dystonia (DYT).

Background: Previous studies using positron emission tomography and transcranial magnetic stimulation suggested the possible role of ST in modulating the sensorimotor cortex excitability in DYT patients. However, the mechanisms underlying the ST effect in DYT subjects remain to be fully understood.

Methods: We recruited 17 patients with cervical DYT, treated with botulinum toxin at least three months before, and 15 healthy controls (HC). In 9 patients (DYT-trick), ST almost reversed head rotation to primary position, while 8 patients (DYT-notrick) did not show any trick effect. All groups underwent RS fMRI, and DYT groups repeated RS fMRI performing ST. DYT patients also performed a functional MRI task  in which they were asked to imagine an ipsilateral ST (i.e., slight touch on the cheek/chin).

Results: DYT-notrick subjects showed an increased connectivity of the sensorimotor network relative to HC during RS fMRI without ST. During RS fMRI with ST, DYT trick patients showed a reduced connectivity of the sensorimotor network relative to RS fMRI without ST, while DYT-notrick did not show any ST effect. During the imagination of ST, DYT-trick cases had an increased recruitment of the cerebellum bilaterally compared to DYT-notrick subjects.

Conclusions: This study suggests  an hyperconnectivity of the sensorimotor areas during RS in cervical DYT-notrick subjects. In DYT-trick patients, the ST was associated with a “normalization” of such a phenomenon. The increased activation of the cerebellum in DYT-trick patients during the ST imagination suggests a possible role of this area in modulating cortical activity. These findings call for novel therapies for cervical DYT such as electrical stimulation of cerebellum and modulation of proprioception using vibration or electrocutaneous stimulation devices.

This abstract was presented at the 47th Congress of the Italian Neurological Society (Venice, 22-25 October 2016)

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MDS Abstracts - https://www.mdsabstracts.org/abstract/sensory-trick-phenomenon-in-cervical-dystonia-a-functional-mri-study/