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Parkinsonian Signs in Patients With Cervical Dystonia Treated With Pallidal Deep Brain Stimulation

Mahlknecht, P; Georgiev, D; Akram, H; Brugger, F; Vinke, S; Zrinzo, L; Hariz, M; ... Limousin, P; + view all (2018) Parkinsonian Signs in Patients With Cervical Dystonia Treated With Pallidal Deep Brain Stimulation. Brain , 141 (10) pp. 3023-3034. 10.1093/brain/awy217. Green open access

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Abstract

Pallidal deep brain stimulation is an established treatment in patients with dystonia. However, evidence from case series or uncontrolled studies suggests that it may lead in some patients to specific parkinsonian symptoms such as freezing of gait, micrographia, and bradykinesia. We investigated parkinsonian signs using the Movement Disorder Society Unified Parkinson's Disease Rating Scale motor score by means of observer-blinded video ratings in a group of 29 patients treated with pallidal stimulation and a non-surgical control group of 22 patients, both with predominant cervical dystonia. Additional assessments included MRI-based models of volume of neural tissue activated to investigate areas of stimulation related to dystonic symptom control and those likely to induce parkinsonian signs as well as an EMG analysis to investigate functional vicinity of stimulation fields to the pyramidal tract. Compared with controls, stimulated patients had significantly higher motor scores (median, 25th-75th percentile: 14.0, 8.0-19.5 versus 3.0, 2.0-8.0; P < 0.0001), as well as bradykinesia (8.0, 6.0-14.0 versus 2.0, 0.0-3.0; P < 0.0001) and axial motor subscores (2.0, 1.0-4.0 versus 0.0, 0.0-1.0; P = 0.0002), while rigidity and tremor subscores were not different between groups. Parkinsonian signs were partially reversible upon switching stimulation off for a median of 90 min in a subset of 19 patients tolerating this condition. Furthermore, the stimulation group reported more features of freezing of gait on a questionnaire basis. Quality of life was better in stimulated patients compared with control patients, but parkinsonian signs were negatively associated with quality of life. In the descriptive imaging analysis maximum efficacy for dystonia improvement projected to the posteroventrolateral internal pallidum with overlapping clusters driving severity of bradykinesia and axial motor symptoms. The severities of parkinsonian signs were not correlated with functional vicinity to the pyramidal tract as assessed by EMG. In conclusion, parkinsonian signs, particularly bradykinesia and axial motor signs, due to pallidal stimulation in dystonic patients are frequent and negatively impact on motor functioning and quality of life. Therefore, patients with pallidal stimulation should be monitored closely for such signs both in clinical routine and future clinical trials. Spread of current outside the internal pallidum is an unlikely explanation for this phenomenon, which seems to be caused by stimulation of neural elements within the stimulation target volume.

Type: Article
Title: Parkinsonian Signs in Patients With Cervical Dystonia Treated With Pallidal Deep Brain Stimulation
Location: England
Open access status: An open access version is available from UCL Discovery
DOI: 10.1093/brain/awy217
Publisher version: https://doi.org/10.1093/brain/awy217
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: dystonia, deep brain stimulation, movement disorders: imaging, bradykinesia, gait, magnetic resonance imaging bradykinesia corticospinal tract dystonia electromyography glucose-6-phosphate isomerase glycosylphosphatidylinositols movement disorders muscle rigidity surgical procedures, operative tremor diagnostic imaging quality of life deep brain stimulation cervical dystonia unified parkinson's disease rating scale freezing of gait motor symptoms
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology > Clinical and Movement Neurosciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Brain Sciences > UCL Queen Square Institute of Neurology > Department of Neuromuscular Diseases
URI: https://discovery.ucl.ac.uk/id/eprint/10058563
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