The Canadian multicenter trial of pallidal deep brain stimulation for cervical dystonia: preliminary results in three patients

Zelma H. T. Kiss M.D., Ph.D., Kristina Doig B.N., R.N., Michael Eliasziw Ph.D., Ranjiit Ranawaya M.D., and Oksana Suchowersky M.D.
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  • Departments of Clinical Neuroscience and Community Health Sciences, University of Calgary, Alberta, Canada
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Object

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is beneficial for generalized dystonia and has been proposed as a treatment for cervical dystonia. The Canadian Stereotactic/Functional and Movement Disorders Groups designed a pilot project to investigate the following hypothesis: that bilateral DBS of the GPi will reduce the severity of cervical dystonia at 1 year of follow up, as scored in a blinded fashion by two neurologists using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Secondary outcome measures included pain and disability subscores of the TWSTRS, Short Form–36 quality of life index, and the Beck Depression Inventory.

Methods

Three patients have undergone surgery in Calgary with a followup duration of 7.4 ± 5.9 months (mean ± standard deviation). One patient underwent inadvertent ineffective stimulation for the first 3 months and did not experience a benefit until DBS programming was corrected. All three patients had rapid response to stimulation, with the muscles relaxing immediately and abnormal movements improving within days. Total TWSTRS scores improved by 79%, and severity subscores improved significantly, from 15.7 ± 2.1 to 7.7 ± 2.9 (paired ttest, p = 0.02). Pain and disability subscores improved from 25.5 ± 4.1 to 3.3 ± 3.1 (paired ttest, p = 0.002) and from 13.3 ± 4.9 to 3.3 ± 4.2 (paired ttest, p = 0.06), respectively.

Conclusions

Although it is too early to reach broad conclusions, this report of preliminary results confirms the efficacy of DBS of the GPi for cervical dystonia.

Abbreviations used in this paper:

BDI = Beck Depression Inventory; DBS = deep brain stimulation; GPe = globus pallidus externus; GPi = globus pallidus internus; IPG = implantable pulse generator; MR = magnetic resonance; PD = Parkinson disease; SF36 = Short Form–36; TWSTRS = Toronto Western Spasmodic Torticollis Rating Scale.

Object

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is beneficial for generalized dystonia and has been proposed as a treatment for cervical dystonia. The Canadian Stereotactic/Functional and Movement Disorders Groups designed a pilot project to investigate the following hypothesis: that bilateral DBS of the GPi will reduce the severity of cervical dystonia at 1 year of follow up, as scored in a blinded fashion by two neurologists using the Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS). Secondary outcome measures included pain and disability subscores of the TWSTRS, Short Form–36 quality of life index, and the Beck Depression Inventory.

Methods

Three patients have undergone surgery in Calgary with a followup duration of 7.4 ± 5.9 months (mean ± standard deviation). One patient underwent inadvertent ineffective stimulation for the first 3 months and did not experience a benefit until DBS programming was corrected. All three patients had rapid response to stimulation, with the muscles relaxing immediately and abnormal movements improving within days. Total TWSTRS scores improved by 79%, and severity subscores improved significantly, from 15.7 ± 2.1 to 7.7 ± 2.9 (paired ttest, p = 0.02). Pain and disability subscores improved from 25.5 ± 4.1 to 3.3 ± 3.1 (paired ttest, p = 0.002) and from 13.3 ± 4.9 to 3.3 ± 4.2 (paired ttest, p = 0.06), respectively.

Conclusions

Although it is too early to reach broad conclusions, this report of preliminary results confirms the efficacy of DBS of the GPi for cervical dystonia.

Abbreviations used in this paper:

BDI = Beck Depression Inventory; DBS = deep brain stimulation; GPe = globus pallidus externus; GPi = globus pallidus internus; IPG = implantable pulse generator; MR = magnetic resonance; PD = Parkinson disease; SF36 = Short Form–36; TWSTRS = Toronto Western Spasmodic Torticollis Rating Scale.

Contributor Notes

Address reprint requests to: Zelma H. T. Kiss, M.D., Ph.D., Room 182A, HMRB, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada. email: zkiss@ucalgary.ca.

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