Outcomes of Unilateral Pallidotomy in Focal and Hemidystonia Cases: A Single-Blind Cohort Study

Abstract

Background: The role of deep brain stimulation in the treatment of dystonia has been widely documented. However, there is limited literature on the outcome of lesioning surgery in unilateral dystonia.

Objective: We restrospectively reviewed our cases of focal and hemidystonia undergoing unilateral Pallidotomy at our institute to evaluate the short-term and long-term outcome.

Methods: Patients who underwent radiofrequency lesioning of GPi for unilateral dystonia between 1999 and 2019 were retrospectively reviewed. All patients were evaluated using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and Dystonia Disability Scale (DDS) preoperatively at the short term follow-up (<1 year) and at long-term follow-up (2-7.5 years). Video recordings performed at these time points were independently reviewed by a blinded movement disorders specialist.

Results: Eleven patients were included for analysis. The preoperative, short-term, and long-term follow-up motor BFMDRS and DDS scores were 15.5 (IQR [interquartile range]: 10.5, 23.75) and 10.5 (IQR: 6.0, 14.5); 3.0 (IQR: 1.0, 6.0, P = 0.02) and 3.0 (IQR: 3.0, 8.0, P = 0.016); and 14.25 (IQR: 4.0, 20.0, P = 0.20) and 10.5 (IQR: 2.0, 15.0, P = 0.71) respectively. For observers B, the BFMDRS scores at the same time points were 19 (IQR: 12.5, 27.0), 7.5 (IQR: 6.0, 15.0, P = 0.002), and 21 (IQR: 7.0, 22.0, P = 0.65) respectively. The improvement was statistically significant for all observations at short-term follow-up but not at long-term follow-up.

Conclusion: Pallidotomy is effective for hemidystonia or focal dystonia in the short term. Continued benefit was seen in the longer term in some patients, whereas others worsened. Larger studies may be able to explain this in future.

Keywords: hemidystonia; lesioning; pallidotomy.

FIG. 1

MRI (magnetic resonance imaging) T1‐weighted (A) coronal and (B) axial sequence showing lesion in the right pallidum. The lesion borders the inferior margin of the optic tract (A) and the medial margin of the internal capsule (B).

FIG. 2

Postoperative plot of lesion sites at the AC–PC (anterior commissure–posterior commissure) plane, with the x and y coordinates scaled to the Schaltenbrand Wahren atlas AC–PC length. The variability in the lesion sites is due to the individual variability in the GPi (globus pallidus internus) and therefore cannot be reproduced effectively here. However, each individual lesion when evaluated was within the GPi. On the left side, the star, plus, and square represent cases 1, 4, and 6. On the right side, the star, triangle, diamond, circle, and square represent cases 3, 5, 8, 9, and 11, respectively.

FIG. 3

(A) Preoperative Bland–Altman plot with good coherence between the two observers. (B) Postoperative (short‐term) Bland–Altman plot with good coherence between the two observers. (C) Postoperative (long‐term) Bland–Altman plot with good coherence between the two observers.