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Unilateral Pallidotomy Vs. Unilateral Electrical Stimulation of GPI in bilateral symptoms of Parkinson’s disease at one year follow-up
Soto J, Jiménez F, Madrigal A, Velasco F, Velasco M ,Carrillo JD and Castro G.
Functional Neurosurgery, Stereotactic and Radiosurgery Unit
General Hospital of México.

Background: Although, deep brain stimulation (DBS) of subthalamic nucleus (STN) is a gold standard in surgical treatment of Parkinson’s disease (PD); alternative targets are options in control of tremor, rigidity and bradikinesia. DBS of globus pallidus (Gpi) or pallidotomy could get around 35% improvement in Unified Parkinson’s Disease Rating Scale (UPDRS) in patients with PD in Höehn and Yahr (H-Y) III to V with rigidity, bradikinesia, gait disturbance and imbalance. In addition to this, ablative surgery of STN is not a usual procedure and the cost of bilateral DBS devices is not easy to get. The principal question of this study was: Does unilateral DBS of Gpi have more effective clinical outcome than unilateral pallidotomy in patients with PD in H-Y III to V? Hypothesis: Either unilateral pallidotomy or unilateral DBS of Gpi improve 50% UPDRS score in patients with PD H-Y III to V.

Objectives: Primary: To evaluate UPDRS score baseline versus one year of follow-up in two different groups of surgical treatment in advanced PD patients. Secondary: To evaluate UPDRS sub-score of contralateral, ipsilateral and bilateral symptoms of PD patients. To determinate side effects in each procedure.

Methods: We selected thirty patients with PD in H-Y III to V for a clinical assay in a one year follow-up. Inclusion criteria were: Bilateral symptoms of PD with rigidity, bradikinesia, gait disturbance and imbalance. Improvement minor of 50% according UPDRS with pharmacotherapy and important side effects. Ages from 30 to 75 years. Each patient was randomized and assigned to pallidotomy or DBS of Gpi contralateral to predominant symptoms. Stereotactic surgery was performed for ablative procedure or lead implantation using Zamorano-Dujovni frame and Praezis image fusion software. Target coordinates were 9/10 of AC-PC length lateral to midline, 1.5/10 anterior to intercomissural point and 2/10 caudal to AC-PC level. Trans-operative macro-stimulation was made in all cases. The lesion in pallidotomy cases was made with N50 (Leibinger) radiofrequency system with 90ºc during 90 seconds. In DBS cases MRI was made one day after implantation in order to check right location of leads (Medtronic 3387) and generator pulse was implanted (Medtronic 7495-91). Neuromodulation started one week post-operative period. Parameters of monopolar stimulation were 1.5 to 3 V, 60 to 330 ms, 130 Hz in continuous program. Wilcoxon test was used to evaluate statistical differences in ordinal variables of two related samples and U-Mann Whitney test in ordinal variables of two no related samples.

Results: No statistical differences are showed between groups in demographics conditions. Final scores between pallidotomy vs DBS of Gpi are not statistical different but they did not get 50% improvement in UPDRS of base line score. Pallidotomy is more efficient than DBS of Gpi to improve final conditions of patients, particularly in Schwab and England scale (S-E) and UPDRS. There are not statistical differences between two procedures in control of contralateral or ipsilateral symptoms but pallidotomy is more efficient in bilateral control of rigidity and DBS of Gpi is more efficient in control of imbalance. There were not mortality and morbidity was transient
Conclusion: Either pallidotomy or DBS of Gpi have similar bilateral effects principally in rigidity and imbalance.


Final score improvement in UPDRS is minor than 50% but S-E score can get improve in general conditions with unilateral procedure without side effects.

We can use unilateral ablative procedure in initial treatment of advanced PD.


Pallidotomy

H – Y

S - E

UPDRS

NYPDS

%improvement

20

30

20

40

p

p < 0.016

p < 0.003

P < 0.002

p < 0.003

Electrical Stimulation

H – Y

S - E

UPDRS

NYPDS

%improvement

20

10

14

40

p

p < 0.054

p < 0.506

p < 0.009

p < 0.003

Final Score

H – Y

S - E

UPDRS

NYPDS

Pallidotomy

3

80

34

6

Electrical Stimulation

3

70

36

7

p

NA

p < 0.091

p < 0.833

p < 0.608

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