Efficacy of bilateral pallidotomy

Surgical Treatment of Parkinson's Disease: Devices and Lesion Approaches

Surgical treatments have transformed the management of Parkinson's disease (PD). Therapeutic options available for the management of PD motor complications include deep brain stimulation (DBS), ablative or lesioning procedures (pallidotomy, thalamotomy, subthalamotomy), and dopaminergic medication infusion devices. The decision to pursue these advanced treatment options is typically done by a multidisciplinary team by considering factors such as the patient's clinical characteristics, efficacy, ease of use, and risks of therapy with a goal to improve PD symptoms and quality of life. DBS has become the most widely used surgical therapy, although there is a re-emergence of interest in ablative procedures with the introduction of MR-guided focused ultrasound. In this article, we review DBS and lesioning procedures for PD, including indications, selection process, and management strategies.

Deep Brain Stimulation of the Subthalamic Nucleus in Patients with Parkinson Disease with Prior Pallidotomy or Thalamotomy

Objective. To evaluate the efficacy of deep brain stimulation of the subthalamic nucleus (STN DBS) in patients with Parkinson disease (PD) who previously underwent lesioning of the basal ganglia. Material and methods. The study included 22 patients who underwent STN DBS. Eleven patients had undergone prior unilateral pallidotomy (n = 6) or VL/VIM thalamotomy (n = 5) while the other 11 patients had not. The primary outcome was the change from baseline in the motor subscore of the Unified Parkinson Disease Rating Scale (UPDRS-III) 12 months after STN DBS. Secondary outcomes included change in motor response complications (UPDRS-IV) and change in levodopa equivalent daily dose (LEDD). Results. In the group with prior lesioning UPDRS-III improved by 45%, from 51.5 ± 9.0% (range, 35–65) to 26.5 ± 8.4 (range, 21–50) (p < 0.01) and UPDRS-IV by 75%, from 8.0 ± 2.01 (range, 5–11) to 2.1 ± 0.74 (range, 1–3) (p < 0.01). In the group without prior lesioning UPDRS-III improved by 61%, from 74.2% ± 7.32 (range, 63–82) to 29.3 ± 5.99 (range, 20–42) (p < 0.01) and UPDRS-IV by 77%, from 9.1 ± 2.46 (range, 5–12) to 2.0 ± 1.1 (range, 1–4) (p < 0.01). Comparing the two groups (with and without lesioning) no significant differences were found either in UPDRS-III (p > 0.05) or UPDRS-IV scores (p > 0.05) at 12 months post-DBS. The LEDD was reduced by 51.4%, from 1008.2 ± 346.4 to 490.0 ± 194.3 in those with prior surgery (p < 0.01) and by 55.0%, from 963.4 ± 96.2 to 433.3 ± 160.2 in those without (p < 0.01).UPDRS-III improved by 51.8%, from 53.7 ± 4.6 (range, 50–62) to 25.0 ± 3.8 (range, 21–31) in those with prior pallidotomy (p < 0.01), and by 37.5%, from 48.8 ± 12.6 (range, 35–65) to 29.8 ± 13.6 (range, 22–50) in those with prior thalamotomy (p < 0.01). This numerical difference in improvement was not statistically significant (p > 0.05). Conclusion. Our comparative study indicates that bilateral STN DBS is effective and can be used in patients with Parkinson disease with prior unilateral stereotactic destructive operations on subcortical structures. The results in our patient cohort are generally consistent with previously published reports of smaller series from multiple centers worldwide.

[The preliminary results of subthalamic nucleus stimulation after destructive surgery in Parkinson's disease]

OBJECTIVE

To evaluate the efficacy of bilateral electrical stimulation (ES) of the subthalamic nucleus (STN) in patients with Parkinson's disease (PD) after preceding pallidotomy or ventrolateral (VL) thalamotomy.

MATERIAL AND METHODS

The study included 9 patients with bilateral STN ES who had undergone previous unilateral destructive surgery on the subcortical structures: pallidotomy (5 patients) and VL thalamotomy (4). A control group consisted of 9 patients with STN ES, without prior destructive surgery. A clinical and neurological examination included quantitative assessment of motor disturbances using the Hoehn-Yahr scale and Unified Parkinson's disease rating scale (UPDRS). UPDRS was used to evaluate the motor activity (IIIrd part of the scale) and severity of drug-induced dyskinesia and motor fluctuations (IVth part of the scale).

RESULTS

In the group of STN ES with preceding destruction of the subcortical structures, an improvement in motor functions in the early period (6 months) was 45%, and severity of drug-induced complications was decreased by 75%. In a group of STN DBS without destruction, motor disturbances were improved by 61%, and drug-induced complications were decreased by 77%. Improvement in motor functions amounted to 51.9% in patients with preceding pallidotomy (GPi destruction) and 37.5% in a group with preceding VL thalamotomy. The equivalent dose of levodopa was reduced by 51.39%, from 1,008±346 to 490±194, in the study group and by 55.04%, from 963±96 to 433±160, in the control group.

CONCLUSION

Bilateral STN neurostimulation is effective after unilateral stereotaxic destruction of the subcortical structures in PD patients.

Deep brain stimulation exacerbates hypokinetic dysarthria in a rat model of Parkinson's disease

Motor symptoms of Parkinson's disease (PD) follow the degeneration of dopaminergic neurons in the substantia nigra pars compacta. Deep brain stimulation (DBS) treats some parkinsonian symptoms, such as tremor, rigidity, and bradykinesia, but may worsen certain medial motor symptoms, including hypokinetic dysarthria. The mechanisms by which DBS exacerbates dysarthria while improving other symptoms are unclear and difficult to study in human patients. This study proposes an animal model of DBS-exacerbated dysarthria. We use the unilateral, 6-hydroxydopamine (6-OHDA) rat model of PD to test the hypothesis that DBS exacerbates quantifiable aspects of vocalization. Mating calls were recorded from sexually experienced male rats under healthy and parkinsonian conditions and during DBS of the subthalamic nucleus. Relative to healthy rats, parkinsonian animals made fewer calls with shorter and less complex vocalizations. In the parkinsonian rats, putatively therapeutic DBS further reduced call frequency, duration, and complexity. The individual utterances of parkinsonian rats spanned a greater bandwidth than those of healthy rats, potentially reducing the effectiveness of the vocal signal. This utterance bandwidth was further increased by DBS. We propose that the parkinsonism-associated changes in call frequency, duration, complexity, and dynamic range combine to constitute a rat analog of parkinsonian dysarthria. Because DBS exacerbates the parkinsonism-associated changes in each of these metrics, the subthalamic stimulated 6-OHDA rat is a good model of DBS-induced hypokinetic dysarthria in PD. This model will help researchers examine how DBS alleviates many motor symptoms of PD while exacerbating parkinsonian speech deficits that can greatly diminish patient quality of life.