Comparison of unilateral pallidotomy and subthalamotomy findings in advanced idiopathic Parkinson's disease

Prognostic factors of unilateral prelemniscal radiations radiofrequency lesions: A surgical technique for the treatment of Parkinson's disease motor symptoms

OBJECTIVE

A group of patients with Parkinson's disease (PD) were managed with unilateral prelemniscal radiation radiofrequency lesions (U-Raprl). The current study aims to evaluate prognostic factors that could influence clinical response.

METHODS

Patients previously diagnosed with PD managed with U-Raprl were included in the study, classifying them into two groups according to their percentage of clinical response (</≥ 50%) at 5 years of follow-up in relation to the part III of the Unified Parkinson's Disease Rating Scale (UPDRS-III), analyzing the possible factors associated with their response (age, evolution of PD, Hoehn and Yahr scale (HYS), and levodopa dose). To show differences between groups before and after the intervention, a T-test was performed, and a Mann-Whitney U test was carried out to determine differences between the response groups, added to an effect size calculation using a Cohen's d (α = 0.05, and β = 0.20).

RESULTS

Thirty-four patients were included, where the most prevalent symptoms were tremor and rigidity, with 52.9% percentage of males, 59.3 ± 6.4 mean age, and 7.4 ± 2.1 of mean evolution of PD. Analysis shows differences between groups (p < 0.05) according to the HYS, UPDRS, and levodopa intake, after the intervention. The analysis of the groups according to their response showed differences between the HYS (p < 0.01, ∆ > 1.5), Age (p < 0.0001, ∆ = 2.38), Evolution (p < 0.0001, ∆ = 2.38), and post-operative UPDRS (p < 0.01, ∆ = 1.38). The qualitative analysis of the distribution regarding the responder group shows that those patients with an age under 58 years, an evolution fewer than 7 years, and a preoperative HYS score smaller than 2, showed a response ≥ 50% according to the UPDRS-III in all cases.

CONCLUSION

U-Raprl is a highly effective procedure with a 5-year persistence of improvement. The most relevant prognostic factors to consider for a clinical response according to UPDRS-III greater than 50% are age under 58 years, less than 7 years of PD evolution, and HYS less or equal to 3.

Device-Assisted and Neuromodulatory Therapies for Parkinson's Disease: A Network Meta-Analysis

BACKGROUND

Device-assisted and neuromodulatory therapies are the standard of care for Parkinson's disease (PD) with disabling motor complications. We aimed to compare and rank the currently available advanced therapies for PD on patient relevant outcomes.

METHODS

We searched various databases for randomized controlled trials that studied subthalamic nucleus deep brain stimulation (STN-DBS), globus pallidus interna (GPi) DBS, pallidotomy, subthalamotomy, continuous subcutaneous apomorphine infusion (CSAI), or intrajejunal levodopa infusion (IJLI), in patients with PD and motor complications. Primary outcome was the quality of life (QOL) at 6 months. Secondary outcomes included Unified Parkinson's Disease Rating Scale III and II, ON time, OFF time, levodopa equivalent daily doses, and adverse events (AE). Data were pooled using a Bayesian network meta-analysis, summarized as mean difference (MD) with 95% credibility intervals (CrI) and visualized in forest plots/league tables. Surface under the cumulative ranking curve plots determined the ranking probability.

RESULTS

We identified 6745 citations and included 26 trials. STN-DBS (MD, -8.0; 95% CrI, -11, -5.8), GPi-DBS (MD, -7.1; 95% CrI, -11, -2.9), and IJLI (MD, -7.0; 95% CrI, -12, -1.8) led to better QOL than medical therapy alone, without significant differences among them. STN-DBS had the highest probability of being ranked the best treatment for QOL (79.6%), followed by IJLI (63.5%) and GPi-DBS (62.8%).

CONCLUSIONS

In advanced PD, STN-DBS alleviates more patient and clinician relevant outcomes, followed by GPi-DBS and IJLI. In resource limited settings, unilateral pallidotomy may improve motor symptoms and activities of daily living, although overall QOL may not be improved. © 2022 International Parkinson and Movement Disorder Society.

Ablative brain surgery: an overview

Background: Ablative therapies have been used for the treatment of neurological disorders for many years. They have been used both for creating therapeutic lesions within dysfunctional brain circuits and to destroy intracranial tumors and space-occupying masses. Despite the introduction of new effective drugs and neuromodulative techniques, which became more popular and subsequently caused brain ablation techniques to fall out favor, recent technological advances have led to the resurgence of lesioning with an improved safety profile. Currently, the four main ablative techniques that are used for ablative brain surgery are radiofrequency thermoablation, stereotactic radiosurgery, laser interstitial thermal therapy and magnetic resonance-guided focused ultrasound thermal ablation. Object: To review the physical principles underlying brain ablative therapies and to describe their use for neurological disorders. Methods: The literature regarding the neurosurgical applications of brain ablative therapies has been reviewed. Results: Ablative treatments have been used for several neurological disorders, including movement disorders, psychiatric disorders, chronic pain, drug-resistant epilepsy and brain tumors. Conclusions: There are several ongoing efforts to use novel ablative therapies directed towards the brain. The recent development of techniques that allow for precise targeting, accurate delivery of thermal doses and real-time visualization of induced tissue damage during the procedure have resulted in novel techniques for cerebral ablation such as magnetic resonance-guided focused ultrasound or laser interstitial thermal therapy. However, older techniques such as radiofrequency thermal ablation or stereotactic radiosurgery still have a pivotal role in the management of a variety of neurological disorders.

Alterations in neuronal activity in basal ganglia-thalamocortical circuits in the parkinsonian state

In patients with Parkinson’s disease and in animal models of this disorder, neurons in the basal ganglia and related regions in thalamus and cortex show changes that can be recorded by using electrophysiologic single-cell recording techniques, including altered firing rates and patterns, pathologic oscillatory activity and increased inter-neuronal synchronization. In addition, changes in synaptic potentials or in the joint spiking activities of populations of neurons can be monitored as alterations in local field potentials (LFPs), electroencephalograms (EEGs) or electrocorticograms (ECoGs). Most of the mentioned electrophysiologic changes are probably related to the degeneration of diencephalic dopaminergic neurons, leading to dopamine loss in the striatum and other basal ganglia nuclei, although degeneration of non-dopaminergic cell groups may also have a role. The altered electrical activity of the basal ganglia and associated nuclei may contribute to some of the motor signs of the disease. We here review the current knowledge of the electrophysiologic changes at the single cell level, the level of local populations of neural elements, and the level of the entire basal ganglia-thalamocortical network in parkinsonism, and discuss the possible use of this information to optimize treatment approaches to Parkinson’s disease, such as deep brain stimulation (DBS) therapy.

Subthalamotomy in the treatment of Parkinson's disease: clinical aspects and mechanisms of action

Parkinson's disease (PD) is a neurodegenerative condition that can be pharmacologically treated with levodopa. However, important motor and nonmotor symptoms appear with its long-term use. The subthalamic nucleus (STN) is known to be involved in the pathophysiology of PD and to contribute to levodopa-induced complications. Surgery is considered in patients who have advanced PD that is refractory to pharmacotherapy and who display disabling dyskinesia. Deep brain stimulation of the STN is currently the main surgical procedure for PD, but lesioning is still performed. This review covers the clinical aspects and complications of subthalamotomy as one of the lesion-based options for PD patients with levodopa-induced dyskinesias. Moreover, the authors discuss the possible effects of subthalamic lesioning.

Drug-induced dyskinesia in Parkinson's disease. Should success in clinical management be a function of improvement of motor repertoire rather than amplitude of dyskinesia?

BACKGROUND

Dyskinesia, a major complication in the treatment of Parkinson's disease (PD), can require prolonged monitoring and complex medical management.

DISCUSSION

The current paper proposes a new way to view the management of dyskinesia in an integrated fashion. We suggest that dyskinesia be considered as a factor in a signal-to-noise ratio (SNR) equation where the signal is the voluntary movement and the noise is PD symptomatology, including dyskinesia. The goal of clinicians should be to ensure a high SNR in order to maintain or enhance the motor repertoire of patients. To understand why such an approach would be beneficial, we first review mechanisms of dyskinesia, as well as their impact on the quality of life of patients and on the health-care system. Theoretical and practical bases for the SNR approach are then discussed.

SUMMARY

Clinicians should not only consider the level of motor symptomatology when assessing the efficacy of their treatment strategy, but also breadth of the motor repertoire available to patients.

The Movement Disorder Society Evidence-Based Medicine Review Update: Treatments for the motor symptoms of Parkinson's disease

The objective was to update previous evidence-based medicine reviews of treatments for motor symptoms of Parkinson's disease published between 2002 and 2005. Level I (randomized, controlled trial) reports of pharmacological, surgical, and nonpharmacological interventions for the motor symptoms of Parkinson's disease between January 2004 (2001 for nonpharmacological) and December 2010 were reviewed. Criteria for inclusion, clinical indications, ranking, efficacy conclusions, safety, and implications for clinical practice followed the original program outline and adhered to evidence-based medicine methodology. Sixty-eight new studies qualified for review. Piribedil, pramipexole, pramipexole extended release, ropinirole, rotigotine, cabergoline, and pergolide were all efficacious as symptomatic monotherapy; ropinirole prolonged release was likely efficacious. All were efficacious as a symptomatic adjunct except pramipexole extended release, for which there is insufficient evidence. For prevention/delay of motor fluctuations, pramipexole and cabergoline were efficacious, and for prevention/delay of dyskinesia, pramipexole, ropinirole, ropinirole prolonged release, and cabergoline were all efficacious, whereas pergolide was likely efficacious. Duodenal infusion of levodopa was likely efficacious in the treatment of motor complications, but the practice implication is investigational. Entacapone was nonefficacious as a symptomatic adjunct to levodopa in nonfluctuating patients and nonefficacious in the prevention/delay of motor complications. Rasagiline conclusions were revised to efficacious as a symptomatic adjunct, and as treatment for motor fluctuations. Clozapine was efficacious in dyskinesia, but because of safety issues, the practice implication is possibly useful. Bilateral subthalamic nucleus deep brain stimulation, bilateral globus pallidus stimulation, and unilateral pallidotomy were updated to efficacious for motor complications. Physical therapy was revised to likely efficacious as symptomatic adjunct therapy. This evidence-based medicine review updates the field and highlights gaps for research.

Relative contributions of local cell and passing fiber activation and silencing to changes in thalamic fidelity during deep brain stimulation and lesioning: a computational modeling study

Deep brain stimulation (DBS) and lesioning are two surgical techniques used in the treatment of advanced Parkinson's disease (PD) in patients whose symptoms are not well controlled by drugs, or who experience dyskinesias as a side effect of medications. Although these treatments have been widely practiced, the mechanisms behind DBS and lesioning are still not well understood. The subthalamic nucleus (STN) and globus pallidus pars interna (GPi) are two common targets for both DBS and lesioning. Previous studies have indicated that DBS not only affects local cells within the target, but also passing axons within neighboring regions. Using a computational model of the basal ganglia-thalamic network, we studied the relative contributions of activation and silencing of local cells (LCs) and fibers of passage (FOPs) to changes in the accuracy of information transmission through the thalamus (thalamic fidelity), which is correlated with the effectiveness of DBS. Activation of both LCs and FOPs during STN and GPi-DBS were beneficial to the outcome of stimulation. During STN and GPi lesioning, effects of silencing LCs and FOPs were different between the two types of lesioning. For STN lesioning, silencing GPi FOPs mainly contributed to its effectiveness, while silencing only STN LCs did not improve thalamic fidelity. In contrast, silencing both GPi LCs and GPe FOPs during GPi lesioning contributed to improvements in thalamic fidelity. Thus, two distinct mechanisms produced comparable improvements in thalamic function: driving the output of the basal ganglia to produce tonic inhibition and silencing the output of the basal ganglia to produce tonic disinhibition. These results show the importance of considering effects of activating or silencing fibers passing close to the nucleus when deciding upon a target location for DBS or lesioning.

Systematic review of levodopa dose equivalency reporting in Parkinson's disease

Interpretation of clinical trials comparing different drug regimens for Parkinson's disease (PD) is complicated by the different dose intensities used: higher doses of levodopa and, possibly, other drugs produce better symptomatic control but more late complications. To address this problem, conversion factors have been calculated for antiparkinsonian drugs that yield a total daily levodopa equivalent dose (LED). LED estimates vary, so we undertook a systematic review of studies reporting LEDs to provide standardized formulae. Electronic database and hand searching of references identified 56 primary reports of LED estimates. Data were extracted and the mean and modal LEDs calculated. This yielded a standardized LED for each drug, providing a useful tool to express dose intensity of different antiparkinsonian drug regimens on a single scale. Using these conversion formulae to report LEDs would improve the consistency of reporting and assist the interpretation of clinical trials comparing different PD medications.

Bursts and oscillations as independent properties of neural activity in the parkinsonian globus pallidus internus

Bursts and oscillatory modulations in firing rate are hallmark features of abnormal neuronal activity in the parkinsonian Globus Pallidus internus (GPi). Although often implicated together in the pathophysiology of parkinsonian signs, little is known about how burst discharges and oscillatory firing (OF) relate to each other. To investigate this question, extracellular single-unit neuronal activity was recorded from 132 GPi cells in 14 Parkinson's disease patients. We found that burst firing was equally prevalent in OF and non-oscillatory firing (NOF) cells (p>0.5). More than half of the cells were characterized by either aperiodic bursty activity or OF, but not both. OF and NOF cells had statistically-indistinguishable levels of mean burstiness (p=0.8). Even when bursting and OF co-existed in individual cells, levels of burstiness and oscillatory power were seldom correlated across time. Interestingly, however, the few OF cells with spectral peaks between 8-13 Hz (α-range) were substantially burstier than other cells (p<0.01) and showed an unique burst morphology and stronger temporal correlations between oscillatory power and burstiness. We conclude that independent mechanisms may underlie the burst discharges and OF typical of most neurons in the parkinsonian GPi.