Long term outcome of unilateral pallidotomy: follow up of 15 patients for 3 years

Radiofrequency Lesioning for Movement and Psychiatric Disorders-Experience of 107 Cases

Background

Radiofrequency lesioning (RFL) though used since the 1950s, had been replaced by DBS in the 1990s. The availability of magnetic resonance-guided focused ultrasound for lesioning has renewed the interest in RFL.

Objective

This paper analysis RFL in contemporary Functional Neurosurgery for various indications and its outcome. Complication rates of RFL are compared with the same author’s experience of DBS.

Methods

One hundred and seven patients underwent RFL between 1998 and 2019. Indications included Parkinson’s Disease (PD), tremors, dystonia, and obsessive-compulsive disorders (OCD). The surgeries performed include thalamotomy (29), pallidotomy (49), subthalamotomy (23), and anterior capsulotomy/nucleus accumbens lesioning (6). Appropriate rating scales were used for preoperative and postoperative evaluations.

Results

There was a 25% recurrence rate of tremors for PD after thalamotomy. Writer’s cramp rating scale improved from a mean of 10.54–1.6 in task specific dystonia (TSD) patients, after thalamotomy. In PD patients, after pallidotomy, contralateral motor Unified Parkinson’s Disease Rating Scale (UPDRS) and dyskinesia scores, improved by 41 and 57%, respectively, at 1-year. Burke-Fahn-Marsden Dystonia Rating Scale in hemidystonia patients improved from 18.04 to 6.91, at 1-year. There was 32 and 31% improvement in total and motor UPDRS, respectively, in the subthalamotomy patients, at 2-year. All patients of OCD were in remission. There were three deaths in the pallidotomy group. Postoperative, dysarthria, confusion, hemiparesis, dyskinesia, and paraesthesia occurred in 12 patients, of which, 7 were transient.

Conclusion

RFL is a useful option in a select group of patients with tremors and dystonia. It is our preferred treatment option for TSD and OCD.

Understanding Parkinson's disease and deep brain stimulation: Role of monkey models

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder affecting over 10 million people worldwide. In the 1930s and 1940s there was little understanding regarding what caused PD or how to treat it. In a desperate attempt to improve patients' lives different regions of the neuraxis were ablated. Morbidity and mortality were common, but some patients' motor signs improved with lesions involving the basal ganglia or thalamus. With the discovery of l-dopa the advent of medical therapy began and surgical approaches became less frequent. It soon became apparent, however, that medical therapy was associated with side effects in the form of drug-induced dyskinesia and motor fluctuations and surgical therapies reemerged. Fortunately, during this time studies in monkeys had begun to lay the groundwork to understand the functional organization of the basal ganglia, and with the discovery of the neurotoxin MPTP a monkey model of PD had been developed. Using this model scientists were characterizing the physiological changes that occurred in the basal ganglia in PD and models of basal ganglia function and dysfunction were proposed. This work provided the rationale for the return of pallidotomy, and subsequently deep brain stimulation procedures. In this paper we describe the evolution of these monkey studies, how they provided a greater understanding of the pathophysiology underlying the development of PD and provided the rationale for surgical procedures, the search to understand mechanisms of DBS, and how these studies have been instrumental in understanding PD and advancing the development of surgical therapies for its treatment.

Comparison of contralateral pallidotomy vs. pallidal stimulation after prior unilateral pallidotomy for Parkinson's disease

OBJECTIVES

Pallidal stimulation and pallidotomy are known to improve the symptoms of Parkinson's disease (PD). However, it is not known which modality produces greater benefit in patients who have already undergone unilateral pallidotomy. It is also suggested that the original pallidal surgery provides a greater benefit than subsequent pallidal surgery. The aim of this study was to analyze which modality produced greater PD symptom improvement in patients with a prior pallidotomy and whether the chronological order of the pallidal surgery influenced the size of the improvement.

METHODS

Five patients who had undergone a prior unilateral pallidotomy for PD were studied. Because of ongoing Parkinsonian symptoms, all patients subsequently underwent contralateral pallidal surgery, either a further pallidotomy or pallidal stimulation. All surgeries were performed by a single functional neurosurgeon and the patients prospectively assessed and scored at routine follow-ups. Paired-sample t-tests were used to detect differences in outcomes after first and second surgeries.

RESULTS

Two patients underwent pallidal stimulation and three underwent a second pallidotomy. Mean follow-up was 13.5 months and 12.3 months, respectively. Greater percentage improvements in the majority of scores were found after pallidal stimulation compared with a second pallidotomy, namely Unified Parkinson's Disease Rating Scale (UPDRS) II off (25.22% vs. -3.27%), UPDRS III off (36.15% vs. 5.21%), rigidity (58.34% vs. 11.54%), tremor (5.56% vs. -30.48%), bradykinesia (48.55% vs. -2.23%), gait composite (16.52% vs. -51.79%), dyskinesia duration (83.33% vs. 66.67%), dyskinesia disability (100% vs. 66.67%), speech (10% vs. -50%), and the proportion of the day spent in the "off" state (50% vs. 25%). Comparing outcomes after the first surgery to those after the second surgery, statistical differences were found in dyskinesia duration improvement and ipsilateral dyskinesia improvement after the second surgery (p < 0.004 and p = 0.021, respectively).

CONCLUSIONS

Pallidal stimulation produced greater symptom improvement than a second pallidotomy and subsequent surgery did not produce inferior results to the original pallidal surgery.

Functional surgery for Parkinson's disease treatment: a structured analysis of a decade of published literature

The aim of this study was to analyse and compare published data during the last decade on the different approaches to Parkinson's disease surgery. Eighty-eight papers published between 1990 and 2001 fulfilled the inclusion criteria. Full-text and prospective papers on lesion and stimulation of GPi or STN were assessed. Descriptive analysis of surgery procedure and population under study was performed, as well as a meta-analysis of the most consistently reported variables. A total of 1702 patients underwent surgery with a mean age of 58.75 years (range 46.5 - 72.5), mean duration of illness 13.6 years (8.1 - 18.1) and a male:female ratio 1.5:1. Mean postoperative follow-up was 9 months (1 - 52). Single blind assessment was performed in two papers, while double blind evaluation was used in 6. In the GPi group, no difference was found between the pre- and postoperative levodopa equivalent daily dose (960.39 v. 943.13; p > 0.05), while the STN group showed a marked reduction (1104.8 v. 483.04; p < 0.05) of this dosage. Meta-analysis of the most consistently reported variables (UPDRS total score, UPDRS motor score, UPDRS ADL score and Schwab & England score showed that Nucleus, Bilaterality of Approach and Surgical Procedure were the best moderators for defining outcome. Bilateral DBS STN procedures proved to be associated with better outcome. Microelectrode recording was not found to be a moderator that influenced outcome. Although there was a significant improvement of dyskinesias among the different approaches described in the papers, the heterogeneity of data makes it impossible to perform a structured analysis on this item.

Five-year follow-up of unilateral posteroventral pallidotomy in Parkinson's disease

BACKGROUND

Neurocognitive outcome research of individuals with Parkinson's disease after unilateral pallidotomy is inconsistent. Although some studies reported few cognitive changes, other investigations have more consistently shown both transient and long-term cognitive decline postoperatively.

METHODS

We report the long-term motor and neurocognitive outcome 5 years post surgery for 18 patients with Parkinson's disease (12 men and 6 woman; all right-handed) who underwent right or left unilateral posteroventral pallidotomy.

RESULTS

Pallidotomy patients revealed long-term motor benefits from the surgery in their "off" state and control of dopa-induced dyskinesias in their "on" state, which is consistent with previous research. We found mild declines in oral and visuomotor information processing speed, verbal recognition memory, and mental status 5 years after surgery, which differs from previous literature regarding the long-term neurocognitive outcome after pallidotomy. Differences between the right and left pallidotomy patients for both motor and cognitive skills were not found.

CONCLUSION

Although deep brain stimulation is presently the treatment of choice, pallidotomy continues to be performed around the world. Consequently, although unilateral pallidotomy should be considered a treatment option for patients with Parkinson's disease who suffer from severe unilateral disabling motor symptoms or dyskinesias, the long-term neurocognitive outcome should also be considered in treatment decisions.

Pallidotomy versus pallidal stimulation

Both posteroventral pallidotomy and pallidal deep brain stimulation (DBS) have a documented effect on Parkinsonian symptoms. DBS is more costly and more laborious than pallidotomy. The aim of this study was to analyse the respective long-term effect of each surgical procedure on contralateral symptoms in the same patients. Five consecutive patients, two women and three men, who at first surgery had a mean age of 64 years and a mean duration of disease of 18 years, received a pallidotomy contralateral to the more symptomatic side of the body. At a mean of 14 months later, the same patients received a pallidal DBS on the side contralateral to the pallidotomy. All patients had on-off phenomena and dyskinesias. There were three left-sided and two right-sided pallidotomies, and, subsequently, two left-sided and three right-sided pallidal DBS. The latest evaluation was performed 37 months (range 22-60) after the pallidotomy and 22 months (range 12-33) after the pallidal DBS. Mean UPDRS motor score pre-operatively was 49 and at last follow-up 33 (32.7% improvement, p<0.05). Appendicular items 20-26 contralateral to pallidotomy remained improved more significantly than contralateral to DBS. Dyskinesia scores were also improved more markedly contralateral to the pallidotomy. Two patients exhibited moderate dysarthria and one patient severe dysphonia following DBS. Symptoms contralateral to the chronologically older pallidotomy, especially dyskinesias, rigidity and tremor, were still more improved than symptoms contralateral to the more recent pallidal DBS, despite numerous post-operative patient visits to optimise stimulation parameters.

Surgical treatment for Parkinson's disease

Since the early 1930s, physicians have developed and refined various surgical therapies for the treatment of Parkinson's disease. In this review we examine some of the problems associated with early surgical therapies, the development of new techniques and targets, and the results of clinical trials examining the safety and efficacy of these techniques. Ablative techniques include pallidotomy, thalamotomy, and, more recently, subthalamotomy. Because of concern over the high incidence of side-effects associated with bilateral ablative procedures, alternative approaches were explored. Deep brain stimulation (DBS) was subsequently developed and successfully applied in the internal globus pallidus, subthalamic nucleus, and thalamus for the treatment of Parkinson's disease. Recent approaches include biological neurorestorative techniques--surgical therapies with transplantation, gene therapy, and growth factors are all being studied. Although a great deal of work remains to be done, advances in surgical therapies for the treatment of Parkinson's disease are moving forward at an unprecedented pace.

Lesion therapy for Parkinson's disease and other movement disorders: Update and controversies

An analysis of the international literature on lesioning for movement disorders was undertaken to review lesion therapy for Parkinson's disease (PD) and other movement disorders and to highlight important controversies surrounding this surgical technique. Lesions have been placed throughout the neuraxis with varying approaches and success. Our understanding of the pathophysiological basis underlying the development of PD and other movement disorders has led to a better understanding of why lesioning certain portions of the nervous system should improve motor function. Advances in imaging technology and electrophysiological techniques used for localization of brain structures, such as microelectrode mapping, have improved the ability to accurately identify and lesion target structures deep in the brain. This improvement has led to an increase in the degree and consistency of clinical benefit. The major controversies in lesion therapy include: (1) which target for which disorder; (2) determination of the optimal lesion site and whether the external globus pallidus (GPe) should be included in the pallidotomy lesion for PD; (3) determination of the size of the lesion; (4) whether bilateral lesions can be placed without the high incidence of side effects reported by some investigators; (5) whether microelectrodes aid in the ability to improve clinical outcomes or increase the risk of side effects by making multiple microelectrode penetrations; (6) whether the subthalamic nucleus (STN) should be explored further as a lesioning target; and (7) whether lesioning should be abandoned entirely in favor of deep brain stimulation (DBS). Many important questions and controversies regarding lesion therapy remain unanswered. It is unlikely given the pro-DBS environment that these questions will be answered in the near future. We should, however, be careful not to abandon an effective therapy before fully exploring through randomized trials the relative effect of different surgical approaches for the treatment of patients with movement disorders.

Long-term motor effect of unilateral pallidal stimulation in 26 patients with advanced Parkinson disease

OBJECT

The aim of this study was to evaluate the long-term effects of unilateral pallidal stimulation on motor function in selected patients with advanced Parkinson disease (PD).

METHODS

The authors enrolled 26 patients with idiopathic PD in whom there was an asymmetric distribution of symptoms and, despite optimal pharmocological treatment, severe response fluctuations and/or dyskinesias. After the patient had received a local anesthetic agent, a quadripolar electrode (Medtronic model 3387) was implanted at the side opposite the side affected or, if both sides were affected, the side contralateral to the more affected side. No serious complications occurred. After 3 months, the total Unified PD Rating Scale (UPDRS) Part III score decreased by 50.7% while patients were in the off-medication state (from 26.5 +/- 9.2 to 13.1 +/- 6.1) and by 55.4% while they were in the on-medication state (from 10.6 +/- 6.3 to 4.7 +/- 4.4). Only during the on state was the contralateral effect clearly more pronounced. The UPDRS Part IVa score decreased by 75% (from 3.7 +/- 2.5 to 0.9 +/- 1.1) and the UPDRS Part IVb score by 54.7% (from 3.3 +/- 1.3 to 1.5 +/- 1.3). At long-term follow-up review (32.7 +/- 10.7 months), there was an 8.3% increase in the UPDRS Part III score while patients were in the off state (from 26.5 +/- 9.2 to 28.7 +/- 7.6) and a 40.2% increase in this score while patients were in the on state (from 10.6 +/- 6.3 to 14.9 +/- 5.1). The UPDRS Part IVa score decreased by 28.1% (from 3.7 +/- 2.5 to 2.7 +/- 2.3) and the UPDRS Part IVb score increased by 3.5% (from 3.3 +/- 1.3 to 3.4 +/- 1.6).

CONCLUSIONS

Based on these unsatisfactory results at long-term review, the authors conclude that unilateral pallidal stimulation is not an effective treatment option for patients with advanced PD.

GPi pallidotomy for Parkinson's disease with drug-induced psychosis

Levodopa-induced psychosis may seriously threaten the ability of patients with Parkinson's disease (PD) to continue leading an independent life. A retrospective assessment of the therapeutic effects of the globus pallidus internus (GPi) pallidotomy on the activities of daily living (ADL) of seven PD patients presenting with mild or moderate degrees of psychosis was carried out. Their scores according to the Unified Parkinson's Disease Rating Scale (UPDRS) Part I-2 (maximum=4) were 2 or 3 (mean +/- SD=2.4 +/- 0.5). Bilateral procedure was needed in 5 out of 7 patients to obtain sufficient improvement of motor symptoms. At 3 months after surgery, UPDRS part III motor scores in the 'off' state were significantly decreased and motor fluctuations were abolished. Nevertheless, their score of Schwab and England (S-E) ADL scale scores responded poorly to the surgery, while the scores in other 12 patients without psychosis was significantly improved after pallidotomy. The data indicate that GPi pallidotomy ameliorates the motor symptoms in patients with drug-induced psychosis (DIP), but has no significant impact on their consequent daily activities. A regression model for all 19 patients who underwent pallidotomy revealed that postoperative S-E scale was affected by the preoperative UPDRS Part I-2 rather than by Part III motor score. The present study suggested that DIP, even if its degree is not severe, may be a limiting factor of the therapeutic potential of pallidotomy in patients with PD.

Effects of pallidotomy and levodopa on walking and reaching movements in Parkinson's disease

We examined the effects of levodopa and unilateral pallidotomy on quantitative measures of walking and reaching in Parkinson's disease (PD). We also compared quantitative measures of movement with standard clinical rating scales. We used kinematic measures and the Unified Parkinson's Disease Rating Scale (UPDRS) motor subscale (subscale III) to evaluate the movement of 10 people with PD. Subjects were tested after withholding PD medications for at least 8 hours and again 30 to 45 minutes after taking the first morning dose of levodopa. They were studied in this manner before unilateral pallidotomy and then 3.5 to 10 months after surgery. The UPDRS motor subscale was performed in each state. Kinematic data were collected as subjects reached to a target and walked. The UPDRS motor subscale ratings were similar to those reported in the literature: pallidotomy improved the overall motor score and the contralateral bradykinesia + rigidity score, but not the gait + posture score. In contrast, kinematic measures demonstrated that levodopa and pallidotomy had different effects on walking and reaching speed. Both treatments improved walking speed, and the effect was additive. Levodopa improved reaching speed before pallidotomy but did not improve it as much after pallidotomy. Additionally, pallidotomy had inconsistent effects on reaching; some subjects were faster and others were slower. The subjects who initially reached more slowly improved after pallidotomy; the subjects who initially reached more normally (faster) worsened after pallidotomy. On the basis of our results, we speculate that basal ganglia output pathways that control walking and reaching may be distinct, such that bilateral projections to the pedunculopontine area influence walking, whereas ipsilateral thalamocortical projections influence reaching.

Fipamezole (JP-1730) is a potent alpha2 adrenergic receptor antagonist that reduces levodopa-induced dyskinesia in the MPTP-lesioned primate model of Parkinson's disease

Previous studies in the MPTP-lesioned primate model of Parkinson's disease have demonstrated that alpha(2) adrenergic receptor antagonists such as idazoxan, rauwolscine, and yohimbine can alleviate L-dopa-induced dyskinesia and, in the case of idazoxan, enhance the duration of anti-parkinsonian action of L-dopa. Here we describe a novel alpha(2) antagonist, fipamezole (JP-1730), which has high affinity at human alpha(2A) (K(i), 9.2 nM), alpha(2B) (17 nM), and alpha(2C) (55 nM) receptors. In functional assays, the potent antagonist properties of JP-1730 were demonstrated by its ability to reduce adrenaline-induced (35)S-GTPgammaS binding with K(B) values of 8.4 nM, 16 nM, 4.7 nM at human alpha(2A), alpha(2B), and alpha(2C) receptors, respectively. Assessment of the ability of JP-1730 to bind to a range of 30 other binding sites showed that JP-1730 also had moderate affinity at histamine H1 and H3 receptors and the serotonin (5-HT) transporter (IC(50) 100 nM to 1 microM). In the MPTP-lesioned marmoset, JP-1730 (10 mg/kg) significantly reduced L-dopa-induced dyskinesia without compromising the anti-parkinsonian action of L-dopa. The duration of action of the combination of L-dopa and JP-1730 (10 mg/kg) was 66% greater than that of L-dopa alone. These data suggest that JP-1730 is a potent alpha(2) adrenergic receptor antagonist with potential as an anti-dyskinetic agent in the treatment of Parkinson's disease.

Surgical complications in patients with Parkinson's disease after posteroventral pallidotomy

OBJECTIVE

To investigate the potential operative morbidity in posteroventral pallidotomy (PVP) for patients with Parkinson's disease.

METHODS

We designed a retrospective study that included 796 consecutive patients (mean age, 64.9 yr; male, 559; female, 237) with Parkinson's disease. All PVPs (simultaneous bilateral PVP, n = 272; sequential bilateral PVP, n = 88; unilateral PVP, n = 436) were performed during a 7-year period. The total number of operations was 884, and the number of PVP procedures was 1156. In 108 patients, ventral intermediate nucleus thalamotomy was performed simultaneously.

RESULTS

The overall complication rate, including temporary problems, was 15.3% of 884 operations. Permanent complications occurred in 3.6% of total operations. Intracranial hemorrhage occurred in 24 operations (2.7%). In seven of them, the patients required craniotomy and hematoma evacuation and sustained a disabling motor deficit (0.8%). Intracranial hemorrhage occurred more often in patients who underwent microelectrode recording and had a history of chronic hypertension. Hemiparesis without intracranial hematoma occurred in 12 operations (1.4%). Microelectrode recording was a risk factor for postoperative hemiparesis without hemorrhage. In 19 operations (2.1%), patients developed a partial visual field deficit. Speech disturbance after surgery was observed in 23 operations (2.6%) but resolved in 17 by 1 week after surgery. In 55 operations (6.2%), patients developed postoperative confusion. This occurred more often in elderly patients and those with advanced disease. In 17 operations (1.9%), patients required observation in the intensive care unit because of postoperative hypotension.

CONCLUSION

Complications from stereotactic pallidotomy were not frequent. However, the residual symptoms from complications can be serious in many cases.

Cognitive effects of unilateral posteroventral pallidotomy: a 4-year follow-up study

We assessed the long-term neuropsychological effects of unilateral posteroventral pallidotomy in Parkinson's disease. Eleven Parkinson's disease patients, from an original cohort of 15 consecutive patients who underwent pallidotomy, were evaluated. A neuropsychological battery was administered to each patient before (3 days) and after (3 months and 4 years) surgery during the effects of levodopa. The following tests were administered: Rey's Auditory-Verbal Learning Test, Visual Associative Learning test from the Wechsler Memory Scale-Revised, Luria's motor alternation, Benton's Judgment of Line Orientation, Trail Making, phonetic verbal fluency, Stroop test, Petrides' working memory tasks, Beck's depression questionnaire and the Maudsley obsessional-compulsive inventory. In the 3-month postoperative assessment, there was a significant worsening in phonetic verbal fluency and an improvement in Benton's Judgment of Line Orientation test. In the 4-year follow-up assessment, phonetic verbal fluency and Benton's Judgment of Line Orientation test returned to baseline scores. Although there was no significant difference between pre- and postsurgical scores for long-term visual associative memory, there was a significant deterioration between 3-month and 4-year follow-up performances. Our results suggest that unilateral posteroventral pallidotomy may produce transient changes in prefrontal and visuospatial functions, but there is no evidence of permanent neuropsychological effects.

Declines in switching underlie verbal fluency changes after unilateral pallidal surgery in Parkinson's disease

Declines in verbal fluency are consistently reported in patients with Parkinson's disease (PD) after pallidal surgery. In the present study, the clustering and switching components of semantic or category fluency (oral naming of items obtainable in supermarkets) were examined at baseline and four months after unilateral deep brain stimulation or pallidotomy in 45 patients with PD (30 left, 15 right pallidal surgery). Post-operative declines were observed for supermarket fluency total score and switching, but not for average cluster size. These findings support the proposal that semantic fluency decrements after pallidal surgery reflect a disruption of frontal-basal ganglia circuits mediating efficient shifting between semantic categories, or perhaps efficient access to categories, rather than a degradation of semantic stores.

Parkinson's disease: implications for nutritional care

Parkinson's Disease (PD) is a chronic, progressive, neurodegenerative disease. People with PD are particularly susceptible to weight loss and malnutrition. Involuntary movements associated with PD result in increased energy expenditure, while both disease symptoms and medication side-effects can limit food intake. In addition, patients with the disease may choose to follow unconventional nutritional therapies that exacerbate malnutrition. Dietitians play a key role in helping patients with PD to optimize their nutritional status and manage various nutrition-related symptoms and medication side-effects. To assume this role, dietitians need to have current knowledge about PD and its nutritional consequences, as well as strategies for managing a variety of nutrition-related symptoms.

Correlation between tests of attention and performance on grooved and Purdue pegboards in normal subjects

This study investigated the relation between tests of manual dexterity and attentional functions with 49 normal, right-handed medical students (26 women, 23 men, ages 19-30 years) who were assessed with a Purdue Pegboard Test, Grooved Pegboard Test, and a Test for Attentional Performance, comprising measures of tonic and phasic alertness and divided attention. Weak to moderately high partial correlations controlling for finger size were obtained between pegboard test performance of the left hand and phasic alertness (r = .31-.50). Purdue Pegboard Assembly subtest scores were weakly correlated with divided attention (r = -.39). These findings suggest that attention is an important determinant of performance for manual dexterity tests of the nondominant hand.

A metaanalysis comparing the results of pallidotomy performed using microelectrode recording or macroelectrode stimulation

OBJECT

There is an active debate regarding whether pallidotomy should be performed using macroelectrode stimulation or the more sophisticated and expensive method of microelectrode recording. No prospective, randomized trial results have answered this question, although personnel at many centers claim one method is superior. In their metaanalysis the authors reviewed published reports of both methods to determine if there is a significant difference in clinical outcomes or complication rates associated with these methods.

METHODS

A metaanalysis was performed with data from reports on the use of unilateral pallidotomy in patients with Parkinson disease (PD) that were published between 1992 and 2000. A Medline search was conducted for the key word "pallidotomy" and additional studies were added following a review of the references. Only those studies dealing with unilateral procedures performed in patients with PD were included. Papers were excluded if they described a cohort smaller than 10 patients or a follow-up period shorter than 3 months or included cases that previously had been reported. The primary end points for outcome were the percentages of improvement in dyskinesias and in motor scores determined by the Unified PD Rating Scale (UPDRS). Complications were categorized as mortality, intracranial hemorrhage, visual deficit, speech deficit, cognitive decline, weakness, and other. There were no significant differences between the two methods with respect to improvements in dyskinesias (p = 0.66) or UPDRS motor scores (p = 0.62). Microelectrode recording was associated with a significantly higher (p = 0.012) intracranial hemorrhage rate (1.3 +/- 0.4%), compared with macroelectrode stimulation (0.25 +/- 0.2%).

CONCLUSIONS

In reports of patients with PD who underwent unilateral pallidotomy, operations that included microelectrode recording were associated with a small, but significantly higher rate of symptomatic intracranial hemorrhage; however, there was no difference in postoperative reduction of dyskinesia or bradykinesia compared with operations that included macroelectrode stimulation.

Results of chronic subthalamic nucleus stimulation for Parkinson's disease: a 1-year follow-up study

BACKGROUND

Deep brain stimulation (DBS) has been established as an alternative approach for the treatment of advanced Parkinson's disease (PD). Recently, the subthalamic nucleus (STN) has been identified as the optimal target for DBS.

METHODS

Thirty-eight patients have undergone surgery for advanced PD since 1996. They include 12 females and 26 males with a mean age of 55.6 years. The mean stage on the Hoehn and Yahr Scale was 3.5 (off condition). Electrodes (Medtronic DBS 31389) were stereotactically implanted into the STN bilaterally. Targeting was performed using computerized tomography (CT) scans and ventriculography (VG). After 4 days of external stimulation, permanent neurostimulators were implanted. Patients were evaluated preoperatively and 1, 6, and 12 months postoperatively. Evaluations were performed in defined on and off states using the Unified Parkinson's Disease Rating Scale (UPDRS) as well as the Hoehn and Yahr Scale, the dyskinesia scale, and the Activities of Daily Living (ADL) Scale.

RESULTS

Significant improvement of all motor symptoms was found in all patients (UPDRS motor score 32/48 preoperatively versus 15/30 at 12-month follow-up, p < 0.001). Daily off-times were reduced by 35%. Dyskinesias also improved markedly (UPDRS IV: 3.2/3.1 [on/off] vs. 0.9/1.3 at 12 months follow-up). Postoperative L-dopa medication was adjusted (mean reduction: 53%). Complications occurred in two patients (5%) who developed infections, leading to system removal. Systems were replaced after 6 months. Two patients (5%) had a permanent worsening of a previously known depressive state and developed progressive dementia.

CONCLUSIONS

TN stimulation is a relatively safe procedure for treating advanced PD. The possibility of readjusting the stimulation parameters postoperatively improves the therapeutic outcome and reduces side effects in comparison to ablative methods.

Subthalamic nucleus stimulation in patients with a prior pallidotomy

OBJECT

A substantial number of patients with Parkinson disease (PD) who have undergone unilateral stereotactic pallidotomy ultimately develop symptom progression, becoming potential candidates for further surgical treatment. Bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) has been shown to be effective in the treatment of a subset of patients with refractory PD. Microelectrode recording is performed to help localize the STN and guide final placement of the electrode. Potential alterations in physiological features of the STN after pallidotomy may complicate localization of this structure in this group of patients.

METHODS

Bilateral STN DBS surgery guided by microelectrode recording was performed in six patients who had undergone previous unilateral pallidotomies. Physiologically obtained parameters of the STN, including trajectory length, mean firing rate, cell number, and cell density were calculated. These data were compared with those from the side without prior pallidotomy within each patient, as well as with those from our series of 49 subthalamic nuclei explored in 26 patients who had not undergone prior pallidotomy but who underwent bilateral STN stimulator placement. In all patients, analysis of STN cellular activity on the side ipsilateral to the pallidotomy demonstrated a lower mean firing frequency than on the contralateral, intact side. The physiological features on the intact side were not significantly different from those found in our series of patients who had not undergone prior pallidotomy.

CONCLUSIONS

Physicians who perform STN surgery in patients with prior pallidotomy should be aware of the electrophysiological differences between the STN that had undergone pallidotomy and the one that had not, to avoid prolonging recording time to search for the typical STN. The implications of these findings for the current models of information processing in the basal ganglia are discussed.

Updated guidelines for the management of Parkinson's disease

New data on diagnosis, drug therapy, surgery and psychosocial concerns have emerged since the publication of the 1998 Guidelines for the Management of Parkinson's Disease. This article reviews new data and addresses issues left unanswered in the previous guidelines.

Parkinson's disease: surgical options

The introduction of levodopa revolutionized the treatment of Parkinson's disease. However, complications of therapy that diminish functional capacity eventually develop in the majority of patients. Studies in animal models have demonstrated that the parkinsonian state is associated with overactivity in the output nuclei of the basal ganglia. This provides a rationale for surgically targeting these nuclei to diminish this overactivity and reestablish a more balanced output (compensatory strategy). Lesioning and high-frequency stimulation of either the pallidum or the subthalamic nuclei are effective, but many questions remain regarding what surgery is best. Even more questions remain regarding the place of a restorative strategy, namely implantation of fetal midbrain tissue to replace the missing dopamine cells and "cure" the disease. Practical, ethical, and legal issues that complicate the use of human tissue have encouraged initial attempts at xenotransplantation using porcine fetal tissue.

A 10-year follow-up review of patients who underwent Leksell's posteroventral pallidotomy for Parkinson disease

OBJECT

The clinical condition of patients with Parkinson disease (PD) who had undergone posteroventral pallidotomy (PVP) between 1985 and 1990 was evaluated at a mean of 10 years postsurgery. These patients were part of a larger series described in the first paper on Leksell's PVP that was published in 1992.

METHODS

Thirteen consecutive patients who had undergone pallidotomy at the University Hospital of Northern Sweden were tracked. Hospital and clinic records that had been updated regularly by the patients' various neurologists, geriatricians, and other clinicians were reviewed. Emphasis was placed on assessing the evolution of PD symptoms after surgery, and changes in the general health and social condition of the patients. The mean follow-up duration was 10.5 years (range 3-13.5 years). Five patients underwent a total of seven subsequent surgeries for their PD, 4 months to 11 years after the initial pallidotomy. The mean Hoehn and Yahr stage was 3 at the first surgery and 3.7 at the last follow-up review (p < 0.005). Dosages of levodopa and dopamine agonists were increased in all patients, without recurrence or induction of dyskinesias contralateral to the pallidotomy. Contralateral tremor, if it was initially controlled by surgery, remained improved. However, most patients exhibited a gradual recurrence of akinesia and an increase in gait freezing. Cognitive decline and presentation with diseases unrelated to PD were not uncommon.

CONCLUSIONS

The long-term effect of PVP on dyskinesias was not only curative but also appeared to be prophylactic. Contralateral tremor was improved in the majority of patients, although additional surgeries for PD were needed in some patients. Further progression of axial and akinetic symptoms, and an eventual decline in cognition together with other concomitant illnesses, contributed to increased disability in several patients.