MDS-UPDRS to assess non-motor symptoms after STN DBS for Parkinson's disease

Objective: To determine if the non-motor sections of the Movement Disorder Society's (MDS) version of the Unified Parkinson's Disease Rating Scale (UPDRS) could supplement the original UPDRS as a patient completed assessment of changes in non-motor symptoms in Parkinson's disease (PD) patients after bilateral subthalamic nucleus (STN) deep brain stimulation (DBS). Methods: Thirty PD patients who underwent bilateral STN DBS were assessed using the total UPDRS and the non-motor sections of the MDS-UPDRS prior to surgery and one year following surgery. This study focuses on non-motor symptoms as assessed by Part I of the UPDRS and Part 1A and 1B of the MDS-UPDRS. Results: One year following surgery, no individual non-motor symptoms or the total mentation score of the UPDRS were significantly changed. In comparison, the MDS-UPDRS showed significant improvements in sleep and urinary problems and a trend towards improvement in anxiety, constipation, daytime sleepiness, fatigue and pain. Conclusions: This study provides evidence that the MDS-UPDRS non-motor sections, when completed by the patients, can supplement the original version of the UPDRS as an effective method of measuring changes in non-motor symptoms after DBS. It also reinforces the benefits of bilateral STN DBS on non-motor symptoms of PD.     

Only physical aspects of quality of life are significantly improved by bilateral subthalamic stimulation in Parkinson’s disease

Background The well known global improvement of quality of life (QoL) after bilateral high frequency chronic deep brain stimulation of the subthalamic nucleus (STN DBS) in Parkinsons disease (PD) is in contrast to behavioral disturbances as observed after surgery. Indeed the impact of DBS on physical versus mental aspects of QoL in PD remains unknown. Objective To assess the influence of bilateral STN DBS on physical versus mental aspects of QoL in Parkinsons disease. Methods The results of 27 patients for the Unified Parkinsons disease Rating Scale (UPDRS), Parkinsons Disease Questionnaire 39 (PDQ39) and Short Form 36 health survey questionnaire (SF36) were compared before surgery and after 12 months of bilateral STN DBS. Results Comparing off–dopa conditions before versus 12 months after surgery, both UPDRS part II and part III significantly improved: 32.6% and 52%, respectively. UPDRS part I scores did not change significantly at 12 months. As for PDQ39, the global score significantly improved after surgery (21.1 %) as did four subscores: mobility (25.6 %), activity of daily living (34.5 %), stigma (40.1 %) and bodily discomfort (30 %). Three PDQ39 subscores, however, showed no significant changes: emotional well–being (10.7 %), social support (3.2%) and cognition (8.5 %) and one item even worsened: communication (–7.7 %). In SF36, only physical items significantly improved. Conclusion Using clinicians based rating scale, bilateral STN DBS showed significant improvement in PD patients at 12 month follow up. However, using patients self–assessment scales, the clinical benefit of STN DBS was more subtle: physical items of QoL significantly improved, whereas mental items such as emotional well–being, social support, cognition and communication showed no improvement. Our results are suggestive of a dissociation of motor and non–motor symptoms control after bilateral STN DBS in PD patients.     

Short-term quality of life after subthalamic stimulation depends on non-motor symptoms in Parkinson's disease

Background

Subthalamic nucleus (STN) deep brain stimulation (DBS) improves quality of life (QoL), motor, and non-motor symptoms (NMS) in advanced Parkinson's disease (PD). However, considerable inter-individual variability has been observed for QoL outcome.

Neuropsychiatric symptoms three years after subthalamic DBS in PD patients

Objective

To evaluate neuropsychiatric symptoms in PD patients submitted to bilateral deep brain stimulation of the subthalamic nucleus (DBS-STN) by comparison with a control group of PD patients not treated with DBS.

Methods

25 consecutive PD patients bilaterally implanted for DBS of STN (DBS group) were compared to a control group of 25 not operated PD patients (CT group) for mood, anxiety and personality traits. The two group were matched for age, sex, duration and severity of the illness. DBS PD patients were assessed three years after surgery. Mood was evaluated through the Beck Depression Inventory (BDI). Anxiety was measured by means of the State-Trait Anxiety Inventory (STAI X1-X2) and personality traits were evaluated with the Structured Clinical Interview for the DSM-IIIR Axis II Disorders (SCID II).

Results

Comparing the DBS group and the CT group, no significant differences were found for mood (BDI) or state and trait anxiety scores (STAI X1-X2). Obsessive-compulsive traits scores were found to be significantly lower in the DBS group (p < 0.03).

Conclusions

The results of this case-control study suggest that STN DBS does not lead to relevant modifications of mood, anxiety and personality provided that PD patients are well selected for the surgical treatment.     

Clinical outcomes of PD patients having bilateral STN DBS using high-field interventional MR-imaging for lead placement

Objective

Recently, an iMRI-guided technique for implanting DBS electrodes without MER was developed at our center. Here we report the clinical outcomes of PD patients undergoing STN DBS surgery using this surgical approach.

Methods

Consecutive PD patients undergoing bilateral STN DBS using this method were prospectively studied. Severity of PD was determined using the UPDRS scores, Hoehn and Yahr staging score, stand-sit-walk testing, and the dyskinesia rating scale. The primary outcome measure was the change in UPDRS III off medication score at 6 months. DBS stimulation parameters, adverse events, levodopa equivalent daily dose (LEDD), and DBS lead locations were also recorded. Seventeen advanced PD patients (9M/8F) were enrolled from 2007 to 2009.

Results

The mean UPDRS III off medication score improved from 44.5 to 22.5 (49.4%) at 6 months (p = 0.001). Other secondary outcome measures (UPDRS II, III on medication, and IV) significantly improved as well (p < 0.01). LEDD decreased by an average of 24.7% (p = 0.003). Average stimulation parameters were: 2.9 V, 66.4 μs, 154 Hz.

Conclusion

This pilot study demonstrates that STN DBS leads placed using the iMRI-guided method results in significantly improved outcomes in PD symptoms, and these outcomes are similar to what has been reported using traditional frame-based, MER-guided stereotactic methods.     

Caregiver burden worsens in the second year after subthalamic nucleus deep brain stimulation for Parkinson's disease

BackgroundCaregiver burden (CB) in Parkinson's disease (PD) does not improve in the short term after bilateral subthalamic nucleus (STN) deep brain stimulation (DBS), despite motor improvement. This may be due to increased caregiver demands after surgery or the possibility that DBS unresponsive non-motor factors, such as executive dysfunction, contribute to CB.ObjectiveTo evaluate the trajectory of CB in year 2 following bilateral STN DBS surgery for PD, and to test whether post-operative CB changes correlate with changes in executive function in a subgroup with available neuropsychological testing.MethodsThis retrospective analysis included 35 patients with PD whose caregivers completed the Caregiver Burden Inventory (CBI) at baseline and between 9 and 24 months after bilateral STN DBS. 14 of these patients had neuropsychological testing both at baseline and within 6 months of their follow up CBI assessment.ResultsCBI scores showed worsened CB from baseline to follow-up (16.4–21.5, p = 0.006). There was no correlation between change in executive function and change in CBI in the smaller subsample.ConclusionCB worsens in the 2 years after bilateral STN DBS despite improvement in motor symptoms and is not associated with change in executive dysfunction in the setting of advancing PD. These findings have implications on pre-operative counselling for patients and caregivers considering DBS for PD.     

Non-motor outcomes of subthalamic stimulation in Parkinson's disease depend on location of active contacts

Background

Subthalamic nucleus (STN) deep brain stimulation (DBS) improves quality of life (QoL), motor, and non-motor symptoms (NMS) in Parkinson's disease (PD). Few studies have investigated the influence of the location of neurostimulation on NMS.

Cognitive outcome 5 years after bilateral chronic stimulation of subthalamic nucleus in patients with Parkinson's disease

Aim

To assess the long‐term cognitive and behavioural outcome after bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) in patients affected by Parkinson''s disease, with a 5‐year follow‐up after surgery.

Methods

11 patients with Parkinson''s disease treated by bilateral DBS of STN underwent cognitive and behavioural assessments before implantation, and 1 and 5 years after surgery. Postoperative cognitive assessments were carried out with stimulators turned on.

Results

A year after surgery, there was a marginally significant decline on a letter verbal fluency task (p = 0.045) and a significant improvement on Mini‐Mental State Examination (p = 0.009). 5 years after surgery, a significant decline was observed on a letter verbal fluency task (p = 0.007) and an abstract reasoning task (p = 0.009), namely Raven''s Progressive Matrices 1947. No significant postoperative change was observed on other cognitive variables. No patient developed dementia 5 years after surgery. A few days after the implantation, two patients developed transient manic symptoms with hypersexuality and one patient developed persistent apathy.

Conclusion

The decline of verbal fluency observed 5 years after implantation for DBS in STN did not have a clinically meaningful effect on daily living activities in our patients with Parkinson''s disease. As no patient developed global cognitive deterioration in our sample, these findings suggest that DBS of STN is associated with a low cognitive and behavioural morbidity over a 5‐year follow‐up, when selection criteria for neurosurgery are strict.Chronic bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective neurosurgical procedure for treatment of motor symptoms in patients with advanced Parkinson''s disease, who cannot be satisfactorily treated with pharmacological treatments. The safety of this procedure has been investigated by several studies, which have assessed the effects of STN DBS on cognition and behaviour.^1,2,3 Some investigations have also attempted to distinguish between the cognitive effects of surgical intervention and those of DBS of STN in itself.^4,5,6,7All neuropsychological investigations in patients treated by STN DBS showed a postoperative decline of verbal fluency, whereas less consistent effects have been reported on other cognitive tasks in different studies. A postoperative decline of episodic verbal memory, which was detectable 3 months after surgery, has been reported in some investigations.^6,8Different effects of STN DBS on various frontal cognitive functions have been described. STN stimulation may impair response‐inhibition performance on the interference task of the Stroop test, as compared with the off‐stimulation condition.^5,7,9 A positron emission tomography study showed that such impaired performance on the Stroop test in the on‐stimulation condition is associated with decreased activation in both the right anterior cingulate cortex and the right ventral striatum.⁹ Conversely, short‐term STN stimulation may improve performance on cognitive flexibility tasks, including random number generation⁷ and the Modified Wisconsin Card Sorting Test (MWCST).⁵Various behavioural effects have been described in patients with Parkinson''s disease treated by STN DBS. Some studies reported cases of depression¹⁰ or increased apathy,¹¹ whereas cases of mania were described in other studies^12,13,14 and an improvement of depression¹ or apathy¹⁵ was also found.The long‐term cognitive and behavioural effects of bilateral STN DBS were investigated in 70 patients with Parkinson''s disease followed up for 3 years.¹¹ In this study, a decline of verbal fluency, an improvement of depression and an increased apathy were observed 3 years after surgery. Some patients showed behavioural changes (aggressive behaviour, hypomania, depression and psychosis), which were mostly transient. Recently, the long‐term outcome of bilateral DBS of STN was investigated in a multicentre study conducted in 49 patients with Parkinson''s disease followed up for 3 or 4 years.¹⁶ This study showed that stimulation of the STN induced a significant improvement in Parkinsonian motor symptoms and activities of daily living 3–4 years after surgery. Among the adverse events, the authors reported memory decline or psychiatric disturbances (including hallucinations, delirium, depression, apathy and anxiety), which occurred in about 30% of the patients.In two recent investigations, the long‐term outcome of bilateral DBS of STN was investigated in patients with a 5‐year follow‐up.^17,18 In one study conducted on 49 patients with Parkinson''s disease,¹⁷ cognitive performance was assessed by means of the Mattis Dementia Rating Scale (MDRS)¹⁹ and a frontal‐lobe score.⁴ Five years after surgery, there was a marked improvement of both motor function, while off drugs, and activities of daily living, a statistical trend towards a decline on the MDRS (reflecting the appearance of progressive dementia in three patients between the third and the fifth postoperative years) and a significant decline in the average frontal‐lobe score. Another study carried out on 37 patients with Parkinson''s disease¹⁸ also assessed cognitive performance by means of MDRS¹⁹ and a frontal score.²⁰ Five years after the implantation, there was an improvement in Parkinsonian motor symptoms and activities of daily living and a reduction of levodopa‐related motor complications and levodopa daily doses. However, a significant decline in cognitive performance was detected on the MDRS and the frontal score.To our knowledge, no extensive neuropsychological data have been reported so far in patients with a follow‐up >3 years. The aim of the present study was to assess the long‐term cognitive and behavioural outcome after bilateral DBS of the STN in a series of patients followed up for 5 years after surgery.     

Prevalence and determinants of depression in Mexican patients with Parkinson's disease

Objective

To assess the prevalence and associated factors of depression in a Mexican Parkinson's disease (PD) population.

Background

Depressive symptoms are frequent in PD and have been recognized as a major determinant of quality of life. Only two previous studies have partially addressed depression in Mexican PD patients.

Methods

One hundred forty-seven non-demented PD patients were recruited at the movement disorder specialist clinic at the National Institute of Neurology and Neurosurgery, Mexico City. The following sociodemographic variables were collected: gender, age, age at onset, disease duration and disease severity in terms of Hoehn and Yahr stage. PDQ-8, NMSQuest and Beck Depression Inventory (BDI) were applied to all participants.

Results

One hundred forty-seven patients were included (49.7% female). The mean age of the sample was 62.1 ± 11.7 years, the mean age at diagnosis was 55.8 ± 12.3 and the mean duration of the disease was 6.3 ± 5 years. A total of 49 (33.3%) patients were diagnosed with current depression. Depressed patients also scored higher in the NMSQuest even when depression/anxiety items were excluded. Differences were found in gender, UPDRS III score and HY stage, but after the logistic regression analysis was performed only the NMSQuest score and low education remained as statistically significant factors for depression in Mexican PD patients.

Conclusions

Depression prevalence in PD Mexican patients is similar to other international reports. The main associated factor was the presence of non-motor symptoms.     

Prevalence of non motor features in a cohort of Parkinson's disease patients

Background

There is a lack of awareness among physicians of the considerable disability caused by non-motor symptoms (NMS) in PD. The aim of this work is to estimate the prevalence of NMS in a series of patients with Parkinson's disease (PD).

Materials and methods

We studied 112 patients with Parkinson's disease. Motor symptoms were scored on the Unified Parkinson's Disease Rating Scale (UPDRS) part III and the Hoehn and Yahr (HY) Scale. Other symptoms were quantified with the Non-Motor Symptom Questionnaire and Scale (NMSQuest and NMSS) as well as Minimental State Examination (MNSE).

Results

Analysis of the data from the NMSS showed that mood/cognition was the most commonly affected domain (prevalence rate = 87.5%), followed by sleep disturbance/fatigue second (78.6%). However, all other non-motor symptoms scored highly: gastrointestinal and urinary (76.8% for both), sexual dysfunction (73%), cardiovascular (70.5%) with significantly higher percentage in predominantly akinetic/rigid patients. Perceptual problems/hallucinations (9.9%) were infrequent in this population. Dementia was recorded in 22.3% of patients, most of them having a mild degree of dementia. UPDRS scores were correlated with total scores in both NMSQuest and NMSS.

Conclusions

Mood/cognition, sleep disorders, GIT, and sexual disorders were common non motor manifestations in this population of PD patients.     

Changes in cognitive‐emotional and physiological symptoms of depression following STN‐DBS for the treatment of Parkinson’s disease

Background and purpose: Subthalamic nucleus deep brain stimulation (STN‐DBS) has been shown to have beneficial effects on the motor features of Parkinson’s disease (PD), but its impact on non‐motor symptoms, most notably mood, has not been fully explored. Methods: In the first study to independently compare the emotional‐cognitive and somatic/physiological symptoms of depression, we examined mood differences in 17 bilateral STN‐DBS and 22 matched non‐surgical PD patients at baseline and 6 months. Results: The STN‐DBS group reported higher levels of depression at baseline with significant endorsement of physical symptomatology. Postoperatively, no significant between‐group differences in physical symptoms of depression were found. In contrast, a significant group by time interaction for cognitive‐emotional symptoms of depression was found, with the STN‐DBS group reporting an increase in psychological symptoms of distress. The STN‐DBS group also reported an increase in anxiety following surgery. The suicide rate of 5% found in our study is consistent with other postoperative studies in PD. The impact of changes in levodopa and psychotropic medication are also explored. Conclusions: Preliminary results suggest that the motor improvement often observed in patients with PD following bilateral STN‐DBS may be partially offset by an increase in affective‐cognitive symptoms of depression.     

DBS amplitude setting can improve aspects of quality of life in patients with Parkinson’s disease

The DBS STN is a non-curative treatment; its effect on the patient’s quality of life (QoL) determines the therapeutic success of this procedure. We aimed to assess whether stimulation parameters setting may influence also some of the non-motor aspects of QoL. The QoL was assessed by PDQ-39 questionnaire. The questionnaire was administered to patients before and after the DBS surgery. A sham change of stimulation amplitude was performed before the actual increase. After the further amplitude increase in subgroup of patients (mean increase of amplitude of 0.35 V), there was a statistically significant additional improvement of total PDQ-39 score by another 22.9 %. In this group the emotions, stigma and communication subscales improved after the stimulation increase, without further change of UPDRS III. We were able to demonstrate that the increase of stimulation parameters (amplitude) has a potential to improve some non-motor functions and aspects of QoL and thus has an additional effect on quality of life in certain subset of PD patients. The meticulous observation of QoL should be a routine part of assessments before and after the DBS STN surgery, and can even aid during the parameter setting.     

Greater improvement in quality of life following unilateral deep brain stimulation surgery in the globus pallidus as compared to the subthalamic nucleus

While deep brain stimulation (DBS) surgery is a well-accepted treatment for Parkinson disease (PD) that improves overall quality of life (QoL), its effects across different domains of QoL are unclear. The study reported here directly compared the effects of unilateral DBS in subthalamic nucleus (STN) or globus pallidus (GPi) on QoL in 42 non-demented patients with medication-refractory PD. Patients were enrolled in the COMPARE trial, a randomized clinical trial of cognitive and mood effects of STN versus GPi DBS conducted at the University of Florida Movement Disorders Center. Patients underwent motor, mood, verbal fluency and QoL (Parkinson disease questionnaire: PDQ-39) measures before and 6 months following surgery. Groups experienced motor and mood improvements that did not differ by target. Patients with STN DBS evidenced a slight decrement on letter fluency. On average, all patients endorsed better overall QoL after surgery. However, despite similar motor and mood improvements, GPi patients improved more than STN patients (38 vs. 14%, respectively; P = 0.03). Patients reported better QoL on subscales of mobility, activities of daily living (ADLs), emotional well-being, stigma, cognition and discomfort, but not on those of social support and communication. Improvements on the mobility, ADLs, stigma and social support subscales were greater amongst GPi patients. In regression analyses, only depression changes independently predicted changes in overall QoL as well as emotional well-being and social support changes. Within the STN group only, declining category fluency scores correlated with poorer QoL on the communication subscale. Unilateral DBS in both STN and GPi improved QoL overall and in disparate domains 6 months after surgery. Patients receiving GPi DBS reported greater improvements that cannot be explained by differential mood or motor effects; however, verbal fluency changes may have partially contributed to lesser QoL improvements amongst STN patients.     

Effects of subthalamic nucleus deep brain stimulation on sweating function in Parkinson's disease

Purpose

To assess the impact of subthalamic nucleus (STN) deep brain stimulation (DBS) on the sweating function in patients with advanced Parkinson's disease (PD).

Methods

Nineteen patients with idiopathic PD (mean age ± SD, 61.58 ± 9.47) were examined immediately before and 6 months after DBS. Each examination session included registration of autonomic symptoms by means of a semi-structural questionnaire and recording of sympathetic skin response (SSR) from both palms and one sole. The neurophysiological measurements were compared to those of 19 matched for sex and age healthy controls.

Results

Six months post-DBS motor improvement was amounted to 65.9% and the daily levodopa equivalent dose was decreased by 36.4%. Post-operatively, dyshidrosis manifestations were reduced by 66.7% (pre-DBS sudomotor dysfunction in 47.4% of patients and sudomotor fluctuation in 57.1% of the above patients). There were no significant differences in-between pre- and post-DBS results of SSR study. However, the number of patients with at least one abnormal SSR pre-operative was reduced from 6 to 3 post-operative. No correlation was found between this neurophysiological finding and the change of clinical symptoms of hyperhidrosis or the DBS motor improvement.

Conclusions

These results, although based on a small sample, suggest that STN DBS, in addition to the effect to the mobility, might also favorably regulate sweat in idiopathic PD.     

脑深部电刺激对帕金森病非运动症状的疗效(附102例病例分析)

目的 探讨丘脑底核(STN)脑深部电刺激(DBS)对帕金森病(PD)非运动症状的治疗作用.方法 102例PD病人接受STN-DBS手术,手术前后分别进行非运动症状(NMS)量表评估,随访时间6个月至6年.结果 PD患者术前有NMS症状3～18项,平均7.1项.NMS评分与患者的Hoehn-Yahr分级明显相关(相关系数r=0.49,P<0.01).手术后频数明显下降的NMS症状是:疼痛、感觉异常、失眠、多梦、不安腿、体质量下降.结论 所有PD患者都具有NMS症状,出现在PD病程的各个时期.随疾病严重程度的进展,PD患者平均NMS评分明显提高.DBS手术不能改善PD患者的所有NMS症状,但可以减少疼痛、感觉异常、失眠、多梦、不安腿、体质量下降等症状.     

Effect of deep brain stimulation on autonomic dysfunction in patients with Parkinson’s disease

Increasing attention is being paid to the non-motor symptoms of Parkinson’s disease (PD). While deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been shown to clearly improve motor symptoms of PD, the effects of STN DBS on autonomic symptoms have not been well studied. We examined 11 patients undergoing STN DBS for PD. Patients were administered a questionnaire by phone to evaluate pre-operative and post-operative function. Three out of the 11 patients reported marked improvement post-DBS in one or more symptoms of autonomic dysfunction (sweating, bladder, or bowel function). All three patients had early-onset PD (EOPD), whereas the eight patients reporting no significant improvement were those with late-onset PD. Thus, we found that some patients experienced marked improvement in sweating and/or bowel and bladder function after STN DBS, with a trend towards a response in patients with EOPD. Our results suggest the utility of a larger prospective study.     

Weight changes associated with unilateral STN DBS and advanced PD

Weight gain following bilateral subthalamic nucleus deep brain stimulation (STN DBS) in Parkinson disease (PD) has been characterized previously, but little is known about changes in weight following unilateral STN DBS. Weight gain of approximately 10 kg at one year after bilateral STN DBS for PD has been noted in previous studies, and PD in the absence of DBS has been associated with weight loss. A case-control comparison evaluated the change in weight following unilateral STN DBS in PD. In 39 patients who underwent unilateral STN DBS for PD, we measured the weight change over 1 year versus both preoperative weight change and the weight change in 40 age- and disease severity-matched PD controls without DBS. Regression analyses incorporating age, gender, baseline weight in case or control were conducted to assess weight changes. At 12 months following surgery, the mean weight of unilateral STN DBS patients increased by 4.3 ± 7.2 kg versus the preoperative baseline weight (p < 0.001) and this increase was 4.8 kg compared with the controls (p = 0.015). Over a 1 year time interval, weight gain occurred in 41% of the preoperative unilateral STN DBS patients and 45% of the PD controls, while 85% of the unilateral STN DBS patients had gained weight at 12 months after surgery (p < 0.0001, respectively, chi square test). We conclude that unilateral STN DBS in PD is associated with weight gain, which offsets weight loss associated with advanced PD.     

Bilateral STN-DBS fails to improve non-motor fluctuations in a PD patient

We report the case of a 60-year-old woman with Parkinson's disease and severe motor fluctuations. During OFF periods she presented both motor and non-motor symptoms, which ameliorated rapidly after each levodopa dose. After undergoing bilateral STN DBS, motor complications improved markedly while non-motor symptoms remained unchanged. Levodopa response is regarded as a good predictive factor for the prognosis of motor symptoms in PD patients undergoing surgery. However, our case suggests that its relation with the prognosis of non-motor symptoms might be different and remains to be addressed.     

Neuropsychological performance following staged bilateral pallidal or subthalamic nucleus deep brain stimulation for Parkinson's disease.

Deep brain stimulation (DBS) has the potential to significantly reduce motor symptoms in advanced Parkinson's disease (PD). Controversy remains about non-motor effects of DBS and the relative advantages of treatment at two brain targets, the globus pallidus internus (GPi) and the subthalamic nucleus (STN). We investigated effects of DBS on neuropsychological functioning in 42 patients with advanced PD randomly assigned to receive staged bilateral DBS surgery of either the GPi or STN. Patients underwent neuropsychological assessment prior to and 6 months after unilateral surgery. Twenty-nine subsequently underwent surgery to the contralateral side and completed a second follow-up neuropsychological evaluation 15 months later. Unilateral treatment resulted in small but statistically significant reductions in performance on several measures, including verbal fluency and working memory. A similar pattern was observed after bilateral treatment. Reductions in verbal associative fluency were significant only after left-sided treatment. There were few significant differences related to treatment at the two surgical targets. Supplementary analyses suggested that decrements in select neuropsychological domains following DBS are unrelated to age or post-surgical reduction in dopaminergic medication dose. Findings are discussed with reference to possible causes of neuropsychological decline and the need for further controlled studies of specific neuropsychological effects of DBS.     

Temporary deterioration of executive function after subthalamic deep brain stimulation in Parkinson's disease

Objective

Selective impairment of executive function has been shown in Parkinson's Disease (PD) patients undergoing Deep Brain Stimulation (DBS) of the Subthalamic Nucleus (STN). However, some patients experience difficulties in daily life, such as dissension in interpersonal relationships or a loss of lifestyle balance, in the short term after surgery. Our hypothesis is that these difficulties might be related to executive dysfunction. To elucidate the involvement of executive dysfunction in these difficulties, we assessed motor and executive function in the short term and long term after surgery.

Methods

We examined motor function and executive function in 30 patients who underwent bilateral STN–DBS for medically refractory PD. Patients were evaluated for executive function 1 month before surgery, 1 month after surgery, and 12 months after surgery using the Trail Making Test (TMT), the Modified Stroop Color Word Interference Test (MST) and tests of Verbal Fluency (VF).

Results

TMT-B, TMT (B/A), MST-B, VF-phonemic and VF-semantic scores were significantly poorer 1 month after STN–DBS. TMT-B, TMT (B/A) and VF-phonemic recovered to preoperative levels by 12 months after surgery. A reduction in dopaminergic medication 1 month after surgery was significantly correlated with deterioration of TMT (B/A).

Conclusion

Temporary deterioration of executive function may occur in the short term after STN–DBS, whereas motor function is usually improved. PD patients undergoing STN–DBS should be managed during this period to better predict temporary executive dysfunction. Excessive reduction of dopaminergic medication after surgery might, at least in part, result in this deterioration of executive function.