Genko Oyama

Effects of STN and GPi Deep Brain Stimulation on Impulse Control Disorders and Dopamine Dysregulation Syndrome

Objective Impulse control disorders (ICDs) and dopamine dysregulation syndrome (DDS) are important behavioral problems that affect a subpopulation of patients with Parkinsons disease (PD) and typically result in markedly diminished quality of life for patients and their caregivers. We aimed to investigate the effects of subthalamic nucleus (STN) and internal globus pallidus (GPi) deep brain stimulation (DBS) on ICD/DDS frequency and dopaminergic medication usage. Methods A retrospective chart review was performed on 159 individuals who underwent unilateral or bilateral PD DBS surgery in either STN or GPi. According to published criteria, pre- and post-operative records were reviewed to categorize patients both pre- and post-operatively as having ICD, DDS, both ICD and DDS, or neither ICD nor DDS. Group differences in patient demographics, clinical presentations, levodopa equivalent dose (LED), and change in diagnosis following unilateral/bilateral by brain target (STN or GPi DBS placement) were examined. Results 28 patients met diagnostic criteria for ICD or DDS pre- or post-operatively. ICD or DDS classification did not differ by GPi or STN target stimulation. There was no change in DDS diagnosis after unilateral or bilateral stimulation. For ICD, diagnosis resolved in 2 of 7 individuals after unilateral or bilateral DBS. Post-operative development of these syndromes was significant; 17 patients developed ICD diagnoses post-operatively with 2 patients with pre-operative ICD developing DDS post-operatively. Conclusions Unilateral or bilateral DBS did not significantly treat DDS or ICD in our sample, even though a few cases of ICD resolved post-operatively. Rather, our study provides preliminary evidence that DDS and ICD diagnoses may emerge following DBS surgery.

Impaired in vivo dopamine release in parkin knockout mice

parkin is the most frequent causative gene among familial Parkinsons disease (PD). Although parkin deficiency induces autosomal recessive juvenile parkinsonism (AR-JP, PARK2) in humans, parkin knockout (PKO) mice consistently show few signs of dopaminergic degeneration. We aimed to directly measure evoked extracellular dopamine (DA) overflow in the striatum with in vivo voltammetry. The amplitude of evoked DA overflow was low in PKO mice. The half-life time of evoked DA overflow was long in PKO mice suggesting lower release and uptake of dopamine. Facilitation of DA overflow by repetitive stimulation enhanced in the older PKO mice. Decreased dopamine release and uptake in young PKO mice suggest early pre-symptomatic changes in dopamine neurotransmission, while the enhanced facilitation in the older PKO mice may reflect a compensatory adaptation in dopamine function during the late pre-symptomatic phase of Parkinsons disease. Our results showed parkin deficiency may affect DA release in PKO mice, although it does not cause massive nigral degeneration or parkinsonian symptoms as in humans.

Mechanism and treatment of dropped head syndrome associated with parkinsonism

Dropped head syndrome (DHS) associated with parkinsonism is not frequent, but it markedly reduces the activities of daily living and is refractory. To elucidate the mechanism and treatment of DHS associated with parkinsonism, we assessed 28 parkinsonian patients with DHS (2 men and 26 women) by examining their clinical features and cervical-muscle-needle and surface electromyographic (EMG) recordings. We also evaluated the effects of lidocaine, muscle afferent block (MAB; 1% lidocaine mixed with ethanol), and botulinum toxin injected into the bilateral sternocleidomastoid muscles (SCMs), which were considered to be the affected muscles. In some patients, DHS occurred after the initiation or loading of dopamine agonists (less common after pergolide than cabergoline and pramipexole). Improvement was noted after a reduction in the dopamine agonist dose in some patients, and loading of l-dopa in others. Needle EMG revealed no evidence for weakness of the dorsal neck muscles. Surface EMG showed a gradual increase in SCMs activity upon passive head lifting. Lidocaine injection into SCMs markedly improved DHS, but the effect was temporary. The effect of botulinum toxin and MAB was not satisfactory. Whereas DHS could have a heterogeneous etiology, dopamine receptor sensitivity may play a role in its pathogenesis. For the treatment of DHS in parkinsonian patients, an increase in the dosage of l-dopa and a decrease in that of the dopamine agonist should be considered. Lidocaine injection (lidocaine test) could be useful for determining the most affected muscle before using botulinum toxin or MAB. Further studies are needed to examine the outcome of such treatments that include GPi-DBS.

Are selective serotonin reuptake inhibitors associated with greater apathy in Parkinson's disease?

Apathy is a common neuropsychiatric feature of Parkinsons disease (PD), but little is known of relationships between apathy and specific medications in PD. Following a retrospective database and chart review of 181 Parkinsons patients, relationships between Apathy Scale scores and use of psychotropic and antiparkinsonian medications were examined with multiple regression. Controlling for age, sex, education, and depression, the use of selective serotonin reuptake inhibitors (SSRIs), but not other antidepressants, was associated with greater apathy. Use of monoamine oxidase B inhibitors was associated with less apathy. Longitudinal studies are needed to evaluate a potential SSRI-induced apathy syndrome in PD.

Differential Response of Dystonia and Parkinsonism following Globus Pallidus Internus Deep Brain Stimulation in X-Linked Dystonia-Parkinsonism (Lubag)

Background: X-linked dystonia-parkinsonism (XDP; DYT3; Lubag) is an adult-onset hereditary progressive dystonia/parkinsonism which is typically minimally responsive to pharmacological treatment. Case Report: We report a 63- year-old man with a diagnosis of XDP who underwent bilateral globus pallidus internus deep brain stimulator (GPi-DBS) placement. His course initially began with right hand tremor and dystonia at age 57 and progressed to also include bradykinesia and rigidity. The patient tolerated the procedure without significant complications. GPi-DBS improved his right hand dystonia, but did not significantly improve his parkinsonism. Conclusion: DBS may be a therapeutic option for select cases of XDP, but its specificindications must be carefully discussed, as the available cases have had mixed responses. Whether other targets may be more effective is not known.

Addiction-Like Manifestations and Parkinson's Disease: A Large Single Center 9-Year Experience

ABSTRACT Objective: Characterize potential risk factors and the relationship of dopamine agonist (DA) withdrawal syndrome (DAWS), dopamine dysregulation syndrome (DDS), and impulse control disorders (ICDs) in Parkinsons disease (PD). Methods: A retrospective chart review categorized cases into three groups: DAWS, DDS, and ICDs. Results: A total of 1,040 subjects met inclusion criteria. There were 332 subjects with a history of tapering DAs and 26 (7.8%) developed DAWS. Fourteen (1.3%) and 89 (8.6%) met the criteria for both DDS and ICD. Subjects with DAWS, DDS, and ICDs had a higher baseline dose of DA, levodopa, and total dopaminergic medication (p < .05), compared to those without the three conditions. DDS was found to be related to the DAWS group (p < .001). When comparing to the PD population without DDS, younger age at onset of PD (p = .027), presence of DAWS (p < .001), ICDs (p = .003), and punding (p = .042) were all correlated with the DDS group, while male sex (p = .045), younger age at onset of PD (p < .001), presence of DAWS (p < .001), and presence of DDS (p = .001) and punding (p < .001) were related to the ICD group. Conclusions: There was a strong relationship between DAWS, DDS, and ICD in this large PD cohort. Dopaminergic therapy in a subset of PD patients was strongly associated with addiction-like behavioral issues.

GPi and STN deep brain stimulation can suppress dyskinesia in Parkinson's disease

OBJECTIVES To compare subthalamic nucleus (STN) to globus pallidus internus (GPi) deep brain stimulation (DBS) for control of motor fluctuations and for potential dyskinesia-suppressing qualities. METHODS We conducted a retrospective database review of all patients who underwent GPi or STN DBS for idiopathic Parkinsons disease. Direct dyskinesia suppression (dDS) was defined as improvement in dyskinesia subscore of the unified Parkinsons disease rating scale (UPDRS) part IV (items 32-34), despite lack of reduction in dopaminergic medication dosage. We analyzed the data using methods appropriate for a case-control study. RESULTS A total of 133 patients were evaluated. At the last evaluation Dyskinesia scores and motor fluctuations significantly improved in both the GPi (p < 0.0001) and STN groups (p < 0.0001). The GPi group was more likely than the STN group to experience dDS (odds ratio = 1.95, 95% CI = 0.556, 3.21). However, the association between DBS target and dDS was not statistically significant (Pearson chi-square = 2.286, p = 0.131). CONCLUSIONS The overall clinical outcome of STN and GPi DBS for control of dyskinesia and motor fluctuations was similar. STN and GPi DBS both had some direct dyskinesia suppression effects.

Differential and Better Response to Deep Brain Stimulation of Chorea Compared to Dystonia in Huntington’s Disease

Huntington’s disease (HD) is an autosomal dominant and progressive neurodegenerative syndrome characterized by motor, cognitive and psychiatric manifestations. Chorea and dystonia are features that may be troublesome to some patients and may potentially prove unresponsive to pharmacological treatments. There are several reports on the results of globus pallidus internus deep brain stimulation (DBS) surgery for HD. In these published cases, DBS was utilized mainly to treat disabling chorea. We report our experience with 2 HD cases treated with DBS. The cases illustrate a differential response with a better outcome in the choreic presentation compared to the dystonic presentation. Additionally, DBS worsened gait features in both cases.

High frequency of beta-propeller protein-associated neurodegeneration (BPAN) among patients with intellectual disability and young-onset parkinsonism

Neurodegeneration with brain iron accumulation (NBIA) is a genetically heterogeneous disorder, characterized by the accumulation of iron in regions such as the basal ganglia. We enrolled 28 patients with childhood intellectual disability and young-onset parkinsonism (≤40 years at onset) and 4 patients with infantile neuroaxonal dystrophy. All had been clinically diagnosed, and the prevalence of genetic mutations linked to NBIA (PANK2 [exons 1-7], PLA2G6 [exons 2-17], C19orf12 [exons 1-3], WDR45 [exons 2-11], COASY [exons 1-9], FA2H [exons 1-7], and RAB39B [exons 1, 2]) was evaluated. We detected 7 female patients (25.0%, 7 of 28) with de novo heterozygote WDR45 mutations, which are known to be pathogenic for beta-propeller protein-associated neurodegeneration. All 7 patients had common clinical features. Pathogenic mutations in other NBIA genes were not found. We also screened 98 patients with early-onset parkinsonism without intellectual disability and 110 normal controls of Japanese origin for WDR45 mutations. None had WDR45 mutations. Our data suggest a high frequency of beta-propeller protein-associated neurodegeneration mutations in the Japanese population.

Effect of Deep Brain Stimulation on Parkinson's Nonmotor Symptoms following Unilateral DBS: A Pilot Study.

Parkinsons disease (PD) management has traditionally focused largely on motor symptoms. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) and globus pallidus internus (GPi) are effective treatments for motor symptoms. Nonmotor symptoms (NMSs) may also profoundly affect the quality of life. The purpose of this pilot study was to evaluate NMS changes pre- and post-DBS utilizing two recently developed questionnaires. Methods. NMS-Q (questionnaire) and NMS-S (scale) were administered to PD patients before/after unilateral DBS (STN/GPi targets). Results. Ten PD patients (9 STN implants, 1 GPi implant) were included. The three most frequent NMS symptoms identified utilizing NMS-Q in pre-surgical patients were gastrointestinal (100%), sleep (100%), and urinary (90%). NMS sleep subscore significantly decreased (−1.6 points ± 1.8, P = 0.03). The three most frequent NMS symptoms identified in pre-surgical patients using NMS-S were gastrointestinal (90%), mood (80%), and cardiovascular (80%). The largest mean decrease of NMS scores was seen in miscellaneous symptoms (pain, anosmia, weight change, and sweating) (−7 points ± 8.7), and cardiovascular/falls (−1.9, P = 0.02). Conclusion. Non-motor symptoms improved on two separate questionnaires following unilateral DBS for PD. Future studies are needed to confirm these findings and determine their clinical significance as well as to examine the strengths/weaknesses of each questionnaire/scale.