Peter Hedera

Subthalamic nucleus deep brain stimulation in early stage Parkinson's disease.

BACKGROUNDnDeep brain stimulation (DBS) is an effective and approved therapy for advanced Parkinsons disease (PD), and a recent study suggests efficacy in mid-stage disease. This manuscript reports the results of a pilot trial investigating preliminary safety and tolerability of DBS in early PD.nnnMETHODSnThirty subjects with idiopathic PD (Hoehn & Yahr Stage II off medication), age 50-75, on medication ≥6 months but ≤4 years, and without motor fluctuations or dyskinesias were randomized to optimal drug therapy (ODT) (n = 15) or DBS + ODT (n = 15). Co-primary endpoints were the time to reach a 4-point worsening from baseline in the UPDRS-III off therapy and the change in levodopa equivalent daily dose from baseline to 24 months.nnnRESULTSnAs hypothesized, the mean UPDRS total and part III scores were not significantly different on or off therapy at 24 months. Medication requirements in the DBS + ODT group were lower at all time points with a maximal difference at 18 months. With a few exceptions, differences in neuropsychological functioning were not significant. Two subjects in the DBS + ODT group suffered serious adverse events; remaining adverse events were mild or transient.nnnCONCLUSIONSnThis study demonstrates that subjects with early stage PD will enroll in and complete trials testing invasive therapies and provides preliminary evidence that DBS is well tolerated in early PD. The results of this trial provide the data necessary to design a large, phase III, double-blind, multicenter trial investigating the safety and efficacy of DBS in early PD.

Deep brain stimulation in early Parkinson's disease: Enrollment experience from a pilot trial

BACKGROUNDnDeep brain stimulation (DBS) of the subthalamic nucleus is an accepted therapy for advanced Parkinsons disease (PD). In animal models, pharmacologic ablation and stimulation of the subthalamic nucleus have resulted in clinical improvement and, in some cases, improved survival of dopaminergic neurons. DBS has not been studied in the early stages of PD, but early application should be explored to evaluate safety, efficacy, and the potential to alter disease progression.nnnMETHODSnWe are conducting a prospective, randomized, single-blind clinical trial of optimal drug therapy (ODT) compared to medication plus DBS (ODT + DBS) in subjects with Hoehn & Yahr Stage II idiopathic PD who are without motor fluctuations or dementia. We report here subject screening, enrollment, baseline characteristics, and adverse events.nnnRESULTSn30 subjects (average age 60 ± 6.9 years, average duration of medicine 2.1 ± 1.3 years, average UPDRS-III scores 14.9 on medication and 27.0 off medication) are enrolled in the ongoing study. Twelve of 15 subjects randomized to DBS experienced perioperative adverse events, the majority of which were related to the procedure or device and resolved without sequelae. Frequently reported adverse events included wound healing problems, headache, edema, and confusion.nnnCONCLUSIONnThis report demonstrates that subjects with early stage PD can be successfully recruited, consented and retained in a long-term clinical trial of DBS. Our ongoing pilot investigation will provide important preliminary safety and tolerability data concerning the application of DBS in early stage PD.

Adult-onset leukoencephalopathy with neuroaxonal spheroids and pigmented glia: report of five cases and a new mutation

The objective of this work is to report on a series of five patients with adult-onset leukoencephalopathy with neuroaxonal spheroids and pigmented glia (ALSP). ALSP is a rare adult-onset leukodystrophy, which encompasses hereditary diffuse leukoencephalopathy with axonal spheroids and pigmentary orthochromatic leukodystrophy. This was a retrospective chart review and literature review. Five previously healthy women presented with a rapidly progressive neurological disorder at ages 39, 37, 40, 30, and 47, respectively. All five individuals were initially diagnosed as suffering from multiple sclerosis. The clinical courses of the five patients were dominated by progressive spastic quadriparesis (patient 5, newly diagnosed, has paraparesis at this time) and dementia. Brain magnetic resonance imaging (MRI) showed diffuse cerebral atrophy, corpus callosal atrophy, and diffuse T2 hyperintensities in the subcortical and periventricular white matter with no gadolinium enhancing lesions. Three patients showed involvement of pyramidal tracts from motor cortex to the brainstem. Cerebrospinal fluid was normal in all cases. Diagnosis of ALSP was established by biopsy (two cases) and autopsy (two cases). Histopathology showed the presence of neuroaxonal spheroids in all four cases and pigmented glia in three. In the fifth case, diagnosis was established by genetic analysis alone that showed a disease-causing mutation in the colony-stimulating factor 1 receptor (CSF1R) gene. Genetic analysis was done in three patients with available DNA, and identified the disease-causing mutation in all three, including a novel mutation F828S. ALSP may be suspected in adults with rapid to subacute progression of neurological disease when (1) MRI shows corpus callosal atrophy on a background of generalized brain atrophy and diffuse white matter disease without postcontrast enhancement, (2) CSF studies are normal, and (3) studies for systemic inflammatory diseases and specific leukodystrophies are normal. Diagnosis may be made without histopathological evidence when a disease-causing mutation is demonstrated in the CSF1R gene.

PARK2 patient neuroprogenitors show increased mitochondrial sensitivity to copper

Poorly-defined interactions between environmental and genetic risk factors underlie Parkinsons disease (PD) etiology. Here we tested the hypothesis that human stem cell derived forebrain neuroprogenitors from patients with known familial risk for early onset PD will exhibit enhanced sensitivity to PD environmental risk factors compared to healthy control subjects without a family history of PD. Two male siblings (SM and PM) with biallelic loss-of-function mutations in PARK2 were identified. Human induced pluripotent stem cells (hiPSCs) from SM, PM, and four control subjects with no known family histories of PD or related neurodegenerative diseases were utilized. We tested the hypothesis that hiPSC-derived neuroprogenitors from patients with PARK2 mutations would show heightened cell death, mitochondrial dysfunction, and reactive oxygen species generation compared to control cells as a result of exposure to heavy metals (PD environmental risk factors). We report that PARK2 mutant neuroprogenitors showed increased cytotoxicity with copper (Cu) and cadmium (Cd) exposure but not manganese (Mn) or methyl mercury (MeHg) relative to control neuroprogenitors. PARK2 mutant neuroprogenitors also showed a substantial increase in mitochondrial fragmentation, initial ROS generation, and loss of mitochondrial membrane potential following Cu exposure. Our data substantiate Cu exposure as an environmental risk factor for PD. Furthermore, we report a shift in the lowest observable effect level (LOEL) for greater sensitivity to Cu-dependent mitochondrial dysfunction in patients SM and PM relative to controls, correlating with their increased genetic risk for PD.

Treating post-traumatic tremor with deep brain stimulation: Report of five cases

BACKGROUNDnPost-traumatic tremor is one of the most common movement disorders resulting from severe head trauma. However, literature regarding successful deep brain stimulation (DBS) treatment is scarce, resulting in ambiguity regarding the optimal lead location. Most cases support the ventral intermediate nucleus, but there is evidence to defend DBS of the zona incerta, ventral oralis anterior/posterior, and/or a combination of these targets. We report five patients with disabling post-traumatic tremor treated with DBS of the ventral intermediate nucleus and of the globus pallidus internus.nnnMETHODSnPatients were referred to the Vanderbilt Movement Disorders Division, and surgical intervention was determined by a DBS Multidisciplinary Committee. Standard DBS procedure was followed.nnnRESULTSnPatients 1-4 sustained severe diffuse axonal injuries. Patients 1-3 underwent unilateral ventral intermediate nucleus DBS for contralateral tremor, while Patient 4 underwent bilateral ventral intermediate nucleus DBS. Patients 1-3 experienced good tremor reduction, while Patient 4 experienced moderate tremor reduction with some dystonic posturing of the hands. Patient 5 had dystonic posturing of the right upper extremity with tremor of the left upper extremity. He was treated with bilateral DBS of the globus pallidus internus and showed good tremor reduction at follow-up.nnnCONCLUSIONnUnilateral or bilateral DBS of the ventral intermediate nucleus and bilateral DBS of the globus pallidus internus may be effective and safe treatment modalities for intractable post-traumatic tremor. Further studies are needed to clarify the optimal target for surgical treatment of post-traumatic tremor.

Methods for Surgical Targeting of the STN in Early-Stage Parkinson’s Disease

Patients with Parkinson’s disease (PD) experience progressive neurological decline, and future interventional therapies are thought to show most promise in early stages of the disease. There is much interest in therapies that target the subthalamic nucleus (STN) with surgical access. While locating STN in advanced disease patients (Hoehn–Yahr Stage III or IV) is well understood and routinely performed at many centers in the context of deep brain stimulation surgery, the ability to identify this nucleus in early-stage patients has not previously been explored in a sizeable cohort. We report surgical methods used to target the STN in 15 patients with early PD (Hoehn–Yahr Stage II), using a combination of image guided surgery, microelectrode recordings, and clinical responses to macrostimulation of the region surrounding the STN. Measures of electrophysiology (firing rates and root mean squared activity) have previously been found to be lower than in later-stage patients, however, the patterns of electrophysiology seen and dopamimetic macrostimulation effects are qualitatively similar to those seen in advanced stages. Our experience with surgical implantation of Parkinson’s patients with minimal motor symptoms suggest that it remains possible to accurately target the STN in early-stage PD using traditional methods.

The Allure of High-Risk Rewards in Huntington's disease.

OBJECTIVESnHuntingtons disease (HD) is a neurodegenerative disorder that produces a bias toward risky, reward-driven decisions in situations where the outcomes of decisions are uncertain and must be discovered. However, it is unclear whether HD patients show similar biases in decision-making when learning demands are minimized and prospective risks and outcomes are known explicitly. We investigated how risk decision-making strategies and adjustments are altered in HD patients when reward contingencies are explicit.nnnMETHODSnHD (N=18) and healthy control (HC; N=17) participants completed a risk-taking task in which they made a series of independent choices between a low-risk/low reward and high-risk/high reward risk options.nnnRESULTSnComputational modeling showed that compared to HC, who showed a clear preference for low-risk compared to high-risk decisions, the HD group valued high-risks more than low-risk decisions, especially when high-risks were rewarded. The strategy analysis indicated that when high-risk options were rewarded, HC adopted a conservative risk strategy on the next trial by preferring the low-risk option (i.e., they counted their blessings and then played the surer bet). In contrast, following a rewarded high-risk choice, HD patients showed a clear preference for repeating the high-risk choice.nnnCONCLUSIONSnThese results indicate a pattern of high-risk/high-reward decision bias in HD that persists when outcomes and risks are certain. The allure of high-risk/high-reward decisions in situations of risk certainty and uncertainty expands our insight into the dynamic decision-making deficits that create considerable clinical burden in HD.

Update on the genetics of movement disorders.

The significant contribution of genetic research has resulted in substantial progress in our understanding of the pathophysiology of movement disorders. This will allow for earlier diagnosis of patients with the potential to influence future therapeutics. However, given the complicated patterns of inheritance and consequences for successive generations, a review of the current state of knowledge as well as basic genetic principles is important. In this review we will discuss current classification systems, and clinical and neuropathologic features of the major genetic etiologies for Parkinson disease, dystonia, chorea, and ataxia.

Can lifestyle modification slow progression of Parkinson disease

Parkinson disease (PD), similar to other neurodegenerative conditions, is characterized by relentless clinical progression with gradual worsening of both motor and nonmotor features. Potential neuroprotective therapies focusing on aspects of neurodegeneration in PD such as impaired mitochondrial function with abnormalities of oxidative phosphorylation, increased oxidative stress, and suppressed neuroinflammation, have failed to alter the clinical course of PD.1,2 New insights into PD pathophysiology have identified potential molecular targets, including accumulation and potential prion-like spreading of aggregates containing misfolded α-synuclein protein.3 These therapies are only approaching clinical testing, and their true therapeutic potential remains unknown. Even if successful, they are many years away from clinical availability. Thus, at present, we do not have any proven pharmacologic options to modify the progressive decline of patients with PD.