Interdisciplinary Parkinson's Disease Deep Brain Stimulation Screening and the Relationship to Unintended Hospitalizations and Quality of Life.

OBJECTIVE: To investigate the impact of pre-operative deep brain stimulation (DBS) interdisciplinary assessments on post-operative hospitalizations and quality of life (QoL). BACKGROUND: DBS has been utilized successfully in Parkinson's disease (PD) for the treatment of tremor, rigidity, bradykinesia, off time, and motor fluctuations. Although DBS is becoming a more common management approach there are no standardized criteria for selection of DBS candidates, and sparse data exist to guide the use of interdisciplinary evaluations for DBS screening. We reviewed the outcomes of the use of an interdisciplinary model which utilized seven specialties to pre-operatively evaluate potential DBS candidates. METHODS: The University of Florida (UF) INFORM database was queried for PD patients who had DBS implantations performed at UF between January 2011 and February 2013. Records were reviewed to identify unintended hospitalizations, falls, and infections. Minor and major concerns or reservations from each specialty were previously documented and quantified. Clinical outcomes were assessed through the use of the Parkinson disease quality of life questionnaire (PDQ-39), and the Unified Parkinson's Disease Rating Score (UPDRS) Part III. RESULTS: A total of 164 cases were evaluated for possible DBS candidacy. There were 133 subjects who were approved for DBS surgery (81%) following interdisciplinary screening. There were 28 cases (21%) who experienced an unintended hospitalization within the first 12 months following the DBS operation. The patients identified during interdisciplinary evaluation with major or minor concerns from any specialty service had more unintended hospitalizations (93%) when compared to those without concerns (7%). When the preoperative "concern" shifted from "major" to "minor" to "no concerns," the rate of hospitalization decreased from 89% to 33% to 3%. A strong relationship was uncovered between worsened PDQ-39 at 12 months and increased hospitalization. CONCLUSIONS: Unintended hospitalizations and worsened QOL scores correlated with the number and severity of concerns raised by interdisciplinary DBS evaluations. The data suggest that detailed screenings by interdisciplinary teams may be useful for more than just patient selection. These evaluations may help to stratify risk for post-operative hospitalization and QoL outcomes.

Deep Brain Stimulation in a Case of Mitochondrial Disease.

BACKGROUND: DBS has proven to be an effective therapy for Parkinson's disease, essential tremor, and primary dystonia. Mixed results have been reported in case series for other hyperkinetic disorders, and sparse data are available regarding secondary movement disorders. We report on the clinical effects of bilateral globus pallidus internus (GPi) DBS, a progressive mitochondrial cytopathy. METHODS: A single patient with myoclonus and dystonia syndrome secondary to a mitochondrial cytopathy with history of perinatal hypoxia was identified from our University of Florida DBS database. Demographics, clinical, surgical, and DBS data were documented. RESULTS: At 6 months post-DBS, we observed a 32% (361 to 527) improvement on quality of life (36-item Medical Outcome Study Short-Form Health Survey; SF-36). Objective clinical scales revealed a 33% (143 to 96) improvement in the Unified Myoclonus Rating Scale (UMRS) total score. The UMRS action myoclonus subsection revealed a 29% (69 to 46) improvement. No significant changes were observed in the Burke-Fahn-Mardsen Dystonia Rating Scale (BFMDRS). After 1-year follow-up, a worsening of 59% (527 to 215) was observed in the SF-36 scale, of 19% (28.5 to 35) in the BFMDRS, and of 23% (96 to 124) in the UMRS. However, the frequency and intensity of action myoclonus scores remained lower when compared to baseline scores. CONCLUSIONS: Although we observed a loss of benefit in the long term for most quality-of-life and clinical outcomes, the DBS effects on action myoclonus seemed to remain stable. Longer follow-up studies are necessary to confirm our short-term and unblinded findings.

Impact of an Interdisciplinary Deep Brain Stimulation Screening Model on Post-Surgical Complications in Essential Tremor Patients.

OBJECTIVE: To investigate the relationship of our interdisciplinary screening process on post-operative unintended hospitalizations and quality of life. BACKGROUND: There are currently no standardized criteria for selection of appropriate Deep Brain Stimulation candidates and little hard data exists to support the use of any singular method. METHODS: An Essential Tremor cohort was selected from our institutional Deep Brain Stimulation database. The interdisciplinary model utilized seven specialties who pre-operatively screened all potential Deep Brain Stimulation candidates. Concerns for surgery raised by each specialty were documented and classified as none, minor, or major. Charts were reviewed to identify unintended hospitalizations and quality of life measurements at 1 year post-surgery. RESULTS: Eighty-six percent (44/51) of the potential screened candidates were approved for Deep Brain Stimulation. Eight (18%) patients had an unintended hospitalization during the follow-up period. Patients with minor or major concerns raised by any specialty service had significantly more unintended hospitalizations when compared to patients without concerns (75% vs. 25%, p < 0.005). The rate of hospitalization revealed a direct relationship to the "level of concern"; ranging from 100% if major concerns, 42% if minor concerns, and 7% if no concerns raised, p = 0.001. Quality of life scores significantly worsened in patients with unintended hospitalizations at 6 (p = 0.046) and 12 months (p = 0.027) when compared to baseline scores. No significant differences in tremor scores between unintended and non-unintended hospitalizations were observed. CONCLUSIONS: The number and level of concerns raised during interdisciplinary Deep Brain Stimulation screenings were significantly related to unintended hospitalizations and to a reduced quality of life. The interdisciplinary evaluation may help to stratify risk for these complications. However, data should be interpreted with caution due to the limitations of our study. Further prospective comparative and larger studies are required to confirm our results.

Proceedings of the Second Annual Deep Brain Stimulation Think Tank: What's in the Pipeline.

The proceedings of the 2nd Annual Deep Brain Stimulation Think Tank summarize the most contemporary clinical, electrophysiological, and computational work on DBS for the treatment of neurological and neuropsychiatric disease and represent the insights of a unique multidisciplinary ensemble of expert neurologists, neurosurgeons, neuropsychologists, psychiatrists, scientists, engineers and members of industry. Presentations and discussions covered a broad range of topics, including advocacy for DBS, improving clinical outcomes, innovations in computational models of DBS, understanding of the neurophysiology of Parkinson's disease (PD) and Tourette syndrome (TS) and evolving sensor and device technologies.

Pedunculopontine Nucleus Stimulation: Where are We Now and What Needs to be Done to Move the Field Forward?

Falls and gait impairment in Parkinson's Disease (PD) is a leading cause of morbidity and mortality, significantly impacting quality of life and contributing heavily to disability. Thus far axial symptoms, such as postural instability and gait freezing, have been refractory to current treatment approaches and remain a critical unmet need. There has been increased excitement surrounding the surgical targeting of the pedunculopontine nucleus (PPN) for addressing axial symptoms in PD. The PPN and cuneate nucleus comprise the mesencephalic locomotor region, and electrophysiologic studies in animal models and human imaging studies have revealed a key role for the PPN in gait and postural control, underscoring a potential role for DBS surgery. Previous limited studies of PPN deep brain stimulation (DBS) in treating gait symptoms have had mixed clinical outcomes, likely reflect targeting variability and the inherent challenges of targeting a small brainstem structure that is both anatomically and neurochemically heterogeneous. Diffusion tractography shows promise for more accurate targeting and standardization of results. Due to the limited experience with PPN DBS, several unresolved questions remain about targeting and programing. At present, it is unclear if there is incremental benefit with bilateral versus unilateral targeting of PPN or whether PPN targeting should be performed as an adjunct to one of the more traditional targets. The PPN also modulates non-motor functions including REM sleep, cognition, mood, attention, arousal, and these observations will require long-term monitoring to fully characterize potential side effects and benefits. Surgical targeting of the PPN is feasible and shows promise for addressing axial symptoms in PD but may require further refinements in targeting, improved imaging, and better lead design to fully realize benefits. This review summarizes the current knowledge of PPN as a DBS target and areas that need to be addressed to advance the field.

Comparative study of the influence of Thy1 deficiency and dietary iron deficiency on dopaminergic profiles in the mouse striatum.

Thy-1, a glycosyl-phosphatidylinositol (GPI)-linked integral membrane protein, may play a role in stabilizing synapses. Thy1 was identified in a gene expression analysis as iron responsive, and subsequent cell culture and animal models of iron deficiency expanded this finding to the protein. The importance of Thy1 in influencing neurotransmitter feedback mechanisms led to this study to determine the relative effects of Thy1 deficiency and dietary iron deficiency on the dopaminergic system in the mouse striatum. The model for this analysis was the Thy1 null mutant mouse in the presence or absence of dietary iron deficiency. The results revealed significant differences in dopaminergic profiles associated with Thy1 and iron deficiency and also a sex effect. For example, both iron deficiency and the absence of Thy1 are associated with increased dopamine in both sexes, but the dopamine transporter is increased in these experimental groups only in female mice. In male mice, the increase in dopamine transporter is found only in the Thy1 null mutants. Increases in vesicular monoamine transporter and phosphorylated tyrosine hydroxlyase are found only in iron-deficient mice. In contrast decreased release of dopamine from synaptosomes is found only in the Thy1 null mutant animals. In general, these results indicate that a loss of Thy1 can influence the dopaminergic profile in the striatum. Furthermore, the results reveal consistent differences in the dopaminergic profile in Thy1 knockout mice compared with iron-deficient mice, indicating that the effects of iron deficiency are not due only to a change in Thy1 expression.

Endoplasmic reticulum stress and mitochondrial cell death pathways mediate A53T mutant alpha-synuclein-induced toxicity.

Parkinson's disease (PD) is a neurodegenerative movement disorder characterized by selective loss of dopaminergic neurons and the presence of Lewy bodies. Alpha-synuclein is a major component of Lewy bodies in sporadic PD, and mutations in alpha-synuclein cause autosomal-dominant hereditary PD. Here, we generated A53T mutant alpha-synuclein-inducible PC12 cell lines using the Tet-off regulatory system. Inducing expression of A53T alpha-synuclein in differentiated PC12 cells decreased proteasome activity, increased the intracellular ROS level and caused up to approximately 40% cell death, which was accompanied by mitochondrial cytochrome C release and elevation of caspase-9 and -3 activities. Cell death was partially blocked by cyclosporine A [an inhibitor of the mitochondrial permeability transition (MPT) process], z-VAD (a pan-caspase inhibitor) and inhibitors of caspase-9 and -3 but not by a caspase-8 inhibitor. Furthermore, induction of A53T alpha-synuclein increased endoplasmic reticulum (ER) stress and elevated caspase-12 activity. RNA interference to knock down caspase-12 levels or salubrinal (an ER stress inhibitor) partially protected against cell death and further reduced A53T toxicity after treatment with z-VAD. Our results indicate that both ER stress and mitochondrial dysfunction contribute to A53T alpha-synuclein-induced cell death. This study sheds light into the pathogenesis of alpha-synuclein cellular toxicity in PD and provides a cell model for screening PD therapeutic agents.

Compounds blocking mutant huntingtin toxicity identified using a Huntington's disease neuronal cell model.

Neuronal cell death in HD is believed to be largely a dominant cell-autonomous effect of the mutant huntingtin protein. We previously developed an inducible PC12 cell model which expresses an N-terminal huntingtin fragment with an expanded poly Q repeat (N63-148Q) under the control of the tet-off system. In order to evaluate the ability of compounds to protect against mutant huntingtin toxicity in our model, we measured LDH released by dead cells into the medium. We have now screened the library of 1040 compounds from the NINDS Custom Collection as part of a National Institute of Neurological Disorders and Stroke (NINDS) collaborative project. Each positive compound was tested at 3-8 concentrations. Five compounds significantly attenuated mutant huntingtin (htt)-induced LDH release without affecting the expression level of huntingtin and independent of effect on aggregates. We also tested a broad spectrum caspase inhibitor Z-VAD-fmk and previously proposed candidate compounds. This cell model can provide a method to screen potential therapeutic compounds for treating Huntington's disease.

Inducible PC12 cell model of Huntington's disease shows toxicity and decreased histone acetylation.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by the abnormal expansion of a polyglutamine tract in the huntingtin protein. We have developed PC12 cell lines in which the expression of an N-terminal truncation of huntingtin (N63) with either wild type (23Q) or expanded polyglutamine (148Q) can be induced by the removal of doxycycline. Differentiated PC12 cells induced to express N63-148Q showed cellular toxicity reaching up to 50% at 6 days post-induction. Histone acetyltransferase (HAT) activity and global histone acetylation was significantly decreased in cells expressing truncated huntingtin with mutant but not normal huntingtin. These data suggest that altered chromatin modification via reduction in coactivator activity may cause neuronal transcriptional dysregulation and contribute to cellular toxicity.