An ¹⁸F-FDG PET study of cervical muscle in parkinsonian anterocollis

The underlying etiology of parkinsonian anterocollis has been the subject of recent debate. The purpose of this study is to test the hypothesis that anterocollis in parkinsonian syndromes is associated with dystonia of the deep cervical flexors (longus colli and capitis). Eight patients with anterocollis, six in the setting of parkinsonism and two primary cervical dystonia control subjects with anterocollis underwent prospective structured clinical evaluations (interview, examination and rating scales), systematic electromyography of the cervical extensor musculature and (18)F-FDG PET/CT studies of cervical muscles to examine evidence of hypermetabolism or overactivity of deep cervical flexors. Subjects with parkinsonian anterocollis were found to have hypermetabolism of the extensor and sub-occipital muscles but not in the cervical flexors (superficial or deep). EMG abnormalities were observed in all evaluated patients, but only one patient was definitely myopathic. Meanwhile, both dystonia controls exhibited hypermetabolism of cervical flexors (including the longus colli). In conclusion, we were able to demonstrate hypermetabolism of superficial and deep cervical flexors with muscle (18)F-FDG PET/CT in dystonic anterocollis patients, but not in parkinsonian anterocollis patients. The hypermetabolic changes seen in parkinsonian anterocollis patients in posterior muscles may be compensatory. Alternative explanations for anterocollis include myopathy of the cervical extensors, or unbalanced rigidity of the cervical flexors, but this remains to be proven.

The focal dystonias: current views and challenges for future research

The most common forms of dystonia are those that develop in adults and affect a relatively isolated region of the body. Although these adult-onset focal dystonias are most prevalent, knowledge of their etiologies and pathogenesis has lagged behind some of the rarer generalized dystonias, in which the identification of genetic defects has facilitated both basic and clinical research. This summary provides a brief review of the clinical manifestations of the adult-onset focal dystonias, focusing attention on less well understood clinical manifestations that need further study. It also provides a simple conceptual model for the similarities and differences among the different adult-onset focal dystonias as a rationale for lumping them together as a class of disorders while at the same time splitting them into subtypes. The concluding section outlines some of the most important research questions for the future. Answers to these questions are critical for advancing our understanding of this group of disorders and for developing novel therapeutics.

Phenomenology and classification of dystonia: a consensus update

This report describes the consensus outcome of an international panel consisting of investigators with years of experience in this field that reviewed the definition and classification of dystonia. Agreement was obtained based on a consensus development methodology during 3 in-person meetings and manuscript review by mail. Dystonia is defined as a movement disorder characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements, postures, or both. Dystonic movements are typically patterned and twisting, and may be tremulous. Dystonia is often initiated or worsened by voluntary action and associated with overflow muscle activation. Dystonia is classified along 2 axes: clinical characteristics, including age at onset, body distribution, temporal pattern and associated features (additional movement disorders or neurological features); and etiology, which includes nervous system pathology and inheritance. The clinical characteristics fall into several specific dystonia syndromes that help to guide diagnosis and treatment. We provide here a new general definition of dystonia and propose a new classification. We encourage clinicians and researchers to use these innovative definition and classification and test them in the clinical setting on a variety of patients with dystonia. © 2013 Movement Disorder Society.

Animal models for drug discovery in dystonia

Dystonia is a neurological disorder characterized by involuntary twisting movements and unnatural postures. There are many different forms of dystonia, which affect over three million people worldwide. Effective treatments are available only for a minority of patients, so new treatments are sorely needed. Several animal species have been used to develop models for different forms of dystonia, each with differing strengths and weaknesses. This review outlines the strategies that have been used to exploit these models for drug discovery. Some have been used to dissect the pathogenesis of dystonia for the identification of molecular targets for intervention. Others have been used for the empirical identification of candidate drugs. Therefore, the animal models provide promising new tools for developing better treatments for dystonia.

Intraoperative neurophysiology in DBS for dystonia

Deep brain stimulation (DBS) of the internal segment of the globus pallidus (GPi) has been demonstrated to be an effective therapy for the treatment of primary dystonia as well as tardive dystonia. Results for other forms of secondary dystonia have been less consistent. Although a number of target sites have been explored for the treatment of dystonia, most notably the motor thalamus, the target of choice remains the sensorimotor portion of the GPi. Although the optimal site within the GPi has not been determined, most centers agree that the optimal site involves the posteroventral lateral "sensorimotor" portion of the GPi. Microelectrode recording (MER) can be used to identify boundaries of the GPi and nearby white matter tracts, including the corticospinal tract and optic tract, and the sensorimotor GPi. However, whether or not the use of MER leads to improved outcomes compared with procedures performed without MER has not been determined. Currently, there is no evidence to support or refute the hypothesis that mapping structures with MER provides better short- or long-term outcomes. Centers using MER do not report a preference of one system over another, but there have not been any studies to compare the relative benefits or risks of using more than 1 electrode simultaneously. Comparison studies of different target structures and targeting techniques in dystonia have not been performed. Additional research, which includes comparative studies, is needed to advance our understanding and optimization of DBS targets, techniques, and approaches along with their relative benefits and risks in dystonia.

Prevalence of vitamin d insufficiency in patients with Parkinson disease and Alzheimer disease

BACKGROUND

A role for vitamin D deficiency in Parkinson disease (PD) has recently been proposed.

OBJECTIVE

To compare the prevalence of vitamin D deficiency in a research database cohort of patients with PD with the prevalence in age-matched healthy controls and patients with Alzheimer disease (AD).

DESIGN

Survey study and blinded comparison of plasma 25-hydroxyvitamin D (25[OH]D) concentrations of stored samples in a clinical research database at Emory University School of Medicine.

SETTING

Referral center (PD and AD patients), primary care clinics, and community setting (controls).

PARTICIPANTS

Participants were recruited into the study between May 1992 and March 2007. Every fifth consecutively enrolled PD patient was selected from the clinical research database. Unrelated AD (n = 97) and control (n = 99) participants were randomly selected from the database after matching for age, sex, race, APOE genotype, and geographic location.

MAIN OUTCOME MEASURES

Prevalence of suboptimal vitamin D and mean 25(OH)D concentrations.

RESULTS

Significantly more patients with PD (55%) had insufficient vitamin D than did controls (36%) or patients with AD (41%; P = .02, chi(2)test). The mean (SD) 25(OH)D concentration in the PD cohort was significantly lower than in the AD and control cohorts (31.9 [13.6] ng/mL vs 34.8 [15.4] ng/mL and 37.0 [14.5] ng/mL, respectively; P = .03).

CONCLUSIONS

This report of 25(OH)D concentrations in a predominantly white PD cohort demonstrates a significantly higher prevalence of hypovitaminosis in PD vs both healthy controls and patients with AD. These data support a possible role of vitamin D insufficiency in PD. Further studies are needed to determine the factors contributing to these differences and elucidate the potential role of vitamin D in pathogenesis and clinical course of PD.

Functional organization of the basal ganglia: contributions of single-cell recording studies

Studies of single-cell discharge in the basal ganglia of behaving primates have revealed: characteristic patterns of spontaneous discharge in the striatum, external (GPe) and internal (GPi) globus pallidus, pars reticulata and pars compacta of the substantia nigra, and the subthalamic nucleus (STN); phasic changes in neural discharge in relation to movements of specific body parts (e.g. leg, arm, neck, face); short-latency (sensory) neural responses to passive joint rotation; a somatotopic organization of movement-related neurons in GPe, GPi, and STN; a clustering of functionally similar neurons in the putamen and globus pallidus; greater representation of the proximal than of the distal portion of the limb; changes in neural activity in reaction-time tasks, suggesting a greater role of the basal ganglia in the execution than in the initiation of movement in this paradigm; a clear relation of neuronal activity to direction, amplitude (?velocity) of movement, and force; a preferential relation of neural activity to the direction of movement, rather than to the pattern of muscular activity. Some of these findings suggest that the basal ganglia may play a role in the control of movement parameters rather than (or independent of) the pattern of muscular activity. Loss of basal ganglia output related to amplitude may account for the bradykinesia in Parkinson's disease. The presence of somatotopic organization in the putamen and globus pallidus, together with known topographic striopallidal connections, suggests that segregated, parallel cortico-subcortical loops subserve 'motor' and 'complex' functions.

Deep brain stimulation for neurologic and neuropsychiatric disorders

In the 1960s, ablative stereotactic surgery was employed for a variety of movement disorders and psychiatric conditions. Although largely abandoned in the 1970s because of highly effective drugs, such as levodopa for Parkinson's disease (PD), and a reaction against psychosurgery, the field has undergone a virtual renaissance, guided by a better understanding of brain circuitry and the circuit abnormalities underlying movement disorders such as PD and neuropsychiatric conditions, such as obsessive compulsive disorder. High-frequency electrical deep brain stimulation (DBS) of specific targets, introduced in the early 1990s for tremor, has gained widespread acceptance because of its less invasive, reversible, and adjustable features and is now utilized for an increasing number of brain disorders. This review summarizes the rationale behind DBS and the use of this technique for a variety of movement disorders and neuropsychiatric diseases.

Patient selection and assessment recommendations for deep brain stimulation in Tourette syndrome

In response to recent publicity regarding the potential use of deep brain stimulation (DBS) for reducing tic severity in Tourette's syndrome (TS), the Tourette Syndrome Association convened a group of TS and DBS experts to develop recommendations to guide the early use and potential clinical trials of DBS for TS and other tic disorders. The goals of these recommendations are to ensure that all surgical candidates are (1) fully informed about the risks, benefits, and alternative treatments available; (2) receive a comprehensive evaluation before surgery to ensure that DBS is clearly the appropriate clinical treatment choice; and (3) that early clinical experience will be documented publicly to facilitate rational decision-making for both clinical care and future clinical trials.

Mood disorders in the medically ill: scientific review and recommendations

OBJECTIVE

The purpose of this review is to assess the relationship between mood disorders and development, course, and associated morbidity and mortality of selected medical illnesses, review evidence for treatment, and determine needs in clinical practice and research.

DATA SOURCES

Data were culled from the 2002 Depression and Bipolar Support Alliance Conference proceedings and a literature review addressing prevalence, risk factors, diagnosis, and treatment. This review also considered the experience of primary and specialty care providers, policy analysts, and patient advocates. The review and recommendations reflect the expert opinion of the authors.

STUDY SELECTION/DATA EXTRACTION

Reviews of epidemiology and mechanistic studies were included, as were open-label and randomized, controlled trials on treatment of depression in patients with medical comorbidities. Data on study design, population, and results were extracted for review of evidence that includes tables of prevalence and pharmacological treatment. The effect of depression and bipolar disorder on selected medical comorbidities was assessed, and recommendations for practice, research, and policy were developed.

CONCLUSIONS

A growing body of evidence suggests that biological mechanisms underlie a bidirectional link between mood disorders and many medical illnesses. In addition, there is evidence to suggest that mood disorders affect the course of medical illnesses. Further prospective studies are warranted.

Rodent models for dystonia research: Characteristics, evaluation, and utility

A large number of different genetic and acquired disorders of the nervous system may be associated with dystonia. To elucidate its pathogenesis and to facilitate the discovery of potential novel treatments, there has been a growing interest in the development of animal models and particularly rodent models. Multiple animal models for dystonia have now been developed and partially characterized. The results obtained from studies of these models often lead in very different directions, in part because the different models target different aspects of a very heterogeneous disorder. A recent workshop addressed four main issues affecting those who conduct dystonia research with animal models, including the different ways in which dystonic disorders can be modeled in rodents, key features that constitute a useful model, methods used in the evaluation of these models, and recommendations for future research. This review summarizes the main outcomes of this conference. 2005 Movement Disorder Society.

Motor subcircuits mediating the control of movement velocity: a PET study

The influence of changes in the mean velocity of movement on regional cerebral blood flow (rCBF) was studied using positron emission tomography (PET) in nine healthy right-handed adults while they performed a smooth pursuit visuomanual tracking task. Images of relative rCBF were obtained while subjects moved a hand-held joystick to track the movement of a target at three different rates of a sinusoidal displacement (0.1, 0.4, and 0.7 Hz). Significant changes in rCBF between task conditions were detected using analysis of variance and weighted linear contrasts. The kinematics of arm and eye movements indicated that subjects performed tasks in a similar manner, particularly during the faster two tracking conditions. Significant increases in rCBF during arm movement (relative to an eye tracking only control condition) were detected in a widespread network of areas known for their involvement in motor control. The activated areas included primary sensorimotor (M1S1), dorsal and mesial premotor, and dorsal parietal cortices in the left hemisphere and to a lesser extent the sensorimotor and superior parietal cortices in the right hemisphere. Subcortically, activations were found in the left putamen, globus pallidus (GP), and thalamus, in the right basal ganglia, and in the right anterior cerebellum. Within the cerebral volume activated with movement, three areas had changes in rCBF that correlated positively with the rate of movement: left M1S1, left GP, and right anterior cerebellum. No movement-related sites had rCBF that correlated negatively with the rate of movement. Regressions of mean percent change (MPC) in rCBF onto mean hand velocity yielded two nonoverlapping subpopulations of movement-related loci, the three sites with significant rate effects and regression slopes steeper than 0.17 MPC.cm-1.s-1 and all other sites with nonsignificant rate effects and regression slopes below 0.1 MPC.cm-1. s-1. Moreover, the effects of movement per se and of movement velocity varied in magnitude independently. These results confirm previous reports that movement-related activations of M1S1 and cerebellum are sensitive to movement frequency or some covarying parameter of movement. The activation of GP with increasing movement velocity, not described in previous functional-imaging studies, supports the hypothesis that the basal ganglia motor circuit may be involved preferentially in controlling or monitoring the scale and/or dynamics of arm movements. The remaining areas that were activated equally for all movement rates may be involved in controlling higher level aspects of motor control that are independent of movement dynamics.

Magnetic resonance planned thalamotomy followed by X-ray/CT-guided thalamotomy

Magnetic resonance imaging (MRI) is currently the optimal neuroradiologic technique for visualizing the anterior and posterior commissure for defining the AC-PC line. CT is the optimal technique for electrode and probe guidance during stereotactic thalamotomy. Various possibilities of transferring or overlying MRI and CT are outlined which in some future might result in more refined methods of CT-MRI guidance for stereotactic surgery.