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Biomedical subjects

Anthony E Lang

Publications and source records attributed to Anthony E Lang.

At least 37 records · Page 2Linked to original sources
PubMed2006

Subthalamic nucleus deep brain stimulation: summary and meta-analysis of outcomes.

Subthalamic nucleus (STN) deep brain stimulation (DBS) is currently the most common therapeutic surgical procedure for patients with Parkinson's disease (PD) who have failed medical management. However, a recent summary of clinical evidence on the effectiveness of STN DBS is lacking. We report the results of such a systematic review and meta-analysis. A comprehensive review of the literature using Medline and Ovid databases from 1993 until 2004 was conducted. Estimates of change in absolute Unified Parkinson's Disease Rating Scale (UPDRS) scores after surgery were generated using random-effects models. Sources of heterogeneity were explored with meta-regression models, and the possibility of publication bias was evaluated. Patient demographics, reduction in medication requirements, change in dyskinesia, daily offs, quality of life, and a ratio of postoperative improvement from stimulation compared to preoperative improvement by medication from each study were tabulated and average scores were calculated. Adverse effects from each study were summarized. Thirty-seven cohorts were included in the review. Twenty-two studies with estimates of standard errors were included in the meta-analysis. The estimated decreases in absolute UPDRS II (activities of daily living) and III (motor) scores after surgery in the stimulation ON/medication off state compared to preoperative medication off state were 13.35 (95% CI: 10.85-15.85; 50%) and 27.55 (95% CI: 24.23-30.87; 52%), respectively. Average reduction in L-dopa equivalents following surgery was 55.9% (95% CI: 50%-61.8%). Average reduction in dyskinesia following surgery was 69.1% (95% CI: 62.0%-76.2%). Average reduction in daily off periods was 68.2% (95% CI: 57.6%-78.9%). Average improvement in quality of life using PDQ-39 was 34.5% +/- 15.3%. Univariable regression showed improvements in UPDRS III scores were significantly greater in studies with higher baseline UPDRS III off scores, increasing disease duration prior to surgery, earlier year of publication, and higher baseline L-dopa responsiveness. Average baseline UPDRS III off scores were significantly lower (i.e., suggesting milder disease) in later than in earlier studies. In multivariable regression, L-dopa responsiveness, higher baseline motor scores, and disease duration were independent predictors of greater change in motor score. No evidence of publication bias in the available literature was found. The most common serious adverse event related to surgery was intracranial hemorrhage in 3.9% of patients. Psychiatric sequelae were common. Synthesis of the available literature indicates that STN DBS improves motor activity and activities of daily living in advanced PD. Differences between available studies likely reflect differences in patient populations and follow-up periods. These data provide an estimate of the magnitude of the treatment effects and emphasize the need for controlled and randomized studies.

Deep Brain Stimulation↗
PubMed2006

Development of dyskinesias in a 5-year trial of ropinirole and L-dopa.

A 5-year trial of ropinirole and levodopa in early Parkinson's disease showed that ropinirole is associated with reduced incidence of dyskinesias. This post hoc analysis investigated whether the dyskinesia-sparing benefit of ropinirole is lost when levodopa is added to the regimen and evaluated other risk factors for developing dyskinesias. Patients receiving levodopa had a significantly higher risk of dyskinesias than those taking ropinirole monotherapy (hazard ratio [HR], 6.67; 95% confidence interval [CI], 3.23-14.29; P < 0.001). When patients randomized to ropinirole were treated with supplementary levodopa, the development of dyskinesias was not significantly different from that in those receiving levodopa from the start (HR, 0.80; 95% CI, 0.48-1.33; P = 0.39). However, the onset of dyskinesias was delayed by around 3 years compared with levodopa monotherapy. Adjusted analyses taking into account baseline and on-treatment factors that influenced use of supplementary levodopa or the development of dyskinesias produced similar results. In conclusion, the risk of developing dyskinesias during maintained initial ropinirole monotherapy is very low. Only once levodopa is added does the risk substantially change. Early use of ropinirole postpones the onset of dyskinesias, but these benefits decline when levodopa therapy is started, with no evidence of a subsequent rapid "catch-up" or a persisting preventive effect.

Antiparkinson Agents↗
PubMed2006

Pathological gambling in Parkinson's disease improves on chronic subthalamic nucleus stimulation.

Pathological gambling (PG) related to dopaminergic treatment in Parkinson's disease (PD) is part of a spectrum of behavioral disorders called the dopamine dysregulation syndrome (DDS). We describe a series of PD patients with preoperative active PG due to dopaminergic treatment from a total of 598 patients who have undergone surgery for subthalamic nucleus stimulation for disabling motor fluctuations. The patients had systematic open assessment of behavioral symptoms and standardized assessments of motor symptoms, mood, and apathy. Seven patients (6 men, 1 woman; age, 54 +/- 9 years; levodopa equivalent dose, 1,390 +/- 350 mg/day) had preoperative PG over a mean of 7 years, intolerant to reduction in medication. Six had nonmotor fluctuations and four had other behavioral symptoms consistent with a diagnosis of the DDS. After surgery, motor symptoms improved, allowing for 74% reduction of dopaminergic treatment, below the dosage of gambling onset. In all patients, PG resolved postoperatively after 18 months on average (range, 0-48), although transient worsening occurred in two. Improvement paralleled the time course and degree of reduction in dopaminergic treatment. Nonmotor fluctuations, off period dysphoria, and other symptoms of the DDS improved. Two patients developed persistent apathy. In conclusion, PG and other symptoms of the DDS-associated dopaminergic treatment improved in our patients following surgery. Dopaminergic dysregulation commonly attributed to pulsatile overstimulation of the limbic dopaminergic system may be subject to desensitization on chronic subthalamic stimulation, which has a relative motor selectivity and allows for decrease in dopaminergic treatment.

Adult↗
PubMed2006

Rapidly progressive sporadic dentatorubral pallidoluysian atrophy with intracytoplasmic inclusions and no CAG repeat expansion.

A 48-year-old man developed progressive hemidystonia and postural impairment with falls, followed by choreoathetosis, hyporeflexia, ataxia, supranuclear vertical gaze palsy, and dementia, lasting only 3.5 years from symptom onset to death. Family history and genetic testing were unrevealing. Neuropathology showed findings identical to genetic dentatorubral pallidoluysian atrophy (DRPLA), except for the absence of intranuclear inclusions and the presence of intracytoplasmic inclusions in the pons, striatum, thalamus, and subthalamic nucleus. This case expands the clinical and neuropathological spectrum of DRPLA and supports the hypothesis that aggregates may not be intrinsically pathogenic.

Disease Progression↗
PubMed2006

Criteria for deep-brain stimulation in Parkinson's disease: review and analysis.

Deep-brain stimulation is currently the most effective surgical treatment for advanced Parkinson's disease. The relevant targets to date are the subthalamic nucleus and the globus pallidus internus, although the thalamus (ventralis intermedius nucleus) is preferred in tremor-dominant, aged Parkinson's disease patients. Long-term benefit in cardinal parkinsonian signs, motor fluctuations and dyskinesia has been reported in 5-year follow-up studies of subthalamic nucleus deep-brain stimulation. However, some psychiatric consequences have raised important issues and emphasized the need for an experienced deep-brain stimulation surgical team. This team should be multidisciplinary and involve movement disorder neurologists, neurosurgeons, neuropsychologists and psychiatrists. The recent observation that deep-brain stimulation of the pedunculopontine nucleus improves axial signs, possibly even in those less responsive to levodopa, brings new hope to the management of advanced Parkinson's disease.

Deep Brain Stimulation↗
PubMed2005

Identification of a VPS13A founder mutation in French Canadian families with chorea-acanthocytosis.

Mutations in VPS13A cause chorea-acanthocytosis (ChAc), an autosomal recessive neurodegenerative disorder. VPS13A is located in a tail-to-tail arrangement with GNA14 on chromosome 9q21. ChAc shows substantial allelic heterogeneity, with no single VPS13A mutation causing the majority of cases. We examined 11 patients in four French Canadian ChAc pedigrees for mutations in VPS13A. Affected members of three families were homozygous for a 37-kb deletion of the four terminal exons of VPS13A (EX70_EX73del). This deletion also encompasses the two terminal exons of GNA14. Two affected females in family 4 were homozygous for the splicing mutation 4242+1G>T. Remarkably, the affected males in this highly consanguineous pedigree were compound heterozygotes for EX70_EX73del and 4242+1G>T. PCR analysis of the deletion breakpoint junction revealed that an additional patient with French Canadian ancestry was heterozygous for the EX70_EX73del allele. The identification of a common 9q21 haplotype associated with EX70_EX73del in at least four apparently unrelated ChAc families implies that ChAc shows a founder effect in French Canadians, and that routine testing for EX70_EX73del in suspected ChAc cases may therefore be worthwhile in this population. The deletion breakpoint PCR described here will enable rapid identification of both homozygous and heterozygous carriers of EX70_EX73del.

Age of Onset↗
PubMed2005

Firing rates of pallidal neurons are similar in Huntington's and Parkinson's disease patients.

According to the now classical basal ganglia-thalamocortical circuitry model, the chorea of Huntington's disease (HD) and the hypokinesia in Parkinson's disease (PD) are explained by a decrease in the inhibitory output (reduced firing rates) from the globus pallidus internus (GPi) in HD and increased output in PD. Differences between firing patterns might also be a factor contributing to the different symptoms, however. To test the predictions of the model we examined neuronal firing rates and patterns in two HD patients and 14 PD patients. Single-cell, microelectrode recordings were obtained from awake patients undergoing stereotactic surgery for implantation of deep brain stimulating (DBS) electrodes in the GPi. The mean neuronal firing rate in the GPi of HD patients was 81.8+/-4.3 Hz (mean+/-SEM), which was not significantly different from that in PD patients (89.9+/-3.0 Hz). Firing pattern analyses using measurements of burst index, coefficient of variation, and percentage participation of spikes in bursts revealed, however, that GPi neurons in HD patients fired in a more regular pattern (fewer "bursts") than in PD patients. These results suggest that the rate-based model does not adequately explain the motor abnormalities present in the two HD patients studied. Furthermore, the findings did reveal a difference between firing patterns in the HD and PD groups, thereby supporting the role of altered firing patterns in the pathophysiology of these diseases.

Action Potentials↗
PubMed2005

Apraxia in movement disorders.

The definition of apraxia specifies that the disturbance of performed skilled movements cannot be explained by the more elemental motor disorders typical of patients with movement disorders. Generally this does not present a significant diagnostic problem when dealing with 'higher-level' praxic disturbances (e.g. ideational apraxia), but it can be a major confound in establishing the presence of limb-kinetic apraxia. Most motor disturbances characteristic of extrapyramidal disorders, particularly bradykinesia and dystonia, will compromise the ability to establish the presence of loss of dexterity and deftness that constitutes this subtype. The term 'apraxia' has also been applied to other motor disturbances, such as 'gait apraxia' and 'apraxia of eyelid opening', that perhaps are misnomers, demonstrating the lack of a coherent nomenclature in this field. Apraxia is a hallmark of corticobasal degeneration (CBD) and historically this has received the most attention among the movement disorders. Corticobasal degeneration is characterized by various forms of apraxia affecting limb function, particularly ideomotor apraxia and limb-kinetic apraxia, although buccofacial and oculomotor apraxia can be present as well. The syndrome of parkinsonism and prominent apraxia, designated the 'corticobasal syndrome' (CBS), may be caused by a variety of other central nervous system pathologies including progressive supranuclear palsy (PSP), Alzheimer's disease, dementia with Lewy bodies and frontotemporal dementias. Distinct from the CBS, PSP and Parkinson's disease can demonstrate varying degrees of apraxia on selected tests, especially in those patients with more severe cognitive dysfunction. Diseases that cause the combination of apraxia and a primary movement disorder most often involve a variety of cerebral cortical sites as well as basal ganglia structures. Clinical-pathological correlates and functional imaging studies are compromised by both this diffuse involvement and the confusion experienced in the clinical evaluation of apraxia in the face of the additional elemental movement disorders. Finally, although apraxia results in clear disability in patients with the CBS, it is not clear how milder ideomotor apraxia found on specific testing contributes to patients' overall day-to-day motor disability.

Alzheimer Disease↗
PubMed2005

Analysis of the glucocerebrosidase gene in Parkinson's disease.

Parkinson's disease (PD) is a common progressive neurodegenerative disorder characterized clinically by a combination of motor symptoms. Identifying novel PD genetic risk factors is important for understanding its pathogenesis. A recent study suggested that up to 21% of subjects with PD may have mutations in the glucocerebrosidase (GBA) gene. We investigated the GBA gene for mutations in 88 PD cases and 122 normal controls and detected the presence of heterozygous GBA mutations in 5 PD cases and in 1 control. Sequencing of the entire open reading frame of the GBA gene in a subset of 25 cases with early-onset PD (<50 years of age) uncovered no additional mutations. Our results demonstrate a marginally significant association of GBA mutations with PD and suggest that variations in the GBA gene may constitute a rare susceptibility factor for PD (P = 0.048).

Adolescent↗
PubMed2005

Pallidal deep brain stimulation influences both reflexive and voluntary saccades in Huntington's disease.

Deep brain stimulation (DBS) of the globus pallidus internus (GPi) is being evaluated as a potential new therapy for patients with Huntington's disease (HD). In addition to skeletal movement disorders, HD patients have difficulty initiating voluntary saccades and have difficulty in suppressing rapid saccades toward newly appearing stimuli. We measured several saccade parameters in an HD patient who had marked improvement of clinical symptoms with bilateral GPi DBS to determine whether oculomotor performance improved in parallel with clinical scores. Oculomotor performance was assessed using three testing paradigms: pro-saccades, anti-saccades, and memory-guided saccades. The data from the HD patient was also compared to that of two healthy controls. Pallidal DBS decreased pro-saccade latency, total movement time, and the number of correctly executed trials, as well as increasing saccade gain. Memory-saccade performance was negatively affected with stimulation: saccade gain decreased, latency increased, and the patient's ability to suppress unwanted saccades decreased with stimulation. Our data demonstrate a task-specific improvement of oculomotor deficits in this HD patient with pallidal DBS, supporting a role of GPi in oculomotor control.

Adult↗
PubMed2005

Does severity of Parkinson's disease vary according to season?

In temperate climates, many factors that may influence function in Parkinson's disease (PD) vary according to season. We examined whether severity of PD, as measured by the Unified Parkinson's Disease Rating Scale (UPDRS), varied with the season of evaluation. We found no evidence for seasonal fluctuation in the UPDRS scores, suggesting that, although considerable day-to-day variation may exist in PD, there is little monthly or seasonal variation.

Adult↗
PubMed2005

Treatment of progressive supranuclear palsy and corticobasal degeneration.

Success in treating patients with progressive supranuclear palsy and corticobasal degeneration remains exceedingly low. This finding probably relates to the widespread distribution of the pathological changes that account for the varied and complex spectrum of clinical manifestations. Dopaminergic drugs are regularly used for the parkinsonian features; however, these rarely result in more than modest benefit, and when better or sustained responses are obtained, as sometimes occurs in progressive supranuclear palsy, the clinical features are atypical and diagnosis is often delayed or not made in life. A variety of other treatments have been used in both disorders, sometimes directed at other specific features such as dystonia or myoclonus, and these treatments will be reviewed. Greater success in treating these disorders will require advances in our understanding of their cause(s) or the pathogenetic mechanisms underlying the neurodegenerative processes. The similarities in the molecular pathology of these four-repeat tauopathies suggests that important advances in the management of one will have a definite impact on the treatment of the other.

Amantadine↗
PubMed2005

Normalization of voice in spasmodic dysphonia during transient global amnesia.

We report on the case of a 69-year-old woman with Parkinson's disease and long-standing history of spasmodic dysphonia that reversed during an episode of transient global amnesia (TGA). To our knowledge, this phenomenon has not been reported before. We suggest possible mechanisms by which the pathophysiology of dystonia could reverse during TGA.

Aged↗
PubMed2005

Alterations of striatal neurons in benign hereditary chorea.

Benign hereditary chorea (BHC) recently has been associated with mutations in TITF-1 gene, although a pathological study of an individual with BHC and a TITF-1 mutation revealed no significant gross or microscopic abnormalities using standard methods. Immunohistochemical staining of striatal tissue from a BHC-affected postmortem brain was performed using antibodies against neurotransmitters of interneurons whose tangential migration is mediated by TITF-1. There was a loss of most TITF-1-mediated striatal interneurons in the BHC specimen compared to four matched control brains.

Antibodies↗