The natural history of neurological manganism over 18 years.

We investigated the clinical features and progression of four patients with chronic manganese intoxication, 18 years after cessation of exposure. Because the results were to be compared with previous observations, we employed the same scoring system. The clinical manifestations were foot dystonia, wide based gait, rigidity, and difficulty in walking backwards. Resting tremor was rarely seen, but tongue tremor was found in 2 patients. The asymmetry initially present in 2 patients persisted 18 years later. Measurements had previously revealed rapid progression in the initial 10 years. We found a plateau over the following decade.

Autosomal dominant dystonia-plus with cerebral calcifications.

OBJECTIVE: To report genealogic, clinical, imaging, neuropathologic, and genetic data from a Canadian kindred with dystonia and brain calcinosis originally described in 1985. METHODS: The authors performed clinical examinations and CT and PET studies of the head and analyzed blood samples. One autopsy was performed. RESULTS: The family tree was expanded to 166 individuals. No individuals were newly affected with dystonia, but postural tremor developed in two. The mean age at symptom onset was 19 years. Eight individuals had dystonia: three focal, one segmental, one multifocal, and three generalized. Seven displayed additional signs: chorea, intellectual decline, postural tremor, and dysarthria. CT studies were performed on five affected and 10 at-risk family members. All affected individuals and eight at-risk individuals had brain calcinosis. PET scans in two individuals showed reduced D(1)- and D(2)-receptor binding and reduced uptake of 6-[(18)F]fluoro-l-dopa. Autopsy of one affected individual showed extensive depositions of calcium in the basal ganglia, thalamus, cerebral white matter, and cerebellum. No specific immunohistochemistry abnormalities were seen. Genome search data showed no evidence of linkage to the previously described loci IBGC1, DYT1, and DYT12. CONCLUSIONS: The phenotype of this family consists of dystonia-plus syndrome. Brain calcium deposits vary in severity and distribution, suggesting that calcifications alone are not entirely responsible for the observed clinical signs. Further studies are needed to elucidate the etiology of this heterogeneous group of disorders.

Genetic heterogeneity in familial idiopathic basal ganglia calcification (Fahr disease).

Familial idiopathic basal ganglia calcification (IBGC, Fahr disease) is an inherited neurologic condition characterized by basal ganglia and extra-basal ganglia brain calcifications, parkinsonism, and neuropsychiatric symptoms. The authors examined six families for linkage to the previously identified genetic locus (IBGC1) located on chromosome 14q. The authors found evidence against linkage to IBGC1 in five of the six families supporting previous preliminary studies demonstrating genetic heterogeneity in familial IBGC.

Functional imaging in Tourette's syndrome.

The cause or causes of Tourette's syndrome (TS) remain unknown. Functional imaging studies have evaluated several implicated neurotransmitter systems and focused predominantly on the frequency or severity of tics. The results have been inconclusive and frequently contradictory with little light shed on pathogenetic mechanisms. However, metabolic derangements have been demonstrated within regions of the basal ganglia, limbic system and sensori-motor cortex and are in keeping with the concept of TS as both a motor and behavioral disorder. TS has long been regarded an involuntary movement disorder. However, many patients have stated that without the premonitory sensation, there would be no tics. For this reason, it has been suggested that the premonitory urge may be considered the involuntary component of TS and the performance of the tic merely a voluntary response. Future studies are needed to differentiate functional changes relating to urge from those associated with the performance of tics and tic suppression.

Autosomal dominant parkinsonism associated with variable synuclein and tau pathology.

Since the original 1995 report of a parkinsonian kindred, four individuals have been affected (mean age at onset, 65 years). All four had cardinal signs of Parkinson disease (PD) and good response to levodopa. Four autopsies showed neuronal loss and gliosis in the substantia nigra. Lewy bodies (LB) limited to brainstem nuclei were detected in one case, diffuse LB in the second, neurofibrillary tangles (NFT) without LB in the third, and neither NFT nor LB in the fourth. Genetic studies suggested linkage to the PARK8 locus on chromosome 12.

Clinical presentation of primary progressive multiple sclerosis 10 years after the incidental finding of typical magnetic resonance imaging brain lesions: the subclinical stage of primary progressive multiple sclerosis may last 10 years.

BACKGROUND: Subclinical multiple sclerosis (MS) has been identified incidentally at autopsy; apparently unaffected individuals with an affected twin have demonstrated magnetic resonance imaging (MRI) changes consistent with MS, and 'MRI relapses' are several times more common than clinical relapses. CASE DESCRIPTION: A 39-year-old, right-handed man underwent MRI and PET scanning in 1986 as a 'normal' control in a Parkinson's disease study, where his father was the proband. MRI indicated multiple areas of abnormal signal intensity in a periventricular and grey-white matter junction distribution. Repeated clinical evaluations over the next 10 years were unchanged until 1996, when he complained of progressive weakness of the right foot and clumsiness in the right hand. MRI now indicated a further area of high signal intensity in the right posterior cord at the level of C5/C6. There was mild pyramidal distribution weakness in the right leg with an extensor plantar response on the same side. Over the next five years there has been mild progression in weakness and fatigue and intermittent Lhermitte's phenomenon. At no stage has there been a history of relapse, cerebrospinal fluid examination was normal and evoked responses (visual and somatosensory) are normal. CONCLUSION: This case demonstrates the phenomenon of subclinical MS, unusually supported by prolonged clinical and MRI follow-up. The patient eventually became symptomatic nine years after MRI diagnosis and is following a primary progressive course. Although MRI is known to be sensitive in identifying subclinical 'attacks', the pattern illustrated here may actually be quite typical of primary progressive MS and is compatible with the later onset seen in this subgroup of patients.

Familial and sporadic Parkinson's disease usually display the same clinical features.

We examined the clinical features of familial (n = 26) and sporadic (n = 52) Parkinson's disease (PD) in patients presenting over the age of 40 years. Familial PD cases were tested for alpha-synuclein or parkin mutations as appropriate. No mutations were found in any of the families investigated. We found no between-group differences in the age at onset of PD, the pattern or severity of parkinsonian features, the dose of antiparkinsonian medications or treatment related complications. Cases of familial and sporadic PD in our cohort of patients display similar clinical features. This may suggest similar etiologies for both familial and sporadic PD.

SCA-2 presenting as parkinsonism in an Alberta family: clinical, genetic, and PET findings.

The authors describe an Alberta family with levodopa-responsive parkinsonism without cerebellar abnormalities. Genetic testing showed expanded repeats for SCA-2; other mutations for parkinsonism were excluded. The expanded allele shows interruption of the CAG repeat with CAA. PET in two affected members showed reduced fluorodopa uptake in striatum and normal raclopride binding. Families with autosomal dominant, levodopa-responsive parkinsonism should be tested for the SCA-2 mutation.

Apomorphine-induced changes in synaptic dopamine levels: positron emission tomography evidence for presynaptic inhibition.

The authors developed a novel positron emission tomography method to estimate changes in the synaptic level of dopamine ([DA]) induced by direct dopamine agonists (for example, apomorphine) in patients with Parkinson disease. The method is based on the typical asymmetry of the nigrostriatal lesion that often occurs in Parkinson disease. Using the between-side difference (ipsilateral (I) and contralateral (C) putamen to the more affected body side) of the inverse of the putamen [11C]raclopride binding potential (BP), the authors obtained [equation: see text] at baseline (that is, before apomorphine administration) and [equation: see text] after apomorphine administration (assuming the concentration of apomorphine is equal in both putamina). The between-side difference in the estimated synaptic concentration of dopamine (diff[DA]) should remain constant unless apomorphine affects dopamine release differently between the two sides. The authors found that apomorphine given subcutaneously at doses of 0.03 and 0.06 mg/kg induced significant changes in their estimate of diff[DA] (P < 0.05). Such changes were more pronounced when only patients with a stable response to levodopa were considered (P < 0.01). These findings provide in vivo evidence that direct dopamine agonists can inhibit the release of endogenous dopamine. The authors propose that this effect is mainly mediated by the activation of presynaptic D2/D3 dopamine receptors.

Expectation and dopamine release: mechanism of the placebo effect in Parkinson's disease.

The power of placebos has long been recognized for improving numerous medical conditions such as Parkinson's disease (PD). Little is known, however, about the mechanism underlying the placebo effect. Using the ability of endogenous dopamine to compete for [11C]raclopride binding as measured by positron emission tomography, we provide in vivo evidence for substantial release of endogenous dopamine in the striatum of PD patients in response to placebo. Our findings indicate that the placebo effect in PD is powerful and is mediated through activation of the damaged nigrostriatal dopamine system.

The long-term response to levodopa in dopa-responsive dystonia.

We report the long-term response to levodopa in 20 patients with dopa-responsive dystonia (DRD). We found an inverse correlation between the daily dose of levodopa and duration of treatment (r=-0.59, P<0.01). Mild dyskinesias were present in 20% of our patients. Dyskinetic patients were on a higher dose of levodopa than non-dyskinetics. Dyskinesias responded to a reduction in levodopa, with no deterioration in motor function. We propose that the dopamine turnover might decrease with time, which would lead to a decrease in the requirement for levodopa and the occurrence of dyskinesias late in the course of DRD.

Positron emission tomography of dopamine pathways in familial Parkinsonian syndromes.

Positron emission tomography (PET) scan is considered to be the most useful tool with which to assess the integrity of nigrostriatal function in the living brain. Recently, different genetic defects have been associated with a variety of familial parkinsonian syndromes, the clinical phenotypes of which have varying degrees of similarities to idiopathic parkinsonism (IP), (sporadic Parkinson's disease). This review summarizes: (1) the PET scan findings (fluorodopa uptake and raclopride binding) in both familial parkinsonian syndromes and IP; and (2) the similarities and differences of the clinical and PET features between familial parkinsonian syndromes and IP. This analysis demonstrates that more similarities than differences exist in PET scan findings in the different familial parkinsonian syndromes with the exception of pallido-ponto-nigral degeneration (PPND), that is perhaps best considered as multisystem degeneration. As a result of this analysis, we believe that while different genetic defects may underlie different mechanisms of nigrostriatal degeneration, the final pattern of nigrostriatal dysfunction is essentially similar to that of IP. 'Parkinson's disease', therefore, may not represent a single disease entity, but rather the final manifestation of different pathogenetic mechanisms-mediated by genetic or environmental factors, or an interaction of genetic and environmental factors.

Transdermal dopaminergic D(2) receptor agonist therapy in Parkinson's disease with N-0923 TDS: a double-blind, placebo-controlled study.

N-0923 is a non-ergot, dopaminergic D(2) agonist designed to be transdermally available. It has anti-parkinsonian effects when infused intravenously. An adhesive matrix patch was developed to deliver N-0923 transdermally (N-0923 TDS). In this phase II trial, we evaluated the effectiveness of various doses of N-0923 TDS at replacing levodopa. Eighty-five Parkinson's disease (PD) patients were randomized to placebo or one of four doses of N-0923 TDS for 21 days. Change in daily levodopa dose was the primary efficacy measure. Significantly greater reductions in levodopa dose were achieved as compared to placebo for the two highest doses of N-0923 TDS. Patients treated with 33.5 mg and 67 mg N-0923 TDS decreased levodopa use by 26% and 28%, vs. 7% for placebo. N-0923 TDS was safe and well tolerated.

Daytime somnolence in patients with Parkinson's disease.

We studied daytime sleepiness in 160 patients with Parkinson's disease and 40 normal subjects. We compared the prevalence of daytime sleepiness in patients who were taking levodopa alone, levodopa with bromocriptine, levodopa with ropinirole, and levodopa with pramipexole. We found that (1) all these anti-Parkinson drugs can cause daytime sleepiness; (2) 'dozing off' correlated highly with 'falling asleep without warning'; (3) after statistical adjustment for confounding variables there was no significant difference among the risks for any of these anti-Parkinson drugs causing daytime somnolence.

Biochemical variations in the synaptic level of dopamine precede motor fluctuations in Parkinson's disease: PET evidence of increased dopamine turnover.

Motor fluctuations are a major disabling complication in the treatment of Parkinson's disease. To investigate whether such oscillations in mobility can be attributed to changes in the synaptic levels of dopamine, we studied prospectively patients in the early stages of Parkinson's disease with a follow-up after at least 3 years of levodopa treatment. At baseline, 3 positron emission tomography (PET) scans using [11C]raclopride before and after (1 hour and 4 hours) orally administered levodopa were performed on the same day for each patient. Patients who developed "wearing-off" fluctuations during the follow-up period had a different pattern of levodopa-induced changes in [11C]raclopride binding potential (BP) from that observed in patients who were still stable by the end of the follow-up. Thus, 1 hour post-levodopa the estimated increase in the synaptic level of dopamine was 3 times higher in fluctuators than in stable responders. By contrast, only stable responders maintained increased levels of synaptic dopamine in the PET scan performed after 4 hours. These results indicate that fluctuations in the synaptic concentration of dopamine precede clinically apparent "wearing-off" phenomena. The rapid increase in synaptic levels of dopamine observed in fluctuators suggests that increased dopamine turnover might play a relevant role in levodopa-related motor complications.

Site-specific invasion of the basal ganglia by Nocardia asteroides GUH-2.

Nocardia asteroides GUH-2 (GUH-2) invades the nigrostriatal region of the brain in mice [15]. Selective dopaminergic neuronal dropout in the substantia nigra results in parkinsonian changes characterized by movement disorders responsive to L-dopa [15]. This is the only reported example of an experimental bacterial model for parkinsonism. Following i.v. inoculation of GUH-2 into the non-human primate Macaca fasicularius, the nocardiae preferentially invaded and grew within the basal ganglia (substantia nigra, caudate, putamen, and globus pallidus) often without inducing apparent inflammation. Reduced, limited growth of nocardiae occurred in the white matter of the cerebral cortex, medulla, and hippocampus, whereas neither significant adherence to nor growth within the meninges was observed. Twenty-four hours after injection, nocardial cells were found within capillary endothelial cells, the basal lamina, neurons, astroglia and in axonal extensions. The bacteria, in endothelial cells, were surrounded by a unit membrane, but in the basal lamina they appeared to be free and not membrane bound. After the organisms passed into the brain parenchyma, the nocardiae once again became surrounded by membrane, often being encapsulated by numerous layers with the innermost layer tightly adherence to the bacterial surface. There was a propensity for nocardial growth within and along myelinated axons, either with or without disruption to the surrounding myelin sheath. There was electron microscopic evidence that the nocardiae induced a neurodegenerative response especially in the substantia nigra region. Thus, the early interactions of GUH-2 within the primate brain appeared to be similar to those reported in the mouse.

Long term outcome of unilateral pallidotomy: follow up of 15 patients for 3 years.

OBJECTIVES: With the advent of new antiparkinsonian drug therapy and promising results from subthalamic and pallidal stimulation, this study evaluated the long term efficacy of unilateral pallidotomy, a technique which has gained popularity over the past decade for the management of advanced Parkinson's disease. METHODS: The 15 patients reported here are part of the original cohort of 24 patients who underwent posteroventral pallidotomy for motor fluctuations and disabling dyskinesias 3 years ago as part of a prospective study. Evaluation scales included the unified Parkinson's disease rating scale, the Goetz dyskinesia scale, and the Purdue pegboard test. RESULTS: When compared with the prepallidotomy scores, the reduction in the limb dyskinesias and off state tremor scores persisted on the side contralateral to pallidotomy at the end of 3 years (dyskinesias were reduced by 64% (p<0.01) and tremor by 63% (p<0.05). Other measures tended to deteriorate. The dosage of antiparkinsonian medications did not change significantly from 3 months prepallidotomy to 3 years postpallidotomy. CONCLUSIONS: Although unilateral pallidotomy is useful in controlling the contralateral dyskinesias and tremor 3 years after surgery, all other early benefits disappear and activities of daily living continue to worsen.

Nigrostriatal dopamine system and motor lateralization.

The mechanism by which most people favor use of the right hand remains unknown. It has been proposed that asymmetries in the nigrostriatal dopamine system may be related to motor lateralization in humans. We explored this hypothesis in vivo by using [18F]fluorodopa positron emission tomography. Whereas the degree of right hand preference was found to correlate with left putamen dominance as assessed by asymmetry in fluorodopa uptake (K(i)), right caudate dominance was positively correlated with the level of performance during simultaneous bimanual movements in right-handed normal subjects. In addition, right-handed patients with Parkinson's disease with higher right than left caudate K(i) performed much better in bimanual movement tests than those in whom the K(i) value of the left caudate was higher than that of the right. These findings support the notion that the nigrostriatal dopaminergic system may play a role in motor lateralization, and suggest a functional model for bimanual movements. We propose that the skill for performing simultaneous bilateral hand movements in right-handed subjects might depend upon both the activation (through the dominant left putamen circuitry) of the left supplementary motor area (SMA), and the inhibition (through the right caudate circuitry) of motor programs stored in the right SMA.