Efficacy and safety of pallidal stimulation in primary dystonia: results of the Spanish multicentric study

BACKGROUND

Dystonia is a complex clinical syndrome originated by a wide range of aetiologies. The diagnosis of dystonia is made after the evaluation of aetiological, phenomenological and genetic factors. Medications, except in patients with dopa-responsive dystonia, are of limited efficacy. Botulinum toxin injections are not applicable to patients with generalised dystonia, since many muscular groups contribute to disability. Clinical studies in children and adults with primary generalised dystonia (PGD) have reported beneficial effects of bilateral GPi deep brain stimulation (DBS) in both motor symptoms and disability produced by dystonia as well as a favourable impact of DBS in the health-related quality of life (HRQoL). Some clinical aspects of GPi stimulation in primary dystonia still remain controversial such as the influence of disease duration or age at onset in determining the postoperative clinical outcome.

RESULTS

The authors report the results of a multicentric study designed to assess the tolerability and clinical effects of bilateral pallidal DBS on motor impairment, functional disability, quality of life, pain and mood in patients with medically refractory primary generalised or segmental dystonia.

[Use of 11C-(+)-alpha -dihydrotetrabenazine for the assessment of dopaminergic innervation in animal models of Parkinson's disease]

AIM

This study evaluates the utility of (11)C-(+)-alpha -dihydrotetrabenazine ((11)C-(+)DTBZ) in the quantification of dopaminergic innervation by positron emission tomography (PET) in rat and monkey, two animal species used as animal models of Parkinson's disease.

MATERIAL AND METHODS

Healthy control animals (n = 10) and the effect of 6-hydroxidopamine (6-OHDA) neurotoxic were studied in rats. (18)F-DOPA PET studies and digital quantitative autoradiography were also carried out. Studies with Macaca fascicularis were performed in control and 1-methyl 4-phenyl 1, 2, 3, 6-tetrahydropyridine (MPTP) treated animals.

RESULTS

In both species high quality images were generated in which clear uptake of (11)C-(+)DTBZ was found in the striatum. (11)C-(+)DTBZ uptake quantification was estimated by creating parametric images and binding potential (BP) calculation. BP in control rats was 1.10 +/- 0.16 (mean +/- standard deviation [SD], whereas 6-OHDA produced a decrease in the uptake depending on the lesion degree. Images obtained with (18)F-DOPA were not adequate for the analysis as they did not discriminate the stratum whereas digital quantitative autoradiography studies confirmed the high affinity of striatum by (11)C-(+)DTBZ. In monkeys, final BP values were 1.31 and 1.06 and MPTP treatment reduced uptake by 40 %.

CONCLUSIONS

The quality of PET images and the decrease of uptake in 6-OHDA and MPTP lesions show that (11)C-(+)DTBZ is an adequate radiotracer for the study of dopaminergic innervation in these animal models.

Motor behavioural changes after intracerebroventricular injection of 6-hydroxydopamine in the rat: an animal model of Parkinson's disease

At the beginning of the 1970s, different studies reported behavioural disturbances after the intracerebroventricular (icv) administration of 6-hydroxydopamine (6-OHDA) in the rat. Despite the fact that this neurotoxic agent degenerates brain dopaminergic (DA-) cells, its potential utility to produce a rat model of Parkinson's disease (PD) was never systematically studied because the aphagia and adipsia were often observed. In the present study, a procedure that induces a marked DA-cell degeneration that bypasses these and other undesirable complications of icv injection of 6-OHDA is reported. Lesioned animals (50-500 microg of 6-OHDA) showed a persistent motor syndrome composed of hypokinesia, purposeless chewing and catalepsy. The intensity of motor signs was dose-dependent, and recovered partially after administration of DA-receptor agonists, exposure to sensorial stimuli and stress, three procedures that reduce motor dysfunctions in Parkinson's disease (PD). Lesioned animals showed bilateral and symmetrical midbrain DA-cell degeneration with the highest cell-loss in A9 group (substantia nigra), followed by A8 (retrorubral field) and A10 (ventral tegmental area) groups. The similarity between the behavioural syndrome and the topographical profile of cell-loss after icv injection of 6-OHDA in rats and the clinical and neuropathological features of PD indicates that this may be a convenient animal model of PD particularly useful for checking in rats the possible efficacy of new anti-parkinsonian drugs on specific parameters of motor dysfunctions.

Dopamine cell degeneration induced by intraventricular administration of 6-hydroxydopamine in the rat: similarities with cell loss in parkinson's disease

In an attempt to find a convenient rat model to study cell vulnerability in Parkinson's disease, we have investigated the cell-loss profile in different midbrain dopaminergic nuclei and subnuclei of rats injected with 6-hydroxydopamine (6-OHDA) in the third ventricle. Following administration of different doses (5-1000 microgram) of 6-OHDA, motor behavior was evaluated and tyrosine hydroxylase-immunostained neurons were counted in the A8 group and different subdivisions of A9 and A10 groups. Animals developed hypokinesia, repetitive chewing movements, and catalepsia. Signs of cell degeneration were evident from the first day after injection, reaching the definitive pattern at the end of the first week. There was a similar degeneration in both brain sides, the A9 group showing the highest degree of cell-loss, followed by A8 and A10 groups. In the A9 group, the degeneration mostly affected those subgroups located in its ventral, lateral, and posterior regions. In the A10 group the degeneration mainly affected the parabrachial pigmented nucleus, the paranigral nucleus and the ventral tegmental area. This topographic pattern of degeneration is very similar to that previously described in Parkinson's disease, suggesting that this model may be a useful tool in the study of the cell vulnerability mechanisms in this neurodegenerative disorder. In addition, our results also showed that small dopaminergic neurons are more resistant to degeneration than the large ones. In some DA subgroups, the cells that contained calbindin but not calretinin were less vulnerable to the neurotoxic effect of 6-OHDA.

The impact of deep brain stimulation on executive function in Parkinson's disease

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or the internal segment of the globus pallidus (GPi) improves Parkinson's disease and increases frontal blood flow. We assessed the effects of bilateral DBS on executive function in Parkinson's disease patients, seven with electrodes implanted in the STN and six in the GPi. Patients were assessed off medication with stimulators off, on and off again. The groups showed differential change with stimulation on the Reitan Trail-Making test (TMT B) (STN more improved) and on some measures of random number generation and Wisconsin Card Sorting (STN improved, GPi worse with stimulation). Across the groups, stimulation speeded up responding (Stroop control trial, TMT A) and improved performance on paced serial addition and missing digit tests. Conversely, conditional associative learning became more errorful with stimulation across the two groups. In general, change in performance with stimulation was significant for the STN but not the GPi group. These results support two opposite predictions. In support of current models of Parkinson's disease, 'releasing the brake' on frontal function with DBS improved aspects of executive function. Conversely, disruption of basal ganglia outflow during DBS impaired performance on tests requiring changing behaviour in novel contexts as predicted by Marsden and Obeso in 1994.

Impact of deep brain stimulation on upper limb akinesia in Parkinson's disease

Recent pathophysiological models of Parkinson's disease have led to new surgical approaches to treatment including deep brain stimulation (DBS) and lesioning of basal ganglia structures. Various measures of upper limb akinesia were assessed in 6 patients with bilateral DBS of the internal pallidum and 6 with DBS of the subthalamic nucleus. Stimulation improved a number of aspects of motor function, and particularly movement time, and force production. Time to initiate movements, and to perform repetitive movements also improved but less dramatically. Processes indicating preparatory motor processes showed no significant change. Few significant differences were found between the internal pallidum and subthalamic nucleus groups. In general, the effects of DBS closely parallel previous reports of the effects of dopaminergic medication. It is suggested that disrupted pallidal output in Parkinson's disease interferes with the rate, level, and coordination of force production but has little effect on preparatory processes. The similarity of the effects of subthalamic nucleus and internal pallidum stimulation suggests this disrupted outflow is the most important determinant of upper limb akinesia in Parkinson's disease. The effects of DBS were similar to the effects of unilateral pallidal lesions reported elsewhere.

A hemangioendothelioma-derived cell line: its use as a model for the study of endothelial cell biology

The purpose of our research was to develop a stable murine cell line that could serve as a general model for the study of microvascular endothelial cells. To do so we have characterized an endothelial cell line originally derived from a mouse hemangioendothelioma. Endothelioma cells synthesize angiotensin-converting enzyme, express surface receptors for acetylated low density lipoprotein, produce thrombospondin and show intracellular staining with an antibody to von Willebrand antigen. The response of endothelioma cells to endothelial cell mitogens, known angiogenesis-inducing factors, extracellular matrix substrate (Matrigel), and various cytokines was measured. Endothelioma cells show an increased proliferative response to extracts from hypothalamus but only marginally to recombinant fibroblast growth factor or purified endothelial cell growth factor. Rearrangement of cells forming tube-like connections were induced by Matrigel. The chemokinetic responses generally correlated with angiogenesis-inducing properties of the test substances. The results support the conclusion that the endothelioma cell line maintains characteristic endothelial cell properties and behaves in vitro in a manner similar to microvascular endothelial cells.

[Alcoholism, polyneuropathy, and liver disease. A prospective electrophysiologic study]

A prospective clinical and electrophysiologic study was performed in 50 alcoholic patients in order to assess the incidence and clinical manifestations of alcoholic polyneuropathy, the value of the electrophysiologic parameters studied, and the influence of liver disease on the appearance of neuropathy. The proposed criteria for polyneuropathy were fulfilled by 24% of the patients. Abolition of the Achillean reflexes was the most frequent clinical finding, while reduced amplitude of muscular potential was the most sensitive electrophysiologic parameter. There were no differences in alcohol consumption, frequency of liver disease, and degree of alteration of liver function in cirrhotics between patients with and without polyneuropathy.