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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A patient with a 2-year history of progressive ataxia and tingling in the right hand had prominent facial myokymia. Magnetic resonance imaging revealed syringomyelia and syringobulbia. After successful syringosubarachnoid shunting, the patient died of massive pulmonary embolism. Postmortem examination revealed a syrinx involving the spinal cord and lower half of the medulla; neither the facial nucleus nor facial nerve fibers were directly involved. We hypothesize that interruption of aberrant corticobulbar fibers in the medulla produced disinhibition of a rhythmic neural generator in the facial nucleus.
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PMID:Facial myokymia in syringobulbia. 218 81

Acute poisoning with organic solvents and other volatile compounds now usually follows deliberate inhalation (volatile substance abuse) or ingestion of these compounds. Solvents from adhesives, typewriter correction and dry cleaning fluids, cigarette lighter refills (butane) and aerosol propellants are commonly abused. The major risk is that of sudden death. Arrhythmias leading to cardiac arrest are thought to cause most deaths, but anoxia, respiratory depression and vagal stimulation leading to cardiac arrest may also contribute, as may indirect causes such as aspiration of vomit or trauma. In the United Kingdom (UK), 3.5 to 10% of young people have at least experimented with volatile substance abuse and mortality is more than 100 per annum. The products abused are cheap and readily available despite legislation designed to limit supply. Volatile substance abuse is not illegal and only a minority of abusers are known to progress to heavy alcohol or illicit drug use. Prevention of abuse by education, not only of children but also of parents, teachers, retailers and health care workers, is important in limiting the problem. However, volatile substance abuse-related deaths are still increasing in the UK despite many measures aimed at prevention. Clinically, volatile substance abuse is characterised by a rapid onset of intoxication and rapid recovery. Euphoria and disinhibition may be followed by hallucinations, tinnitus, ataxia, confusion, nausea and vomiting. It is important not to further alarm the patient if signs of serious toxicity are present, since a cardiac arrest may be precipitated. Further exposure should be prevented and the patient resuscitated and given supplemental oxygen if necessary. Cardiac arrhythmias should be treated conventionally and respiratory failure managed supportively. Long term exposure to n-hexane is associated with the development of peripheral neuropathy, while prolonged abuse (notably of toluene or chlorinated solvents) can cause permanent damage to the central nervous system, heart, liver, kidney and lungs. Knowledge of the routes of absorption, distribution and excretion of volatile compounds, and of the rates governing these processes, is important in understanding the rate of onset, intensity and duration of intoxication, and rate of recovery after volatile substance abuse. In addition, such knowledge is helpful when the clinician is attempting to interpret the results of toxicological analyses performed on samples (blood, other tissues, urine) from such patients. Many volatile substances are partly metabolised, the metabolites being eliminated in exhaled air or in urine. Although metabolism normally results in detoxification, enhanced toxicity may also result as with carbon tetrachloride, chloroform, dichloromethane, n-hexane, trichloroethylene and possibly halothane.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:An introduction to the clinical toxicology of volatile substances. 222 69

Three different domains of behavioral action of ethanol (ETOH) were examined in a battery of seven inbred strains and in the selectively bred Long-Sleep (LS) and Short-Sleep (SS) mice. Sedative effects were examined with the loss of the righting reflex test at 3.8 g/kg. The variation among inbred strains was only half the size of the difference between LS and SS mice which were selectively bred for extremes in this phenotype; such a result is expected for phenotypes controlled polygenically. Blood ETOH levels at waking from the narcosis also showed a range of differences among the inbred strains that was less than the LS/SS difference. Ataxia was measured with the grid test, and the inbred strains fell into two groups, resembling the highly ataxic LS line, and the less ataxic SS line. Biphasic effects of ETOH on locomotor activity were strongly genotype dependent. Variation in degree of activation/disinhibition produced by doses up to 1.5 g/kg (IP) ranged from no activation, in the C57BL/6Abg strain which was larger than that seen for SS mice. The patterns of strain differences for both ataxia and activation were highly different from the duration of loss of righting reflex measure, suggesting multiple independent genetically based "sensitivities" to ETOH.
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PMID:Distinctions among sedative, disinhibitory, and ataxic properties of ethanol in inbred and selectively bred mice. 234 78

In 1914, Von Monakow described diaschisis, the recovery of lost cortical function in regions positionally distant from, but linked by neuronal tracts to, the primary site of cortical damage. Cerebellar diaschisis after cortical insult is detailed in the literature; however, cortical diaschisis after cerebellar insult remains a rarely reported occurrence. We describe a 36-year-old woman with rupture of a right-sided cerebellar arteriovenous malformation who developed such expected cerebellar signs as ataxia, dysmetria, and nystagmus. Days later, the patient developed profound impulsivity, disinhibition, and psychomotor agitation. Single photon emission computed tomography (SPECT) showed decreased perfusion of the bilateral frontal and temporal lobes, consistent with regional loss of neural activity. Eventual clinical improvement corresponded with reperfusion of those regions, identified on follow-up SPECT. This case documents cortical diaschisis following cerebellar insult and shows that diaschisis must be considered in patients with cerebral injury manifesting cortical deficits remote from the site of primary pathology.
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PMID:Cerebral diaschisis following cerebellar hemorrhage. 916 80

The study examined the effects of the benzodiazepine receptor partial agonist, Ro 19-8022, on anxiety-like, aggressive, social and locomotor behaviours in timid ('anxious') and aggressive mice in the social conflict test. To test the hypothesis that Ro 19-8022 acts as a partial agonist in this model, i.e. it reduces anxiety-like and aggressive behaviours without affecting motor coordination, its effects were compared to those of the full agonist, nitrazepam. Both Ro 19-8022 and nitrazepam decreased anxiety-like behaviour in timid mice and aggressive behaviour in aggressive mice. The effect of the full agonist, nitrazepam, was dose-dependent while the effect of the partial agonist, Ro 19-8022, was lower in magnitude and reflected its partial agonistic properties. Both drugs stimulated social behaviour in both groups of mice, presumably due to disinhibition of anxiety or aggression. The marked difference was in their effects on motor coordination, as nitrazepam, but not Ro 19-8022, produced motor impairment at higher doses. Thus, Ro 19-8022 produces anxiolytic-like and potent anti-aggressive effects without causing muscle relaxation or ataxia in the present model. Our data confirm that the main behavioural differences between partial and full benzodiazepine receptor agonists are in their side-effect profiles.
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PMID:Behavioural effects of a benzodiazepine receptor partial agonist, Ro 19-8022, in the social conflict test in mice. 1087 19

The nervous mouse mutation causes a relatively selective degeneration of Purkinje cells in the cerebellar cortex. The mutants were compared to age-matched controls of the same background strain in tests of motor activity and coordination, spontaneous alternation, and spatial learning in the Morris water maze. As expected from their ataxia, the nervous mutants were impaired in stationary beam, coat-hanger, and rotorod tests of motor coordination. The nervous mutants were also impaired in the submerged but not in the visible platform condition of the Morris water maze, attributable to a spatial deficit, and displayed a higher level of motor activity in an automated chamber. The deficit in spontaneous alternation rates seen in nervous mutants is accountable by reduced motivation, disinhibition, or spatial disorientation.
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PMID:Motor coordination, exploration, and spatial learning in a natural mouse mutation (nervous) with Purkinje cell degeneration. 1264 22

Many diseases involve the cerebellum and produce ataxia, which is characterized by incoordination of balance, gait, extremity and eye movements, and dysarthria. Cerebellar lesions do not always manifest with ataxic motor syndromes, however. The cerebellar cognitive affective syndrome (CCAS) includes impairments in executive, visual-spatial, and linguistic abilities, with affective disturbance ranging from emotional blunting and depression, to disinhibition and psychotic features. The cognitive and psychiatric components of the CCAS, together with the ataxic motor disability of cerebellar disorders, are conceptualized within the dysmetria of thought hypothesis. This concept holds that a universal cerebellar transform facilitates automatic modulation of behavior around a homeostatic baseline, and the behavior being modulated is determined by the specificity of anatomic subcircuits, or loops, within the cerebrocerebellar system. Damage to the cerebellar component of the distributed neural circuit subserving sensorimotor, cognitive, and emotional processing disrupts the universal cerebellar transform, leading to the universal cerebellar impairment affecting the lesioned domain. The universal cerebellar impairment manifests as ataxia when the sensorimotor cerebellum is involved and as the CCAS when pathology is in the lateral hemisphere of the posterior cerebellum (involved in cognitive processing) or in the vermis (limbic cerebellum). Cognitive and emotional disorders may accompany cerebellar diseases or be their principal clinical presentation, and this has significance for the diagnosis and management of patients with cerebellar dysfunction.
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PMID:Disorders of the cerebellum: ataxia, dysmetria of thought, and the cerebellar cognitive affective syndrome. 1537 47

In the present study, timing of conditioned eyeblink responses (CRs) was investigated in cerebellar patients and age-matched controls using a standard delay paradigm. Findings were compared with previously published data of CR incidences in the same patient population (Gerwig et al., 2003; Timmann et al., 2005). Sixteen patients with pure cortical cerebellar degeneration (spinocerebellar ataxia type 6 and idiopathic cerebellar ataxia), 14 patients with lesions within the territory of the superior cerebellar artery, and 13 patients with infarctions within the territory of the posterior inferior cerebellar artery were included. The affected cerebellar lobules and possible involvement of cerebellar nuclei were determined by three-dimensional magnetic resonance imaging (MRI) in patients with focal lesions (n = 27). Based on a voxel-by-voxel analysis, MRI lesion data were related to eyeblink conditioning data. CR incidence was significantly reduced, and CRs occurred significantly earlier in patients with cortical cerebellar degeneration and lesions of the superior cerebellum compared with controls. Incidence and timing of CRs was not impaired in patients with lesions restricted to the posterior and inferior cerebellum. Voxel-based MRI analysis revealed that cortical areas within the anterior lobe (Larsell lobule HV) were most significantly related to timing deficits, whereas reduced CR incidences were related to more caudal parts (lobule HVI) of the superior cerebellar cortex. The present data suggest that different parts of the superior cerebellar cortex may be involved in the formation of the stimulus association and appropriate timing of conditioned eyeblink responses in humans. Extracerebellar premotoneuronal disinhibition, however, is another possible explanation for changes in CR timing.
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PMID:Timing of conditioned eyeblink responses is impaired in cerebellar patients. 1582 44

A central aspect of the cerebellar cognitive affective syndrome is the dysregulation of affect that occurs when lesions involve the 'limbic cerebellum' (vermis and fastigial nucleus). In this case series we describe neuropsychiatric disturbances in adults and children with congenital lesions including cerebellar agenesis, dysplasia, and hypoplasia, and acquired conditions including cerebellar stroke, tumor, cerebellitis, trauma, and neurodegenerative disorders. The behaviors that we witnessed and that were described by patients and families included distractibility and hyperactivity, impulsiveness, disinhibition, anxiety, ritualistic and stereotypical behaviors, illogical thought and lack of empathy, as well as aggression and irritability. Ruminative and obsessive behaviors, dysphoria and depression, tactile defensiveness and sensory overload, apathy, childlike behavior, and inability to appreciate social boundaries and assign ulterior motives were also evident. We grouped these disparate neurobehavioral profiles into five major domains, characterized broadly as disorders of attentional control, emotional control, and social skill set as well as autism spectrum disorders, and psychosis spectrum disorders. Drawing on our dysmetria of thought hypothesis, we conceptualized the symptom complexes within each putative domain as reflecting either exaggeration (overshoot, hypermetria) or diminution (hypotonia, or hypometria) of responses to the internal or external environment. Some patients fluctuated between these two states. We consider the implications of these neurobehavioral observations for the care of patients with ataxia, discuss the broader role of the cerebellum in the pathogenesis of these neuropsychiatric symptoms, and revisit the possibility of using cerebellar stimulation to treat psychiatric disorders by enhancing cerebellar modulation of cognition and emotion.
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PMID:The neuropsychiatry of the cerebellum - insights from the clinic. 1778 22

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a progressive neurological disorder that affects older adult carriers, predominantly males, of premutation alleles (55 to 200 CGG repeats) of the fragile X (FMR1) gene. Principal features of FXTAS are intention tremor, ataxia, parkinsonism, cognitive decline, and peripheral neuropathy; ancillary features include, autonomic dysfunction, and psychiatric symptoms of anxiety, depression, and disinhibition. Although controlled trials have not been carried out in individuals with FXTAS, there is a significant amount of anecdotal information regarding various treatment modalities. Moreover, there exists a great deal of evidence regarding the efficacy of various medications for treatment of other disorders (eg, Alzheimer disease) that have substantial phenotypic overlap with FXTAS. The current review summarizes what is currently known regarding the symptomatic treatment, or potential for treatment, of FXTAS.
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PMID:Treatment of fragile X-associated tremor ataxia syndrome (FXTAS) and related neurological problems. 1868 48


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