U-Serve and Save gas station, ca. 1989

U Serve and Save Garage, Osoyoos, Dumont's Corner

The cerebellum in dystonia - help or hindrance?

Contains fulltext : 109767.pdf (publisher's version ) (Closed access)Dystonia has historically been considered a disorder of the basal ganglia. This review aims to critically examine the evidence for a role of the cerebellum in the pathophysiology of dystonia. We compare and attempt to link the information available from both clinical and experimental studies; work detailing cerebellar connectivity in primates; data that suggests a role for the cerebellum in the genesis of dystonia in murine models; clinical observation in humans with structural lesions and heredodegenerative disorders of the cerebellum; and imaging studies of patients with dystonia. The typical electrophysiological findings in dystonia are the converse to those found in cerebellar lesions. However, certain subtypes of dystonia mirror cerebellar patterns of increased cortical inhibition. Furthermore, altered cerebellar function can be demonstrated in adult onset focal dystonia with impaired cerebellar inhibition of motor cortex and abnormal eyeblink classical conditioning. We propose that abnormal, likely compensatory activity of the cerebellum is an important factor within pathophysiological models of dystonia. Work in this exciting area has only just begun but it is likely that the cerebellum will have a key place within future models of dystonia.1 januari 201

A gait paradigm reveals different patterns of abnormal cerebellar motor learning in primary focal dystonias

Accumulating evidence points to a role of the cerebellum in the pathophysiology of primary dystonia. The aim of this study was to investigate whether the abnormalities of cerebellar motor learning in primary dystonia are solely detectable in more pure forms of cerebellum-dependent associative motor learning paradigms, or whether these are also present in other motor learning paradigms that rely heavily on the cerebellum but in addition require a more widespread sensorimotor network. Twenty-six patients with various forms of focal dystonia and 10 age-matched healthy controls participated in a motor learning paradigm on a split-belt treadmill. By using reflective markers, three-dimensional kinematics were recorded using a 6-camera motion analysis system. Adaptation walking parameters were analyzed offline, comparing the different dystonia groups and healthy controls. Patients with blepharospasm and writer's cramp were significantly impaired on various adaptation walking parameters. Whereas results of cervical dystonia patients did not differ from healthy controls in terms of adaptation walking parameters, differences in parameters of normal gait were found. We have here demonstrated abnormal sensorimotor adaptation with the split-belt paradigm in patients with blepharospasm and writer's cramp. This reinforces the current concept of cerebellar dysfunction in primary dystonia, and that this extends beyond more pure forms of cerebellum-dependent associative motor learning paradigms. However, the finding of normal adaptation in cervical dystonia patients indicates that the pattern of cerebellar dysfunction may be slightly different for the various forms of primary focal dystonia, suggesting that actual cerebellar pathology may not be a primary driving force in dystonia

Toxic leukoencephalopathy presenting as lethal catatonia

INTRODUCTION: Catatonia is a syndrome that can present in different forms and can occur in multiple psychiatric and somatic conditions. This case report describes lethal catatonia caused by delayed toxic leukoencephalopathy after excessive use of cocaine and methadone. The characteristic radiographic imaging and biphasic course are discussed. CASE REPORT: A 54-year-old woman was presented unconsciously at the emergency department after intoxication with methadone and cocaine. After initial recovery, her condition deteriorated unexpectedly, resulting in lethal catatonia. Magnetic resonance imaging (MRI) showed hyperintense white matter abnormalities and diffusion restriction, evident for leukoencephalopathy. DISCUSSION: Catatonia can develop in multiple psychiatric and somatic diseases, including toxic leukoencephalopathy. A biphasic course and specific MRI findings are characteristics for delayed toxic leukoencephalopathy, due to intoxication with drugs

A single session of cerebellar theta burst stimulation does not alter writing performance in writer's cramp

Contains fulltext : 153089.pdf (publisher's version ) (Closed access)5 p

Cerebellar brain inhibition is decreased in active and surround muscles at the onset of voluntary movement

Contains fulltext : 97708.pdf (publisher's version ) (Closed access)Highly selective activation of the desired muscles for each movement and inhibition of adjacent muscles is attributed to surround inhibition (SI) which differentially modulates corticospinal excitability in active and surrounding muscles. Cerebellar brain inhibition (CBI) is another inhibitory neuronal network which is known to be active at rest and during tonic muscle contraction. The way in which CBI may be modulated at movement onset and its relationship with SI has not previously been investigated. We assessed motor evoked potential (MEP) size and CBI in first dorsal interosseus (FDI) and abductor digiti minimi (ADM) muscles at rest and during a simple motor task where FDI was an active muscle and ADM was not involved in the movement (surround muscle). At onset of movement, MEP size in ADM was significantly suppressed, confirming the existence of SI. In contrast, CBI in both muscles was found to be significantly decreased at the onset of the movement. This was confirmed even after adjustments for changes in MEP size occurring due to onset of muscle activity in FDI and the effects of SI in ADM. Our findings fail to functionally link SI with CBI, but they do indicate a non-topographically specific modulation of CBI in association with initiation of voluntary movement

Validation of a dystonia screening questionnaire: testing in a cohort of mixed neurological disorders.

Contains fulltext : 87511.pdf (publisher's version ) (Closed access)1 november 201

A distinctive pattern of cortical excitability in patients with the syndrome of dystonia and cerebellar ataxia

Item does not contain fulltextOBJECTIVE: The syndrome of dystonia and cerebellar ataxia (DYTCA) is a recently described condition where cervical dystonia and mild cerebellar ataxia are the major clinical features. Here we attempted to explore the pathophysiology of this condition by comparing measurements of cortical excitability between patients with DYTCA, typical primary dystonia and healthy controls. METHODS: Motor threshold, active MEP recruitment and CSP duration were measured and the excitability of the intracortical inhibitory and excitatory circuits was assessed at rest using a paired pulse protocol. RESULTS: We identified a distinctive pattern of cortical excitability in DYTCA patients different from that found in primary dystonia, namely hyperexcitable short-interval intracortical inhibition. CONCLUSION: DYTCA patients have a noticeably dissimilar excitability profile from patients with primary dystonia. SIGNIFICANCE: A tendency for increased SICI has been previously described in cerebellar syndromes and the altered excitability profile seen in these patients is therefore possibly a consequence of the cerebellar dysfunction in DYTCA. A direct link between reduced intracortical inhibition and dystonia has recently been questioned and our results additionally suggest that reduced motor cortex inhibition is not a prerequisite for dystonia to occur

Cerebellar theta burst stimulation impairs eyeblink classical conditioning.

Contains fulltext : 110511.pdf (publisher's version ) (Closed access)Theta burst stimulation (TBS) protocols of repetitive transcranial magnetic stimulation (rTMS) have after-effects on excitability of motor areas thought to be due to LTP- and LTD-like processes at cortical synapses. The present experiments ask whether, despite the low intensities of stimulation used and the anatomy of the posterior fossa, TBS can also influence the cerebellum. Acquisition and retention of eyeblink classical conditioning (EBCC) was examined in 30 healthy volunteers after continuous theta burst stimulation (cTBS) over the right cerebellar hemisphere. In subjects who received cerebellar cTBS, conditioned responses were fewer and their onsets were earlier (in the last half of the acquisition blocks) than those from control subjects. There was, however, no effect of cerebellar cTBS on the re-acquisition of EBCC in another session of EBCC 7-10 days later. There was also no effect of cerebellar cTBS on the re-acquisition of EBCC in subjects not naive to EBCC when the stimulation was delivered immediately before a re-acquisition session. Control experiments verified that suppressive effects of cTBS on EBCC were not due to changes in motor cortical excitability or sensory disturbance caused by cTBS. Based on previous EBCC studies in various cerebellar pathologies, our data are compatible with the hypothesis that cerebellar cTBS has a focal cerebellar cortical effect, and are broadly in line with data from studies of EBCC in various animal models. These results confirm that cerebellar TBS has measurable effects on the function of the cerebellum, and indicate it is a useful non-invasive technique with which to explore cerebellar physiology and function in humans

Patients with primary cervical dystonia have evidence of discrete deficits in praxis

Item does not contain fulltextBACKGROUND: Functional imaging and electrophysiological data from patients with primary dystonia reveal widespread abnormalities in brain areas associated with higher motor functions but to date there has been little investigation of the functional consequences of these abnormalities. The aim of this study was to use a battery of tests of praxis, based on those tests used in routine clinical examination, to uncover evidence of higher motor dysfunction in patients with primary cervical dystonia. METHODS: Praxis was assessed in 13 patients with primary cervical dystonia without hand involvement and in 29 age and sex matched controls. A semiquantitative praxis assessment was used which combined timed tests of meaningful and meaningless movements with copying of transitive and intratransitive hand movements and pantomime of tool use. Control tasks consisted of evaluation of motor speed, strength and a number of additional cognitive tasks. RESULTS: Patients made significantly more errors in copying meaningless gestures and were slow in the performance of meaningless sequences of hand movements. Copying meaningful gestures and performance of meaningful sequences of hand movements were normal. CONCLUSION: This study has identified a discrete deficit in praxis in dystonia patients and suggests additional functional consequences from the widespread pathophysiological abnormalities seen in primary dystonia