Sonographic diagnosis of catheter malposition in a patient with postoperative plexus lesion after right internal jugular vein catheterization--case report

PURPOSE

Postoperative brachial plexus lesion has been reported only rarely after catheterization of the right internal jugular vein (RIJV), and then is usually considered to be the result of puncture hematoma.

CLINICAL FEATURES

We here present the case of plexus brachialis injury after catheterization of the RIJV with ultrasonography showing direct compression of the plexus brachialis by a central venous catheter without evidence of puncture hematoma.

CONCLUSION

Every case of plexus brachialis injury after catheterization of the RIJV should be followed up by an emergency sonogram to rule out hematoma or catheter malposition. Running head: Sonographic diagnosis of catheter malposition after RIJV catheterization.

Prospective differentiation of multiple system atrophy from Parkinson disease, with and without autonomic failure

OBJECTIVE

To report preliminary results of a prospective ongoing study of multiple system atrophy (MSA) and Parkinson disease (PD), with a large subset of patients with PD with autonomic failure (25%), to evaluate autonomic indices that distinguish MSA from PD.

METHODS

We used consensus criteria, detailed autonomic studies (Composite Autonomic Symptom Scale, Composite Autonomic Scoring Scale, thermoregulatory sweat test, and plasma catecholamines), and functional scales (Unified MSA Rating Scale [UMSARS] I-IV and Hoehn-Yahr grading) on a prospective, repeated, and ongoing basis.

RESULTS

We report the results of a study on 52 patients with MSA (mean [SD], age, 61.1 [7.8] years; body mass index (calculated as weight in kilograms divided by height in meters squared), 27.2 [4.6]; Hoehn-Yahr grade, 3.2 [0.9]; UMSARS I score, 21.5 [7.4]; and UMSARS II score, 22.7 [9.0]) and 29 patients with PD, including PD with autonomic failure (mean [SD], age, 66.0 [8.1] years; body mass index, 26.6 [5.5]; Hoehn-Yahr grade, 2.2 [0.8]; UMSARS I score, 10.4 [6.1]; and UMSARS II score, 13.0 [5.9]). Autonomic indices were highly significantly more abnormal in MSA than PD (P < .001) for the Composite Autonomic Scoring Scale (5.9 [1.9] vs 3.3 [2.3], respectively), Composite Autonomic Symptom Scale (54.4 [21.8] vs 24.7 [20.5], respectively), and thermoregulatory sweat test (percentage anhidrosis, 57.4% [35.2%] vs 9.9% [17.7%], respectively). These differences were sustained and greater at 1-year follow-up, indicating a greater rate of progression of dysautonomia in MSA than PD.

CONCLUSIONS

The severity, distribution, and pattern of autonomic deficits at study entry will distinguish MSA from PD, and MSA from PD with autonomic failure. These differences continue and are increased at follow-up. Our ongoing conclusion is that autonomic function tests can separate MSA from PD. Autonomic indices support the notion that the primary lesion in PD is ganglionic and postganglionic, while MSA is preganglionic.

Striatal transplantation in a rodent model of multiple system atrophy: effects on L-Dopa response

Progressive degeneration of striatal projection neurons is thought to account for the loss of L-Dopa response observed in the majority of patients with the parkinsonian variant of multiple system atrophy (MSA-P). Here we have investigated the effects of E14 embryonic striatal allografts on dopaminergic responsiveness in the unilateral double-lesion rat model of MSA-P by using tests of complex motor behavior. Both sham and graft animals showed an increase in apomorphine-induced rotations as well as an improvement in cylinder test performance following surgical intervention. In contrast, L-Dopa responsiveness of stepping behavior was improved only in grafted animals. The restoration of apomorphine-induced rotation correlated with the P-zone volume of grafts. Our findings indicate that transplantation of embryonic striatal grafts might, at least to some extent, restore responsiveness to L-Dopa in tasks of complex motor behavior. Therefore, striatal transplantation should be further defined preclinically as a possible therapeutic option for patients with MSA-P and a failing L-Dopa response.

SNCA variants are associated with increased risk for multiple system atrophy

To test whether the synucleinopathies Parkinson's disease and multiple system atrophy (MSA) share a common genetic etiology, we performed a candidate single nucleotide polymorphism (SNP) association study of the 384 most associated SNPs in a genome-wide association study of Parkinson's disease in 413 MSA cases and 3,974 control subjects. The 10 most significant SNPs were then replicated in additional 108 MSA cases and 537 controls. SNPs at the SNCA locus were significantly associated with risk for increased risk for the development of MSA (combined p = 5.5 x 10(-12); odds ratio 6.2) [corrected].

Recent developments in multiple system atrophy

Multiple system atrophy (MSA) is a rare late onset neurodegenerative disorder which presents with autonomic failure and a complicated motor syndrome including atypical parkinsonism, ataxia and pyramidal signs. MSA is a glial alpha-synucleinopathy with rapid progression and currently poor therapeutic management. This paper reviews the clinical features, natural history and novel diagnostic criteria for MSA as well as contemporary knowledge on pathogenesis based on evidence from neuropathological studies and experimental models. An outline of the rationale for managing symptomatic deterioration in MSA is provided together with a summary of novel experimental therapeutic approaches to decrease disease progression.

Striatal transplantation for multiple system atrophy--are grafts affected by alpha-synucleinopathy?

Multiple system atrophy (MSA), a fatal neurodegenerative disorder, is the second most common cause of parkinsonism and frequently associated with autonomic failure. Previous work from our laboratory has shown that striatal grafts survive and exert functional effects in toxin-induced rodent models of MSA-P, the parkinson variant characterized by levodopa resistance due to loss of striatal medium-sized spiny neurons. It is unknown whether oligodendroglial alpha-synuclein signature lesions affect graft survival in MSA. Recent reports on neurotransplantation in Parkinson's disease patients suggest a possible host-to-graft disease propagation of alpha-synuclein pathology which may be relevant to transplantation in MSA as well. We here demonstrate that embryonic E14 striatal allografts show reduced p-zone volume and dopaminergic graft re-innervation accompanied by increased gliosis in a transgenic MSA mouse model featuring alpha-synuclein oligodendrogliopathy. Oligodendrocytes expressing host-specific alpha-synuclein migrate into the graft tissue after 3 months of survival. Our data suggest that the presence of MSA-like alpha-synuclein oligodendrogliopathy and related to it pro-inflammatory microenvironment may compromise the connectivity and neurorestorative outcome of striatal grafts.

Multiple system atrophy: a primary oligodendrogliopathy

To this day, the cause of multiple system atrophy (MSA) remains stubbornly enigmatic. A growing body of observations regarding the clinical, morphological, and biochemical phenotypes of MSA has been published, but the interested student is still left without a clue as to its underlying cause. MSA has long been considered a rare cousin of Parkinson's disease and cerebellar degeneration; it is rich in acronyms but poor in genetic and environmental leads. Because of the worldwide research efforts conducted over the last two decades and the discovery of the alpha-synuclein-encoding SNCA gene as a cause of rare familial Parkinson's disease, the MSA field has seen advances on three fronts: the identification of its principal cellular target, that is, oligodendrocytes; the characterization of alpha-synuclein-rich glial cytoplasmic inclusions as a suitable marker at autopsy; and improved diagnostic accuracy in living patients resulting from detailed clinicopathological studies. The working model of MSA as a primary glial disorder was recently strengthened by the finding of dysregulation in the metabolism of myelin basic protein and p25alpha, a central nervous system-specific phosphoprotein (also called tubulin polymerization promoting protein, TPPP). Intriguingly, in early cases of MSA, the oligodendrocytic changes in myelin basic protein and p25alpha processing were recorded even before formation of glial cytoplasmic inclusions became detectable. Here, we review the evolving concept that MSA may not just be related to Parkinson's disease but also share traits with the family of demyelinating disorders. Although these syndromes vary in their respective cause of oligodendrogliopathy, they have in common myelin disruption that is often followed by axonal dysfunction.

Red flags for multiple system atrophy

The clinical diagnosis of multiple system atrophy (MSA) is fraught with difficulty and there are no pathognomonic features to discriminate the parkinsonian variant (MSA-P) from Parkinson's disease (PD). Besides the poor response to levodopa, and the additional presence of pyramidal or cerebellar signs (ataxia) or autonomic failure as major diagnostic criteria, certain other clinical features known as "red flags" or warning signs may raise the clinical suspicion of MSA. To study the diagnostic role of these features in MSA-P versus PD patients, a standardized red flag check list (RFCL) developed by the European MSA Study Group (EMSA-SG) was administered to 57 patients with probable MSA-P and 116 patients with probable PD diagnosed according to established criteria. Those red flags with a specifity over 95% were selected for further analysis. Factor analysis was applied to reduce the number of red flags. The resulting set was then applied to 17 patients with possible MSA-P who on follow-up fulfilled criteria of probable MSA-P. Red flags were grouped into related categories. With two or more of six red flag categories present specificity was 98.3% and sensitivity was 84.2% in our cohort. When applying these criteria to patients with possible MSA-P, 76.5% of them would have been correctly diagnosed as probable MSA-P 15.9 (+/-7.0) months earlier than with the Consensus criteria alone. We propose a combination of two out of six red flag categories as additional diagnostic criteria for probable MSA-P.

Second consensus statement on the diagnosis of multiple system atrophy

BACKGROUND

A consensus conference on multiple system atrophy (MSA) in 1998 established criteria for diagnosis that have been accepted widely. Since then, clinical, laboratory, neuropathologic, and imaging studies have advanced the field, requiring a fresh evaluation of diagnostic criteria. We held a second consensus conference in 2007 and present the results here.

METHODS

Experts in the clinical, neuropathologic, and imaging aspects of MSA were invited to participate in a 2-day consensus conference. Participants were divided into five groups, consisting of specialists in the parkinsonian, cerebellar, autonomic, neuropathologic, and imaging aspects of the disorder. Each group independently wrote diagnostic criteria for its area of expertise in advance of the meeting. These criteria were discussed and reconciled during the meeting using consensus methodology.

RESULTS

The new criteria retain the diagnostic categories of MSA with predominant parkinsonism and MSA with predominant cerebellar ataxia to designate the predominant motor features and also retain the designations of definite, probable, and possible MSA. Definite MSA requires neuropathologic demonstration of CNS alpha-synuclein-positive glial cytoplasmic inclusions with neurodegenerative changes in striatonigral or olivopontocerebellar structures. Probable MSA requires a sporadic, progressive adult-onset disorder including rigorously defined autonomic failure and poorly levodopa-responsive parkinsonism or cerebellar ataxia. Possible MSA requires a sporadic, progressive adult-onset disease including parkinsonism or cerebellar ataxia and at least one feature suggesting autonomic dysfunction plus one other feature that may be a clinical or a neuroimaging abnormality.

CONCLUSIONS

These new criteria have simplified the previous criteria, have incorporated current knowledge, and are expected to enhance future assessments of the disease.

Survival in multiple system atrophy

We here report survival in patients with multiple system atrophy (MSA) in a large, prospectively studied group of patients with MSA. Eighty-five of 100 patients were known to have died. Three patients were rediagnosed as having PD. Twenty-four patients came to autopsy, which showed MSA in 22 and idiopathic Parkinson's disease in 2. The median survival time was 8.6 and 7.3 years for men and women, respectively (hazard ratio for women was 1.49, 95% CI 0.97-2.31, P = 0.07). Except for rediagnosis as PD, no predictive factors for better survival could be identified. These data confirm the relatively poor prognosis of MSA of less than 9 years on average.

Impact of ambiguity and risk on decision making in mild Alzheimer's disease

Decisions under ambiguity and decisions under risk are crucial types of decision making in daily living at any age. This is the first study assessing these two types of decisions in patients with mild dementia of Alzheimer's type (DAT) by means of the Iowa Gambling Task (IGT) and a newly developed, Probability-Associated Gambling (PAG) task. While rules for gains and losses are implicit in the IGT, in the PAG task rules are explicit and winning probabilities, which change from trial to trial, can be estimated. Results of the IGT indicated that DAT patients made more disadvantageous decisions than healthy controls. Patients also shifted more frequently among decks, i.e. under ambiguity decisions were taken randomly and no advantageous strategy was established over time by DAT patients. Thus, not only actual choices but also development of advantageous strategies may be revealing about decision making in the IGT. Compared to controls, patients demonstrated less advantageous choices in the PAG task as well. They gambled more often in the low winning probabilities and less frequently in the high probabilities than healthy participants. Patients' performance on both tasks correlated with measures of executive functions. Findings of the present investigation are consistent with the early pathological cerebral changes and related (cognitive, emotional) deficits reported for DAT. As suggested by our study, decisions under ambiguity as well as decisions under risk are impaired in mild DAT. It may thus be expected that patients with mild DAT have difficulties in taking decisions in every-day life situations, both in cases of ambiguity (information on probability is missing or conflicting, and the expected utility of the different options is incalculable) and in cases of risk (outcomes can be predicted by well-defined or estimable probabilities).

Microglial activation mediates neurodegeneration related to oligodendroglial alpha-synucleinopathy: implications for multiple system atrophy

The role of microglial activation in multiple system atrophy (MSA) was investigated in a transgenic mouse model featuring oligodendroglial alpha-synuclein inclusions and loss of midbrain dopaminergic neurons by means of histopathology and morphometric analysis. Our findings demonstrate early progressive microglial activation in substantia nigra pars compacta (SNc) associated with increased expression of iNOS and correlating with dopaminergic neuronal loss. Suppression of microglial activation by early long-term minocycline treatment protected dopaminergic SNc neurons. The results suggest that oligodendroglial overexpression of alpha-synuclein may induce neuroinflammation related to nitrosive stress which is likely to contribute to neurodegeneration in MSA. Further, we detected increased toll-like receptor 4 immunoreactivity in both transgenic mice and MSA brains indicating a possible signaling pathway in MSA which needs to be further studied as a candidate target for neuroprotective interventions.

Diffusion weighted imaging best discriminates PD from MSA-P: A comparison with tilt table testing and heart MIBG scintigraphy

Both diffusion weighted magnetic resonance imaging (DWI) of the basal ganglia and meta-iodobenzylguanidin (MIBG) scintigraphy of the heart have been reported useful in the differential diagnosis of patients with Parkinson's disease (PD) vs. the parkinson variant of multiple system atrophy (MSA-P). Their diagnostic value, however, has never been directly compared in patients with parkinsonism and autonomic dysfunction. We have studied 9 patients with PD and 9 patients with MSA-P matched for age and disease severity. Regional trace of the diffusion tensor values were determined in the putamina. Cardiac MIBG uptake was quantified by comparing regions of interest over heart and mediastinum Heart/Mediastinum (H/M) ratio. Furthermore, all patients underwent tilt testing. PD patients showed significantly lower H/M ratios than normal controls; however, there was considerable overlap between the two patient groups. We did not detect any significant differences of blood pressure response to passive tilt between the two patient groups. Sensitivity of MIBG scintigraphy versus DWI for the differentiation of MSA-P from PD was 55.6% vs. 100%, specificity 88.8% vs. 100%, and area under the curve 0.802 vs. 1.000. Our data suggest that DWI is superior to both tilt table testing and MIBG scintigraphy in the differential diagnosis of PD versus MSA-P.

Rasagiline is neuroprotective in a transgenic model of multiple system atrophy

Rasagiline is a novel selective irreversible monoamine oxidase-B (MAO-B) inhibitor recently introduced for the symptomatic treatment of Parkinson disease. Like other propargylamines rasagiline has also shown neuroprotective effects independent of MAO-B-inhibition in various in vitro and in vivo models. The present study was performed to test the potential of rasagiline as a disease-modifying agent in multiple system atrophy (MSA) using a transgenic mouse model previously described by our group. (PLP)-alpha-synuclein transgenic mice featuring glial cytoplasmic inclusion pathology underwent 3-nitropropionic acid intoxication to model full-blown MSA-like neurodegeneration. Two doses of rasagiline were used (0.8 and 2.5 mg/kg) for a treatment period of 4 weeks. Rasagiline-treated animals were compared to placebo saline-treated mice by evaluation of motor behaviour and neuropathology. Motor behavioural tests including pole test, stride length test and general motor score evaluation showed improvements in motor deficits associated with 2.5 mg/kg rasagiline therapy. Immunohistochemistry and histology showed significant reduction of 3-NP-induced neuronal loss in striatum, substantia nigra pars compacta, cerebellar cortex, pontine nuclei and inferior olives of MSA mice receiving 2.5 mg/kg rasagiline. The results of the study indicate that rasagiline confers neuroprotection in a transgenic mouse model of MSA and may therefore be considered a promising disease-modifying candidate for human MSA.

Voxel based morphometry reveals specific gray matter changes in primary dystonia

The present study assessed patterns of brain tissue alterations in different types of primary dystonia using voxel-based morphometry (VBM). Nine patients with primary generalized dystonia (GD), 11 patients with primary cervical dystonia (CD), and 11 patients with primary focal hand dystonia (FHD) as well as 31 age and gender-matched controls were included. When compared with healthy controls, patients with primary dystonia (n=31) showed gray matter volume increase bilaterally in the globus pallidus internus, nucleus accumbens, prefrontal cortex, as well as unilaterally in the left inferior parietal lobe. This is the first study using VBM in patients with different types of primary dystonia, showing a common pattern of gray matter changes.

Progression of brain atrophy in multiple system atrophy. A longitudinal VBM study

In this study, we aimed to determine the progression of brain atrophy in the parkinson variant of multiple system atrophy (MSA-P). Voxel-based morphometry was applied to two consecutive high resolution MR images of 14 patients with probable MSA-P in comparison to 14 patients with Parkinson's disease (PD). The time interval between baseline and follow-up investigations (1.0 +/- 0.5 SD years in MSAP and 1.4 +/- 0.6 SD years in PD patients) was introduced as covariate in the statistical analysis. Additionally, correlation analyses were performed between the progression maps and clinical data. We observed marked progression of brain atrophy in the MSA-P cohort, the regions including striatum, mesencephalon, thalamus and cerebellum, but also cortical regions such as the primary sensorimotor cortex, supplementary motor area, lateral premotor cortex, medial frontal gyrus, middle frontal gyrus, orbito-frontal cortex,insula, posterior parietal cortex and hippocampus. Short disease duration was correlated with progression of atrophy in the striatum whereas longer disease duration was correlated with increasing atrophy in the cortical areas and cerebellar hemispheres. The UPDRS-III score was not significantly correlated with any brain region. Our data suggest that cortical atrophy is prominent in MSA-P and early degeneration of the basal ganglia drives late onset cortical atrophy.

Cervical dystonia in spinocerebellar ataxia type 2: clinical and polymyographic findings

Eighteen patients from three large multigenerational families with genetically established spinocerebellar ataxia type 2 (SCA2) were examined, with special attention to the presence of dystonic features. Cervical dystonia (CD) was diagnosed according to standardised clinical criteria. CD was scored using the Tsui score. Polymyography was performed in six cases using bilateral surface electrode recordings of the sternocleidomastoid and trapezius muscles together with needle electrode recordings of the splenius capitis muscles bilaterally. CD was found in 11 of 18 patients (61%), and was the presenting symptom in one case. Severity of CD was mild to moderate, with Tsui scores ranging from 5 to 12 points. Polymyography in 6 of 11 SCA2 patients with CD showed the typical pattern of dystonia with spontaneous, involuntary muscle activation at rest in at least one neck muscle with disturbed reciprocal inhibition of antagonistic neck muscles. CD appears to be a common clinical feature in SCA2 and may precede ataxia and gait disturbance. By contrast, none of the 18 patients had dystonic features in other body regions. CD has probably been underreported in patients with the ataxic SCA2 phenotype and should be considered as an additional clinical manifestation in patients with hereditary ataxia.

Differentiation of SCA2 from MSA-C using proton magnetic resonance spectroscopic imaging

PURPOSE

To assess and compare biochemical and volumetric features of the cerebellum in patients with spinocerebellar ataxia type 2 (SCA2) and patients with the cerebellar variant of multiple system atrophy (MSA-C).

MATERIALS AND METHODS

Nine genetically assigned SCA2 patients and six MSA-C patients who met the clinical criteria of MSA-C underwent a clinical and neuroradiological workup with respect to cerebellar features. The MR protocol consisted of a sagittal T1-weighted three-dimensional fast low-angle shot (3D FLASH) sequence and a transversal T2- and spin-density-weighted turbo spin-echo sequence. The proton magnetic resonance spectroscopic imaging ((1)H-MRSI) protocol consisted of two chemical shift imaging (CSI) sequences (echo time (TE) = 20 and 135 msec).

RESULTS

Both short- and long-TE MR spectroscopy (MRS) images showed significant decreases in values for N-acetylaspartate to creatine (NAA/Cr), and choline to creatine (Cho/Cr) ratios in MSA-C and SCA2 compared to normal controls, though there was no difference between the two patient groups. In contrast, distinct cerebellar lactate (Lac) peaks were detected in seven SCA2 patients, and small peaks were detected in two. However, we did not detect any definite Lac peak in MSA-C or control subjects.

CONCLUSION

MRSI revealed Lac pathology in SCA2 but not in MSA-C. Whether this indicates distinct pathogenetic mechanisms of cerebellar degeneration remains to be established.

Progression of dysautonomia in multiple system atrophy: a prospective study of self-perceived impairment

To assess severity and progression of self-perceived dysautonomia and their impact on health-related quality of life (Hr-QoL) in multiple system atrophy (MSA), twenty-seven patients were recruited by the European MSA Study Group (EMSA-SG). At baseline, all patients completed the Composite Autonomic Symptom Scale (COMPASS) and the 36 item Short Form Health Survey (SF-36), and they were assessed using the 3-point global disease severity scale (SS-3) and the Unified MSA Rating Scale (UMSARS). After 6 months follow-up, the self completed COMPASS Change Scale (CCS), the SF-36, SS-3, and UMSARS were obtained. MSA patients showed marked self-perceived dysautonomia at baseline visit and pronounced worsening of dysautonomia severity on the CCS at follow-up. Severity and progression of dysautonomia did not correlate with age, disease duration, motor impairment and overall disease severity at baseline. There were no significant differences between genders and motor subtypes. Baseline COMPASS scores were, however, inversely correlated with SF-36 scores. Progression of self-perceived dysautonomia did not correlate with global disease progression. Hr-QoL scores were stable during follow-up. This is the first study to investigate self-perceived dysautonomia severity in MSA and its evolution over time. Our data suggest that dysautonomia should be recognized as a key target for therapeutic intervention in MSA.

Valvular heart disease in Parkinson's disease vs. controls: An echocardiographic study

Restrictive valvulopathy has been reported in association with dopamine agonist therapy in parkinsonian patients. The majority of reports have been related to pergolide, but anecdotal cases following treatment with bromocriptine or cabergoline have also been presented. It is presently unclear whether the potential induction of restrictive cardiac valvulopathy is a class effect of all dopamine agonists or if there is a differential risk between ergot and nonergot compounds. In this study, the frequency of a valvular regurgitation as assessed by routine transthoracic echocardiography was compared between 75 patients with Parkinson's disease (PD) treated with pergolide (n = 29), cabergoline (n = 13), pramipexole or ropinirole (n = 33), and 49 age-matched nonparkinsonian controls. The exposure to pergolide and cabergoline was associated with higher frequencies of valvular regurgitation grades 2 and 3 (31% and 47%) compared with age-matched controls (13%), while there was no increase of valvular regurgitation grades 2 and 3 in patients treated with nonergot compounds (10%). Evidence for restrictive valvulopathy was found in one patient treated with pergolide and cabergoline each. While this study shows similarly increased frequencies of valvular regurgitation in patients treated with the ergot agonists pergolide and cabergoline in comparison to both normal controls and patients treated with nonergot agonists, evidence for restrictive valvulopathy was only found in two cases. These results highlight the need for further prospective studies of the prevalence and underlying mechanisms of cardiac valvulopathy in PD patients treated with different dopamine agonists.

Orthostatic hypotension and attention in Parkinson's disease with and without dementia

To compare frequency and degree of orthostatic hypotension (OH) in Parkinson's disease (PD) and Parkinson's disease with dementia (PDD) and its effect on attention and word fluency, blood pressure (BP) and heart rate changes during tilt were determined in 10 PD and 8 PDD patients. Attention and word fluency were evaluated in supine and tilted position using standard neuropsychological tests. OH defined as systolic BP (SBP) drop of >/=20 mmHg and/or diastolic BP (DBP) drop of >/=10 mmHg was present in 5 PDD patients and in 2 PD patients. SBP drop was significantly greater in PDD than in PD patients (P < 0.05). Whereas word fluency was unaffected by tilt in both patient groups, attention as assessed with the Test of Everyday Attention (TEA) deteriorated significantly in the PDD group, correlating with blood pressure response (DeltaSBP and TEA-2, r = 0.828, P < 0.05; DeltaDBP and TEA-2, r = 0.828, P < 0.05). We conclude that OH is frequent in PDD and should be addressed therapeutically since it may exacerbate attentional dysfunction.

Loss of dopaminergic responsiveness in a double lesion rat model of the Parkinson variant of multiple system atrophy

The Parkinson variant of multiple system atrophy (MSA-P) is a distinct atypical parkinsonian disorder with a loss of dopaminergic neurons comparable to that found in Parkinson's disease (PD). The additional loss of striatopallidal projections is thought to account for levodopa unresponsiveness in MSA-P. Whereas histological features of MSA-P have been successfully reproduced in the double lesion rat model, loss of levodopa responsiveness has so far not been demonstrated. In the current study, 6-hydroxydopamine (6-OHDA) induced unilateral lesions of the substantia nigra produced a marked contralateral forelimb stepping deficit, which improved significantly after challenge with levodopa (P < 0.001). This response was abolished by the subsequent striatal quinolinic acid (QA) lesion. In the cylinder test, the marked asymmetry observed after 6-OHDA lesioning was reversed by levodopa to baseline levels. After QA, cylinder test performance under levodopa failed to reach baseline (P = 0.001) or 6-OHDA + levodopa (P = 0.002) levels. Nigral cell loss (90% +/- 5%) correlated with both stepping test (r = 0.608; P = 0.008) and cylinder test results (r = 0.656; P = 0.005). Lesion extent of the dorsal striatum correlated significantly with the loss of levodopa response (r = 0.593; P = 0.01) in the stepping test. These findings contribute further to the behavioral characterization of the double lesion rat model of MSA, improving its value in the evaluation of future neurorestorative strategies.