Christoph Scherfler

Role of DAT-SPECT in the diagnostic work up of Parkinsonism

The diagnosis of idiopathic Parkinsons disease (PD) can be achieved with high degrees of accuracy in cases with full expression of classical clinical features. However, diagnostic uncertainty remains in early disease with subtle or ambiguous signs. Functional imaging has been suggested to increase the diagnostic yield in parkinsonian syndromes with uncertain clinical classification. Loss of striatal dopamine nerve terminal function, a hallmark of neurodegenerative Parkinsonism, is strongly related to decreases of dopamine transporter (DAT) density, which can be measured by single photon emission computed tomography (SPECT). The use of DAT‐SPECT facilitates the differential diagnosis in patients with isolated tremor symptoms not fulfilling PD or essential tremor criteria, drug‐induced, psychogenic and vascular Parkinsonism as well as dementia when associated with Parkinsonism. This review addresses the value of DAT‐SPECT in early differential diagnosis, and its potential as a screening tool for subjects at risk of developing PD as well as issues around the assessment of disease progression.

Time course of symptomatic orthostatic hypotension and urinary incontinence in patients with postmortem confirmed parkinsonian syndromes: a clinicopathological study

OBJECTIVE Although both orthostatic hypotension and urinary incontinence have been reported in a number of parkinsonian syndromes, such as Parkinson’s disease (PD), multiple system atrophy (MSA), dementia with Lewy bodies (DLB), corticobasal degeneration (CBD), and progressive supranuclear palsy (PSP), differences in the evolution of these features have not been studied systematically in pathologically confirmed cases. METHODS 77 cases with pathologically confirmed parkinsonian syndromes (PD, n=11; MSA, n=15; DLB, n=14; CBD, n=13; PSP, n=24), collected up to 1994, formed the basis for a multicentre clinicopathological study organised by the NINDS to improve the differential diagnosis of parkinsonian disorders. The present study determined the time course—that is, latency to onset and duration from onset to death, of symptomatic orthostatic hypotension, and urinary incontinence in the NINDS series. Furthermore, the diagnostic validity of a predefined latency to onset within 1 year of disease onset of symptomatic orthostatic hypotension or urinary incontinence was analysed. RESULTS Significant group differences for latency, but not duration, of symptomatic orthostatic hypotension and urinary incontinence were found. Latencies to onset of either feature were short in patients with MSA, intermediate in patients with DLB, CBD, and PSP, and long in those with PD. Symptomatic orthostatic hypotension occurring within the first year after disease onset predicted MSA in 75% of cases; early urinary incontinence was less predictive for MSA (56%). CONCLUSION Latency to onset, but not duration, of symptomatic orthostatic hypotension or urinary incontinence differentiates PD from other parkinsonian syndromes, particularly MSA.

White and gray matter abnormalities in idiopathic rapid eye movement sleep behavior disorder: A diffusion-tensor imaging and voxel-based morphometry study

We applied diffusion‐tensor imaging (DTI) including measurements of mean diffusivity (MD), a parameter of brain tissue integrity, fractional anisotropy (FA), a parameter of neuronal fiber integrity, as well as voxel‐based morphometry (VBM), a measure of gray and white matter volume, to detect brain tissue changes in patients with idiopathic rapid eye movement (REM) sleep behavior disorder (iRBD).

Dopaminergic dysfunction in unrelated, asymptomatic carriers of a single parkin mutation

Parkin disease is usually autosomal recessive; however, two studies have shown that asymptomatic heterozygotes have nigrostriatal dysfunction and even manifest subtle extrapyramidal signs. The authors used 18F-dopa PET to study 13 asymptomatic parkin heterozygotes and found a significant reduction of 18F-dopa uptake in caudate, putamen, ventral, and dorsal midbrain compared with control subjects. Four had subtle extrapyramidal signs. Parkin heterozygosity is a risk factor for nigrostriatal dysfunction and in some may contribute to late-onset Parkinson disease.

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 Parkinsons 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.

Progression of multiple system atrophy (MSA): A prospective natural history study by the European MSA study group (EMSA SG)

The disease‐specific Unified Multiple System Atrophy Rating Scale (UMSARS) has been developed recently and validated for assessing disease severity in multiple system atrophy (MSA). Here, we aimed at (1) assessing rates of disease progression in MSA and (2) validating UMSARS for sensitivity to change over time. Impairment was assessed at two time points 12 months apart using UMSARS Part I (historical review), UMSARS Part II (motor examination), as well as measures of global disease severity, including UMSARS Part IV, Hoehn and Yahr (HY) Parkinsons disease staging, Schwab England Activities of Daily Living (SE ADL), and a three‐point global Severity Scale (SS3). Fifty patients (male:female ratio, 1:0.9; possible MSA, 16%; probable MSA, 84%; MSA‐parkinsonian, 58%; MSA‐cerebellar, 42%) were assessed twice with an interval of 12.3 months. UMSARS II scores progressed by 57.3% (P < 0.0001) and UMSARS I scores by 35.6% (P < 0.0001) in relation to the respective baseline scores with no differences between motor subtypes, diagnostic categories and gender. Significant inverse correlations between (1) UMSARS I or UMSARS II progression and (2) baseline disability measures (i.e., the respective UMSARS or SS3 scores) and disease duration were found. Furthermore, the increases in HY staging, SE ADL and SS3 correlated significantly with UMSARS I, UMSARS II, and UMSARS IV progression. This report is the first prospective study showing rapid annual UMSARS rates of decline in MSA. Our data contribute to the ongoing validation process of UMSARS, and they facilitate the planning and implementation of future neuroprotective intervention trials.

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 Parkinsons 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.

Progression of putaminal degeneration in multiple system atrophy: A serial diffusion MR study

By using diffusion-weighted imaging (DWI), we have recently shown abnormal diffusivity in the putamen of patients with the Parkinson variant of multiple system atrophy (MSA-P) which also correlated with disease severity, indicating the capability of putaminal diffusivity to serve as a marker for disease progression. We therefore performed a serial DWI study in 10 patients with MSA-P compared to 10 patients with Parkinsons disease (PD) to evaluate the dynamic evolution of diffusion properties in the basal ganglia including putamen, caudate nucleus and globus pallidum by means of the trace of the diffusion tensor (Trace(D)). For comparison, we have also analyzed the frequency and semiquantitative grading of MSA-P-related structural changes on conventional MRI including putaminal atrophy, lateral hyperintense margination of the putamen and putaminal signal hypointensity relative to the globus pallidum on T2 MR images. None of the Trace(D) values in the basal ganglia regions in the PD group changed significantly at follow-up compared to baseline. In MSA-P, a significant increase of the Trace(D) was found in the putamen, which correlated with motor progression as assessed by the Unified Parkinsons Disease Rating Scale (UPDRS). No significant change of any of the abnormal putaminal findings on routine MRI was obtained. We suggest that abnormal diffusivity in the putamen is sensitive to change over time in MSA-P and correlates with motor progression indicating that DWI may serve to monitor disease progression in MSA-P in an objective and quantitative manner.

Cortical atrophy in the cerebellar variant of multiple system atrophy: a voxel-based morphometry study.

This study aimed to determine in vivo the atrophy patterns in clinically established cerebellar variant of multiple‐system atrophy (MSA‐C) using voxel‐based morphometry (VBM). Thirteen patients with MSA‐C (12 probable, 1 possible) and 13 healthy controls matched for age and sex were included. High‐resolution MR images were acquired with a 1.5 T scanner. Images were normalized onto a study‐specific template, segmented into the tissue compartments, modulated with the Jacobian determinants, and finally smoothed with a Gaussian kernel filter of 10 mm. The general linear model was used to assess statistical differences in gray and white matter. Infratentorial atrophy was observed in the cerebellar hemispheres, vermis, mesencephalon, and pons of MSA‐C patients. Supratentorial volume loss was found in orbitofrontal and mid‐frontal regions as well as in temporomesial and insular areas of both hemispheres. A negative correlation was observed between a cerebellar ataxia score and the volume of cerebellar hemispheres, peduncles, and pons. To compare this atrophy pattern to that of spinocerebellar ataxia (SCA2), which was previously reported by our group, a conjunction analysis was assessed. We observed a volume loss shared by both disorders comprising the cerebellum, vermis, pons, mesencephalon, orbitofrontal, mid‐frontal, and temporomesial cortex of both hemispheres as well as the left insular cortex.

Simultaneous Intrastriatal 6-Hydroxydopamine and Quinolinic Acid Injection: A Model of Early-Stage Striatonigral Degeneration

Animal models reproducing early stages of striatonigral degeneration (SND), the core pathology underlying parkinsonism in multiple system atrophy, are lacking. We have developed a new model of early-stage SND by using a simultaneous unilateral administration of quinolinic acid (QA) and 6-hydroxydopamine (6-OHDA) into the putaminal equivalent of the rat striatum. Spontaneous and drug-induced behavior, thigmotactic scanning, paw reaching deficits, and histopathology were studied in rat groups: group 1 (control), group 2 (QA), group 3 (6-OHDA), and group 4 (QA + 6-OHDA). The double toxin administration resulted in reduction of the spontaneous and the amphetamine-induced ipsiversive bias in the 6-OHDA group and in a reduction of the apomorphine-induced ipsiversive rotations in the QA group. Simultaneous QA and 6-OHDA also reduced the thigmotactic bias observed in the 6-OHDA rats. Combined toxin elicited a nonsignificant contralateral deficit in paw reaching but a significant deficit on the ipsilateral side. Histopathology revealed a significant reduction of the lesioned striatal surface (-27%) with neuronal loss and increased astrogliosis in group 4 compared to group 2, consistent with an exacerbation of QA toxicity by additional 6-OHDA. By contrast, the mean loss of the TH-positive neurons in the ipsilateral substantia nigra pars compacta (SNc) of group 4 was less marked (-15%) than in the 6-OHDA group (-36%), indicating a possible protective action of intrastriatal QA upon 6-OHDA retrograde SNc degeneration. This study shows that a combined unilateral intrastriatal administration of QA and 6-OHDA may serve as a model of early stage SND which is more suitable for early therapeutic interventions.