Petra Katschnig-Winter

Quantitative Susceptibility Mapping in Parkinson's Disease

Background Quantitative susceptibility mapping (QSM) and R2* relaxation rate mapping have demonstrated increased iron deposition in the substantia nigra of patients with idiopathic Parkinson’s disease (PD). However, the findings in other subcortical deep gray matter nuclei are converse and the sensitivity of QSM and R2* for morphological changes and their relation to clinical measures of disease severity has so far been investigated only sparsely. Methods The local ethics committee approved this study and all subjects gave written informed consent. 66 patients with idiopathic Parkinson’s disease and 58 control subjects underwent quantitative MRI at 3T. Susceptibility and R2* maps were reconstructed from a spoiled multi-echo 3D gradient echo sequence. Mean susceptibilities and R2* rates were measured in subcortical deep gray matter nuclei and compared between patients with PD and controls as well as related to clinical variables. Results Compared to control subjects, patients with PD had increased R2* values in the substantia nigra. QSM also showed higher susceptibilities in patients with PD in substantia nigra, in the nucleus ruber, thalamus, and globus pallidus. Magnetic susceptibility of several of these structures was correlated with the levodopa-equivalent daily dose (LEDD) and clinical markers of motor and non-motor disease severity (total MDS-UPDRS, MDS-UPDRS-I and II). Disease severity as assessed by the Hoehn & Yahr scale was correlated with magnetic susceptibility in the substantia nigra. Conclusion The established finding of higher R2* rates in the substantia nigra was extended by QSM showing superior sensitivity for PD-related tissue changes in nigrostriatal dopaminergic pathways. QSM additionally reflected the levodopa-dosage and disease severity. These results suggest a more widespread pathologic involvement and QSM as a novel means for its investigation, more sensitive than current MRI techniques.

Validation of "laboratory-supported" criteria for functional (psychogenic) tremor

In a small group of patients, we have previously shown that a combination of electrophysiological tests was able to distinguish functional (psychogenic) tremor and organic tremor with excellent sensitivity and specificity.

Cerebellar learning distinguishes inflammatory neuropathy with and without tremor

Objectives: This study aims to investigate if patients with inflammatory neuropathies and tremor have evidence of dysfunction in the cerebellum and interactions in sensorimotor cortex compared to nontremulous patients and healthy controls. Methods: A prospective data collection study investigating patients with inflammatory neuropathy and tremor, patients with inflammatory neuropathy without tremor, and healthy controls on a test of cerebellar associative learning (eyeblink classical conditioning), a test of sensorimotor integration (short afferent inhibition), and a test of associative plasticity (paired associative stimulation). We also recorded tremor in the arms using accelerometry and surface EMG. Results: We found impaired responses to eyeblink classical conditioning and paired associative stimulation in patients with neuropathy and tremor compared with neuropathy patients without tremor and healthy controls. Short afferent inhibition was normal in all groups. Conclusions: Our data strongly suggest impairment of cerebellar function is linked to the production of tremor in patients with inflammatory neuropathy.

Facial Emotion Recognition in Parkinson's Disease: An fMRI Investigation

Background Findings of behavioral studies on facial emotion recognition in Parkinson’s disease (PD) are very heterogeneous. Therefore, the present investigation additionally used functional magnetic resonance imaging (fMRI) in order to compare brain activation during emotion perception between PD patients and healthy controls. Methods and Findings We included 17 nonmedicated, nondemented PD patients suffering from mild to moderate symptoms and 22 healthy controls. The participants were shown pictures of facial expressions depicting disgust, fear, sadness, and anger and they answered scales for the assessment of affective traits. The patients did not report lowered intensities for the displayed target emotions, and showed a comparable rating accuracy as the control participants. The questionnaire scores did not differ between patients and controls. The fMRI data showed similar activation in both groups except for a generally stronger recruitment of somatosensory regions in the patients. Conclusions Since somatosensory cortices are involved in the simulation of an observed emotion, which constitutes an important mechanism for emotion recognition, future studies should focus on activation changes within this region during the course of disease.

Tremor associated with Klinefelter syndrome – A case series and review of the literature

BACKGROUND Previous case series suggested a link between Klinefelter syndrome (KS) and essential tremor (ET) or an ET-like syndrome. METHODS We investigated three KS-patients with tremor including tremor-analyzes and discuss our data in context to findings from a literature review. The clinical outcome after deep brain stimulation (DBS) is also reviewed. RESULTS Tremor in KS is predominantly a postural and kinetic tremor that resembles ET. Our patients were further characterized by absent family history for tremor in first degree relatives, lack of subjective alcohol responsiveness inquired by history, and tremor onset in childhood. One of our patients and two cases from literature improved after DBS of the ventral intermediate nucleus (VIM) of the thalamus. CONCLUSIONS Tremor in KS shares several features with ET. If other characteristics such as family history, alcohol responsiveness, and age at tremor onset may serve as discriminating factors from ET, needs to be further investigated. First observations suggest that VIM-DBS may be efficacious.

Intact emotion recognition and experience but dysfunctional emotion regulation in idiopathic Parkinson's disease

BACKGROUND A specific non-motor impairment in Parkinsons disease (PD) concerns difficulties to accurately identify facial emotions. Findings are numerous but very inconsistent, ranging from general discrimination deficits to problems for specific emotions up to no impairment at all. By contrast, only a few studies exist about emotion experience, altered affective traits and states in PD. OBJECTIVE To investigate the decoding capacity for affective facial expressions, affective experience of emotion-eliciting images and affective personality traits in PD. METHODS The study sample included 25 patients with mild to moderate symptom intensity and 25 healthy controls (HC) of both sexes. The participants were shown pictures of facial expressions depicting disgust, fear, and anger as well as disgusting and fear-relevant scenes. Additionally, they answered self-report scales for the assessment of affective traits. RESULTS PD patients had more problems in controlling anger and disgust feelings than HC. Higher disgust sensitivity in PD was associated with lower functioning in everyday life and lower capacity to recognize angry faces. Furthermore, patients reported less disgust towards poor hygiene and spoiled food and they stated elevated anxiety. However, the clinical group displayed intact facial emotion decoding and emotion experience. Everyday life functionality was lowered in PD and decreased with stronger motor impairment. Furthermore, disease duration was negatively associated to correct classification of angry faces. CONCLUSIONS Our data indicate that problems with emotion regulation may appear already in earlier disease stages of PD. By contrast, PD patients showed appropriate emotion recognition and experience. However, data also point to a deterioration of emotion recognition capacity with the course of the disease. Compensatory mechanisms in PD patients with less advanced disease are discussed.

A priori collaboration in population imaging: The Uniform Neuro-Imaging of Virchow-Robin Spaces Enlargement consortium

Virchow‐Robin spaces (VRS), or perivascular spaces, are compartments of interstitial fluid enclosing cerebral blood vessels and are potential imaging markers of various underlying brain pathologies. Despite a growing interest in the study of enlarged VRS, the heterogeneity in rating and quantification methods combined with small sample sizes have so far hampered advancement in the field.

Role of Disgust Proneness in Parkinson’s Disease: A Voxel-Based Morphometry Study

The knowledge about personality traits in Parkinsons disease (PD) is still limited. In particular, disgust proneness has not been investigated as well as its neuronal correlates. Although several morphometric studies demonstrated that PD is associated with gray matter volume (GMV) reduction in olfactory and gustatory regions involved in disgust processing, a possible correlation with disgust proneness has not been investigated. We conducted a voxel-based morphometry analysis to compare GMV between 16 cognitively normal male PD patients with mild to moderate symptoms and 24 matched control subjects. All participants had answered questionnaires for the assessment of disgust proneness, trait anger and trait anxiety. We correlated questionnaire scores with GMV in both groups. The clinical group reported selectively reduced disgust proneness toward olfactory stimuli associated with spoilage. Moreover, they showed GMV reduction in the central olfactory system [orbitofrontal cortex (OFC) and piriform cortex]. Disgust items referring to olfactory processing were positively correlated with OFC volume in PD patients. Our data suggest an association between PD-associated neurodegeneration and olfactory related facets of the personality trait disgust proneness.

Anticardiolipin antibodies are associated with cognitive dysfunction in stroke-free individuals

The presence of anticardiolipin antibodies (aCLs) has been associated with vascular occlusive events. The role of aCLs as a risk factor for stroke has been a matter of debate, and scarce information exists on the relationship between aCLs and other cerebral disorders. Reports exist for seizures, chorea and subtle cognitive dysfunction. The association between aCLs and cognition was further explored and the relationship between aCL titres and brain magnetic resonance imaging (MRI) findings was evaluated in a large cohort of community‐dwelling individuals.

Levodopa-responsive Holmes’ Tremor Caused by a Single Inflammatory Demyelinating Lesion

Background Holmes’ tremor is characterized by a combination of rest, postural, and kinetic tremor that is presumably caused by interruption of cerebello-thalamo-cortical and nigrostriatal pathways. Medical treatment remains unsatisfactory. Case Report A 16-year-old girl presented with Holmes’ tremor caused by a transient midbrain abnormality on magnetic resonance imaging (MRI). To explore the discrepancy between persistent tremor and resolved MRI changes, we performed dopamine transporter single-photon emission computed tomography (DaT-SPECT) with a 123I-ioflupane that revealed nearly absent DaT binding in the right striatum. Levodopa dramatically improved the tremor. Discussion This is only the second report of a transient midbrain MRI abnormality disrupting nigrostriatal pathways. The case highlights the sometimes limited sensitivity of morphologic imaging for identifying the functional consequences of tissue damage and confirms that DaT imaging may serve as a predictor for levodopa responsiveness in Holmes’ tremor.