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Clinical Neuroscience

SEPTEMBER 30, 2020

Neuroscience highlights: Main cell types underlying memory and spatial navigation

KRABOTH Zoltán, KÁLMÁN Bernadette

Interest in the hippocampal formation and its role in navigation and memory arose in the second part of the 20th century, at least in part due to the curious case of Henry G. Molaison, who underwent brain surgery for intractable epilepsy. The temporal association observed between the removal of his entorhinal cortex along with a significant part of hippocampus and the developing severe memory deficit inspired scientists to focus on these regions. The subsequent discovery of the so-called place cells in the hippocampus launched the description of many other functional cell types and neuronal networks throughout the Papez-circuit that has a key role in memory processes and spatial information coding (speed, head direction, border, grid, object-vector etc). Each of these cell types has its own unique characteristics, and together they form the so-called “Brain GPS”. The aim of this short survey is to highlight for practicing neurologists the types of cells and neuronal networks that represent the anatomical substrates and physiological correlates of pathological entities affecting the limbic system, especially in the temporal lobe. For that purpose, we survey early discoveries along with the most relevant neuroscience observations from the recent literature. By this brief survey, we highlight main cell types in the hippocampal formation, and describe their roles in spatial navigation and memory processes. In recent decades, an array of new and functionally unique neuron types has been recognized in the hippocampal formation, but likely more remain to be discovered. For a better understanding of the heterogeneous presentations of neurological disorders affecting this anatomical region, insights into the constantly evolving neuroscience behind may be helpful. The public health consequences of diseases that affect memory and spatial navigation are high, and grow as the population ages, prompting scientist to focus on further exploring this brain region.

Clinical Neuroscience

JULY 30, 2020

[Advanced Parkinson’s disease characteristics in clinical practice: Results from the OBSERVE-PD study and sub-analysis of the Hungarian data]

TAKÁTS Annamária, ASCHERMANN Zsuzsanna, VÉCSEI László, KLIVÉNYI Péter, DÉZSI Lívia, ZÁDORI Dénes, VALIKOVICS Attila, VARANNAI Lajos, ONUK Koray, KINCZEL Beatrix, KOVÁCS Norbert

[The majority of patients with advanced Parkinson’s disease are treated at specialized movement disorder centers. Currently, there is no clear consensus on how to define the stages of Parkinson’s disease; the proportion of Parkinson’s patients with advanced Parkinson’s disease, the referral process, and the clinical features used to characterize advanced Parkinson’s disease are not well delineated. The primary objective of this observational study was to evaluate the proportion of Parkinson’s patients identified as advanced patients according to physician’s judgment in all participating movement disorder centers across the study. Here we evaluate the Hungarian subset of the participating patients. The study was conducted in a cross-sectional, non-interventional, multi-country, multi-center format in 18 countries. Data were collected during a single patient visit. Current Parkinson’s disease status was assessed with Unified Parkinson’s Disease Rating Scale (UPDRS) parts II, III, IV, and V (modified Hoehn and Yahr staging). Non-motor symptoms were assessed using the PD Non-motor Symptoms Scale (NMSS); quality of life was assessed with the PD 8-item Quality-of-Life Questionnaire (PDQ-8). Parkinson’s disease was classified as advanced versus non-advanced based on physician assessment and on questions developed by the Delphi method. Overall, 2627 patients with Parkinson’s disease from 126 sites were documented. In Hungary, 100 patients with Parkinson’s disease were documented in four movement disorder centers, and, according to the physician assessment, 50% of these patients had advanced Parkinson’s disease. Their mean scores showed significantly higher impairment in those with, versus without advanced Parkinson’s disease: UPDRS II (14.1 vs. 9.2), UPDRS IV Q32 (1.1 vs. 0.0) and Q39 (1.1 vs. 0.5), UPDRS V (2.8 vs. 2.0) and PDQ-8 (29.1 vs. 18.9). Physicians in Hungarian movement disorder centers assessed that half of the Parkinson’s patients had advanced disease, with worse motor and non-motor symptom severity and worse QoL than those without advanced Parkinson’s disease. Despite being classified as eligible for invasive/device-aided treatment, that treatment had not been initiated in 25% of these patients.]

Clinical Neuroscience

MAY 30, 2020

Alexithymia is associated with cognitive impairment in patients with Parkinson’s disease

SENGUL Yildizhan, KOCAK Müge, CORAKCI Zeynep, SENGUL Serdar Hakan, USTUN Ismet

Cognitive dysfunction (CD) is a common non-motor symptom of Parkinson’s disease (PD). Alexithy­mia is a still poorly understood neuropsychiatric feature of PD. Cognitive impairment (especially visuospatial dysfunction and executive dysfunction) and alexithymia share com­mon pathology of neuroanatomical structures. We hypo­thesized that there must be a correlation between CD and alexithymia levels considering this relationship of neuroanatomy. Objective – The aim of this study was to evaluate the association between alexithymia and neurocognitive function in patients with PD. Thirty-five patients with PD were included in this study. The Toronto Alexithymia Scale–20 (TAS-20), Geriatric Depression Inventory (GDI) and a detailed neuropsychological evaluation were performed. Higher TAS-20 scores were negatively correlated with Wechsler Adult Intelligence Scale (WAIS) similarities test score (r =-0.71, p value 0.02), clock drawing test (CDT) scores (r=-0.72, p=0.02) and verbal fluency (VF) (r=-0.77, p<0.01). Difficulty identifying feelings subscale score was negatively correlated with CDT scores (r=-0.74, p=0.02), VF scores (r=-0.66, p=0.04), visual memory immediate recall (r=-0.74, p=0.01). VF scores were also correlated with difficulty describing feelings (DDF) scores (r=-0.66, p=0.04). There was a reverse relationship bet­ween WAIS similarities and DDF scores (r=-0.70, p=0.02), and externally oriented-thinking (r=-0.77,p<0.01). Executive function Z score was correlated with the mean TAS-20 score (r=-62, p=0.03) and DDF subscale score (r=-0.70, p=0.01) Alexithymia was found to be associated with poorer performance on visuospatial and executive function test results. We also found that alexithymia was significantly correlated with depressive symptoms. Presence of alexithymia should therefore warn the clinicians for co-existing CD.

Clinical Neuroscience

NOVEMBER 20, 2015

[Earlier and more efficiently: the role of deep brain stimulation for parkinson’s disease preserving the working capabilities]

DELI Gabriella, BALÁS István, KOMOLY Sámuel, DÓCZI Tamás, JANSZKY József, ASCHERMANN Zsuzsanna, NAGY Ferenc, BOSNYÁK Edit, KOVÁCS Norbert

[Background – The recently published “EarlyStim” study demonstrated that deep brain stimulation (DBS) for the treatment of Parkinson’s disease (PD) with early fluctuations is superior to the optimal pharmacological treatment in improving the quality of life and motor symptoms, and preserving sociocultural position. Our retrospective investigation aimed to evaluate if DBS therapy was able to preserve the working capabilities of our patients. Methods – We reviewed the data of 39 young (<60 years-old) PD patients who underwent subthalamic DBS implantation at University of Pécs and had at least two years follow-up. Patients were categorized into two groups based on their working capabilities: Patients with active job (“Job+” group, n=15) and retired patients (without active job, “Job-” group, n=24). Severity of motor symptoms (UPDRS part 3), quality of life (EQ-5D) and presence of active job were evaluated one and two years after the operation. Results – As far as the severity of motor symptoms were concerned, similar (approximately 50%) improvement was achieved in both groups. However, the postoperative quality of life was significantly better in the Job+ group. Majority (12/15, 80%) of Job+ group members were able to preserve their job two years after the operation. However, only a minimal portion (1/24, 4.2%) of the Job- group members was able to return to the world of active employees (p<0.01, McNemar test). Conclusion – Although our retrospective study has several limitations, our results fit well with the conclusions of “EarlyStim” study. Both of them suggest that with optimal timing of DBS implantation we may preserve the working capabilities of our patients.]

Clinical Neuroscience

JANUARY 30, 2016

Facial virus inoculations infect vestibular and auditory neurons in rats

HELFFERICH Frigyes, LOURMET Guillaume, SZABÓ Rebeka Éva, BOLDOGKŐI Zsolt, PALKOVITS Miklós

Background and purpose – There is growing evidence for the viral origin of the Bell’s facial palsy, vestibular neuritis and sudden sensorineural hearing loss, however their exact pathophysiology is still unknown. We investigated the possibility of brainstem infections following peripheral viral inoculations in rats. Methods – Pseudorabies virus, a commonly used neurotropic viral retrograde tracer was injected into the nasolabial region of rats. Five and 6 days after injections, infected brainstem nuclei were demonstrated by immunohistochemical techniques. Results – Infected neurons were found in the motor facial, the medial vestibular, and the sensory trigeminal nuclei, as well as in the medial nucleus of the trapezoid body. Conclusion – Pseudorabies virus infects auditory and vestibular sensory neurons in the brainstem through facial inoculation. The possible routes of infections: 1. trans-synaptic spread constituted by facio-vestibular anastomoses: primarily infected motor facial neuron infects neurons in the medial vestibular nucleus, 2. via trigeminal sensory nerves: the sensory trigeminal complex innervated by GABAergic medial vestibular neurons, and 3. one bisynaptical route: infected facial motoneurons may receive indirect input from the medial vestibular nucleus and the trapezoid body via connecting neurons in the sensory trigeminal complex. We may assume that latent infections of these areas may precede the infections of the peripheral organs and the reactivation of the virus exerts the symptoms.