Subthalamic nucleus activity in the processing of body and mental action verbs in people with Parkinson's disease.

Local field potentials evoked by body action and mental action verbs were recorded in the subthalamic nucleus (STN) of 18 patients with Parkinson's disease through the electrodes implanted for deep brain stimulation. Compared with the medication on-condition, the medication off-condition showed a difference in activity in the early time segments, mainly in the right STN, with larger amplitudes for body action verbs. In the on-condition a similar pattern was detected in the left STN. These patterns of early differences in activity evoked by different types of verbs might indicate the potential of the STN to rapidly detect relevant behavioural clues in verbal content and to integrate these in subsequent cortico-subcortical interactions. In addition, these lateralizations allow speculations about shifts in processing activity correlating with dopaminergic denervation. Whether this detection relies on phonological, semantic or grammatical clues remains an open question.

The white matter architecture underlying semantic processing: A systematic review.

From a holistic point of view, semantic processes are subserved by large-scale subcortico-cortical networks. The dynamic routing of information between grey matter structures depends on the integrity of subcortical white matter pathways. Nonetheless, controversy remains on which of these pathways support semantic processing. Therefore, a systematic review of the literature was performed with a focus on anatomo-functional correlations obtained from direct electrostimulation during awake tumor surgery, and conducted between diffusion tensor imaging metrics and behavioral semantic performance in healthy and aphasic individuals. The 43 included studies suggest that the left inferior fronto-occipital fasciculus contributes to the essential connectivity that allows semantic processing. However, it remains uncertain whether its contributive role is limited to the organization of semantic knowledge or extends to the level of semantic control. Moreover, the functionality of the left uncinate fasciculus, inferior longitudinal fasciculus and the posterior segment of the indirect arcuate fasciculus in semantic processing has to be confirmed by future research.

The network integration of epileptic activity in relation to surgical outcome.

OBJECTIVE: Epilepsy is a network disease with epileptic activity and cognitive impairment involving large-scale brain networks. A complex network is involved in the seizure and in the interictal epileptiform discharges (IEDs). Directed connectivity analysis, describing the information transfer between brain regions, and graph analysis are applied to high-density EEG to characterise networks. METHODS: We analysed 19 patients with focal epilepsy who had high-density EEG containing IED and underwent surgery. We estimated cortical activity during IED using electric source analysis in 72 atlas-based cortical regions of the individual brain MRI. We applied directed connectivity analysis (information Partial Directed Coherence) and graph analysis on these sources and compared patients with good vs poor post-operative outcome at global, hemispheric and lobar level. RESULTS: We found lower network integration reflected by global, hemispheric, lobar efficiency during the IED (p < 0.05) in patients with good post-surgical outcome, compared to patients with poor outcome. Prediction was better than using the IED field or the localisation obtained by electric source imaging. CONCLUSIONS: Abnormal network patterns in epilepsy are related to seizure outcome after surgery. SIGNIFICANCE: Our finding may help understand networks related to a more "isolated" epileptic activity, limiting the extent of the epileptic network in patients with subsequent good post-operative outcome.

Time-varying effective EEG source connectivity: the optimization of model parameters.

Adaptive estimation methods based on general Kalman filter are powerful tools to investigate brain networks dynamics given the non-stationary nature of neural signals. These methods rely on two parameters, the model order p and adaptation constant c, which determine the resolution and smoothness of the time-varying multivariate autoregressive estimates. A sub-optimal filtering may present consistent biases in the frequency domain and temporal distortions, leading to fallacious interpretations. Thus, the performance of these methods heavily depends on the accurate choice of these two parameters in the filter design. In this work, we sought to define an objective criterion for the optimal choice of these parameters. Since residual- and information-based criteria are not guaranteed to reach an absolute minimum, we propose to study the partial derivatives of these functions to guide the choice of p and c. To validate the performance of our method, we used a dataset of human visual evoked potentials during face perception where the generation and propagation of information in the brain is well understood and a set of simulated data where the ground truth is available.

Estimating EEG Source Dipole Orientation Based on Singular-value Decomposition for Connectivity Analysis.

In the last decade, the use of high-density electrode arrays for EEG recordings combined with the improvements of source reconstruction algorithms has allowed the investigation of brain networks dynamics at a sub-second scale. One powerful tool for investigating large-scale functional brain networks with EEG is time-varying effective connectivity applied to source signals obtained from electric source imaging. Due to computational and interpretation limitations, the brain is usually parcelled into a limited number of regions of interests (ROIs) before computing EEG connectivity. One specific need and still open problem is how to represent the time- and frequency-content carried by hundreds of dipoles with diverging orientation in each ROI with one unique representative time-series. The main aim of this paper is to provide a method to compute a signal that explains most of the variability of the data contained in each ROI before computing, for instance, time-varying connectivity. As the representative time-series for a ROI, we propose to use the first singular vector computed by a singular-value decomposition of all dipoles belonging to the same ROI. We applied this method to two real datasets (visual evoked potentials and epileptic spikes) and evaluated the time-course and the frequency content of the obtained signals. For each ROI, both the time-course and the frequency content of the proposed method reflected the expected time-course and the scalp-EEG frequency content, representing most of the variability of the sources (~ 80%) and improving connectivity results in comparison to other procedures used so far. We also confirm these results in a simulated dataset with a known ground truth.

Carbamazepine and oxcarbazepine in adult patients with Dravet syndrome: Friend or foe?

PURPOSE: In newly diagnosed patients with Dravet syndrome sodium channel blockers are usually avoided. However, in many adult patients the diagnosis was made long after the initiation of therapy. The purpose of our study was to acquire information concerning the potential risks and benefits of (ox)carba(ma)zepine withdrawal in adult patients with genetically confirmed Dravet syndrome. METHOD: We identified 16 adults with Dravet syndrome, living in a tertiary care facility for people with epilepsy and an intellectual disability. We reviewed clinical history, genetic findings, the type and duration of sodium channels blockers that were used, seizure types and frequency, and the effect of a change in these medications. RESULTS: The study population consisted of 9 men and 7 women. Median age was 35 years (range 20-61 years). An attempt to withdraw carbamazepine (CBZ) was made in 9 patients. In 3 of these patients an increase in tonic-clonic seizures was observed. An attempt to withdraw oxcarbazepine (OXC) was made in 3 patients, leading to a complete stop in 2 patients. 3 of the 4 deaths in the withdrawal-group were related to epilepsy. CONCLUSION: In adult patients with Dravet syndrome withdrawal of CBZ or OXC is not without risks. We suggest that (ox)carba(ma)zepine withdrawal should be considered in these patients but only if there is a good reason to do so and only if they are closely monitored.

Electrophysiological registration of phonological perception in the subthalamic nucleus of patients with Parkinson's Disease.

Phonological processing is usually associated with the activation of cortical areas, especially in the left cerebral hemisphere. This study examined if phonologically elicited evoked potentials can be recorded directly from the subthalamic nucleus in patients with Parkinson's Disease (PD). Seven PD patients who had undergone implantation of deep brain electrodes for the stimulation of the subthalamic nucleus were included. Local field potentials were recorded in a pre-attentive auditory phonological task, an attentive auditory phonological discrimination task, and a word recognition task. Auditory evoked potentials related to phonological, but not lexical processing, could be demonstrated in the subthalamic nucleus for all three tasks. Only minor changes were found after levodopa administration. This study demonstrates that the subthalamic nucleus is involved in early phonological perception, which puts the subthalamic nucleus in a position to modify phonological perception in a larger cortico-subcortical network.

[Hallucinations and vivid dreams by use of metoprolol]. / Hallucinaties en levendige dromen bij metoprololgebruik.

A 71-year-old man had had visual hallucinations and vivid dreams for two years after starting to take metoprolol. When metoprolol was replaced by atenolol the patient's symptoms disappeared within five days. Side-effects of beta-blockers on the central nervous system are relatively uncommon. The mechanisms underlying these side-effects are not fully understood. Lipophilic beta-blockers can cross the blood-brain barrier, whereas hydrophilic beta-blockers cannot. Doctors need to be alerted to the varying side-effects of specific beta-blockers.

Sensorineural hearing impairment in patients with Pmp22 duplication, deletion, and frameshift mutations.

OBJECTIVE: To characterize and distinguish the types of sensorineural hearing impairment (SNHI) that occur in hereditary motor and sensory neuropathy Type 1a (HMSN-1a) and hereditary neuropathy with liability to pressure palsies (HNPP), which are caused by deletion or frameshift mutation. STUDY DESIGN: Prospective study. SETTING: Ambulatory patients in a university hospital. PATIENTS: Twelve patients with HMSN-1a due to a duplication of the PMP22 gene on chromosome 17p11.2, 16 patients with HNPP due to the common PMP22 deletion (HNPP del), and 11 HNPP patients with a frame shift mutation (heterozygous PMP22 G-insertion) (HNPP mut), all confirmed by molecular genetic analysis. INTERVENTIONS: Pure-tone audiograms and speech audiograms were obtained. MAIN OUTCOME MEASURES: Results of cross-sectional analysis comprising linear regression of hearing threshold on age. RESULTS: Pure-tone audiograms showed mild to moderate SNHI, predominant at the low and the high frequencies. SNHI showed significant progression by approximately 0.4 dB per year at 0.25 to 4 kHz and up to 1 to 2 dB per year at 4 to 8 kHz. Patients with HMSN-1a had substantial, presumably congenital, SNHI but did not show significant progression beyond presbyacusis. Patients with HNPP showed postnatal onset at age 11 years with progression of SNHI in excess of presbyacusis by 0.4 dB per year. All three types of neuropathy showed normal speech recognition. CONCLUSIONS: All three types of neuropathy showed SNHI with normal speech recognition. HMSN-1a showed stable SNHI without progression beyond presbyacusis. HNPP showed progression beyond presbyacusis with postnatal onset. The differences in SNHI may be explained by the differences in PMP22 expression. The progressive SNHI in HNPP might be explained by the liability for exogenous factors associated with this disorder.

Recurrent staphylococcal bacteraemia and subhepatic abscess associated with gallstones spilled during laparoscopic cholecystectomy two years earlier.

This is the first report of Staphylococcus aureus bacteraemia and subhepatic abscess in association with intraperitoneal gallstones spilled during laparoscopic cholecystectomy two years earlier. Spilled gallstones can lead to abscess formation in the late postoperative period by acting as foreign bodies that can become infected during bacteraemia and then become a source of recurrent bacteraemia.

Mohs micrographic surgery for an erosive adenomatosis of the nipple.

BACKGROUND: Erosive adenomatosis of the nipple is a rare but distinct benign tumor of the nipple. It is usually considered to be derived from the apocrine sweat ducts of the nipple epithelium but probably of lactiferous duct origin. Total excision is the treatment of choice. OBJECTIVE: We report the clinical and histological features of this rare tumor, and the surgical technique employed. METHODS: Treatment consisted of Mohs micrographic surgery (MMS), fresh tissue technique, followed by primary closure. RESULTS: The described procedure resulted in a cure of the erosive adenomatosis of the nipple. CONCLUSION: Total excision of erosive adenomatosis of the nipple can be obtained by MMS. This technique prevents recurrence of the disease and minimizes resulting deformation of this important anatomic area.

Red and blue telangiectasias. Differences in oxygenation?

BACKGROUND: Leg telangiectasias are visible, ectatic dermal arteriols, capillaries, or veins with a diameter of 0.1-1 or 2 mm. Their origin is still not known and different opinions have been published. OBJECTIVE: In our study we were interested in the different colors of telangiectasias and we wanted to demonstrate whether a difference in blood gases is causing the difference in color between red and blue telangiectasias. METHODS: We measured a capillary astrup in 20 patients, who had red as well as blue telangiectasias on the lower limb. Therefore, we took two samples, one of a red and one of a blue telangiectasia. By this we measured the oxygen saturation and the carbon dioxide concentration of the samples. Furthermore, we introduced the appearance of telangiectasias in two rather newly developed techniques, such as high-frequency 20- and 50-MHz ultrasound and laser Doppler perfusion imaging (LDPI). RESULTS: Red telangiectasias of all 20 patients had an average oxygen concentration of 5.9 kPa, (range, 3.94-7.46 kPa); their average CO2 concentration was 5.45 kPa (range, 4.54-7.06 kPa). Blue telangiectasias had an average oxygen concentration of 5.11 kPa (range, 3.12-7.0 kPa); their average CO2 concentration was 6.07 kPa (range, 5.38-7.36 kPa). Statistically work-up with a paired student's t-test showed a higher oxygen saturation of the red telangiectasias and a higher carbon dioxide concentration of the blue vessels. CONCLUSION: As telangiectasias are assumed to be located in the capillary bed, the reason for differences in oxygenation could possibly be found in underlying physiological and anatomical principles of the capillary loops with the red telangiectasia representing the arterial loop of the capillary and the blue telangiectasia representing the venous loop of the capillary. With high frequency ultrasound and LDPI it is possible to get useful information for finding the underlying feeder veins, which "feed" the superficial telangiectasias. Injecting into the nutritional vessel telangiectases can potentially decrease the number of side effects and, may reduce the number of necessary injections.

Erythema chronicum migrans: an electron-microscopic study.

Spirochaetal organisms are found in skin specimens obtained by biopsy from a erythema chronicum migrans lesion. The histological picture shows a logical localization of a lymphohistiocytic cell infiltrate: deep dermal in the central papule and superficial in the erythematous border. The electron-microscopic characteristics of the micro-organisms in these specimens (regular waving appearance with coils every 0.8-1.2 microns, oblique striation of periplasmatic fibrils, cross-section of 0.3 micron, membranes) correspond to the spiral-like structure of Borreliae isolated from blood. The Borreliae seem to move freely through the matrix of the dermis and are not phagocytized. This brings on the typical clinical picture of the centrifugally spreading erythematous band.