Accuracy of the Bedside Examination in Patients With Suspected Acute Unilateral Peripheral Vestibulopathy.

OBJECTIVE: Acute unilateral peripheral vestibulopathy (AUPVP) is a frequent form of peripheral vestibular vertigo characterized by unilateral vestibular organ dysfunction. Diagnostic challenges in anamnesis and bedside examination can lead to potential misdiagnoses. This study investigated the sensitivity of bedside examinations in diagnosing AUPVP. METHODS: This retrospective analysis examined 136 AUPVP inpatients at a level 3 university hospital between 2017 and 2019. Demographic data and bedside test results were collected. Instrumental otoneurological tests included caloric testing and video head impulse test (HIT). The sensitivity of each bedside parameter was computed based on the instrumental diagnostics, and statistical analyses were performed. RESULTS: The study included 76 men and 60 women, with a mean age of 59.2 years. Spontaneous nystagmus exhibited a sensitivity of 92%, whereas the absence of skew deviation was identified with a sensitivity of 98%. Abnormal bedside HIT showed a sensitivity of 87%. The combined HINTS (HIT, nystagmus, and test of skew) had a sensitivity of 83%. The Romberg test and Fukuda test demonstrated sensitivities of 26% and 48%, respectively. CONCLUSION: The sensitivity of bedside tests varied from 26% to 98%. This aligns with previous literature, highlighting the challenge of differentiating AUPVP from vestibular pseudoneuritis solely through bedside examination. Although the tests excel in excluding central causes, they are insufficient for diagnosing AUPVP with certainty. In addition, the bedside examination sensitivities vary widely, and early radiological imaging can be misleading. Therefore, this study underlines the necessity of prompt otoneurological testing for accurate exclusion of vestibular pseudoneuritis and thus improve patient outcomes.

The epidemiology of lymphatic filariasis in Ghana, explained by the possible existence of two strains of Wuchereria bancrofti.

INTRODUCTION: Lymphatic filariasis is a debilitating disease caused by the filarial worm Wuchereria bancrofti. It is earmarked for elimination by the year 2020 through the Global Program for the Elimination of LF (GPELF). In Ghana, mass treatment has been on-going since the year 2000. Earlier studies have revealed differing epidemiology of LF in the North and South of Ghana. This study was therefore aimed at understanding the possible impacts of W. bancrofti diversity on the epidemiology and control of LF in Ghana. METHODS: The Mitochondrial, Cytochrome C Oxidase I gene of W. bancrofti samples was sequenced and analyzed. The test sequences were grouped into infrapopulations, and pairwise differences (π) and mutation rates (θ) were computed. The amount of variance within and among populations was also computed using the AMOVA. The evolutionary history was inferred using the Maximum Parsimony method. RESULTS: Seven samples from the South and 15 samples from the North were sequenced, and submitted to GenBank with accession numbers GQ479497- GQ479518. The results revealed higher mutation frequencies in the southern population, compared to the northern population. Haplotype analyses revealed a total of 11 haplotypes (Hap) in all the 22 DNA sequences, with high genetic variation and polymorphisms within the southern samples. CONCLUSION: This study showed that there is considerable genetic variability within W. bancrofti populations in Ghana, differences that might explain the observed epidemiology of LF. Further studies are however required for an in-depth understanding of LF epidemiology and control.

Assessment of Spinothalamic Tract Function Beyond Pinprick in Spinal Cord Lesions: A Contact Heat Evoked Potential Study.

Background Although a mainstay of clinical sensory examination after damage in the spinal cord, pinprick sensation represents only one afferent modality conveyed in the spinothalamic tract. As an objective outcome, complementary information regarding spinothalamic tract conduction may be elucidated by measuring contact heat evoked potentials (CHEPs). Objective To assess the value of CHEPs to measure spinothalamic tract function in spinal cord disorders compared with pinprick scoring. Methods CHEPs were examined using a standard (35°C) and increased baseline (42°C) contact heat temperature. Pinprick sensation was rated as absent, impaired, or normal according to the International Standards for the Neurological Classification of Spinal Cord Injury. Results Fifty-nine dermatomes above, at, and below the sensory level of impairment were analyzed in 37 patients with defined spinal cord disorder. In dermatomes with absent or impaired pinprick sensation, CHEPs using a standard baseline temperature were mainly abolished (3/16 and 8/35, respectively). However, when applying an increased baseline temperature, CHEPs became recordable (absent: 11/16; impaired: 31/35). Furthermore, CHEPs with increased baseline temperature allowed discerning between dermatomes with absent, impaired, and normal pinprick sensation when using an objective measure (ie, N2P2 amplitude). In contrast, the pain perception to contact heat stimulation was independent of pinprick scores. Conclusion Applying pinprick testing is of limited sensitivity to assess spinothalamic tract function in spinal cord disorders. The application of CHEPs (using standard and increased baseline temperatures) as an objective readout provides complementary information of spinothalamic tract functional integrity beyond pinprick testing.

Differences in cortical coding of heat evoked pain beyond the perceived intensity: an fMRI and EEG study.

Imaging studies have identified a wide network of brain areas activated by nociceptive stimuli and revealed differences in somatotopic representation of highly distinct stimulation sites (foot vs. hand) in the primary (S1) and secondary (S2) somatosensory cortices. Somatotopic organization between adjacent dermatomes and differences in cortical coding of similarly perceived nociceptive stimulation are less well studied. Here, cortical processing following contact heat nociceptive stimulation of cervical (C4, C6, and C8) and trunk (T10) dermatomes were recorded in 20 healthy subjects using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG). Stimulation of T10 compared with the C6 and C8 revealed significant higher response intensity in the left S1 (contralateral) and the right S2 (ipsilateral) even when the perceived pain was equal between stimulation sites. Accordingly, contact heat evoked potentials following stimulation of T10 showed significantly higher N2P2 amplitudes compared to C6 and C8. Adjacent dermatomes did not reveal a distinct somatotopical representation. Within the assessed cervical and trunk dermatomes, nociceptive cortical processing to heat differs significantly in magnitude even when controlling for pain perception. This study provides evidence that controlling for pain perception is not sufficient to compare directly the magnitude of cortical processing [blood oxygen level dependence (BOLD) response and amplitude of evoked potentials] between body sites.

Acute effects of heroin on emotions in heroin-dependent patients.

BACKGROUND: Euphoria has been described in heroin-dependent individuals after heroin administration. However, affective disturbances and disorders are common in heroin dependence. The present study examined the acute effects of heroin on emotions in heroin-dependent patients. METHODS: This randomized controlled crossover trial included 28 heroin-dependent patients (67.9% male, n = 19) in stable heroin-assisted treatment and 20 healthy controls. The patients were administered heroin or saline (placebo), the controls were administered saline. Data measuring mood, affects and heroin craving (BDI, AMRS, STAI, STAXI, and HCQ) were assessed before and 60 minutes after substance injection. RESULTS: Before substance injection, heroin-dependent patients showed significantly higher levels of anxiety and depression than healthy controls (p < .0001). Heroin administration-but not placebo administration-was associated with a significant decrease in all negative emotions, including craving, and a significant increase in emotional well-being (p < .0001), irrespective of perceived intoxication and sedation. After the experiment, the patients did not differ from healthy controls in their emotions, once they had received heroin. CONCLUSIONS: Heroin dampens craving, negative emotions, and increases positive emotions. These findings indicate that heroin regulates emotions and underscore the clinical benefit of opioid substitution treatment for heroin-dependent patients.

Differences in spinothalamic function of cervical and thoracic dermatomes: insights using contact heat evoked potentials.

INTRODUCTION: After spinal cord injury, contact heat evoked potentials (CHEPs) may represent a means to refine the clinical assessment of sensory function from each spinal cord segment by quantifying nociception, including conduction along the spinothalamic tract. METHODS: The influence of stimulation site (i.e., dermatomes) on CHEPs and thermal thresholds in 19 healthy subjects (mean age, 45.2 ± 18.3 years) divided into 2 age classes (younger subjects, n = 10; mean age, 28.8 ± 5.2 years; older subjects, n = 9; mean age, 63.4 ± 3.4 years) at 5 different dermatomes (C4, C5, C6, C8, and T4) was assessed. RESULTS: In terms of distance from the body midline (i.e., spinal cord entry), there was a reduction in CHEP amplitudes from proximal (C4 and T4) to distal (C6 and C8) dermatomes with a corresponding reduction in nociceptive perception (i.e., pain threshold and rating). Within primary and secondary cortical sensory areas, including areas associated with affective noxious processing, the cortical source density analysis showed a similar current density distribution between C4 and C8 dermatomes but consistent higher current densities for C4. CONCLUSIONS: The study supports CHEPs as a feasible tool for assessing discrete dermatomes corresponding to spinal cord segments. The results suggest that the proximodistal pattern in the intensity of perceived pain and CHEP amplitudes is likely attributable to the distribution of heat nociceptors and the increase in conduction distance from proximal to distal dermatomes. The present findings emphasize on the importance that if patients are assessed segment by segment, the underlying topographical differences need to be accounted for.

Improved diagnosis of spinal cord disorders with contact heat evoked potentials.

OBJECTIVE: To evaluate the sensitivity of contact heat evoked potentials (CHEPs) compared with dermatomal somatosensory evoked potentials (dSSEPs) and clinical sensory testing in myelopathic spinal cord disorders (SCDs). METHODS: In a prospective cohort study, light-touch (LT) and pinprick (PP) testing was complemented by dermatomal CHEPs and dSSEPs in patients with a confirmed SCD as defined by MRI. Patients with different etiologies (i.e., traumatic and nontraumatic) and varying degrees of spinal cord damage (i.e., completeness) were included. SCD was distinguished into 3 categories according to MRI pattern and neurologic examination: a) complete, b) incomplete-diffuse, and c) central or anterior cord damage. RESULTS: Seventy-five patients were included (complete n = 7, incomplete-diffuse n = 33, central/anterior n = 35). In total, 319 dermatomes were tested with combined CHEPs and dSSEPs. CHEPs, dSSEPs, and clinical sensory testing were comparably sensitive to detect the myelopathy in complete (CHEPs 100%, dSSEPs 91%, PP and LT 82%) and incomplete-diffuse (CHEPs 92%, dSSEPs and PP 86%, LT 81%, p > 0.05 for all comparisons) cord damage. In central/anterior cord damage, CHEPs showed a significantly higher sensitivity than dSSEPs (89% compared with 24%, p < 0.001) and clinical sensory testing (PP 62%, LT 57%, p < 0.05). A subclinical sensory impairment was detected more frequently by CHEPs than dSSEPs (60% compared with 29%, p = 0.001). CONCLUSIONS: Assessment of spinothalamic pathways with CHEPs is reliable and revealed the highest sensitivity in all SCDs. Specifically in incomplete lesions that spare dorsal pathways, CHEPs are sensitive to complement the clinical diagnosis.

Test-retest reliability of contact heat-evoked potentials from cervical dermatomes.

The purpose of this study was to investigate the test-retest reliability of contact heat-evoked potentials (CHEPs) in neurologically healthy subjects from cervical dermatomes (C4-C8). Seventeen individuals underwent test-retest examination of cervical CHEPs. Peak latencies and peak-to-peak amplitude of N2-P2 and ratings of perceived intensity were analyzed using test-retest reliability statistics (intraclass correlation coefficients [ICCs] and Bland-Altman confidence parameters). For comparison, a group of similar age and gender was also examined with dermatomal somatosensory-evoked potentials (dSSEPs, n = 17). The ICC values for CHEP latency and amplitude parameters were significant (P < 0.05) and corresponded to at least "fair" reliability, while peak-to-peak amplitude demonstrated "substantial" (≥0.81) reliability for all dermatomes. The coefficients of repeatability (i.e., 2SD of the difference between examinations) confirm that CHEPs and dSSEPs are reliable according to measures of latency. Superior peak-to-peak amplitude test-retest reliability was found for CHEPs. In conclusion, the test-retest reliability of dSSEP and CHEP parameters supports the fact that these outcomes can be used to objectively track changes in spinal conduction in the dorsal column and spinothalamic tract, respectively. The reliable acquisition of CHEPs may depend on the intensity of the sensation reported by the subject for a given area of skin stimulated.

The effects of practice distribution upon the regional oscillatory activity in visuomotor learning.

BACKGROUND: The aim of this study was to investigate the effects of a massed compared to a distributed practice upon visuomotor learning as well as upon the regional oscillatory activity in the sensorimotor cortex. METHODS: A continuous visuomotor tracking task was used to assess visuomotor learning; the underlying neuronal correlates were measured by means of EEG. The massed practice group completed a continuous training of 60 minutes, while the distributed practice group completed four 15 minutes practice blocks separated by rest intervals. RESULTS: While the massed and the distributed practice group did not differ in performance, effects of practice distribution were evident in the regional oscillatory activity. In the course of practice, the massed training group showed a higher task-related theta power and a strong task-related power decrease in the upper alpha frequency over the sensorimotor cortex compared to the distributed practice group. CONCLUSIONS: These differences in the regional oscillatory activity indicate a higher cognitive effort and higher attention demands in the massed practice group. The results of this study support the hypothesis, that a distributed practice is superior to a massed practice in visuomotor learning.

Coherent intracerebral brain oscillations during learned continuous tracking movements.

The aim of the present study was to assess changes in electroencephalogram (EEG) phase locking between fronto-parietal areas, including the frontal and parietal motor areas, during audiomotor learning of continuous tracking movements. Subjects learned to turn a steering wheel according to a given trajectory in order to minimise the discrepancy between a changing foreground stimulus (controllable by the subjects) and a constant background stimulus. The results of the present study show that increasing practice of continuous tracking movements that are continuously performed in the presence of auditory feedback is not accompanied by decrease in phase locking between areas involved. Moreover, the study confirms that internally produced movements show enhanced coherent activities compared to externally guided movements and therefore suggests that the motor-parietal network is more engaged during internally produced than externally produced movements.

Coherence and phase locking of intracerebral activation during visuo- and audio-motor learning of continuous tracking movements.

The aim of the present study was to assess changes in EEG coherence and phase locking between fronto-parietal areas, including the frontal and parietal motor areas, during early audio- and visuo-motor learning of continuous tracking movements. Subjects learned to turn a steering-wheel according to a given trajectory in order to minimise the discrepancy between a changing foreground stimulus (controllable by the subjects) and a constant background stimulus (uncontrollable) for both the auditory and the visual modality. In the auditory condition, we uncovered a learning-related increase in inter-hemispheric phase locking between inferior parietal regions, suggesting that coupling between areas involved in audiomotor integration is augmented during early learning stages. Intra-hemispheric phase locking between motor and superior parietal areas increased in the left hemisphere as learning progressed, indicative of integrative processes of spatial information and movement execution. Further tests show a significant correlation of intra-hemispheric phase locking between the motor and the parietal area bilaterally and movement performance in the visual condition. These results suggest that the motor-parietal network is operative in the auditory and in the visual condition. This study confirms that a complex fronto-parietal network subserves learning of a new movement that requires sensorimotor transformation and demonstrates the importance of interregional coupling as a neural correlate for successful acquisition and implementation of externally guided behaviour.