Distribution of amygdala input to the nucleus accumbens septi: An electrophysiological investigation

Summary The nucleus accumbens septi (NAS) receives afferent input from the amygdala via the stria terminalis and from the hippocampus via the fimbria. Extracellular recordings from 196 NAS neurons in halothane-anesthetized rats revealed heterogeneous response patterns following stimulation of the amygdala. The observation that 30% of anterior NAS units but only 16% of posterior NAS units were responsive to amygdala stimulation suggested a topographical arrangement of amygdala efferents. Comparing the effects of amygdala and fimbria stimulation revealed that the two afferent pathways converge onto individual NAS neurons, but that the two sites of stimulation can differentially influence other neurons. The present results clarify the topographical distribution of amygdala input to the NAS, confirm that inputs from two limbic structures are integrated within the NAS, and further illustrate the electrophysiological heterogeneity of NAS neurons.     

A descriptive investigation of dysphagia in adults with intellectual disabilities

Background   Dysphagia has rarely been investigated in adults with intellectual disabilities (ID) despite being a serious condition affecting health and quality of life.
Method   This study collected information about 101 adults with ID, living in community settings, referred for an assessment of their eating and drinking. Ninety-nine people were classified as having dysphagia from clinical and videofluoroscopic assessments. This information was used to give an indication of the prevalence of dysphagia in adults with ID and identify the co-occurrence of physiological and anatomical indicators and associated negative health conditions.
Results   Details of the characteristics and conditions associated with dysphagia are provided. These include cerebral palsy, increased physical disability and cognitive impairment. A tentative indication of the current prevalence of dysphagia was found (8.15%).
Conclusion   Findings indicate that dysphagia is a significant issue for people with ID warranting further investigation. Practice implications detailed include increasing awareness of 'at risk' groups, changes in dysphagia with ageing, medication use and illness, and how findings can inform assessment and training.     

Intraluminal impedance detects failure of pharyngeal bolus clearance during swallowing: a validation study in adults with dysphagia

Abstract  Multichannel intraluminal impedance (MII) detects bolus flow through a healthy pharynx. The aim of this study was to determine whether the technique detects bolus flow and retention in patients with pharyngeal dysphagia; develop appropriate impedance-based criteria for assessing patients and to provide some preliminary insights into the clinical utility of the technique. Pharyngo-oesophageal pressure and impedance were recorded simultaneously with videofluoroscopy (VF) during swallows in six patients with dysphagia. Agreement, as to the presence or absence of bolus material, between the VF and MII was expressed using the Cohen's Kappa statistic. To test whether the impedance criteria for the detection of bolus passage in dysphagia could be improved, a Kappa statistic was calculated in an iterative process for a range of impedance values (100%–0%) defining bolus head entry and bolus tail clearance from the pharynx. Bolus presence according to the MII criteria previously derived by us in healthy controls demonstrated a modest correlation with VF when applied to this dysphagia population [0.37, 0.5 and 0.58 in the hypopharynx, upper oesophageal sphincter (UOS) and proximal oesophagus respectively]. In the patient population, the optimal impedance criteria were 50% for bolus head entry and 20% for bolus tail clearance. Adopting these criteria demonstrated enhanced agreement between VF and impedance; yielding Kappa coefficients of 0.42 in the hypopharynx, 0.54 in the UOS and 0.62 in the proximal oesophagus. With the adoption of appropriate criteria, pharyngeal impedance measurement can accurately detect bolus passage and failed or impaired clearance during swallowing in patients with dysphagia.     

Reversible electrophysiological abnormalities in hypokalemic paralysis: Case report of two cases

Compound muscle action potential (CMAP) amplitude declines during a paralytic attack in patients with hypokalemic periodic paralysis (HPP). However, serial motor nerve conduction studies in hypokalemic paralysis have not been commonly reported. We report two cases with hypokalemic paralysis, who had severely reduced CMAPs in all motor nerves at presentation during the episode of quadriparesis. However, the amplitude of CMAPs increased and reached normal levels, as the serum potassium concentration and motor power returned to normal state.     

Sonographic analysis of laryngeal elevation during swallowing

Background: Swallowing disorders are common symptoms in many neurological diseases. The aim of this pilot-study was to analyse vertical laryngeal excursion during swallowing non-invasively using ultrasound sonographic techniques in patients with dysphagia compared with healthy volunteers. Methods: Data were obtained from 42 healthy volunteers (mean age: 57 ± 19 years) and 18 patients (mean age: 63 ± 8 years) with dysphagia due to different neurological diseases using a 7.5 MHz linear array probe, which was placed in longitudinal position above the larynx. This allowed visualization of the contour and the acoustic shadow of the hyoid bone and the thyroid cartilage. The distance between the hyoid bone and the upper end of the thyroid cartilage during laryngeal elevation was readily assessed by video-mode function. Results: In healthy subjects we found a mean distance of 220 (± 30) mm at rest; the shortest distance during swallowing of 5 or 10 ml water was 85 (± 11) mm and represents a reduction of 61 % (± 3) under physiological conditions. The mean relative laryngeal elevation in the patients with neurogenic dysphagia was reduced to only 42 % (± 10) (p < 0.0001). Conclusions: Ultrasound is a viable and non-invasive method in the investigation of laryngeal elevation during swallowing. It allows direct visualization of impaired laryngeal motion in patients with neurogenic dysphagia. Received: 29 May 2002, Received in revised form: 10 October 2002, Accepted: 21 October 2002 Correspondence to V. Kuhl, MD     

Neural activation of swallowing and swallowing‐related tasks in healthy young adults: An attempt to separate the components of deglutition

Understanding the underlying neural pathways that govern the highly complex neuromuscular action of swallowing is considered crucial in the process of correctly identifying and treating swallowing disorders. The aim of the present investigation was to identify the neural activations of the different components of deglutition in healthy young adults using functional magnetic resonance imaging (fMRI). Ten right‐handed young healthy individuals were scanned in a 3‐Tesla Siemens Allegra MRI scanner. Participants were visually cued for both a “Swallow” task and for component/control tasks (“Prepare to swallow”, “Tap your tongue”, and “Clear your throat”) in a randomized order (event‐related design). Behavioral interleaved gradient (BIG) methodology was used to address movement‐related artifacts. Areas activated during each of the three component tasks enabled a partial differentiation of the neural localization for various components of the swallow. Areas that were more activated during throat clearing than other components included the posterior insula and small portions of the post‐ and pre‐central gyri bilaterally. Tongue tapping showed higher activation in portions of the primary sensorimotor and premotor cortices and the parietal lobules. Planning did not show any areas that were more activated than in the other component tasks. When swallowing was compared with all other tasks, there was significantly more activation in the cerebellum, thalamus, cingulate gyrus, and all areas of the primary sensorimotor cortex bilaterally. Hum Brain Mapp 2009. © 2009 Wiley‐Liss, Inc.     

An electrophysiological investigation on typhoid polyneuritis

Polyneuritis is a rare neurological complication of typhoid fever. A clinical and electrophysiological investigation of a very severe and purely motor form of typhoid polyneuritis is reported.

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Sommario La polinevrite è una rara complicanza neurologica della febbre tifoide. Viene descritto un caso di una forma esclusivamente motoria di polinevrite tifica, clinicamente e elettrofisiologicamente ad evoluzione sfavorevole.

     

The importance of the reproducibility of oropharyngeal swallowing in amyotrophic lateral sclerosis. An electrophysiological study

Objective

To investigate electrophysiologically the reproducibility of oropharyngeal swallowing in patients with ALS.

An electrophysiological exploration of the double crush hypothesis

The double crush hypothesis has not been rigorously evaluated in humans. We therefore analyzed cases of C6, C7, and C8 radiculopathy and exploited the fact that the median sensory response is of C6/C7 origin and the median motor response is primarily of C8 origin. We hypothesized that C6 and/or C7 cases would demonstrate an increased frequency of median mononeuropathy by sensory criteria, and C8 cases would demonstrate an increased frequency of median mononeuropathy by motor criteria. We also hypothesized that median sensory and motor response parameters among these same groups would be altered in ways consistent with a proximal influence on distal nerve conduction studies. Although median mononeuropathy was unexpectedly common (22.1%) among cases of cervical radiculopathy (which may explain the clinical acceptance of the double crush hypothesis), none of the hypotheses was supported. This study identified no evidence to support a neurophysiological explanation for the double crush hypothesis. © 1999 John Wiley & Sons, Inc. Muscle Nerve 22: 71–77, 1999     

Myopathy in Marinesco-Sjögren syndrome: an electrophysiological study

ABSTRACT Electrophysiological studies were performed in 7 patients with Marinesco-Sjögren syndrome in order to search for neuromuscular involvement in this multiorgan disorder. In 6 patients muscle biopsies were also obtained. Light microscopic examinations of the biopsies showed extensive myopathic changes, and in two patients ragged red fibers were found. Electron microscopy showed subsarcolemmal accumulation of abnormal mitochondria in all. Concentric needle EMG revealed unequivocal myopathic changes, more extensive in the anterior tibial than in the biceps brachii muscle. Motor and sensory conduction velocities in the peripheral nerves were normal. There were remarkably high amplitudes of sensory responses. Macro EMG studies in the biceps brachii muscle in four patients showed increased amplitude and area of the macro MUPs. This may be due to abnormal membrane function. Both electrophysiological and morphological findings confirm myopathic features of Marinesco-Sjögren syndrome.     

Comparative electrophysiological study of response to botulinum toxin type B in Japanese and Caucasians

Ethnic differences in the muscle‐relaxing effect of botulinum toxin type B (BTX‐B) were examined by means of electrophysiological measurements in Japanese and Caucasian volunteers. This was a randomized, single‐blinded, single‐center study of 24 Japanese and 24 Caucasian healthy adult male subjects in Japan. BTX‐B (20 U, 100 U, or 500 U/0.2 mL) or placebo was administered to the extensor digitorum brevis (EDB) muscle in the left lower limb as a single dose (in each dose group, 6 subjects received the test drug and two received placebo). The inhibitory effect of BTX‐B on the M wave amplitude of EDB muscle generated by stimulation of the deep peroneal nerve was measured frequently during 2 weeks after administration, and then at weeks 4 (day 28) and 12 (day 84). The inhibitory effect of BTX‐B on the M wave amplitude of EDB muscle was dose‐dependent in both Japanese and Caucasian subjects, and the dose‐response curves were similar. These findings demonstrate that the muscle‐relaxing effect of BTX‐B in Japanese subjects is electrophysiologically similar to that in Caucasians. © 2007 Movement Disorder Society     

An electrophysiological investigation of discourse coherence in healthy adults

This study used event-related potentials (ERPs) to investigate discourse-coherence processing. Because there are scant data on ERP indices of discourse coherence in typical adults, it is important to study a non-clinical population before examining clinical populations. Twelve adults listened to a story with sentences in a coherent versus incoherent order. Sequences of nonsense syllables served as a control. ERPs in the 200–400?ms time window, reflecting phonological and lexical processing, and in the 600–900?ms time window, reflecting later discourse processing for integration, were investigated. Results revealed a right anterior and posterior positivity that was greater for coherent than for incoherent discourse during the 600–900?ms time window. These findings point to an index of discourse coherence and further suggest that ERPs can be used as a clinical tool to study discourse-processing disorders in populations with brain damage, such as aphasia and traumatic brain injury.     

An electrophysiological investigation of skeletal muscle in Parkinson's disease

Thirty-one patients with Parkinson's disease were subjected to an electrophysiological study of the extensor digitorum brevis (EDB) muscle and its motor innervation.Twenty-two patients showed a reduction of the number of functional motor units in the EDB and many of the surviving units were abnormally large. Eight patients showed a prolonged terminal latency on stimulation of the deep peroneal nerve and finally, 11 patients showed a decremental response in the EDB on repetitive stimulation of the deep peroneal nerve.The observations have been interpreted as indicating both a loss and dysfunction of the α-motoneurones innervating skeletal muscle in Parkinson's disease.