No description available.

No description available.

No description available.

Title: H-reflex, depending on the position of the joint Aim: The aim of this study is to determine whether the position of the ankle joint influences the parameters of the soleus muscle H-reflex. We are interested in a change of amplitude, latency and threshold of the H-reflex. Method: To measure H-reflex, we have used surface elektromygraphy. We examined two different positions of the foot in probands lying on the bed on their stomach. The first position was with the feet out of bed, around 90 degrees at the ankle joint (rest position). At the second position, the foot moved the bed and was in position in plantar flexion. Stimulation were performed over the tibial nerve in the popliteal fossa. The response, we recorded the surface electrode over the soleus muscle. Results: By changing the position of the ankle from rest to plantar flexion there was no statistically significant changes in amplitude, latency or threshold of the H-reflex. In plantar flection, we found a reduction of Hmax/Mmax ratio, which is probably due to reduced excitability alpha motoneurons through reciprocal ihibition from stretched muscle of the leg. Keywords: H-reflex, soleus muscle, joint position, surface EMG

Název práce: Náborová křivka H-reflexu v diagnostice radikulárních syndromů Cíle práce: Ověření spolehlivosti vyšetření náborové křivky H-reflexu a M-vlny diagnostice kompresivní radikulopatie Metody práce: U 24 osob s jednostranným kořenový syndromem S1 byl vyšetřen H-reflex m. soleus oboustranně bipolární stimulací n.tibialis v popliteální jamce. Elektromyografický signál byl digitalizován a následně byla hodnocena data pro asymptomatickou a symptomatickou končetinu. Hodnoceny byly prahy pro vyvolání H-reflexu a M-vlny, latence a amplitudy H-reflexu a M-vlny, strmost náborové křivky, její maxima Hmax. a Mmax. a poměr Hmax/Max . Tyto hodnoty pro symptomatickou stranu a asymptomatickou stranu byly statisticky porovnány. Výsledky: Výsledky měření potvrdily, že vyšetření náborové křivky H-reflexu je vhodnou diagnostickou metodou k objektivizaci radikulopatie S1. Na symptomatické straně došlo k signifikantnímu poklesu Mmax., Hmax, poměru Hmax/Mmax a sklonu náborové křivky H-reflexu. Klíčová slova: radikulopatie, EMG, H-reflex, M-vlna, náborová křivka

Dissertation submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree Master of Science. 2013 / The Babinski sign is a pathological response elicited by a stimulus to the lateral plantar border of thesole of the foot. The resulting reflex involves dorsiflexion (upward motion) of the toes, most notably the hallux, with accompanying flexion in the ankle, knee and hip. It is an important part of the clinical neurological examination and aids in the diagnosis of central nervous system dysfunction. There is however no wholly standardised method to elicit this reflex or interpret it, resulting in possible variation in its utility. The resulting aim of the studies constituting this dissertation were therefore to: 1) assess what techniques and pressures are used to elicit the reflex in a group of neurologists;2) to investigate the relationship between input variables of the reflex and the resultant output variables as measured with the use of electromyography and kinematics;3) compare objective variables, relating to toe, foot and leg movement, of the pathological reflex to the healthy response; 4) assess the inter-rater reliability of the reflex and 5) determine what aspects of the reflex are most closely related to the ratings of the students and neurologists. A specialized custom-built Babinski hammer was constructed to measure the duration of the stroke and pressures exerted on the foot of a single healthy subject by neurologists (n=12). The relationship between the recorded pressures and the movement of the toes (measured kinematically), muscle activity in the tibialis anterior and the pain felt by the subject (gauged using a visual analogue scale) were evaluated. Following this, the average pressure used by the neurologists was used to elicit the reflex in six patients with known positive Babinski responses and six healthy gender and age matched controls. These reflexes were compared with kinematic (measurement of toe, foot and leg movement) and electromyographic (muscle activity of the involved muscles) methods. These reflexes were recorded and the recorded footage was shown to 12 medical students and 12 neurologists who were asked to interpret if 3 the responses were pathological or non-pathological. Kinematic and electromyographic descriptions of each reflex made it possible to assess what aspects of the reflex are important for classification of a pathological response for both medical students and neurologists. A large amount of intra- and inter-rater variability was shown amongst the neurologists in how they elicited the reflex. The amount of pressure applied was shown to be significantly related to hallux movement (p<0.01) as well as to the degree of pain felt by the subject (p<0.01). Significant differences were found between the patients and controls for change in hallux angle (p<0.0001), movement latency (p<0.05)and the maximum electromyographic amplitude of tibialis anterior(p<0.01). The inter-rater reliability of the medical students and the neurologists showed substantial agreement between raters (kappa = 0.67 and 0.72 respectively). Both neurologists and students made use of the change in hallux angle, time taken to reach maximum ankle angle, movement latency and the maximum amplitude of gastrocnemius when rating the reflex. Neurologists alone observed time taken to reach maximum hallux angle and change in ankle angle as being important while medical students‘ alone looked at maximum amplitude of biceps femoris. In conclusion, I found a large variation between the techniques of neurologists when assessing the Babinski reflex. This variation is related to variation in aspects of the resultant reflex. The pathological response (the Babinski sign) has shorter movement latency and less activity in the tibialis anterior muscle than the flexor response seen in healthy individuals. Ratings of pre-recorded Babinski responses had substantial agreement when both neurologists and medical students assessed pathology. In order to assess them both groups made use of the speed of the reflex, the direction of hallux movement and concurrent withdrawal activity in the leg to differentiate between a pathological and a healthy response.

Vagal and spinal sensory afferent innervation are responsible for to regulation of neurogenic inflammation in the airways. Neurogenic inflammation is a complex process involving vasodilatation,plasma protein extravasation and edema,glandular secretion and immunoinflammatory cell chemotaxis and activation. Plasma extravasation is the result of the activation of sensory nerve endings and the subsequent prodution of neuropeptides, namely, tachykinins such as substance P, neurokinin A and neurokinin B. SP was more potent than NKA or NKB in increasing microvascular permeability, which indicate that tachykinin NK-1 receptors are mainly involved in neurogenic inflammation in the airways of rat. When 6-hydroxydopamine¡]6-OHDA¡^was infused into the tracheal lumen,it causes plasma extravasation in the tracheal mucosa mediated by sensory nerve axons. Local application of 6-OHDA to stellate ganglion, had no effect on neurogenic inflammation and SP-IR innervation in the airways.The present study was to investigate the effect of intravenous injection of 6-OHDA on plasma leakage in the airways.This study also used the NK-1 receptor antagonist L-732,138 to investigate if 6-OHDA-induced plasma leakage in the airways was related to NK-1 receptors. India ink was used as tracer dye to label the leaky microvessels to evaluate the magnitude of inflammation . We found that 6-OHDA in the doses of 25 mg/kg and 50 mg/kg caused an extensive increase in plasma extravasation in the trachea and bronchi. But the vehicle¡]1 ¢ML-ascorbic acid and 0.4 ¢MNaCl, pH 3.4¡^caused a slight plasma leakage. Intravenous administration of L-732,138 decrease 6-OHDA induced plasma leakage. But one week after vagal transection, 6-OHDA-induced plasma extravasation in the ipsilateral airways was not significatly reduced. It is suggested that intravenous 6-OHDA stimulated bronchopulmonary C-fibers and resulted in vagal C-fiber release of tachykinins that produced acute inflammation in the lower airways. Intravenous application of L-732,138 significantly reduced the 6-OHDA-induced plasma leakage, suggesting that NK-1 receptors in the venular endothelial cells mediate the inflammatory response in the layynx,trachea,bronchi.and esophagus of the rat .

The aim of this study was to determine whether there was an association between a failed test of cough reflex sensitivity and history of chest infection in a general population of rest home residents. One hundred rest home residents from four different levels of care (rest home, hospital, dementia and psycho-geriatric) were recruited and their cough reflex assessed using a solution of 0.6 Mol/L citric acid nebulised and presented via a facemask.Participant’s records were then checked to see if there were any documented episodes of chest infection in the 6 month period prior to cough reflex testing.The results showed that out of 100 participants, 4 failed the cough reflex test. Of the 4 that failed the test, 3 had no documented episodes of chest infections recorded in the 6 month period prior to cough reflex testing. Data was not available for one participant who was deceased by the time of collection of the second data set. As such, there was no direct association demonstrated between a failed cough reflex test and development of chest infection or aspiration pneumonia. The results of the study are unexpected in two ways. Firstly, the relatively low number of participants who failed the cough reflex test is surprising as 72% of the participants for whom a full data set was obtained had neurological conditions that are known predisposing factors for reduced cough reflex sensitivity. Secondly, the finding of no association between a failed cough reflex test and history of recorded chest infection is not consistent with other studies. There is however an established body of research that indicates the causes of aspiration pneumonia are multifactorial and not solely dependent upon aspiration. The characteristics of participants and the implications of the findings are described. The potential use of cough reflex testing as a tool to screen against the risks of silent aspiration in relation to assessment of oro-pharyngeal dysphagia in this frail, elderly population is discussed.

No description available.

The visual grasp reflex provides automatic orienting of gaze (the visual axis in space) to novel visual stimuli. Previous studies have demonstrated activation of neck muscles of awake monkeys appearing at a short fixed latency (55 to 95 ms) after visual target presentation, regardless of whether or when saccades are made. The purpose of these early visually-driven muscle activations may be to prime head rotation required as a part of the coordinated eye-head movement to the target. Similar orienting responses might be found for visually guided reaching. Here, we explore early visually-driven muscle activations of the human upper limb immediately preceding planar reaching movements. Subjects performed reaches towards small visual peripheral targets while upper limb kinematics were recorded and intramuscular electromyography was collected from four shoulder and elbow muscles. Subjects maintained their right hand at a central fixation marker that was extinguished for a gap period (200 ms) prior to appearance of a peripheral target. Subjects were instructed to reach to the target as quickly as possible. Some subjects exhibited a short burst of muscle activity (about 20 ms duration) time-locked to visual target onset. This burst occurred around 85 ms to 105 ms after target onset and preceded the onset of muscle activity associated with volitional arm motion by about 100 ms. Notably, this burst was dependent on target location: visually-driven muscle activity occurred in right shoulder extensor muscles for rightward targets and was absent for leftward targets. In order to better dissociate the visual burst from volitional motor activity, we employed a delay paradigm. No time-locked muscle activity was present in the delay task either after the target appeared or after the fixation marker was extinguished. This suggests that the visual burst is dependent on the imminence of voluntary movement and the laterality of the target. We conclude that the appearance of a visual target can result in short-latency activity on the arm musculature that is appropriate for orienting the arm to the target. / Thesis (Master, Neuroscience Studies) -- Queen's University, 2007-09-27 09:42:55.337