Afferent Impulses Research Articles

Real‐time activation of central cholinergic circuits during recognition memory

Short latency afferent inhibition (SAI) is a paired-pulse transcranial magnetic stimulation (TMS) protocol that consists in the inhibition of the motor evoked potentials (MEPs) by afferent sensory impulses. SAI is thought to be mediated by cholinergic projections over M1 and can be considered a putative marker of central cholinergic activity. It is known that memory processes are regulated by acetylcholine. Nonetheless, the influence of memory tasks on SAI has not been investigated. Here we tested changes in SAI circuits in healthy subjects performing a computerized non-verbal recognition memory task (RMT) requiring to recognize previously encoded faces. SAI protocol was recorded during five phases of the RMT: baseline, encoding, consolidation, retrieval, and post-task. In the control task, subjects were asked to judge a visual feature of not previously presented faces. SAI protocol was applied over the same conditions as in the RMT. We found that SAI remarkably increases during the retrieval phase of the RMT as compared to baseline. On the other hand no change was observed during the control task. These findings show that SAI can be modulated by ongoing memory processes and support the hypothesis that SAI can be considered as a neurophysiological marker of central cholinergic activity.

Serotonergic transmission at Merkel discs: modulation by exogenously applied chemical messengers and involvement of Ih currents.

The Merkel disc is a main type of tactile end organ consisting of Merkel cells and Aβ-afferent endings that responds to tactile stimulation with slowly adapting type 1 (SA1) afferent impulses. Our recent study has shown that Merkel discs in whisker hair follicles are serotonergic synapses using endogenous serotonin to transmit tactile signals from Merkel cells to Aβ-afferent endings. In this study, we hypothesize that tactile sensitivity of Merkel discs can be modulated by chemical messengers. We tested this hypothesis by determining whether and how SA1 responses of mouse whisker hair follicles may be affected by exogenously applied chemical messengers. We found that SA1 responses were potentiated by serotonin at low concentration (10μM) but almost completely occluded by serotonin at high concentration (2mM). In contrast, SA1 responses were not significantly affected by ATP and its metabolically stable analog α,β-methylene-ATP, glutamate, γ-aminobutyric acid (GABA), and histamine. SA1 responses were also not affected by antagonists for P2X receptors, ionotropic glutamate receptors, and ionotropic GABA and glycine receptors. Whole-cell patch-clamp recordings reconfirm the presence of both ionotropic and metabotropic 5-HT receptors on afferent neurons and their terminals innervating whisker hair follicles. All whisker afferent neurons expressed hyperpolarization-activated inward currents (Ih ), which are potentiated by serotonin through the activation of metabotropic 5-HT receptors. Taken together, the findings substantiate the serotonergic mechanism of tactile transmission at Merkel discs and identify the involvement of Ih currents in postsynaptic excitatory actions of serotonin. In addition, the findings do not favor any significant involvement of ATP, glutamate, histamine, GABA, or glycine in tactile transmission at the Merkel discs of whisker hair follicles.

GABAA Receptors: Involvement in the Formation of Respiratory Reactions to Hypoxic Stimulation under Conditions of Mitochondrial Dysfunction

In experiments on Wistar rats, the role of the state of GABAA receptors in the formation of respiratory responses to hypoxic loading was studied under conditions of the norm and experimental mitochondrial dysfunction; the latter was induced by single systemic injections of 3 mg/kg rotenone, a nonselective blocker of complex I in the respiratory chain of the mitochondria. Volume-time parameters of respiration were characterized according to the parameters of respiratory EMG discharges of the diaphragmatic muscle (amplitude, frequency, and integral intensity). Changes in EMG activity of the diaphragm induced by inhalation of a hypoxic gas mixture (12% О2 + 88% N2) were estimated prior to and after injections of the blocker of GABAA and GABAB receptors bicuculline (bicuculline methiodide, 1.0 mg/kg) in control rats and animals with mitochondrial dysfunction. The development of mitochondrial dysfunction was accompanied by suppression of the respiratory reaction to hypoxic loading, which was manifested in a dramatic decrease in the frequency and integral intensity of EMG discharges of the diaphragmatic muscle. These data can be considered an indication of the considerable involvement of GABAA receptors localized at the postsynaptic membranes of peripheral chemoreceptors in the formation of respiratory response to hypoxic stimulation (including the stage of depression of ventilation); this was observed in both control rats and animals with mitochondrial dysfunction. The involvement of a GABA-ergic link in the formation of respiratory activity related to hypoxic stimulation acquires special significance under conditions of experimental mitochondrial dysfunction leading to occlusion of afferent impulsation coming from peripheral chemoreceptors.

Tenth case of bilateral hemifacial spasm treated by microvascular decompression: Review of the pathophysiology.

Background:Bilateral hemifacial spasm (BHFS) is a rare neurological syndrome whose diagnosis depends on excluding other facial dyskinesias. We present a case of BHFS along with a literature review.Methods:A 64-year-old white, hypertense male reported involuntary left hemiface contractions in 2001 (aged 50). In 2007, right hemifacial symptoms appeared, without spasm remission during sleep. Botulinum toxin type A application produced partial temporary improvement. Left microvascular decompression (MVD) was performed in August 2013, followed by right MVD in May 2014, with excellent results. Follow-up in March 2016 showed complete cessation of spasms without medication.Results:The literature confirms nine BHFS cases bilaterally treated by MVD, a definitive surgical option with minimal complications. Regarding HFS pathophysiology, ectopic firing and ephaptic transmissions originate in the root exit zone (REZ) of the facial nerve, due to neurovascular compression (NVC), orthodromically stimulate facial muscles and antidromically stimulate the facial nerve nucleus; this hyperexcitation continuously stimulates the facial muscles. These activated muscles can trigger somatosensory afferent skin nerve impulses and neuromuscular spindles from the trigeminal nerve, which, after transiting the Gasser ganglion and trigeminal nucleus, reach the somatosensory medial posterior ventral nucleus of the contralateral thalamus as well as the somatosensory cortical area of the face. Once activated, this area can stimulate the motor and supplementary motor areas (extrapyramidal and basal ganglia system), activating the motoneurons of the facial nerve nucleus and peripherally stimulating the facial muscles.Conclusions:We believe that bilateral MVD is the best approach in cases of BHFS.

The Effect of Anesthesia on Thyroid Hormones and Cortisol Levels Following Major Urological Surgery

This study was designed to evaluate the effect of anesthesia on thyroid hormones (T3, T4, rT3), thyrotropin(TSH), and cortisol levels in patients undergoing major urological surgery. The study included fifty patients scheduled for elective major urological surgery where 70% of the patients underwent general anesthesia, while30% underwent regional anesthesia. All patients were in stable control general conditions. The study showed that the thyroid hormones, thyrotropin and cortisol levels were affected with general anesthesia more than regional. The levels of these hormones responded to anesthetics and surgical stresses. This response was thought to be mainly mediated by afferent neurogenic impulses from the area of injury. Therefore, abolition of sensory as well as autonomic afferent stimuli by neurogenic blockaded types of anesthesia such as (epidural anesthesia) that may help in reducing the excretion and metabolic response to surgery.

Central regulation of pain in patients with joint disease and approaches to therapy

The paper reviews investigations studies that have demonstrated that chronic pain syndrome is mixed in rheumatic diseases. The nervous system is involved in its pathogenesis with different frequency and different mechanisms. Under the influence of afferent pain impulses from damaged joints, there are changes in the excitability of spinal cord neurons, which is called central sensitization (CS). A number of patients have enhanced CS and clinical manifestations as neuropathic sensitive phenomena. The mixed model of the development of chronic pain in joint diseases and its presence along with nociceptive (inflammatory) and neuropathic pain components may explain the discrepancy between joint inflammatory and structural changes and pain intensity, the presence of distant pain and sensitive disorders in the areas outside the joint, and sometimes the efficiency of anti-inflammatory therapy. The presence of the neuropathic pain component serves as a rationale for combined therapy by adding centrally acting drugs, such as anticonvulsants.

Local Anaesthetic Effect of Methanolic Leaves Extract of Lannea schimperi (Hoschst. Ex Rich) Eng.

Local anaesthetics provide relief from pain when applied locally to nerve tissue by blocking conduction of sensory nerve impulse from the receptor to the brain cortex. This study aimed at evaluating local anaesthetic activity of the methanolic leaves extract of Lannea schimperi. Six groups of five animals were used; groups I-IV were used for intracutaneous wheal test in guinea pigs for infiltration anaesthesia, while group V and VI were used for guinea pig corneal reflex method of surface anaesthesia. The result indicated a significant ( 0.05) dose dependent local anaesthetic activity of the methanolic leaves extract of Lannea schimperi with faster onset and longer duration of action at 24 mg/ml than at 12 mg/ml of the extract. Additions of 5 μg of adrenaline into the 24 mg/ml preparation also prolonged the duration of local anaesthetic activity of the extract. The extract at 24 mg/ml significantly (0.05) inhibited corneal reflex, lidocaine was used as a standard drug in positive control group, while normal saline was used as negative control in all the treated groups. The patent data therefore revealed that the methanolic leaves extract Lannea schimperi possess local anaesthetic principles that may require further scientific elucidation.

Neurological Disease Burden in Geriatric Patients: Bangladesh Perspectives

No Abstract is availableJournal of Current and Advance Medical Research 2016;3(1):1

Potential Future Pharmacological Treatment of Bladder Dysfunction.

In the last decades, a number of new antimuscarinic drugs have been introduced for treatment of the overactive bladder (OAB), defined symptomatically (OAB syndrome) or urodynamically (detrusor overactivity). Recently, three new drug principles have been approved for clinical use, the β3 -adrenoceptor agonist, mirabegron, the phosphodiesterase-5 inhibitor, tadalafil and the blocker of afferent and efferent nerves, botulinum toxin. However, new alternatives are continuously being explored. OAB is a filling disorder, and ATP is involved in the generation of afferent impulses. One way of blocking the ATP afferent pathway is through the use of P2X3 receptor antagonists. In animal models, this strategy appears to work very well, but whether it translates effectively to man remains to be established. Evidence suggests that components of the endocannabinoid system are involved in regulation of bladder function. Clinical studies of cannabinoid extracts on LUTS are scarce and essentially restricted to patients with MS, and the results have so far not been convincing. Amplification of endocannabinoid activity by inhibiting their degradation via fatty acid amide hydrolase inhibitors may be an attractive approach, but no clinical experiences in OAB have been reported. Studies of the lower urinary tract have indicated that several transient receptor potential (TRP) channels, including TRPV1, TRPV2, TRPV4, TRPM8 and TRPA1, are expressed in the bladder and may act as sensors of stretch and/or chemical irritation. Animal studies have shown that inhibition of these pathways can be effective for the reduction in bladder activity. However, the roles of these channels for normal function and in pathological states have not been established, and so far adverse effects (hyperthermia) have hampered development of antagonists.

Relationship of functional status of persons having chronic ‘non-affective psychosis’ with anxiety, depression and self-esteem of family caregivers

Acute pain associated with herpes zoster (HZ) is the most debilitating symptom, which if not treated in early phase may lead to postherpetic neuralgia (PHN), a potentially crippling disorder with prolonged intractable chronic pain. The socioeconomic consequences secondary to prolonged severe pain include decreased socialization, depression, fatigue, restricted daily activities, and poor quality of life. HZ and PHN impose a significant economic burden in the form of direct inpatient care and loss of productivity. Early interventional treatments attenuate central sensitization by interrupting the transmission of nociceptive afferent impulses to the central nervous system and minimize nerve damage by improving blood flow to the nervous tissue in addition to the local anti-inflammatory action of corticosteroids. Interventions treatment options have been increasingly used as a part of multimodal approach in the management of acute pain of HZ in addition to pharmacological agent. This article reviews the various interventional treatment options which have used in the recent years for the management of acute pain of HZ and subsequent prevention of PHN.

Three-dimensional Reconstruction of Peripheral Nerve Internal Fascicular Groups.

Peripheral nerves are important pathways for receiving afferent sensory impulses and sending out efferent motor instructions, as carried out by sensory nerve fibers and motor nerve fibers. It has remained a great challenge to functionally reconnect nerve internal fiber bundles (or fascicles) in nerve repair. One possible solution may be to establish a 3D nerve fascicle visualization system. This study described the key technology of 3D peripheral nerve fascicle reconstruction. Firstly, fixed nerve segments were embedded with position lines, cryostat-sectioned continuously, stained and imaged histologically. Position line cross-sections were identified using a trained support vector machine method, and the coordinates of their central pixels were obtained. Then, nerve section images were registered using the bilinear method, and edges of fascicles were extracted using an improved gradient vector flow snake method. Subsequently, fascicle types were identified automatically using the multi-directional gradient and second-order gradient method. Finally, a 3D virtual model of internal fascicles was obtained after section images were processed. This technique was successfully applied for 3D reconstruction for the median nerve of the hand-wrist and cubital fossa regions and the gastrocnemius nerve. This nerve internal fascicle 3D reconstruction technology would be helpful for aiding peripheral nerve repair and virtual surgery.

A Brain–Kidney Connection: The Delicate Interplay of Brain and Kidney Physiology

The central nervous system (CNS) and kidneys are strongly interconnected. Afferent impulses from the CNS regulate renal blood flow, glomerular filtration rate (GFR), and affect renal sodium handling [1]. Vasopressin hormone is secreted from the posterior pituitary gland and acts on the collecting ducts of the distal nephron to regulate water balance and serum osmolality. However, the kidney is not a target organ that solely responds to impulses from the CNS. Impulses originating from the kidney are carried via unmyelinated and thinly myelinated fibers to the CNS and the contralateral kidney to regulate CNS activity and coordinate renal sodium handling with the contralateral kidney. In animal models with acute kidney injury (AKI), the levels of inflammatory cytokines increase in the brain with evidence of anatomic and functional brain injuries [2]. Both organs also share a common feature—a tight autoregulatory mechanism that maintains constant blood flow over a wide range of blood pressures. It is unclear, however, whether both the renal and brain autoregulatory mechanisms are interconnected in such a way that changes that occur in one organ affect the blood flow in the other. In this issue of Neurocritical Care, two articles by two separate NeuroICU teams report some important observations on the connection between the brain and kidney vascular beds and autoregulatory mechanisms. The first article by Dias et al. [3] reports a retrospective small series of 18 TBI patients in which various laboratory values were analyzed, including serum creatinine. The authors estimated both creatinine clearance (CrCL) and GFR using two creatinine-based equations: the Cockroft–Gault and the four-point Modification of Diet in Renal Diseases (MDRD) equations, respectively. ICP recording with mean arterial pressure (MAP) via a multimodal monitoring (MMM) computer was obtained, and the authors utilized the MMM data to acquire pressure-reactivity index (PRX) as a surrogate for cerebrovascular auto regulation (CVAR) and correlated PRX with CrCL and GFR, as well as other physiological and laboratory parameters. The authors’ data suggest that patients with brain injuries with better CVAR as measured by PRX were statistically associated with renal hyperfiltration, augmented renal clearance (ARC), and potentially better outcomes. While these findings are intriguing, the results should be interpreted with great caution. First, this study was not intended to monitor GFR, and therefore no ‘‘gold standard’’ method for GFR measurement, such as continuous infusion of iothalamate, was utilized. Second, intravenous fluid infusion in critically ill patients and mannitol use in TBI patients will affect serum creatinine concentration without any meaningful change in kidney function [4]. Third, although using creatinine-based equations to calculate CrCl (in the case of CG) and GFR (in the case of MDRD) seems appealing, in reality, serum creatinine is the only variable in these equations that demonstrates day-to-day changes, while the remaining variables in the equation such as age, gender, and race will remain constant. In addition, it is unclear whether ideal body weight, admission weight, or daily weight was utilized in calculating CrCl by CG. MDRD is intended for chronic kidney disease (CKD) patients and is biased in patients without CKD. Because of the way ‘‘hyperfiltration’’ was actually measured and reported, the whole idea of ARC should be taken with a grain of salt. A fourth W. D. Freeman (&) Departments of Neurosurgery, Neurology and Critical Care, Mayo Clinic, 4500 San Pablo Rd, Jacksonville, FL 32224, USA e-mail: freeman.william1@mayo.edu

Strong Manual Acupuncture Manipulation Could Better Inhibit Spike Frequency of the Dorsal Horn Neurons in Rats with Acute Visceral Nociception.

Afferent impulses from visceral nociception can be regulated by acupuncture at spinal cord level; however, the effects of different manual acupuncture (MA) manipulations on the afferent impulses are still unknown. Here, we analyzed the spike frequency of excitatory gastric-related wide dynamic range (WDR) neurons in spinal dorsal horn (SDH) following acute gastric distension (GD) in rats and compared their responses to MA manipulations with four different frequencies (0.5, 1, 2, and 3 Hz) at Zusanli (ST36). Results indicated that the spike frequency was increased by acute GD stimulation. Under acute GD circumstances, the spike frequency was further activated by weak MA stimulation (0.5 and 1 Hz), while being significantly inhibited by strong MA stimulation (2 and 3 Hz). After 10 minutes of the strong MA stimulation, same intensity of acute GD caused less spike frequency. Our previous researches had demonstrated that different MA manipulations could increase spike frequency in an intensity-dependent manner in normal rats; these findings suggest that acupuncture may have different modulatory effects depending on the state of the stomach. Since neuronal spike frequency was related to the level of nociception, the results suggest that strong MA manipulation may have better effect on acute visceral nociception.

Case for local infiltration analgesia: Is all the evidence in black and white?

Post-operative pain has the potential for significant adverse effects on the physiology and can also drown the patient into psychological suffering. The source and degree of nociceptive stimulation differ among individuals and surgeries and hence multimodal analgesic approaches have been encouraged for pain relief. With local infiltration or infiltration in the pain sensitive planes, afferent impulses from the site of incision and injury are reduced. This reduces the sensitisation and consequent hyperalgesia. The risks associated with parenteral administration of analgesics, risks associated with central neuraxial block and the injury and injection to surrounding structures in nerve and plexus blocks are avoided. As part of multimodal technique, there can be a reduction in requirements of opioids. Simplicity and safety are the hallmarks of the technique.

A comparative study of labetalol and fentanyl on the sympathomimetic response to laryngoscopy and intubation in vascular surgeries

Background: Stress response to laryngoscopy and intubation causes autonomic or endocrine disturbance such as hypertension, tachycardia, and arrhythmias that may be potentially dangerous in cardiovascular disease patients. These changes are maximum at 1 min after intubation and last for 5-10 min. Labetalol is a selective α1- and nonselective β1- and β2-adrenergic antagonist. It lowers blood pressure (BP) by decreasing systemic vascular resistance by α1-blockade and reflex tachycardia attenuated by simultaneous β-blockade. Fentanyl is a potent synthetic opioid agonist with rapid onset and short duration of action. It blocks afferent nerve impulses resulting from stimulation of the pharynx and larynx during intubation. This is a prospective, randomized, control trial carried out to compare the effect of labetalol and fentanyl on sympathomimetic response to laryngoscopy and intubation in vascular surgeries. Materials and Methods: Eighty four patients [American Society of Anesthesiologists (ASA) grade I and II] scheduled for vascular surgeries were divided into three groups (28 each). Group A received fentanyl 2 μg/kg intravenous (IV), Group B received labetalol 0.25 mg/kg IV, and Group C received 10 mL saline IV. The groups were compared for heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and rate pressure product (RPP). Results: The groups were comparable as per their demographic data and preoperative vitals. All the vitals decreased significantly (P 0.05). The incidence of hypertension and tachycardia was higher in Group C. No hypotension, bradycardia, and abnormal electrocardiogram (ECG) were recorded in any group. Conclusion: In lower doses, labetalol is a better agent than fentanyl in attenuating the sympathomimetic response to laryngoscopy and intubation but the difference is not significant. However, both effectively blunt the pressure response.

Autonomic Hyperreflexia after Spinal Cord Injury

The most important complication of spinal cord lesions above T6 level is the phenomenon of Autonomic Hyperreflexia (AH). Symptoms and signs of AH result from the predominant parasympathetic excitation above the level of injury, and sympathetic excitation below the level of injury. Various noxious and nonnoxious stimuli below the level of injury can thus trigger off a mass autonomic response. The main triggering factor of AH is related with the urinary tract. The main treatment of AH is removal of the triggering factors. The development of intraoperative AH and hypertension can be prevented either by general anesthesia, which blunts autonomic reflexes, or regional anesthesia (spinal or epidural), which blocks afferent and autonomic efferent neural impulses.

Earth’s Magnetic Field and Cosmic Radiation in CNS Function: Anomalous Magnetic Fields, Cause of Mental Diseases

Biosphere is characterized by the existence of Earth’s magnetic field (EMF) and cosmic radiation (CR). By measuring the EMF in beds of mentally ill people (MI), anomalous magnetic fields (AMF) were measured. That’s why we approached the study of central nervous system (CNS). Aims: To explain physiology of the CNS, how to use cosmic radiation (CR) in occurring brain micro power; To prove that neurons have magnetic characteristics; To explain brain amplifier and capacitor; To explain brain waves, alertness and sleep-REM phase, memory and reproduction as well as congenital instincts; To clarify consciousness; To determine correlation between AMF and MI people’s heads; If possible, to keep track of the health status of patients after relocation from AMF and to prove that the cause of MI people are AMF. Methodology: Literature study of the physiology and functioning of the CNS. By knowing physics, electric engineering and biochemistry, we explained the functioning of the CNS. Measuring of AMF was performed with proton magnetometer in 19 beds of MI people (depression, schizophrenia, epilepsy and Parkinson’s disease) and in 2 beds of healthy people. Geophysical interpretation of measured values was performed and the results are shown on sketches. MI people were transferred in natural EMF and their health status was monitored. Results: Physiology of the CNS and goals were explained. The brain generates micro electric power using CR. The cerebrum is the capacitor. The brain is the amplifier of afferent and efferent micro power impulses. The electroencephalogram, the emergence of brain micro powers, brain waves, alertness and sleep-REM phase, memory and reproduction as well as congenital instincts were explained. The consciousness was defined. AMF balance in MI people’s beds is presented on sketches. By measuring, spatial correlation between AMF and the patient’s head is determined, which indicates the cause of MI people. Monitoring of the health status of patients after relocation from AMF, did not give reliable recovery results due to the short monitoring time of patients, except in epilepsy. Conclusion: The CNS with CR is generator of micro electric power in the body. The main function of the CNS is explained. The correlation between AMF and MI people’s heads on about 500 patients was determined. With the help of psychiatrist, it’s necessary to determine how much of a help, in treatment of MI people, living in natural EMF is. The causes of MI people are AMF in people’s living area.

P2X₇ receptor of rat dorsal root ganglia is involved in the effect of moxibustion on visceral hyperalgesia.

Irritable bowel syndrome (IBS) and inflammatory bowel disease often display visceral hypersensitivity. Visceral nociceptors after inflammatory stimulation generate afferent nerve impulses through dorsal root ganglia (DRG) transmitting to the central nervous system. ATP and its activated-purinergic 2X7 (P2X7) receptor play an important role in the transmission of nociceptive signal. Purinergic signaling is involved in the sensory transmission of visceral pain. Moxibustion is a therapy applying ignited mugwort directly or indirectly at acupuncture points or other specific parts of the body to treat diseases. Heat-sensitive acupoints are the corresponding points extremely sensitive to moxa heat in disease conditions. In this study, we aimed to investigate the relationship between the analgesic effect of moxibustion on a heat-sensitive acupoint "Dachangshu" and the expression levels of P2X7 receptor in rat DRG after chronic inflammatory stimulation of colorectal distension. Heat-sensitive moxibustion at Dachangshu acupoint inhibited the nociceptive signal transmission by decreasing the upregulated expression levels of P2X7 mRNA and protein in DRG induced by visceral pain, and reversed the abnormal expression of glial fibrillary acidic protein (GFAP, a marker of satellite glial cells) in DRG. Consequently, abdominal withdrawal reflex (AWR) score in a visceral pain model was reduced, and the pain threshold was elevated. Therefore, heat-sensitive moxibustion at Dachangshu acupoint can produce a therapeutic effect on IBS via inhibiting the nociceptive transmission mediated by upregulated P2X7 receptor.

English

Epidural Analgesia is used for relief of pain during and following surgical operations, for relief of chronic pain, for relief of pain in labour, reduction of bleeding by producing sympathetic blockade and hypotension during surgery or to supplement light general anaesthesia, thereby suppressing the transmission of afferent impulses and autonomic and hormonal response to surgery. The commonly used drugs for epidural analgesia are 2% xylocaine and 0.5% bupivacaine. Mixing of the local anaesthetics and altering the pH have been found to be safe and cost effective.1,2 our study was a prospective randomized controlled double blind study to investigate effect of the benefits of usage of a compounded solution (2% xylocaine and 0.5% bupivacaine in a 1:1 ratio) over a single drug (0.5% bupivacaine) and ascertain whether it can be recommended for routine use in epidural analgesia in regular anaesthetic practice.3,4,5 The following parameters are Studied 1) The time of onset of analgesia. 2) The quality of analgesia. 3) The degree of motor blockade. 4) Duration of analgesia. 5) Safety of compounding local anaesthetics. METHODS AND MATERIAL: One Hundred Adult Patients of either sex ranging between 20-60 years of age belonging to ASA grade 1 and II were studied. All patients were at random divided into 2 groups fifty in each group. Group A received 0.5% bupivacaine 15cc. Group B received a mixture of 0.5% bupivacine and 2% xylocaine (7.5cc + 7.5cc) RESULTS: Mean time of onset of analgesia in group B was lower (11.50 + 2.05) as compared to group A (22.24 + 2.18) and this difference was statistically highly significant (P<0.001). 16% of group A and 6% of group B required to be changed over to general anaesthesia. Grade IV motor blockade was seen only in 24% of group A and 30% of the group B which is significant. Mean duration of action in group A was higher (128.90 + 6.70) than in group B (98.30 + 5.29) and this difference was statistically significant. CONCLUSIONS: The compounded solution of 0.5% bupivacaine and 2% lignocaine in 1:1 ratio totaling 15cc is superior to 0.5% bupivacaine alone as single agent for epidural blockade in view of rapid onset, better motor and sensory blockade, and better quality of analgesia and less incidence of complications.

54. Cutaneous silent period in brachial plexus injury

Objectives The cutaneous silent period (CSP) is a spinal inhibitory reflex mediated primarily by small-diameter A-delta fibers, which enter the spinal dorsal horn and suppress activity in spinal motor nuclei in neighboring myotomes. The aim of the study was to define if CSP testing may be particularly useful in evaluation of brachial plexus injury, especially contributing to diagnosis of root avulsion. Methods In 11 patients with traumatic brachial plexus injury (8 males, age 18–62 years) we performed clinical examination, myelo CT and neurophysiological testing. Needle EMG was obtained from the main root muscles of C5–C8 myotomes. CSP was recorded by painful stimuli while the subject maintains a moderately strong voluntary muscle contraction and impulses were delivered to thumb (C6 dermatome), middle (C7) and little (C8) fingers. Results Clinical and EMG examination proved motor root damage of C5 in 3 subjects, C5 and C6 in 3 subjects, C5–C7 in 3 subjects, C5–C8 in 2 subjects. The CSP was partially absent in 3 subjects, however, well preserved in 8 subjects. Conclusion in theory, CSP can be used to quickly monitor afferent impulses travelling through damaged cervical roots, however, in brachial plexus avulsion CSP abnormalities were found only in a few cases. CSP is a robust protective plurisegmental spinal reflex, which is maintained even with a preservation of minimal functional afferent fibers and/or because the afferent signal is amplified within the spinal cord. Supported by Research Projects of Charles University PRVOUK P34, Grant Project of Czech Ministry of Health NT12282, NT13693.