The homuncular jigsaw: investigations of phantom limb and body awareness following brachial plexus block or avulsion

Many neuropsychological theories agree that the brain maintains a relatively persistent representation of one's own body, as indicated by vivid "phantom" experiences. It remains unclear how the loss of sensory and motor information contributes to the presence of this representation. Here, we focus on new empirical and theoretical evidence of phantom sensations following damage to or an anesthetic block of the brachial plexus. We suggest a crucial role of this structure in understanding the interaction between peripheral and central mechanisms in health and in pathology. Studies of brachial plexus function have shed new light on how neuroplasticity enables "somatotopic interferences", including pain and body awareness. Understanding the relations among clinical disorders, their neural substrate, and behavioral outcomes may enhance methods of sensory rehabilitation for phantom limbs

The challenge of evaluating pain and a pre-incisional local anesthetic block.

Background. Our objective was to test the effectiveness of a local anesthetic line block administered before surgery in reducing postoperative pain scores in dogs undergoing ovariohysterectomy (OVHX). Methods. This study is a prospective, randomized, blinded, clinical trial involving 59 healthy female dogs. An algometric pressure-measuring device was used to determine nociceptive threshold, and compared to three subjective pain scales. Group L/B received a line block of lidocaine (4 mg/kg) and bupivacaine (1 mg/kg) subcutaneously in the area of the incision site and saline subcutaneously as premedication; group L/BM (positive control) received a similar block and morphine (0.5 mg/kg) subcutaneously for premedication; and group SS (negative control) received a saline line block and saline premedication. Criteria for rescue analgesia were defined before the study. Dogs were assessed prior to surgery, at extubation (time 0) and at 2, 4, 6, 8 and 24 h post-recovery. The data were analyzed with one-way ANOVA, and a Split Plot Repeated Measures ANOVA with one grouping factor and one repeat factor (time). P < 0.05 was considered statistically significant. Results. Approximately 33% of dogs required rescue analgesia at some point during the study, with no significant difference between groups. There was no significant difference between treatment groups with any assessment method. Conclusions. As there were no statistically significant differences between positive and negative controls, the outcome of this technique cannot be proven

Electrostatic Contributions of Aromatic Residues in the Local Anesthetic Receptor of Voltage-Gated Sodium Channels

Antiarrhythmics, anticonvulsants, and local anesthetics target voltage-gated sodium channels, decreasing excitability of nerve and muscle cells. Channel inhibition by members of this family of cationic, hydrophobic drugs relies on the presence of highly conserved aromatic residues in the pore-lining S6 segment of the fourth homologous domain of the channel. We tested whether channel inhibition was facilitated by an electrostatic attraction between lidocaine and {pi} electrons of the aromatic rings of these residues, namely a cation-{pi} interaction. To this end, we used the in vivo nonsense suppression method to incorporate a series of unnatural phenylalanine derivatives designed to systematically reduce the negative electrostatic potential on the face of the aromatic ring. In contrast to standard point mutations at the same sites, these subtly altered amino acids preserve the wild-type voltage dependence of channel activation and inactivation. Although these phenylalanine derivatives have no effect on low-affinity tonic inhibition by lidocaine or its permanently charged derivative QX-314 at any of the substituted sites, high-affinity use-dependent inhibition displays substantial cation-{pi} energetics for 1 residue only: Phe1579 in rNaV1.4. Replacement of the aromatic ring of Phe1579 by cyclohexane, for example, strongly reduces use-dependent inhibition and speeds recovery of lidocaine-engaged channels. Channel block by the neutral local anesthetic benzocaine is unaffected by the distribution of {pi} electrons at Phe1579, indicating that our aromatic manipulations expose electrostatic contributions to channel inhibition. These results fine tune our understanding of local anesthetic inhibition of voltage-gated sodium channels and will help the design of safer and more salutary therapeutic agents

Sites of Anesthetic Block of the Lateral and Medial Palmar Metacarpal Nerves in Equines of Indeterminate Breed

Background: Local anesthesia blockage at equines claudication diagnosis besides favoring the beginning of the therapy and relieving patient’s pain, it allows the identification of the specific affected region and its origin, however, if it is done incorrectly (by improper volume of anesthetics application and/or mistakenly nerve identification due to the lack of anatomic referential) it may cause inflammation, infection or even tissue necrosis. The aim was describing anatomically lateral and medial palmar metacarpal nerves in equines to improve diagnostic anesthetic block techniques on four metacarpophalangeal articulation joints of the specie.Materials, Methods & Results: A number of 20 thoracic limbs from 10 equines of indeterminate breed were used to be fixated in 10% phormaldehyde and with a marked arterial system by water solution of red dyed latex. The structures were identified by dissection, and their denomination bases on Nomina Anatomica Veterinaria (N.A.V.) by the International Committee on Veterinary Gross Anatomical Nomenclature. The study had been approved by the Board of Ethics in Animal Use of the University Center of Patos de Minas (UNIPAM), protocol n° 18/17. The lateral and medial palmar metacarpal nerves have been observed in all of the specimens originated from the deep branch of lateral palmar nerve, immediately distal to the intercarpal articulation. After its origin, the first nerve stretched ipsilaterally from the common trunk, whilst the second nerve positioned counter-lateral manner after superficially crossing the interosseus muscle. Both penetrated at the level of the mid third of the referred muscle and the metacarpal bone III and, assumed respectively a parallel medial position to the metacarpal bone IV and lateral to the metacarpal II, being intimately associated to the palmar face of the metacarpal bone III. Distally, those nerves emerged from a palmar position to a lateral and medial to the distal extremity of the metacarpal bones, corresponding and adjacent to the metacarpophalangeal articulation palmar recession, where they had finally ramified to partially innervate the associated articular capsule and the subcutaneous tissue of the region.Discussion: The lateral and medial palmar metacarpal nerves present similar origin and disposition to the above described, however, besides largely mentioned in literature, we point out here as recommended by N.A.V., no use of terms like axial and abaxial as position indicators for equine. As a part of block anesthetic diagnosis of four metacarpophalangeal articulation points, it is hereby suggested for the studied nerves desensitization, should be palpated the distal extremities of the metacarpal bones IV and II. After the identification, using thumb located from the extremity at proximal direction way, introduce the needle bilaterally for 1.5 cm downright between the above mentioned metacarpal bones and the interosseus muscle, being these latter and the flexor muscle tendons drawn in the palmar direction. Thus, it becomes valid to affirm that the technique of four-point diagnostic anesthetic block of the metacarpophalangeal articulation has been perfected for equines, and that it will limit the chances of false results on account of misplaced puncturing of nearby structures, such as, for example, the synovial recesses, mentioned as the location of the utmost gravity, hence septic synovitis may come in play

Temperature Changes seen in Lower Extremities after CPN Local Anesthetic Block

Many older patients often suffer from walking issues such as Drop Foot. Drop Foot is caused by the malfunction of nerves in the foot, resulting in the loss of control of the front foot muscle. Within all of our patients, there has been a common fibular palsy, caused by the entrapment of the peroneal nerve. Due to this, they cannot lift up their foot. Some cases are permanent, while others are temporary. In the temporary cases, we have indicated a Phoenix Sign. The Phoenix Sign indicates that a nerve, presumed to be dead, has the capability to be recessed back to life. To ensure that this nerve can be brought back to life, our study is testing the effects of Lidocaine on the patient’s lower extremities. Lidocaine is a local anesthetic, used as a sodium channel blocker and vaso-dilator. Thermography will be used to see if there are any temperature changes in the foot and lower extremities after the Phoenix Sign Block

HRV analysis in local anesthesia using Continuous Wavelet Transform (CWT)

Spectral analysis of Heart Rate Variability (HRV) is used for the assessment of cardiovascular autonomic control. In this study Continuous Wavelet Transform (CWT) has been used to evaluate the effect of local anesthesia on HRV parameters in a group of fourteen patients undergoing axillary brachial plexus block. A new method which takes signal characteristics into account has been presented for the estimation of the variable boundaries associated with the low and the high frequency band of the HRV signal. The variable boundary method might be useful in cases when the power related to respiration component extends beyond the traditionally excepted range of the high frequency band (0.15-0.4 Hz). The statistical analysis (non-parametric Wilcoxon signed rank test) showed that the LF/HF ratio decreased within an hour of the application of the brachial plexus block compared to the values fifteen minutes prior to the application of the block. These changes were observed in thirteen of the fourteen patients included in this study

The Occipital Nerves Applied Strain Test to Support Occipital Neuralgia Diagnosis

Introduction: Occipital neuralgia (ON) is a disabling cephalalgia form with demanding diagnostic workflow. We report the description and reliability analyses of the occipital nerves applied strain (ONAS) test for occipital neuralgia (ON) early-stage diagnosis in cephalalgia patients. Methods: In a retrospective and observational study, we evaluated, among n = 163 consecutive cephalalgia patients, the sensitivity, specificity, and prior probability [positive (PPV) and negative (NPV) predictive values] of the ONAS test against two reference tests (occipital nerve anesthetic block and the painDETECT questionnaire). Multinomial logistic regression (MLR) and v2 analyses verified the ONAS test outcome’s dependence upon independent variables (gender, age, pain site, block test, and painDETECT outcomes). We assessed inter-rater agreement with Cohen’s kappa statistic. Results: ONAS test showed sensitivity and specificity of 81 and 18%, respectively, against the painDETECT and of 94 and 46%, respectively, against the block test. PPV was >70% against both tests, while NPV was 81% against the block test and 26% against the painDETECT. Interrater agreement Cohen’s kappa was excellent. Significant association (X2 analyses) and relationship (MLR) were found only between ONAS test and pain site but not with the other independent predictors. Conclusions: The ONAS test showed satisfactory reliability among cephalalgia patients; thus, it might be considered a valuable early stage tool for ON diagnosis in these patients.PLAIN LANGUAGE SUMMARY We report the description and reliability features of an occipital neuralgia diagnostic tool. The latter is based on the assertion that applying a strain on putatively compromised occipital nerves prompts abnormal nerve discharges and subjective pain reactions and thus may reveal occipital neuralgia. Among 163 cephalalgia patients, the test showed sensitivity and specificity of 81 and 18%, respectively, against the painDETECT questionnaire and 94 and 46%, respectively, against the occipital nerves’ block test. Interrater agreement was excellent, and significant associations and relationships were found only between the tool and congruent pain site but not with the other independent predictors. This tool may help clinicians’ early detection of occipital neuralgia in cephalalgia patients

The challenge of evaluating pain and a pre-incisional local anesthetic block

Background. Our objective was to test the effectiveness of a local anesthetic line block administered before surgery in reducing postoperative pain scores in dogs undergoing ovariohysterectomy (OVHX).Methods. This study is a prospective, randomized, blinded, clinical trial involving 59 healthy female dogs. An algometric pressure-measuring device was used to determine nociceptive threshold, and compared to three subjective pain scales. Group L/B received a line block of lidocaine (4 mg/kg) and bupivacaine (1 mg/kg) subcutaneously in the area of the incision site and saline subcutaneously as premedication; group L/BM (positive control) received a similar block and morphine (0.5 mg/kg) subcutaneously for premedication; and group SS (negative control) received a saline line block and saline premedication. Criteria for rescue analgesia were defined before the study. Dogs were assessed prior to surgery, at extubation (time 0) and at 2, 4, 6, 8 and 24 h post-recovery. The data were analyzed with one-way ANOVA, and a Split Plot Repeated Measures ANOVA with one grouping factor and one repeat factor (time). P < 0.05 was considered statistically significant.Results. Approximately 33% of dogs required rescue analgesia at some point during the study, with no significant difference between groups. There was no significant difference between treatment groups with any assessment method.Conclusions. As there were no statistically significant differences between positive and negative controls, the outcome of this technique cannot be proven

Local anesthesia for treatment of hernia in elder patients: Levobupicavaine or Bupivacaine?

BACKGROUND: Inguinal hernia is one of the most common diseases in the elderly. Treatment of this pathology is exclusively surgical and relies almost always on the use of local anesthesia. While in the past hernia surgery was carried out mainly by general anesthesia, in recent years there has been growing emphasis on the role of local anesthesia. METHODS: The aim of our study was to compare intra-and postoperative analgesia obtained by the use of levobupivacaine to the same obtained by bupivacaine. Bupivacaine is one of the main local anesthetics used in the intervention of inguinal hernioplasty. Levobupivacaine is an enantiomer of racemic bupivacaine with less cardiotoxicity and neurotoxicity. The study was conducted from March 2011 to March 2013. We collected data of eighty patients, male and female, aged between 65 and 86 years, who underwent inguinal hernioplasty with local anesthesia. RESULTS: Evaluation of intra-operatively pain shows that minimal pain is the same in both groups. Mild pain was more frequent in the group who used levobupivacaine. Moderate pain was slightly more frequent in the group who used bupivacaine. Only one reported intense pain. Two drugs seem to have the same effect at a distance of six, twelve, eighteen and twentyfour hours. Bupivacaine shows a significantly higher number of complications, as already demonstrated by previous studies. Degree of satisfaction expressed by patients has been the same in the two groups. Levobupivacaine group has shown a greater request for paracetamol while patients who experienced bupivacaine have showed a higher request of other analgesics. CONCLUSIONS: Clinical efficacy of levobupivacaine and racemic bupivacaine are actually similar, when used under local intervention of inguinal hernioplasty. In the field of ambulatorial surgery our working group prefers levobupivacaine for its fewer side effects and for its easy handling

Morfometria do forame mandibular aplicada ao bloqueio anestésico local do nervo alveolar inferior de javalis (Sus scrofa scrofa Linnaeus, 1758)

Javalis mantidos em criatórios comerciais utilizam os dentes caninos como mecanismo de defesa e ataque a fim de&nbsp;expressar seus instintos naturais, o que pode resultar em fraturas dentárias e da mandíbula propriamente dita. Desta forma,&nbsp;propiciar a dessensibilização local do nervo alveolar inferior é essencial para a execução de procedimentos terapêuticos&nbsp;na cavidade oral destes animais. Logo, objetivou-se realizar a morfometria do forame mandibular desta espécie a fim&nbsp;de correlacioná-lo com as estruturas mandibulares, inferindo, também, sobre a forma mais segura de realização da&nbsp;referida técnica nos espécimes. Para tanto, foram utilizadas seis hemimandíbulas de Sus scrofa scrofa jovens, a partir&nbsp;das quais foram realizadas as mensurações propostas. Em média, a margem lateral do processo condilar distanciou-se&nbsp;142,43 mm da raiz do dente incisivo medial inferior; o eixo longitudinal do corpo da mandíbula mediu 22,3 mm ao&nbsp;nível do diastema existente entre o quarto dente pré-molar e o primeiro dente molar inferiores; e o forame mandibular, a&nbsp;partir do extremo caudal de sua margem ventral, posicionou-se a 26,6 mm da margem ventral do ângulo da mandíbula&nbsp;neste nível, 34,92 mm da margem medial do processo condilar, e 38,63 mm do extremo dorsal da margem caudal do&nbsp;processo coronóide. Na falta de diferenças estatisticamente significantes, e observando que o acidente ósseo estudado&nbsp;posicionou-se no ramo da mandíbula, indica que o procedimento proposto deva ser realizado a partir da introdução da&nbsp;agulha em sentido oblíquo rostroventral por 2,0 cm e angulada a 60º com o referencial anatômico criado pela delimitação&nbsp;medial obtida pelo apoio do dedo polegar na margem lateral do ramo da mandíbula, ventralmente ao arco zigomático,preservando as estruturas próximas e definindo-se uma metodologia anestésica inédita para os Javalis.Boars kept on commercial farms use their canine teeth as a mechanism of defense and attack in order to express their&nbsp;natural instincts, which could result in fractures of the teeth and jaws. Thus, utilizing local desensitization of the inferior&nbsp;alveolar nerve is crucial for executing therapeutic procedures in the oral cavities of those animals. Then, the goal is to&nbsp;carry out the morphometry of the mandibular foramen of that species, correlating it with the mandibular structures,&nbsp;while doing so in the safest manner for the animals. For that purpose, six hemimandibles of young-aged Sus scrofa&nbsp;scrofa were used, from which the proposed measurements were taken. On average, the lateral margin of the condylar&nbsp;process stood 142.43 mm away from the root of the lower medial incisive tooth. The longitudinal axis of the body of the&nbsp;mandible measured 22.3 mm at the level of the diastema that exists between the fourth lower premolar tooth and the&nbsp;first lower molar tooth. The mandibular foramen, from the caudal limit of the ventral margin, would be positioned at26.6 mm from the ventral margin of the angle of the mandible in that level, 34.92 mm away from the medial margin of&nbsp;the condylar process, and 38.63 mm away from the dorsal limit from the caudal margin of the coronoid process. The lack&nbsp;of statistically significant differences, and observing that the osseous accident under scrutiny had been positioned in&nbsp;the ramus of the mandible, indicated that the proposed procedure should be performed from the introduction of the&nbsp;needle in an oblique and rostrodorsal direction for 2.0 cm, and angulated at 60º with the anatomic reference created&nbsp;by the medial demarcation obtained via the support of the thumb on the lateral margin of the ramus of the mandible,&nbsp;ventrally to the zygomatic arch, all while preserving neighboring structures and establishing an unheard-of anesthetic&nbsp;methodology for boars