[Application of radiography for more accurate nerve block. 1) Subarachnoid nerve block].
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A case is presented where reversible abducens nerve block accompanied second and third division trigeminal block with bupivacaine on two occasions. Intraorbital injection through the inferior orbital fissure most likely took place. Careful poistioning of the needle and limitation of the drug volume is mandatory for therapeutic trigeminal nerve blocks with neurolytic solutions.
Local anesthetics block nerve conduction by preventing the increase in membrane permeability to sodium ions that normally leads to a nerve impulse. Among anesthetics containing tertiary amine groups, the cationic, protonated form appears to be more active than the neutral form. However, the neutral forms, as well as uncharged molecules like benzocaine and the aliphatic alcohols, also depress sodium permeability. Studies of single myelinated nerves and squid axons show no direct interaction between calcium ions and local anesthetics, thus disproving theories based on competition between these two agents. Likewise, hypotheses attributing local anesthesia to changes in electrical potentials at the membrane-water interface are disproven by the demonstrated potencies of electrically uncharged anesthetics. Hypotheses that propose that local anesthetics act by expanding the nerve membrane and causing a change in protein conformation that blocks sodium permeability are vague in conception and difficult to test experimentally. Evidence from voltage-clamp studies of single nerve fibers indicates that anesthetic molecules interact with the sodium channels directly, from the inner side of the nerve membrane. Anesthetics bind within sodium channels which have opened during membrane depolarization, preventing the normal sodium ion flux. Anesthetic molecules can dissociate from open channels, but not from channels that remain closed when the nerve is kept at rest. The "gating" properties that regulate the opening and closing of sodium channels are reversibly modified during anesthesia. Specifically, the inactivation function responds more slowly and requires more negative membrane potential changes to reach the same values as in unanesthetized nerves. A second, slow inactivation is observed following external application of tertiary amine anesthetics. The selective binding of anesthetics to open sodium channels provides a simple explanation for Wedenski inhibition, in which the block increases with the frequency of nerve impulses. When impulses occur at higher frequencies more sodium channels are open over a period of time comparable to the time necessary for the anesthetic binding reaction, thus more channels are blocked. In addition the changes of the inactivation function result in a longer refractory period and, thus, a decrease of impulse height at higher frequencies. Charged anesthetic molecules may bind in the pore of the sodium channel. Their binding can be modulated by the electrical field in the membrane. The channel has a higher affinity for larger anesthetic molecules, but this may result from their greater hydrophobicity as well as from their size. The binding site favors molecules that contain more polar linkages between the amine group and the aromatic residue. Binding of amine anesthetics is weakly stereospecific and, surprisingly, shows no absolute requirement for the terminal alkyl ammonium moiety present in most local anesthetics...
Axillary nerve block is a safe and reliable method of providing anesthesia for the upper extremity. It is particularly useful because it can be applied in cases of traumatic injury where general anesthesia might present particular hazards. The use of a large volume of anesthetic solution is important, particularly when it is essential to block the musculocutaneous or axillary nerve.
There have been no new developments concerning field blocks. The need for limiting the dosage of local anesthetic agents is stressed. Two methods for perivascular block are described and the use of CO2 containing local anesthetic solutions is discussed as well as the employment of peripheral nerve stimulators.
To investigate the clinical efficacy and safety of ultrasound-guided thoracic paravertebral block (TPVB) combined with pectoral nerve block (Pecs) in the treatment of acute herpetic neuralgia (AHN) involving the upper thoracic segments in middle-aged and elderly patients, a prospective study was conducted. A total of 70 middle-aged and elderly patients with upper thoracic AHN who visited the Department of Pain Medicine at Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, from June to December 2023, were enrolled and randomly divided into a control group and an experimental group using a random number table, with 35 patients in each group. The control group received TPVB once weekly for a total of 3 sessions, while the experimental group received TPVB combined with Pecs block using the same regimen. Outcome measures included the Visual Analogue Scale (VAS) for pain, Pittsburgh Sleep Quality Index (PSQI), 7-item Generalized Anxiety Disorder Scale (GAD-7), 9-item Patient Health Questionnaire (PHQ-9), treatment satisfaction score, incidence of postherpetic neuralgia (PHN), rescue analgesia, and adverse events. Assessments were conducted at 1, 4, 8, and 12 weeks post-treatment, and between-group differences were compared. Ultimately, 33 patients in the experimental group and 31 in the control group completed the follow-up and were included in the final analysis. The results showed that both groups demonstrated significant improvements in VAS scores, PSQI, GAD-7, PHQ-9, and satisfaction scores compared with baseline (all P<0.05). Compared with the control group, the experimental group exhibited significantly lower VAS scores and higher satisfaction scores at 1, 4, and 8 weeks post-treatment (P<0.05), as well as significantly lower PSQI, GAD-7, and PHQ-9 scores at 4 and 8 weeks (P<0.05). There were no statistically significant differences between the two groups in the incidence of PHN, rescue analgesia, or adverse events (all P>0.05). This study demonstrates that compared with TPVB alone, the combination of TPVB and Pecs block provides better pain relief, improves sleep quality, and alleviates anxiety and depression in middle-aged and elderly patients with upper thoracic AHN, with a favorable safety profile.
Sciatic nerves of rats and tibial nerves of rabbits were kept anaesthetized in situ for periods of 3-11 days by applying silastic cuffs containing lidocaine base or marcaine hydrochloride. To insure a more uniform release of the rapidly diffusing lidocaine base, the drug was contained in compartments at some distance from the nerve and the cuffs were covered with polystyrene. The completeness of anaesthesia and the functional state of the nerve were tested by stimulating the exposed nerves proximal and distal to the cuff and by observing the behaviour of the muscle prior to killing the animals. The ACh sensitivity was tested by electrophoretic application of ACh from micropipettes and by recording the results changes of the resting membrane potential in individual muscle fibres. The ACh sensitivity was found to be present in the extrajunctional area of all muscle fibres including those displaying miniature end-plate potentials. These was no difference between the behaviour of muscles from rats and rabbits and between the action of lidocaine base and marcaine hydrochloride. Previous reports on the absence of extrajunctional ACh sensitivity in muscles of rabbits whose nerves had been treated by lidocaine base were explained by a relatively rapid loss of the drug from the usual type of nerve cuffs (more than 70% of the drug lost in one day), permitting a premature recovery of the nerves from anaesthesia.
Nerve blocks are an effective treatment in patients with many types of acute pain. However, they are much less effective in patients with chronic pain. Candidates for therapeutic nerve blocks should be carefully screened by: assessment of organic disease; evaluation of psychologic and behavioral disorders, and differential nerve blocks. The best candidates for therapeutic nerve blocks have known or inferred organic disease, minimal psychologic or behavioral disorders, and evidence of sympathetic or somatic pain mechanisms.
While applying direct electrical stimulation to the pudendal nerve and recording of electromyographic reactions of bulbocavernosus muscle and/or transverse perineal muscle, pudendal nerve block by phenol was performed for the treatment of dysuria due to detrusor-sphincter dyssynergia, resulting in a favourable response. The technique and the cases treated with this nerve block are presented.
INTRODUCTION: Combining adductor canal block (ACB), infiltration between the popliteal artery and posterior capsule of the knee (IPACK), and genicular nerve blocks provides motor-sparing analgesia in total knee arthroplasty (TKA). Adding nerve blocks targeting the nerve to vastus medialis, vastus intermedius, and anterior femoral cutaneous nerve may improve postoperative pain management without affecting mobility. This study evaluated the effect of an eight-nerve block combination for pain relief after TKA versus local infiltration analgesia (LIA). METHODS: Participants were randomized into intervention or standard treatment groups. The intervention group received an eight-nerve block combination using 40 mL ropivacaine, 5 mg/mL, with 75 µg of clonidine. The control group received LIA comprising 150 mL ropivacaine, 2 mg/mL, supplemented with 0.5 mg adrenaline. The primary outcome was postoperative pain intensity, measured by the numeric rating scale (NRS) at postanesthesia care unit (PACU) arrival, 1 hour, 2 hours after PACU arrival, at ward arrival, evening of surgery, morning of postoperative day 1 (POD1), and at 14:00 POD1. Statistical analysis was performed using the Mann-Whitney U test. Secondary outcomes included 48-hour oral morphine equivalent (OME) consumption and length of hospital stay (LOS). RESULTS: A total of 217 patients scheduled for TKA were randomized. No significant differences were observed in the primary outcome. NRS at rest, presented as median (IQR), did not differ between groups at any time point. At PACU arrival 0 (0-3) vs 0 (0-4), at 1 hour 2 (0-4) vs 2 (0-5), at 2 hours 2 (0-6) vs 2.5 (0-4), at ward arrival 3 (2-5) vs 3 (2-5), on the evening of POD0 4 (3-5) vs 3.5 (2-6), on the morning of POD1 4 (3-6) vs 4 (2-5), and at 14:00 POD1 3 (2-5) vs 3 (2-5) for nerve block and LIA groups, respectively (all P > .05). Exploratory secondary outcomes indicated reduced 48-hour OME consumption presented as median (IQR), 70 mg (52.5-96.3), vs 96 mg (61.3-148.8); P = .008) and shortened hospital stay, median (IQR), 1 day (1-2), vs 2 days, (1-3); P < .001) in the nerve block group compared to the LIA group. CONCLUSIONS: No differences were observed in pain scores between the eight-nerve block combination and LIA. Secondary outcomes revealed a reduction in 48-hour opioid consumption and a modestly shorter hospital stay with nerve block compared to LIA.
Alcohol celiac plexus nerve blocks were done in 100 patients, of whome 97 had intractable abdominal pain from cancer. In most cases, an initial diagnositc block with bupivacaine was followed by the therapeutic block performed by injecting 50 ml of 50 percent ethyl alcohol. Good to excellent pain relief occurred in 94 percent of patients. Fourteen blocks were repeated for recurrent pain. Life duration ranged from 2 days to 14 months after the block. Complications and side effects were infrequently seen but did include a 10 percent incidence of postural hypotension and 1 case of partial leg paralysis. This block is remarkably safe as well as effective and should be employed more frequently.
The cause of sciatica has been studied by blocking spinal nerves of the lumbosacral plexus in intervertebral foramina. The nerve, which is singled out with the aid of an image intensifier, is injected with 1 ml of 1 per cent Xylocain. If the Xylocain injection eliminates the sciatic pain, the surgeon may be confident that a true nerve-root compression is involved, and he can then explore as far as he finds necessary. The correlation between the site of compression and the level indicated by the test was confirmed by operation in 19 patients.
Differential nerve block from peridural anesthesia was used to determine a) if the pressor response to muscle ischemia in man is caused by stimulation of small sensory nerve fibers and b) if these fibers contribute to cardiovascular-respiratory responses during dynamic exercise. Four men exercised at 50-100 W for 5 min. Muscle ischemia and a sustained pressor response were produced by total circulatory occlusion of both legs beginning 30 s before the end of exercise and continuing for 3 min postexercise. During regression of full motor and sensory block, motor strength recovered while sensory block continued; the pressor response was blocked as long as sensory anesthesia persisted (two subjects). During blockade of the pressor response, cardiovascular-respiratory responses to exercise gradually returned from augmented to normal (preblock) levels. Sensory blockade was incomplete in two subjects and the pressor response was not fully blocked. We conclude that stimulation of small sensory fibers during ischemia elicits the pressor response, but that these fibers appear not to contribute to cardiovascular-respiratory responses during mild dynamic exercise with adequate blood flow.
During the past three quarters of a century, nerve blocks have been used with varying success as a primary treatment technique for patients with acute and chronic pain. However, practicing dolorologists soon realized that, in certain individuals, anesthetic blocking of noxious, peripheral afferent sensations did not always amelliorate pain complaints and at times even exaggerated them. The recent advent of the multidisciplinary approach to the management of pain, including neurosurgical procedures, new drugs, electrical stimulation and psychosocial intervention, has helped to clarify the indications for, limitations of, and disadvantages of the use of nerve blocks. The purpose of this article is to place nerve blocks in proper perspective and to define their role among the many methods currently available for the evaluation and control of severe pain.
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Local glossopharyngeal and superior laryngeal nerve block anesthesia for peroral endoscopy was performed on 500 patients (313 bronchoscopies, 162 esophagoscopies, 25 combined bronchoesophagoscopies). The technique allows easy insertion of rigid and flexible scopes or awake tracheal intubation of conscious patients. Glossopharyngeal nerve block causes temporary abolition of the gag reflex and loss of tactile sensation over the posterior third of the tongue and the lateral and posterior wall of the oropharynx and hypopharynx. Superior laryngeal nerve block results in loss of tactile sensation over the posterior surface of the epiglottis and the mucosa of the larynx and upper trachea. Ten of the 500 patients (2%) had an inadequate glossopharyngeal block, and 4 of the 313 patients who had a bronchoscopic examination had an inadequate superior laryngeal block. In the remaining patients, excellent anesthesia was obtained with good patient acceptance and minimal morbidity.
We studied the postoperative course of 20 consecutive patients with T10 to 12 flank incisions, half of whom had intraoperative bupivacaine intercostal nerve blocks. The nerve block patients required less pain medication (p less than 0.001), ambulated 3 days earlier (p less than 0.001) and took a regular diet 2 days sooner (p less than 0.01) than the control patients.
This paper presents the first one year's experience of nerve blocking procedures carried out for the relief of intractable pain. The control of pain is complex and has led to the development of Pain Clinics employing the skills of different specialties. The scope and organisation of such a clinic developed at Auckland Hospital is outlined. Some 103 patients were referred with intractable pain from cancer, musculo-skeletal disorders, neurogenic causes and ischaemic causes and ischaemic problems. Of these, 55 percent derived complete relief. Breakdown of results demonstrate that over 70 percent of patients in the groups of pain of neurogenic and ischaemic origin had complete relief of pain. Recognised complications of major nerve blocking procedures were encountered in a small percentage of patients, but these caused no great concern. Nerve blocks have a definite place in the treatment of chronic pain and form an important adjunct to the overall management.