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At least 55 records · Page 3Linked to original sources
PubMed1996

Injured nerve block alters adjacent nerves spinal interaction in neuropathic rats.

Baseline activity and responses to simultaneous saphenous stimulation of pairs of neurones recorded from sciatic (L5-6) and saphenous (L2) spinal cord segments, in rats with thermal hyperalgesia following sciatic constriction, were analysed before, during and after a sciatic nerve block with a local anaesthetic. In sciatic neurones, during the block, reductions of baseline activity (p < 0.001), increases in threshold of saphenous electrical stimulation (p < 0.01) and reductions of responses to electrical and to natural noxious saphenous stimuli (p < 0.001) were consistently found. The neuronal baseline and evoked activities remained unmodified in saphenous neurones. The contribution of input from injured periphery to central neurone circuitry mechanisms underlying the unmasking of improper afferents is discussed.

Afferent Pathways↗
PubMed2006

[Systemic toxicity caused by local anesthetics after peripheral nerve blocks].

Peripheral nerve blocks have aroused increasing interest in recent years, leading to a rise in the rate of complications. At the same time noteworthy technical advances have been made in areas such as nerve stimulation and ultrasound imaging, and local anesthetics have become safer. Nevertheless, the risk of anesthetic-related systemic toxicity, which manifests with neurological symptoms that tend to be forerunners of cardiovascular ones, can not be ignored. We report 2 cases of systemic toxicity due to the use of a mixture of local anesthetics during nerve blocks for outpatient surgery.

Adult↗
PubMed2000

Effect of alkalinization of lidocaine on median nerve block.

Median nerve blocks were performed in 10 volunteers in a randomized, double-blind, crossover study to compare the effects of 1% plain lidocaine with 1% lidocaine in sodium bicarbonate 0.1 mmol litre-1. Sensations of hot, cold, pinprick and light touch, compound motor and sensory nerve action potentials, and skin temperature were assessed at 2-min intervals. pH was 6.4 +/- 0.1 for plain lidocaine and 7.7 +/- 0.2 for alkalinized lidocaine (P < 0.001). Alkalinized lidocaine produced more rapid inhibition of compound motor action potentials than plain lidocaine (median 4 (range 2-6) vs 9 (2-14) min) (P = 0.039). Alkalinized lidocaine also produced more rapid onset of inhibition of compound motor than sensory nerve action potentials (4 (2-6) vs 8 (4-12) min) (P = 0.0039). There was no significant difference in any other sensory modality between alkalinized and plain lidocaine. These data suggest that addition of bicarbonate to lidocaine for median nerve block significantly increased the rate of motor block without changing the onset or extent of sensory block.

Anesthetics, Local↗
PubMed2001

[Treatment with stellate ganglion block, continuous epidural block and ulnar nerve block of a patient with postherpetic neuralgia who developed complex regional pain syndrome (CRPS)].

We present a case of a 46-year-old female patient with systemic lupus erythematosus who developed herpes zoster of the right eighth cervical nerve. Her whole right forearm, hand and the first through fifth fingers were coated with some gel and protected against pain. She had been suffering from continuous and spasmodic burning pain, hyperalgesia, allodynia, drop in skin temperature, sudmotor disturbance, edema, constructure of the joints, muscle atrophy and bone atrophy of her right upper extremity probably due to postherpetic neuralgia (PHN) associated with complex regional pain syndrome (CRPS). She received right stellate ganglion block (SGB), continuous cervical epidural block and right ulnar nerve block. Reduction of pain and edema as well as improvement in mobility of each joint of her right upper extremity was observed. We suspect that SGB, continuous cervical epidural block and ulnar nerve block are effective and useful alternative treatments in a patient with PHN associated with CRPS of the eighth cervical nerve.

Analgesia, Epidural↗
PubMed1996

[Sciatic nerves block].

Sciatic nerve block is considered difficult to perform, but very useful for lower limb anaesthesia and analgesia. The use of a nerve stimulator makes the technique easier. Functionally, it is better to consider that there are three independent sciatic nerves, namely, the posterior cutaneous nerve, the tibial nerve and the common peroneal nerve. Searching for blocking these three nerves and especially the latter two, specifically improve the reliability and quality of blockade.

Anesthetics, Local↗
PubMedDate not supplied

A comparative study of the percutaneous versus intraoral technique for mental nerve block.

OBJECTIVE: Mental nerve block is frequently used to aid repair of facial lacerations; both percutaneous and intraoral approaches to blocking this nerve are used, but have never been compared. The authors compared the two techniques for pain of administration and effectiveness of anesthesia. METHODS: A prospective, randomized, single-blind, crossover study was conducted using ten healthy volunteers aged 22 to 33 years. Patients having prior experience with mental nerve blocks, lidocaine allergy, active oral/facial infection, or previous facial fractures were excluded. Bilateral mental nerve blocks were done using intraoral technique on one side and percutaneous technique on the other. Both techniques were used by the same investigator and were carried out with 27-gauge needles and 2.5 mL of 2% buffered lidocaine at room temperature injected over 20 seconds. The oral mucosa was topically anesthetized with viscous lidocaine for 1 minute prior to intraoral injection. The orders of the blocks and sides of the face anesthetized were randomized. Subjective and objective pain (visual-analog scale), efficacy (anesthesia of lower lip), time to onset, and duration of anesthesia were evaluated. RESULTS: The intraoral technique was subjectively less painful than the percutaneous approach in nine of ten subjects (p = 0.02). Scores on the visual-analog pain scale were significantly lower for the intraoral technique (p = 0.03). Intraoral injection produced lower-lip anesthesia in 10/10 subjects versus 7/10 for percutaneous (p = 0.25). Times to onset (approximately 1-2 minutes) and durations of anesthesia (approximately one hour) were similar for the two techniques. CONCLUSION: The intraoral approach to the mental nerve block with adjunctive topical anesthesia was subjectively and objectively less painful than the percutaneous approach without adjunctive anesthesia. While the intraoral approach had a greater efficacy of lower-lip anesthesia and a longer duration of action, these differences were not statistically significant.

Adult↗
PubMedDate not supplied

Popliteal sciatic nerve block aided by a nerve stimulator: a reliable technique for foot and ankle surgery.

The reliability of popliteal sciatic nerve blocks was prospectively assessed in 625 blocks performed in 507 patients. The sciatic nerve was approached at the apex of the popliteal fossa, in the midline, with an insulated needle connected to a peripheral nerve stimulator partially designed by one of the authors. When needed, an inguinal paravascular femoral nerve block was also performed. The drugs used were 1% mepivacaine or 0.5% bupivacaine with or without 1:200,000 epinephrine. The sciatic and femoral nerves were blocked with 30 ml and 10 ml of local anesthetic, respectively. The block was sufficient to provide surgical anesthesia in 92%; supplemental analgesia was necessary in 5% and general anesthesia was required in 3% of the cases. Discomfort associated with the block procedure was found to be minimal by 89% of the patients, moderate by 9% and severe by 2%. Overall satisfaction with perioperative analgesia was evaluated by 466 patients: 444 (95%) were completely satisfied, 20 (4%) expressed moderate reservations and two (1%) expressed major reservations. The authors conclude that the technique is a safe and reliable alternative to more common forms of anesthesia for surgery below the knee. They attribute the great success rate to a high popliteal approach, the use of insulated needles, a discriminating mode of nerve stimulation and the systematic search for optimal response to needle stimulation.

Adolescent↗
PubMed1976

Molecular mechanisms of nerve block by local anesthetics.

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...

Action Potentials↗
PubMed1975

Axillary nerve blocks.

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.

Adult↗
PubMed2002

Lumbar plexus block with perineural catheter and sciatic nerve block for total hip arthroplasty.

This case series describes the use of continuous lumbar plexus block with sciatic nerve block as an alternative anesthetic for total hip arthroplasty (THA). A retrospective chart review was performed on 10 consecutive patients who underwent THA at Walter Reed Army Medical Center using continuous lumbar plexus block and sciatic nerve block for anesthesia. Continuous lumbar plexus block with sciatic nerve block without concurrent general anesthesia has not been described previously for THA. Peripheral nerve block may provide superior intraoperative outcomes, as suggested by lower operative blood loss and potentially lower transfusion exposure. Lumbar plexus block with perineural catheter and sciatic nerve block with perioperative sedation is an effective alternative to general anesthesia for THA.

Aged↗
PubMedDate not supplied

A clinical comparison of psoas compartment and inguinal paravascular blocks combined with sciatic nerve block.

The extent of inguinal paravascular blockade and psoas compartment blockade with sciatic nerve block was evaluated in 60 patients. Volumes of 30 ml and 20 ml 0.35% bupivacaine with 1/200,000 epinephrine were injected for lumbar plexus and sciatic nerve block, respectively. Complete lumbar plexus blockade was achieved in 73% of the group who were treated with the psoas compartment technique and 43% of the group who were treated with the inguinal paravascular technique. Sensory blockade of the femoral, lateral femoral cutaneous and obturator nerves was obtained in 100%, 97% and 77% of the patients in the psoas compartment group, and 93%, 63% and 47% of the patients in the inguinal paravascular group, respectively. Sensory blockade of the lateral femoral cutaneous and obturator nerves was more rapid with psoas compartment block. The study suggests that the psoas compartment block is effective in blocking the femoral, lateral femoral cutaneous and obturator nerves, but the inguinal paravascular block is only effective in blocking the femoral nerve.

Adult↗
PubMed2006

Iliac compartment block following ilioinguinal iliohypogastric nerve block.

Transient femoral nerve palsy is a known complication associated with percutaneous ilioinguinal iliohypogastric nerve block. Excess volume and higher concentrations of local anesthetic have been implicated for transient femoral nerve palsy. We encountered partial iliac compartment block involving lateral cutaneous nerve of the thigh and femoral nerve with a lower concentration (0.25%) of bupivacaine administered in the smallest indicated volume of 0.25 ml.kg-1 using a double-shot technique.

Anesthetics, Local↗
PubMed1997

A common epineural sheath for the nerves in the popliteal fossa and its possible implications for sciatic nerve block.

Sciatic nerve block in the popliteal fossa is associated with a highly variable success rate. Frequently, anesthesia is profound in the distribution of both the tibial (TN) and common peroneal nerves (CPN), although the response to nerve stimulation or paresthesia is obtained in the distribution of one division of the nerve. However, anesthesia in the distribution of only one division of the nerve is also a common occurrence under apparently identical clinical circumstances. Looking for a possible role of a common epineural sheath in these phenomena, we injected dye into the epineural sheath of the tibial nerve in 10 cadaver legs and observed its spread within the sheath. Injections of 15 mL and 30 mL of the dye resulted in a proximal spread of 147 +/- 34 mm and 172 +/- 50 mm, respectively, from the injection point 10 cm below the popliteal fossa crease. In a majority of the legs, the dye reached the division of the sciatic nerve in the popliteal fossa, bathing both the TN and CPN. Gross inspection and histologic examination of the sciatic nerve specimens revealed a common epineural sheath enveloping the TN and CPN. The presence of the common epineural sheath and its characteristics may have important clinical implications for sciatic nerve blockade in the popliteal fossa.

Humans↗
PubMed1980

Changes of the cell bodies in the facial nucleus after facial nerve block.

Facial nerve blocks were produced in four monkeys by insertion of a needle into the facial nerve trunk. The sequential changes of nerve cells in the facial nucleus were investigated 4 days, and 2 and 7 months later. Although the facial paralysis recovered in 2 months, considerable changes of cell bodies in the facial nucleus were still obvious which recovered completely only after 7 months. It is postulated that an optimum discharge is generated by those nerve cells in the facial nucleus during the recovery period which in clinical practice could result in 6 months of clinical remission from facial spasm.

Animals↗
PubMed1996

Regional nerve blocks.

Regional nerve blocks are a valuable skill for general practitioners and surgeons who perform surgical procedures under local anaesthetic. Once mastered, these injections provide rapid anaesthesia with minimal pain, little distortion of the tissues and improved aesthetic results. This paper describes techniques applicable to lesions of the face, upper and lower limbs, and to achieve anaesthesia after a fractured rib.

Humans↗