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PubMed1977

Diagnostic, prognostic, and therapeutic nerve blocks.

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.

Ammonium Sulfate↗
PubMed2006

Lower median nerve block impairs precision grip.

The purpose of this study was to investigate precision grip impairment caused by a lower median nerve block at the wrist. The median nerve block was achieved by injecting bupivacaine hydrochloride into the carpal tunnel, which acutely simulated a median neuropathy. Seven healthy male subjects were instructed to grip, lift, and hold an instrumented handle within 60s using precision grip. The same tasks were performed before and after the nerve block. Force and torque data were recorded using two miniature 6-component force/torque transducers. The precision grip was quantified by the safety margin (i.e. the difference between the actual grip force and the minimal grip force to keep the object from dropping), the variation of grip force, and the migration area of center of pressure (i.e. the area defined by the center of pressure at a digit-transducer surface while holding the handle). Two subjects were unable to complete the precision grip tasks after the nerve block, and their data were excluded from the analyses. The median nerve block caused significant increases (P<0.05) in the safety margin of the grip force (>50%), the grip force variation (>80%), and the area of center of pressure migration (>250%). Median nerve block at the wrist impairs the fine motor control during precision grip. Our results corroborate the important role played by sensory function in hand fine motor control. Clinically, the measures related to precision grip have the potential to quantify impairment of hand function caused by neuromuscular disorders, to monitor the progress of a hand disorder, and to evaluate the efficacy of a treatment or rehabilitation procedure.

Adult↗
PubMed1992

Plasma concentrations of lignocaine after obturator nerve block combined with spinal anaesthesia in patients undergoing transurethral resection procedures.

Bilateral obturator nerve block has become a widely accepted technique to avoid adductor contraction during transurethral resection of prostate or bladder tumours. However, little is known about plasma lignocaine concentrations after the block. We conducted this study to assess a safe dose of lignocaine for injection in obturator nerve block. Bilateral obturator nerve block was performed with the aid of a peripheral nerve stimulator in 12 patients after spinal anaesthesia. In group I (n = 6), patients received 2% lignocaine 10 ml (200 mg) for the block; those in group II (n = 6) received 2% lignocaine 15 ml (300 mg). The block was satisfactory and no single adductor contraction was observed in either group during surgery. The peak plasma concentrations of lignocaine were 2.28 (SD 0.29) micrograms ml-1 and 3.75 (0.79) micrograms ml-1 in groups I and II, respectively. The greatest plasma concentration was 5.07 micrograms ml-1 in a patient of group II. There were no symptoms suggesting systemic toxicity. We conclude that bilateral obturator nerve block may be performed safely and effectively with 2% lignocaine 10 ml with the aid of a peripheral nerve stimulator in patients undergoing transurethral resection procedures with spinal anaesthesia.

Aged↗
PubMed1991

Dorsal penile nerve block for newborn circumcision.

Dorsal penile nerve block with lidocaine is safe and effective for reducing the pain associated with newborn circumcision. Administering the anesthesia adds little time or expense to the overall routine. Complications are minor, limited to local bleeding and hematoma formation. Family physicians performing circumcision should be prepared to use penile nerve block and to advocate it to parents who choose newborn circumcision.

Circumcision, Male↗
PubMed1995

Superior laryngeal nerve block: an anatomical study.

Superior laryngeal nerve anaesthesia is frequently used to facilitate endotracheal intubation in the awake patient. We have modified the transcutaneous approach to this nerve block to employ a short bevel needle. This improves tactile perception in performing the procedure thus simplifying identification of the correct depth of injection. This study was designed to determine the anatomical basis of superior laryngeal nerve anaesthesia and to estimate the success rate using our modified technique. At autopsy, 20 cadavers had nerve block performed substituting 0.02% methylene blue for local anaesthetic. Dissection was then performed to identify the anatomical structures stained by the simulated local anaesthetic. Additional dissections were performed in formalin-fixed cadavers. We found that the dye was injected into the paraglottic space bounded laterally by the thyrohyoid membrane and thyroid cartilage, medially by the laryngeal submucosa, caudad by the conus elasticus, cephalad by the hyoid bone, and anteriorly and posteriorly by the anterior and posterior thyrohyoid ligaments, respectively. The internal laryngeal nerve, the sensory branch of the superior laryngeal nerve, passed through this compartment and was heavily stained with simulated local anaesthetic. Resistance to the passage of the short bevel needle was provided by the lateral glossoepiglottic fold, not the thyrohyoid membrane as we had expected. Of 40 injections, 39 were deemed successful for a success rate of 97.5%. We conclude that this is a simple and highly successful technique for performing superior laryngeal nerve anaesthesia.

Cadaver↗
PubMed2002

The antinociceptive and histologic effect of sciatic nerve blocks with 5% butamben suspension in rats.

UNLABELLED: Butamben, a lipophilic local anesthetic of the ester class, produces a differential nerve block of long duration. Epidural and peripheral nerve blocks with butamben, formulated as a 5%--10% suspension, result in prolonged analgesia without significant motor blockade. We evaluated the effect of butamben sciatic nerve block on antinociception using the rat paw formalin test, as well as withdrawal latencies to thermal stimulation, and assessed histologic changes in the nerve. After right sciatic nerve block with butamben 5% or saline, responses to intradermal injection of 5% formalin were recorded in randomly selected groups of 6 animals each on days 1, 2, 5, 10, 21, and 28. In an additional group of 8 thermal challenges to both hind paws were recorded at 1, 2, 5, 7, 10, 14, 17, 21, and 28 days after right sciatic butamben 5% blocks. Butamben injection decreased the formalin-induced flinches on days 2, 5, 10, 21 and 28 and decreased thermal challenges on days 1 through 17. Histologic changes were minimal. This study demonstrates a prolonged antinociceptive effect from butamben nerve block to both formalin-induced nociception and heat hyperalgesia, without an effect on gross motor function or histologic morphology. IMPLICATIONS: Butamben 5% nerve blocks produced a prolonged antinociceptive effect to formalin-induced nociception and heat hyperalgesia, without significant motor effect or evidence of substantial histologic changes.

Anesthetics, Local↗
PubMed1996

Specificity of diagnostic nerve blocks: a prospective, randomized study of sciatica due to lumbosacral spine disease.

Temporary nerve blocks using local anesthetic are employed extensively in the evaluation of pain problems, particularly lumbosacral spine disease. Their specificity and sensitivity in localizing anatomic sources of pain have never been studied formally, however, and so their diagnostic and prognostic value is questionable. There have been anecdotal reports of relief of pain by temporary blocks directed to areas of pain referral, as opposed to areas of documented underlying pathology; but there has been no study to define the frequency or magnitude of this effect. We have examined the specificity and sensitivity of a battery of local anesthetic blocks in a series of 33 patients with a chief complaint of sciatica, attributable in all cases to spinal disease (radiculopathy, with some clinical features of arthropathy). As determined by blinded patient analog ratings in randomized sequence, three different nerve blocks were significantly more effective than control lumbar subcutaneous injection of an identical volume of 3 ml of 0.5% bupivacaine (P < 0.05). Not only paraspinal lumbosacral root blocks and medial branch posterior primary ramus blocks (at or proximal to the pathology), but also sciatic nerve blocks (distal or collateral to the pathology) produced temporary relief in a majority of patients. This confirmed the study hypothesis that false positive results are common, and specificity is low. For sciatic nerve blocks, specificity was between 24% and 36%. Patterns of responses specific to the established diagnosis of radiculopathy (i.e., root block most effective) had sensitivities between 9% and 42%. Statistical analysis of clinical and technical prognostic factors revealed that the only association with pain relief by any block were the effects of other blocks. The strongest association was between relief by sciatic nerve block and relief by medial branch posterior primary ramus (facet) block (P = 0.001, odds ratio 16.0). There were no associations between the results of blocks and clinical findings (history, physical examination, diagnostic imaging) in these patients, chosen for their homogeneous clinical presentation and absence of functional signs. Our findings indicate a limited role for uncontrolled local anesthetic blocks in the diagnostic evaluation of sciatica and referred pain syndromes in general. Negative blocks or a pattern of responses may have some predictive value, but isolated, positive blocks are non-specific. This lack of specificity may, however, be advantageous in therapeutic applications.

Adult↗
PubMed1996

Lidocaine plasma levels following two techniques of obturator nerve block.

STUDY OBJECTIVES: To assess plasma levels and the potential toxicity of lidocaine following two different approaches to the obtruator nerve. DESIGN: Prospective, randomized, clinical trial. SETTING: Operating rooms of a university hospital. PATIENTS: 45 ASA physical status I, II and III patients over 40 years of age, and undergoing transurethral resection of urinary bladder tumors. INTERVENTIONS: A prospective study compared lidocaine plasma levels following direct and indirect (3-in-1) obturator nerve block using lidocaine 1.5% plus 1:200,000 epinephrine. Patients with unilateral urinary bladder tumors were randomized to receive direct obturator nerve block with 15 ml of lidocaine (Group A, n = 20), while those with bilateral tumors received a bilateral direct obturator nerve block with 30 ml (2 x 15 ml) of lidocaine (Group B, n = 12). A third group of patients with unilateral bladder tumors received 3-in-1 indirect) obturator nerve block with 40 ml of lidocaine (Group C, n = 17). Plasma lidocaine concentration was determined every 5 minutes for 30 minutes, and at 45, 60, and 90 minutes after the block. MEASUREMENTS AND MAIN RESULTS: In Group A, mean (+/- SD) peak plasma lidocaine level of 1.35 +/- 0.5 micrograms/ml (range 0.61 to 2.41 micrograms/ml) occurred 45 minutes after injection. In Group B, a peak of 3.63 +/- 2.07 micrograms/ml (0.75 to 7.21 micrograms/ml) occurred 15 minutes after injection. Mean peak level in Group C of 2.08 +/- 0.77 micrograms/ml (0.84 to 3.21 micrograms/ml) occurred 60 minutes after injection Lidocaine concentrations were significantly higher in Groups B and C than in Group A, and they were higher in Group B than in Group C. No patient had any signs of symptoms of local anesthetic toxicity. CONCLUSIONS: Despite a lower total dose of lidocaine administered (450 mg), higher mean and peak plasma levels were reached sooner with bilateral direct obturator nerve block compared with the indirect obturator nerve block (600 mg), indicating a faster blood absorption of lidocaine following direct block. Both types of obturator nerve block prevented adductor muscle contraction in a large percentage of cases.

Absorption↗
PubMedDate not supplied

Development of a standardized peripheral nerve block procedure note form.

OBJECTIVES: Despite the tremendous growth of peripheral nerve blocks, no standard format exists to document their performance. Our objective was to create a peripheral nerve block form based on key elements of literature evidence and on our own group consensus. RESULTS: We describe the process and results of our multi-institutional effort to construct a standardized peripheral nerve block procedure form. CONCLUSION: A form was developed to help meet the medical, legal, and billing requirements of documentation consistent with the performance of peripheral nerve block.

Humans↗
PubMed1997

Effect of sympathetic nerve block on acute inflammatory pain and hyperalgesia.

BACKGROUND: Sympathetic nerve blocks relieve pain in certain chronic pain states, but the role of the sympathetic pathways in acute pain is unclear. Thus the authors wanted to determine whether a sympathetic block could reduce acute pain and hyperalgesia after a heat injury in healthy volunteers. METHODS: The study was made as a randomized, single blinded investigation, in which the volunteers served as their own controls. A lumbar sympathetic nerve block and a contralateral placebo block were performed in 24 persons by injecting 10 ml bupivacaine (0.5%) and 10 ml saline, respectively. The duration and quality of blocks were evaluated by the sympatogalvanic skin response and skin temperature. Bilateral heat injuries were produced on the medial surfaces of the calves with a 50 x 25 mm thermode (47 degrees C, 7 min) 45 min after the blocks. Pain intensity induced by heat, pain thresholds to thermal and mechanical stimulation, and secondary hyperalgesia were assessed before block, after block, and 1, 2, 4, and 6 h after the heat injuries. RESULTS: Of the 24 volunteers, eight were excluded because of somatic block or incomplete sympathetic block. The study revealed no significant differences between sympathetic block and placebo for pain or mechanical allodynia during injury, or pain thresholds, pain responses to heat, or areas of secondary hyperalgesia after the injury. The comparisons were done for the period when the block was effective. CONCLUSION: Sympathetic nerve block did not change acute inflammatory pain or hyperalgesia after a heat injury in human skin.

Acute Disease↗
PubMedDate not supplied

Unintentional neuromuscular blocking agent injection during an axillary brachial plexus nerve block.

OBJECTIVE: We describe the consequences of an unintentional injection of atracurium instead of ropivacaine during an axillary brachial plexus nerve block. CASE REPORT: A 79-year-old woman was scheduled for wrist fracture repair. An axillary brachial plexus block was performed by use of a nerve stimulator. Twenty milliliters of 0.5% ropivacaine with 1:200,000 epinephrine was injected on the radial and then on the median nerves. Two minutes later, the patient became dyspneic and was unable to elevate her head from the pillow. A check of the syringes revealed that one contained 50 mg of atracurium instead of 0.5% ropivacaine. After IV propofol was administered, the trachea was intubated and controlled ventilation started. At the end of surgery (more than 2 hours later), reversal of residual neuromuscular block was performed. The motor and sensory brachial plexus block completely recovered 12 hours after the initial bolus injection. No clinical neurological deficit was reported afterward by the patient. CONCLUSIONS: Unintentional injection of atracurium mixed with ropivacaine during axillary brachial plexus block leads to complete body paralysis that requires general anesthesia and mechanical ventilation. Recovery was complete without any neurological sequela. An analysis of the chain of events that led to the error suggests some recommendations to improve our daily practice.

Aged↗
PubMedDate not supplied

Combined lumbar-plexus and sciatic-nerve blocks: an analysis of plasma ropivacaine concentrations.

BACKGROUND AND OBJECTIVES: Lumbar-plexus and sciatic-nerve blocks are commonly combined for lower-extremity anesthesia using large doses of ropivacaine. Limited information is available about the pharmacokinetics of this practice. We analyzed plasma ropivacaine concentrations after single-injection lumbar-plexus blocks with and without sciatic-nerve blocks. METHODS: Twenty patients having lower-extremity surgery using a lumbar-plexus block with 0.5% ropivacaine with 1:400,000 epinephrine (35 mL, n = 10) or the same lumbar-plexus block with the addition of a sciatic-nerve block (25 mL, n = 10, 60 mL total) using the same solution were enrolled. Venous blood samples were collected at 5, 15, 30, 45, 60, 120, and 240 minutes after block placement and analyzed for total ropivacaine concentration by use of gas chromatography. Individual timepoints, maximum concentrations (C(max)), and time to C(max) (T(max)) were compared. Values are mean +/- SD. RESULTS: Both groups demonstrated a rapid increase in plasma concentration over the first 30 to 45 minutes. Concentrations were greater for those who received both blocks (P = .0005) at all timepoints. The lumbar-plexus block C(max) was less (986 +/- 221 ng/mL) than for the combined blocks (1,560 +/- 351 ng/mL, P = .0004). The T(max) was greater for the lumbar plexus (80 +/- 49 min) than for the combined blocks (38 +/- 22 min, P = .03). There was no relationship between the C(max) and patient age, weight, or body mass index. CONCLUSIONS: The results of this study demonstrate that the plasma ropivacaine concentrations increase quicker when a sciatic-nerve block is added to a lumbar-plexus block, but C(max) remains below the toxicity threshold.

Adult↗
PubMed1997

Local anesthetic administration for awake direct laryngoscopy. Are glossopharyngeal nerve blocks superior?

BACKGROUND: Glossopharyngeal nerve (GPN) blocks may provide reliable analgesia for awake direct laryngoscopy, although this has not been evaluated prospectively. This study was designed to determine if GPN blocks provide a superior route of local anesthetic administration for awake direct laryngoscopy as measured by hemodynamic, gag, and subjective pain responses. METHODS: A prospective, randomized, single-blinded, crossover design was used. All participants (n = 11) were anesthesiologists. Three routes of local anesthetic administration were evaluated: 2 min of 2% viscous lidocaine swish and gargle (S&G); S&G combined with 10% lidocaine spray (S&G/spray); and S&G combined with 1% lidocaine bilateral GPN blocks (S&G/block; anterior tonsillar pillar method). Five minutes after the local anesthetic was administered, laryngoscopy was performed and sustained for 20 s. Noninvasive hemodynamic measurements and serum lidocaine concentrations were determined. Visual analogue scale scores and a poststudy questionnaire were used to assess participants' ability to tolerate local anesthetic administration and laryngoscopy and their choice for use in clinical practice. RESULTS: No significant hemodynamic changes were observed, although there was a modest increase (< 15%) in heart rate in the S&G/block group in the first minute after laryngoscopy. Serum lidocaine concentrations were higher (P < 0.05) in the S&G/block group at 5 and 10 min (0.5 +/- 0.1 and 1.0 +/- 0.2 microgram/ml) compared with the S&G group. Participants' visual analogue scale scores, which assessed their ability to tolerate laryngoscopy, showed that S&G (5.4 +/- 0.9) resulted in more discomfort (P < 0.05) than either S&G/spray (3.5 +/- 0.9) or S&G/block (3.3 +/- 0.7). The laryngoscopist's visual analogue scale scores, which assessed the ease of visualization, revealed a trend (P < 0.08) toward less coughing and gagging with S&G/spray (1.8 +/- 0.9) compared with S&G (4.0 +/- 1.3) and S&G/block (3.7 +/- 1.1). Oropharyngeal discomfort lasting 24 h or more was reported by 91% of participants after S&G/block, whereas no participant reported oropharyngeal discomfort after S&G or S&G/spray. Significantly more participants (73%) indicated their preference for using S&G/spray in future clinical practice compared with S&G (P < 0.01) and S&G/block (P < 0.05). CONCLUSIONS: Glossopharyngeal nerve blocks do not provide a superior route of local anesthetic administration for awake direct laryngoscopy. Two minutes of 2% viscous lidocaine S&G followed by 10% lidocaine spray was the anesthetic route preferred by participants and laryngoscopists.

Anesthetics, Local↗