The effect of anesthetic blockade of greater occipital nerve during the withdrawal period of the medication overuse headache treatment

Background and purpose

Discontinua­tion of medication still remains a key element in the treatment of medication overuse headache (MOH), but there is no consensus on the withdrawal procedure. We aimed to share the promising results of anesthetic blockade of greater occipital nerve (GON), which can be an alternative to existing treatments during the early withdrawal period of MOH treatment.

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Methods

This study was conducted using regular electronic medical records and headache diaries of patients diagnosed with MOH and treated with anesthetic GON blockade with 0.5% bupivacaine solution in a specia­lized headache outpatient clinic. A total of 86 patients who developed MOH while being followed up for chronic migraine were included in the study.

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Results

The treatment schemes for MOH are based on expert consensus and withdrawal strategies are the most challenging part of treatment. In our study, numerical rating scale for headache intensity, overused medication consumption per month, headache frequency (day/month) and the duration of each attack (hour/day) decreased significantly in the first month compared to pre-treatment (p < 0.01). 

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Conclusion

Conclusion – Our study suggests that GON blockade can be used as a good alternative therapy in the treatment of MOH.

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Parasacral ischial plane block for lower limb wound debridement surgeries - A case series

Parasacral ischial plane block is a novel fascial plane approach to sacral plexus. Parasacral ischial plane block is technically less challenging and obviates the need for direct visualisation of sacral plexus. It can reliably be performed in limb-amputated patients where neuromuscular stimulation is less useful. Ten patients of the American Society of Anesthesiologists physical status II-IV, aged between 18 and 70 years, posted for elective lower limb debridement surgeries were enroled in this prospective case series. The time taken to perform the block was ≤4 minutes in all cases. Time taken for full sensory loss was 9 minutes to 15 minutes. None of the patients developed a complete motor blockade till 30 minutes after our observation. None of the patients required intraoperative supplemental analgesia. This block is technically easy, less time-consuming, and provided adequate sensory analgesia in below-knee surgeries.

Stellate ganglion block successfully relieved medically unexplained chronic pain: a case report

Medically unexplained symptoms refers to a clinical syndrome characterized by somatic symptoms that cannot be reasonably explained by any organic disease. Chronic pain can be a type of medically unexplained symptom. The current treatment modalities for chronic pain mainly include drugs and psychotherapy. The use of stellate ganglion block for treatment of chronic pain has rarely been reported. Herein, we report a patient whose chronic pain was completely relieved after receiving a stellate ganglion block.

Primary spread of caudal blockade in children: the possible limiting role of the lumbar spinal cord enlargement (tumenescence) in combination with the cerebrospinal fluid rebound mechanism

BACKGROUND

Despite being the most frequently used pediatric nerve block, certain aspects of the initial intraspinal spread of local anesthetics when performing a caudal block need further elucidation. The fact that injected volumes of 0.7-1.3 mL kg^-1 initially only reach the thoraco-lumbar junction, with only a few vertebral segments difference despite the huge difference in injected volume, still has no apparent explanation. We hypothesize that the narrowing of the epidural space caused by the lumbar spinal enlargement may provide an anatomical barrier causing this restriction of initial spread, alone or in combination with increased intrathecal pressure caused by the "cerebrospinal fluid rebound mechanism." The aim of this observational study was to find support for or refute this hypothesis.

METHODS

Twenty nine MRI scans of the vertebral column, performed in children 0-6 years of age, was identified from the radiographic imaging computer system and analyzed for the vertebral level of the maximum of the lumbar spinal enlargement (Associated anatomical data related to the spinal canal, the dura mater, and the spinal cord were also recorded.

RESULTS

The maximum of the lumbar spinal enlargement was found at a median vertebral level of Th 11 (IQR 11-11).

CONCLUSION

The maximum of the lumbar spinal enlargement is located at the Th 11 vertebral level. Although not entirely conclusive, the findings of the present study do support the notion that the lumbar spinal enlargement, in combination with the CSF rebound mechanism, may be the factors limiting the initial spread of a caudal block to the thoraco-lumbar junction.

Nanogels with High Loading of Anesthetic Nanocrystals for Extended Duration of Sciatic Nerve Block

The development of thermoresponsive nanogels loaded with nanocrystals of the local anesthetic bupivacaine nanocrystals (BNCs) for prolonged peripheral nerve pain relief is reported here. BNCs were prepared using the antisolvent precipitation method from the hydrophobic form of bupivacaine (bupivacaine free base). The as-prepared BNCs were used stand-alone or encapsulated in temperature-responsive poly(ethylene glycol) methyl ether methacrylate (OEGMA)-based nanogels, resulting in bupivacaine NC-loaded nanogels (BNC-nanogels) of monodisperse size. The synthesis protocol has rendered high drug loadings (i.e., 93.8 ± 1.5 and 84.8 ± 1.2 wt % for the NC and BNC-nanogels, respectively) and fast drug dissolution kinetics in the resulting composite material. In vivo tests demonstrated the efficacy of the formulation along with an extended duration of sciatic nerve block in murine models of more than 8 h with a formulation containing only 2 mg of the local anesthetic thanks to the thermoresponsive character of the polymer, which, at body temperature, becomes hydrophobic and acts as a diffusion barrier for the encapsulated drug nanocrystals. The hydrophobicity of the encapsulated bupivacaine free base probably facilitates its pass through cell membranes and also binds strongly to their hydrophobic lipid bilayer, thereby protecting molecules from diffusion to extracellular media and to the bloodstream, reducing their clearance. When using BNC-nanogels, the duration of the anesthetic blockage lasted twice as long as compared to the effect of just BNCs or a conventional bupivacaine hydrochloride solution both containing equivalent amounts of the free drug. Results of the in vivo tests showed enough sensory nerve block to potentially relieve pain, but still having mobility in the limb, which enables motor function when required. The BNC-nanogels presented minimal toxicity in the in vivo study due to their sustained drug release and excellent biocompatibility. The encapsulation of nano-sized crystals of bupivacaine provides a prolonged regional anesthesia with reduced toxicity, which could be advantageous in the management of chronic pain.

Femoral nerve catheters and limb strength asymmetry at 6 months after primary anterior cruciate ligament reconstruction in pediatric patients

BACKGROUND

The postoperative implications of single-injection femoral nerve blockade and femoral nerve catheter placement for anterior cruciate ligament reconstruction are not well defined among pediatric patients. Femoral nerve blockade may be associated with deficits in quadriceps symmetry at 6 months postoperative.

AIMS

We compared outcomes after primary anterior cruciate ligament reconstruction surgery in pediatric patients who received either a single-injection femoral nerve block or femoral nerve catheter and a single-injection popliteal nerve block.

METHODS

We conducted a retrospective chart review of patients 10-19 years of age who underwent anterior cruciate ligament reconstruction with quadriceps tendon-patellar bone autograft by a single orthopedic surgeon at two of our locations. Of 88 patients analyzed, 31 received single-injection femoral nerve blockade (52% female, mean age = 15.6 ± 1.8 years) and 57 received femoral nerve catheter (53% female, mean age = 15.6 ± 1.7 years). Time from surgery to return-to-sport clearance and movement symmetry were compared between groups at approximately 6 months postoperatively.

RESULTS

The single-injection femoral nerve blockade group exhibited significantly greater single-leg squat symmetry than did the femoral nerve catheter group (95.5 ± 6.7% vs 88.3 ± 9.3%; P = 0.02; mean difference = 7.2%, 95% CI = -1.1, 13.3) 6 months postoperatively. There was no difference in time from surgery to return-to-sport clearance between groups (median = 247 [interquartile range = 218-295] days vs 268 [241-331] days; P = 0.22; mean difference = 40 days; 95% CI = -23, 102).

CONCLUSION

Though time to return to sport did not differ, patients in the femoral nerve catheter group exhibited greater single-leg squat asymmetry than did those in the femoral nerve blockade group approximately 6 months postoperatively. Persistent functional deficits may be important to consider when treating pediatric patients undergoing anterior cruciate ligament reconstruction.

[Research of Perioperative Muscle Relaxant Monitor]

Muscle relaxant monitor is a research hotspot in the field of clinical anesthesiology. According to the research status at home and abroad, combing the developing history of muscle relaxant monitor, detecting principle, a variety of electrical stimulation mode, and a variety of detection ways, this study reviews and analyzes the advantages and disadvantages of various testing methods and application status, provides technical research foundation for the degree of nerve block for quantitative assessment of muscle relaxant monitor instrument design. Meanwhile, we advocate that clinicians should use quantitative muscle relaxant monitor as much as possible in the perioperative period to reasonably guide the use of muscle relaxants so as to reduce the risk of complications caused by residual effects of muscle relaxants and provide more scientific and accurate digital guidance for assessing the degree of muscle relaxants of patients.

Effect of combining peri-hamstring injection or anterior obturator nerve block on the analgesic efficacy of adductor canal block for anterior cruciate ligament reconstruction: a randomised controlled trial

BACKGROUND

Pain after anterior cruciate ligament reconstruction (ACLR) with autologous hamstring graft can be attributed to both arthroscopic surgery and the graft donor site. This study investigated whether donor site pain control was superior with the addition of either peri-hamstring injection or anterior division obturator nerve block in comparison with adductor canal block (ACB) alone.

METHODS

Patients scheduled to undergo knee arthroscopy with ACLR using a graft from the ipsilateral hamstring were randomised to one of three groups. All patients received ACB and multimodal analgesia. Subjects in Group H received peri-hamstring local anaesthetic injection while subjects in Group O received an anterior division of the obturator nerve block, and subjects in Group C served as a control group (ACB alone).

RESULTS

In 105 subjects undergoing ACLR, there was no significant difference between groups H, O, and C for the primary outcome of pain on movement as assessed by numerical rating scale (NRS) on knee flexion at 2 h after operation (P=0.11). There was no difference in NRS at any time point in the first 48 h after operation, nor was there a difference in oxycodone consumption between the three groups at 24 h (P=0.2). Worst knee pain was initially at the graft donor site in all three groups, which transitioned to anterior knee pain after 12 h.

CONCLUSIONS

The addition of ultrasound-guided peri-hamstring injection or anterior division of obturator nerve block to ACB did not result in a significant reduction in pain or opioid consumption after ACLR with ipsilateral hamstring graft.

CLINICAL TRIAL REGISTRATION

NCT01868282.

Reversing the Effects of a Peripheral Nerve Block with Normal Saline: A Randomised Controlled Trial

Objective

The objective of the present study was to determine whether or not the effects of peripheral nerve block can be reversed by flushing normal saline down a peripheral nerve block catheter following the completion of arteriovenous (AV) fistula surgery.

Methods

In the present study, 38 patients undergoing AV fistula surgery were recruited, and a brachial plexus block with a peripheral nerve catheter was established. Following surgery, the patients were randomised to either the control group or the washout group, where 10 mL of normal saline was flushed down the peripheral nerve catheter at 15-minute intervals for 1 h while the patients were in the postoperative recovery room. An observer blinded to the patient group allocation assessed motor and sensory functions in all patients at 15-minute intervals for 1 h, and pain scores were recorded.

Results

There was no difference in time to resolution of motor or sensory block in the two groups. The median changes in the motor score were 1.5 out of 10 for the control group and 2 for the washout group (p=0.95). The median changes in the sensory score were 3 out of 10 for the control group and 1 for the washout group (p=0.14). There were no differences in pain scores over the study period in either group (p=0.44).

Conclusion

We were unable to show any useful improvement in block resolution with normal saline washout of supraclavicular or infraclavicular brachial plexus blocks following AV fistula surgery.

[Ultrasound imaging has a potential to exhibit biotechnical advance in perioperative pain management]

The perioperative pain management - instead of the efforts, guidelines and protocols - is underestimated and undertreated. Even in the case of general anaesthesia, the nervous system is overwhelmed by copious quantities of nociceptive stimuli at surgical incision. Stress and pain-modulation processes are triggered which can have significant influence on the outcome. Often the pain-management is discontinued, so a notable part of patients complain about pain in the ward after surgery. Regional anaesthesia conceptually prevents noxious inputs to enter the central nervous system, beyond surgical anaesthesia it is pertinent to achieve excellent analgesia in the immediate postoperative period as well. Based on current literature, this paper provides an overview of the history and role of regional anaesthesia in the multidimensional model of pain. Besides the sensitization caused by nociceptive stimuli - peripheral and central sensitization, descending modulation - there are several biopsychosocial factors involved in pain pathophysiology. Preventing the side effects of general anaesthesia, the ultrasound-guided peripheral nerve blockade is a safe technique with high success rate, rare side effects, achieving long-lasting, excellent analgesia. Continuous perineural catheter placed under ultrasound provides extended pain control. As a part of multimodal analgesia, peripheral nerve blockade prevents central sensitization. After surgery, the pain intensity of patients under peripheral nerve blockade is less, the chronification tendency is decreased, the quality of life and patients' comfort are improved, and the stress-response is attenuated. The greater part of patients are protected from the undesirable side effects of general anaesthesia. Nowadays, it is an unequivocal evidence that the increasingly used peripheral nerve blockades prior to incision are efficient tools in the prevention of chronic postoperative pain. Ultrasound guidance is suitable not only for surgical anaesthesia, but for postoperative pain management as well, however, besides economic factors, the main goal of this technique is to match the best interest of the patients. Orv Hetil. 2019; 160(15): 573-584.

The role of peripheral afferents in persistent inguinal postherniorrhaphy pain: a randomized, double-blind, placebo-controlled, crossover trial of ultrasound-guided tender point blockade

BACKGROUND

Severe, persistent inguinal postherniorrhaphy pain (PIPP) is a debilitating condition that develops in 2-5% of patients. PIPP may be neuropathic in nature, yet the lesion in the peripheral nervous system has not been located. Most PIPP-patients demonstrate a tender point (TP) in the medial aspect of the inguinal region that triggers pain upon minimal pressure. As TPs may play a role in the pathophysiology of PIPP, the aim of this trial was to investigate the analgesic effects of local anaesthetic TP-blockade.

METHODS

A randomized, double-blind, placebo-controlled, crossover trial was performed in 14 PIPP-patients and six healthy volunteers. All participated in two sessions, seven days apart, receiving 10 ml of 0.25% bupivacaine or normal saline via an ultrasound-guided fascial plane block at the TP. The TP-area was used for pain assessments (at rest, on movement, with 100 kPa pressure-algometry) and quantitative sensory testing (pressure pain thresholds, thermal detection/pain thresholds, supra-threshold heat perception), before and after the TP-blockade.

RESULTS

The median (95% CI) reduction in pain was 63% (44.1 to 73.6%) after bupivacaine compared with 36% (11.6 to 49.7%; P=0.003) after placebo. Significant increases in cool detection (P=0.01) and pressure pain thresholds (P=0.009) with decreases in supra-threshold heat pain perception (P=0.003) were seen after bupivacaine only. In four out of six volunteers, increased thermal and evoked-pain thresholds after bupivacaine compared with placebo, was demonstrated.

CONCLUSIONS

This trial demonstrates that peripheral afferent input from the TP-area is important for maintenance of spontaneous and evoked pain in PIPP.

CLINICAL TRIAL REGISTRATION

NCT02065219.

Spread of injectate around hip articular sensory branches of the femoral nerve in cadavers

BACKGROUND

Anatomical knowledge dictates that regional anaesthesia after total hip arthroplasty requires blockade of the hip articular branches of the femoral and obturator nerves. A direct femoral nerve block increases the risk of fall and impedes mobilisation. We propose a selective nerve block of the hip articular branches of the femoral nerve by an ultrasound-guided injection in the plane between the iliopsoas muscle and the iliofemoral ligament (the iliopsoas plane). The aim of this study was to assess whether dye injected in the iliopsoas plane spreads to all hip articular branches of the femoral nerve.

METHODS

Fifteen cadaver sides were injected with 5 mL dye in the iliopsoas plane guided by ultrasound. Dissection was performed to verify the spread of injectate around the hip articular branches of the femoral nerve.

RESULTS

In 10 dissections (67% [95% confidence interval: 38-88%]), the injectate was contained in the iliopsoas plane staining all hip articular branches of the femoral nerve without spread to motor branches. In four dissections (27% [8-55%]), the injection was unintentionally made within the iliopectineal bursa resulting in secondary spread. In one dissection (7% [0.2-32%]) adhesions partially obstructed the spread of dye.

CONCLUSION

An injection of 5 mL in the iliopsoas plane spreads around all hip articular branches of the femoral nerve in 10 of 15 cadaver sides. If these findings translate to living humans, injection of local anaesthetic into the iliopsoas plane could generate a selective sensory nerve block of the articular branches of the femoral nerve without motor blockade.

Hollow Silica Nanoparticles Penetrate the Peripheral Nerve and Enhance the Nerve Blockade from Tetrodotoxin

The efficacy of tetrodotoxin (TTX), a very potent local anesthetic, is limited by its poor penetration through barriers to axonal surfaces. To address this issue, we encapsulated TTX in hollow silica nanoparticles (TTX-HSN) and injected them at the sciatic nerve in rats. TTX-HSN achieved an increased frequency of successful blocks, prolonged the duration of the block, and decreased the toxicity compared to free TTX. In animals injected with fluorescently labeled HSN, the imaging of frozen sections of nerve demonstrated that HSN could penetrate into nerve and that the penetrating ability of silica nanoparticles was highly size-dependent. These results demonstrated that HSN could deliver TTX into the nerve, enhancing efficacy while improving safety.

Physiological and pharmacologic aspects of peripheral nerve blocks

A successful peripheral nerve block not only involves a proper technique, but also a thorough knowledge and understanding of the physiology of nerve conduction and pharmacology of local anesthetics (LAs). This article focuses on what happens after the block. Pharmacodynamics of LAs, underlying mechanisms of clinically observable phenomena such as differential blockade, tachyphylaxis, C fiber resistance, tonic and phasic blockade and effect of volume and concentration of LAs. Judicious use of additives along with LAs in peripheral nerve blocks can prolong analgesia. An entirely new group of drugs-neurotoxins has shown potential as local anesthetics. Various methods are available now to prolong the duration of peripheral nerve blocks.

Infratrochlear neuralgia

INTRODUCTION

The infratrochlear nerve supplies the medial aspect of the upper eyelid, the superolateral aspect of the nose and the lacrimal caruncle. This nerve may contribute to the pain stemming from the trochlea, but infratrochlear neuralgia has not been identified as a specific cause of pain.

METHODS

Over a 10-year period we have been recruiting patients with pain in the internal angle of the orbit that did not show features of trochlear pain.

RESULTS

Seven patients (six female, one male; mean age, 46.1 ± 18.9) presented with pain in the territory of the infratrochlear nerve. The pain appeared in the internal angle of the orbit and upper eyelid (n = 3), the superolateral aspect of the nose (n = 3), or the lacrimal caruncle (n = 1). All patients had a paroxysmal pain, with the attacks lasting five to 30 seconds. Pain attacks were mostly spontaneous, but two patients had triggers. Between attacks, all patients had local allodynia. Pain did not increase with vertical eye movements. Six patients were treated with gabapentin with complete response, and one patient experienced long-lasting relief with an anesthetic blockade of the infratrochlear nerve.

CONCLUSION

Infratrochlear neuralgia should be considered as a possible cause of pain in the internal angle of the orbit.

Lacrimal neuralgia: so far, a missing cranial neuralgia

BACKGROUND

The lacrimal nerve supplies the lacrimal gland, the lateral upper eyelid, and a small cutaneous area adjacent to the external CANTHUS . First division trigeminal neuralgia, supraorbital/supratrochlear neuralgia, and infraorbital neuralgia have been acknowledged as neuralgic causes of pain in the forehead and periorbit. However, the lacrimal nerve has never been identified as a source of facial pain. Here we report two cases of lacrimal neuralgia.

CASE REPORTS

A 66-year-old woman had continuous pain in the lateral aspect of her left superior eyelid and an adjacent area of the temple since age 64. A 33-year-old woman suffered from continuous pain in a small area next to the lateral CANTHUS of her left eye since age 25. In both patients the superoexternal edge of the orbit was tender. In addition, sensory dysfunction could be demonstrated within the painful area. Anaesthetic blockades of the lacrimal nerve with lidocaine 2% resulted in complete but short-lasting relief. Pregabalin provided a complete response in the first patient. The second patient was refractory to various oral and topical drugs and different radiofrequency procedures, but she eventually obtained partial relief with pregabalin.

CONCLUSIONS

Lacrimal neuralgia should be considered among the neuralgic causes of orbital and periorbital pain.

Prolonged nerve blockade in a patient treated with lithium

We report a case of a patient, chronically treated with oral lithium, who presented with an extremely prolonged (42-hour) duration of sensory and motor paralysis following an uneventful infraclavicular block for hand surgery that was performed under ultrasound guidance using bupivacaine and lidocaine. Due to its direct effect on nerve conduction of action potential, we propose that lithium may have had a role in the unusually prolonged duration of a peripheral nerve block.