Nerve injection injury with botulinum toxin

Perineural injections of incobotulinumtoxin-A for diabetic neuropathic pain of the lower extremities: protocol for a phase II, single-centre, double-blind, randomised, placebo-controlled trial (the PINBOT study)

INTRODUCTION

Diabetic neuropathic pain (DNP) is a debilitating complication affecting 15-20% of people with diabetes and is a predictor of depression, poor sleep and decreased quality of life. Current pharmacological treatments are often insufficient and have significant side-effects. Subcutaneous or intradermal botulinumtoxin-A (BonT-A) is an effective and safe treatment for neuropathic pain but is limited by the need to cover the entire affected area with injections. For large cutaneous areas, infiltration of the sensory nerve supply with BonT-A could provide similar effects, with a single injection. We aim to investigate the safety, efficacy, and effects on quality of life, physical activity, depressive symptoms and activities of daily living of perineural injections of BonT-A in patients with DNP of both lower extremities.

METHODS

This study is a double-blind, randomised, placebo-controlled clinical trial. 80 participants with moderate to severe DNP of both legs will be randomised 1:1 to receive injections of either 100 units incobotulinumtoxin-A or a saline placebo around each distal sciatic nerve for two cycles of 12 weeks. Average daily pain scores will be recorded once a day from 1 week prior to the first treatment and through the entire study period. Primary outcomes are differences between groups in daily and weekly mean pain scores. Secondary outcomes are levels of physical activity, depression scores, health-related quality of life, activities of daily living, sensory profiles and motor function, recorded at baseline, 4, 12, 16 and 24 weeks. The use of rescue medication and adverse events will be recorded throughout the study period.

ETHICS AND DISSEMINATION

The study is approved by the Danish Committee on Health Research Ethics and the Danish Medicines Agency. EU-Clinical Trial Information System (EU: 2022-500727-68-01), clinicaltrials.gov (ID: NCT05623111). Results will be published in peer-reviewed journals in open-access formats and data made available in anonymised form.

TRIAL REGISTRATION NUMBER

NCT05623111.

Beyond neuromuscular activity: botulinum toxin type A exerts direct central action on spinal control of movement

Overt muscle activity and impaired spinal locomotor control hampering coordinated movement is a hallmark of spasticity and movement disorders like dystonia. While botulinum toxin A (BoNT-A) standard therapy alleviates mentioned symptoms presumably due to its peripheral neuromuscular actions alone, the aim of present study was to examine for the first time the toxin's trans-synaptic activity within central circuits that govern the skilled movement. The rat hindlimb motor pools were targeted by BoNT-A intrasciatic bilateral injection (2 U per nerve), while its trans-synaptic action on premotor inputs was blocked by intrathecal BoNT-A-neutralising antitoxin (5 i.u.). Effects of BoNT-A on coordinated and high intensity motor tasks (rotarod, beamwalk swimming), and localised muscle weakness (digit abduction, gait ability) were followed until their substantial recovery by day 56 post BoNT-A. Later, (day 62-77) the BoNT-A effects were examined in unilateral calf muscle spasm evoked by tetanus toxin (TeNT, 1.5 ng). In comparison to peripheral effect alone, combined peripheral and central trans-synaptic BoNT-A action induced a more prominent and longer impairment of different motor tasks, as well as the localised muscle weakness. After near-complete recovery of motor functions, the BoNT-A maintained the ability to reduce the experimental calf spasm evoked by tetanus toxin (TeNT 1.5 ng, day 62) without altering the monosynaptic reflex excitability. These results indicate that, in addition to muscle terminals, BoNT-A-mediated control of hyperactive muscle activity in movement disorders and spasticity may involve the spinal premotor inputs and central circuits participating in the skilled locomotor performance.

Comparison of the Effects of Botulinum Toxin Doses on Nerve Regeneration in Rats with Experimentally Induced Sciatic Nerve Injury

This study was designed to compare the effects of various doses of botulinum neurotoxin A (BoNT/A) on nerve regeneration. Sixty-five six-week-old rats with sciatic nerve injury were randomly allocated to three experimental groups, a control group, and a sham group. The experimental groups received a single session of intraneural BoNT/A (3.5, 7.0, or 14 U/kg) injection immediately after nerve-crushing injury. The control group received normal intraneural saline injections after sciatic nerve injury. At three, six, and nine weeks after nerve damage, immunofluorescence staining, an ELISA, and toluidine blue staining was used to evaluate the regenerated nerves. Serial sciatic functional index analyses and electrophysiological tests were performed every week for nine weeks. A higher expression of GFAP, S100β, GAP43, NF200, BDNF, and NGF was seen in the 3.5 U/kg and 7.0 U/kg BoNT/A groups. The average area and myelin thickness were significantly greater in the 3.5 U/kg and 7.0 U/kg BoNT/A groups. The sciatic functional index and compound muscle action potential amplitudes exhibited similar trends. These findings indicate that the 3.5 U/kg and 7.0 U/kg BoNT/A groups exhibited better nerve regeneration than the 14 U/kg BoNT/A and control group. As the 3.5 U/kg and the 7.0 U/kg BoNT/A groups exhibited no statistical difference, we recommend using 3.5 U/kg BoNT/A for its cost-effectiveness.

Human Frontalis Muscle Innervation and Morphology

Due to its clinical importance and due to a suggestion regarding the afferent innervation, the microscopic appearance of the frontalis muscle was investigated.

Effect of Botulinum Toxin Injection and Extracorporeal Shock Wave Therapy on Nerve Regeneration in Rats with Experimentally Induced Sciatic Nerve Injury

This study was designed to compare the roles of botulinum neurotoxin A (BoNT/A) and extracorporeal shock wave therapy (ESWT) in promoting the functional recovery and regeneration of injured peripheral nerves. A total of 45 six-week-old rats with sciatic nerve injury were randomly divided into two experimental groups and one control group. The experimental groups received a single session of intranerve BoNT/A or ESWT immediately after a nerve-crushing injury. The control group was not exposed to any treatment. Differentiation of Schwann cells and axonal sprouting were observed through immunofluorescence staining, ELISA, real-time PCR, and Western blot at 3, 6, and 10 weeks post-nerve injury. For clinical assessment, serial sciatic functional index analysis and electrophysiological studies were performed. A higher expression of GFAP and S100β was detected in injured nerves treated with BoNT/A or ESWT. The levels of GAP43, ATF3, and NF200 associated with axonal regeneration in the experimental groups were also significantly higher than in the control group. The motor functional improvement occurred after 7 weeks of clinical observation following BoNT/A and ESWT. Compared with the control group, the amplitude of the compound muscle action potential in the experimental groups was significantly higher from 6 to 10 weeks. Collectively, these findings indicate that BoNT/A and ESWT similarly induced the activation of Schwann cells with the axonal regeneration of and functional improvement in the injured nerve.

Botulinum Toxin and Neuronal Regeneration after Traumatic Injury of Central and Peripheral Nervous System

Botulinum neurotoxins (BoNTs) are toxins produced by the bacteria Clostridiumbotulinum, the causing agent for botulism, in different serotypes, seven of which (A-G) are well characterized, while others, such as H or FA, are still debated. BoNTs exert their action by blocking SNARE (soluble N-ethylmale-imide-sensitive factor-attachment protein receptors) complex formation and vesicle release from the neuronal terminal through the specific cleavage of SNARE proteins. The action of BoNTs at the neuromuscular junction has been extensively investigated and knowledge gained in this field has set the foundation for the use of these toxins in a variety of human pathologies characterized by excessive muscle contractions. In parallel, BoNTs became a cosmetic drug due to its power to ward off facial wrinkles following the activity of the mimic muscles. Successively, BoNTs became therapeutic agents that have proven to be successful in the treatment of different neurological disorders, with new indications emerging or being approved each year. In particular, BoNT/A became the treatment of excellence not only for muscle hyperactivity conditions, such as dystonia and spasticity, but also to reduce pain in a series of painful states, such as neuropathic pain, lumbar and myofascial pain, and to treat various dysfunctions of the urinary bladder. This review summarizes recent experimental findings on the potential efficacy of BoNTs in favoring nerve regeneration after traumatic injury in the peripheral nervous system, such as the injury of peripheral nerves, like sciatic nerve, and in the central nervous system, such as spinal cord injury.

Intramuscular Neural Distribution of Rhomboid Muscles: Evaluation for Botulinum Toxin Injection Using Modified Sihler's Method

This study describes the nerve entry point and intramuscular nerve branching of the rhomboid major and minor, providing essential information for improved performance of botulinum toxin injections and electromyography. A modified Sihler method was performed on the rhomboid major and minor muscles (10 specimens each). The nerve entry point and intramuscular arborization areas were identified in terms of the spinous processes and medial and lateral angles of the scapula. The nerve entry point for both the rhomboid major and minor was found in the middle muscular area between levels C7 and T1. The intramuscular neural distribution for the rhomboid minor had the largest arborization patterns in the medial and lateral sections between levels C7 and T1. The rhomboid major muscle had the largest arborization area in the middle section between levels T1 and T5. In conclusion, botulinum neurotoxin injection and electromyography should be administered in the medial and lateral sections of C7-T1 for the rhomboid minor and the middle section of T1-T7 for the rhomboid major. Injections in the middle section of C7-T1 should also be avoided to prevent mechanical injury to the nerve trunk. Clinicians can administer safe and effective treatments with botulinum toxin injections and other types of injections by following the methods in our study.

Muscle biopsy substantiates long-term MRI alterations one year after a single dose of botulinum toxin injected into the lateral gastrocnemius muscle of healthy volunteers

Despite numerous clinical and experimental studies on botulinum toxin type A (BoNT/A), long-term alterations of muscle texture and fine structure following BoNT/A treatment have thus far not been studied in normal human skeletal muscle. After obtaining institutional review board approval, we performed a prospective, placebo-controlled, double-blinded follow-up study on two healthy adults using magnetic resonance imaging (MRI) and muscle biopsy to visualize long-term alterations after a single BoNT/A injection into the lateral head of the gastrocnemius muscle. MRI disclosed a high-signal-intensity pattern in short tau inversion recovery sequences, and a reduction of the cross-sectional area in the BoNT/A-injected, but not in the saline-injected contralateral control muscle (at 6 to 9 months in volunteer A: 73%, in B: 62%; at 12 months in A: 88%, and in B: 78%). Enzyme histochemistry, 12 months after injection, confirmed neurogenic atrophy of muscle fibers only in the BoNT/A-injected muscle. Electron microscopy revealed additional degenerative changes at the neuromuscular junction. The data confirm that MRI is a suitable tool to monitor the long-term effect of BoNT/A on skeletal muscle. Neurogenic muscle atrophy following a single BoNT/A injection should be taken into consideration when repeated BoNT/A injections into the same muscles are proposed.

Managing adverse events associated with botulinum toxin type A: a focus on cosmetic procedures

Botulinum toxin A (BTXA) has become a widely used drug in cosmetic dermatology, not only to treat focal hyperhidrosis but also hyperkinetic facial lines, platysma bands, décolleté bands, and other skin features. The spectrum of possible adverse effects of BTXA is broad but fortunately those that have been observed with cosmetic use of this product are generally mild and transient. The major tools for preventing adverse effects from BTXA are knowledge and skill. Use of correct injection techniques is mandatory since most unwanted effects are caused by incorrect technique. Knowledge of the target structures, e.g. the facial and extrafacial muscles, allows physicians to select the optimal dose, time and technique. The most common adverse effects are pain and hematoma. In the periocular region, lid and brow ptosis are important adverse effects. Adverse effects such as pain, hematoma, ecchymosis, and bruising may also occur in the upper and lower face and at extrafacial sites. Other possible adverse effects seen in other indications that the user of BTXA in cosmetic dermatology should be wary of include induction headaches and possible interaction with concomitant medications. Induction of neutralizing antibodies due to cosmetic BTXA treatment has not been observed. This article also outlines recommendations regarding use of BTXA. Of these, the most important for avoiding most unwanted adverse effects are the proper techniques of dilution, storage, and injection, as well as the careful exclusion of patients with any contraindications. Pain, hematoma, ecchymosis, and bruising can be prevented by cooling the skin before and after BTXA injection. Upper lid ptosis may be partly corrected using apraclonidine or phenylephrine eyedrops. If simple rules relating to the indications for and application of BTXA are followed, this is a safe and effective drug in cosmetic dermatology.

Complications of botulinum toxin A use in facial rejuvenation

The esthetic application of botulinum toxin type A (Botox) is a safe treatment modality; nevertheless complications can occur as a result of patient-and physician-related factors. Fortunately, adverse effects and undesirable sequelae after Botox injections are temporary. Complications may be more serious in patients who have more severe rhytids (which require more Botox), previous facial plastic surgery (altered anatomy), and those who have pre-existing neuromuscular disease. The physician can reduce complications by using proper injection techniques, appropriate regional Botox dosing, and by being conservative in the overall approach to Botox-mediated facial rejuvenation.

Botulinum toxin infiltration for pain control after mastectomy and expander reconstruction

INTRODUCTION

We hypothesized botulinum toxin (BT) infiltration of the chest wall musculature after mastectomy would create a prolonged inhibition of muscle spasm and postoperative pain, facilitating tissue expander reconstruction.

METHODS

An Institutional Review Board (IRB)-approved prospective study was conducted of all patients undergoing mastectomy with tissue expander placement during a 2-year period. Study patients versus controls had 100 units of diluted BT injected into the pectoralis major, serratus anterior, and rectus abdominis insertion. Pain was scored using a visual analog scale of 0 to 10. Wilcoxon rank sum test was used for continuous variables and the chi2 test for nominal level data to test for significance.

RESULTS

Forty-eight patients were entered into the study; 22 (46%) with and 26 (54%) without BT infiltration. Groups were comparable in terms of age (55 +/- 11 years versus 52 +/- 10 years; P = 0.46), bilateral procedure (59% versus 61%; P = 0.86), tumor size (2 +/- 2 cm versus 2 +/- 3 cm; P = 0.4), expander size and volume (429 +/- 119 mL versus 510 +/- 138 mL; P = 0.5). The BT group did significantly better with pain postoperatively (score of 3 +/- 1 versus 7 +/- 2; P < 0.0001), during initial (score of 2 +/- 2 versus 6 +/- 3; P = 1.6 x 10(-6)), and final expansion (1 +/- 1 versus 3 +/- 2; P = 0.009). Volume of expansion per session was greater thus expansion sessions required less in the BT group (5 +/- 1 versus 7 +/- 3; P = 0.025). There was a significant increase in narcotic use in control patients in the first 24 hours (17 +/- 10 mg versus 3 +/- 3 mg; P < 0.0001), initial as well as final expansion periods (P = 0.0123 and 0.0367, respectively). One expander in the BT group versus 5 in the control group required removal (P = 0.13). There were no BT-related complications.

CONCLUSION

Muscular infiltration of botulinum toxin for mastectomy and tissue expander placement significantly reduced postoperative pain and discomfort without complications.

Complications of botulinum toxin A use in facial rejuvenation

The esthetic application of botulinum toxin type A is a safe treatment modality; nevertheless, complications can occur as a result of patient- and physician-related factors. Fortunately, adverse effects and undesirable sequelae after Botox injections are temporary. Complications may be more serious in patients who have more severe rhytids (which require more Botox), have undergone previous facial plastic surgery (altered anatomy), and those who have preexisting neuromuscular disease. The physician can reduce complications by using proper injection techniques, appropriate regional Botox dosing, and by being conservative in the overall approach to Botox-mediated facial rejuvenation.

Spasticity associated with cerebral palsy in children: guidelines for the use of botulinum A toxin

Botulinum A toxin produces selective and reversible chemodenervation that can be employed to balance muscle forces across joints in children with cerebral palsy (CP). Currently, there are two commercially available botulinum A toxin formulations (BOTOX) and Dysport). The amount of botulinum A toxin required depends upon the number of muscles that are targeted, and the size of the patient. In order to achieve adequate chemodenervation with botulinum A toxin, the following conditions must be met: (i) a sufficient number of units of toxin must be injected in order to neutralize neuromuscular junction (NMJ) activity; (ii) an appropriate drug volume is required in order to optimize the delivery of the toxin to the NMJs; and (iii) localization of the injecting needle through the fascia of the target muscle is necessary. Localization of the injection may be facilitated by active electromyography, ultrasonography, palpation of the muscle belly, and/or use of anatomic landmarks. Botulinum A toxin injections are indicated for use in pediatric patients with CP to: (i) improve motor function by balancing muscle forces across joints; (ii) improve health-related quality of life by decreasing spasticity and/or decreasing caregiver burden; (iii) decrease pain from spasticity; (iv) enhance self-esteem by diminishing inappropriate motor responses; and (v) provide a presurgical diagnostic tool. Following intramuscular injections of botulinum A toxin, short-term benefits of reduced spasticity are observed in approximately 70-82% of children. The intermediate term (1-2 years) efficacy rate is approximately 50%. The most common deformity treated with toxin injections in pediatric patients with CP is equinus foot deformity. However, efficacy of toxin injections for the management of crouched gait, pelvic flexion contracture, cervical spasticity, seating difficulties, and upper extremity deformity also has been documented. In addition, toxin injections have been shown to manage painful muscle spasticity associated with surgery or application of casts and painful cervical spasticity with or without dystonia. Toxin injections can also be used as a diagnostic tool to determine the appropriateness of other interventions by observing the muscle response to the injection in order to gain additional information for the development of a treatment plan. Botulinum A toxin, when used in appropriate doses, is well tolerated.

Botulinum toxin in motor disorders

Advances in the clinical use of botulinum neurotoxins continue. Of interest to the neurologist is the advanced practice in the treatment of focal dystonia and the new developments on other dyskinesias and on autonomic control of smooth muscle motility. New toxin serotypes are now being tested; their availability will improve clinical practice and will possibly lead to combined treatments. Indications in spasticity and in juvenile cerebral palsy are now under scrutiny. The combination of focal chemodenervation with specific rehabilitation procedures enables new development in this field.

Botulinum A exotoxin for the management of platysma bands

Injections of botulinum A exotoxin are successfully used to treat neuromuscular disorders and to improve hyperkinetic muscles and dynamic rhytids of the upper face. Using these principles, we extended its use to the treatment of the aging neck (hypertrophic platysma muscle bands). A classification system (I to IV) based on horizontal neck rhytids, platysma bands, and skin laxity was devised to categorize the degree of deformity and serve as a guideline for suggested dosages of botulinum. The results correlated with the degree of age-related neck degeneration. Type II (mild horizontal neck rhytids; thin, mild platysma muscle flaccidity; and mild skin laxity) and III (moderate horizontal neck rhytids; thick, moderate platysma muscle flaccidity; and moderate skin laxity) patients were the most satisfied, followed closely by types I and IV. A total of 1500 patients were treated by three independent practices. The majority of them achieved good-to-excellent results, as evaluated by both the physician and patient. The degree of muscle flaccidity and hypertrophy were the factors that most influenced success rates, not the anatomic variations in muscle configuration.

Peripheral nerve injection injury with antiemetic agents

Antiemetics are widely used drugs, frequently administered to alleviate postoperative and postchemotherapeutic nausea and vomiting. While antiemetics do not induce peripheral neurotoxicity when administered systemically, it is not known whether peripheral nerve injury can occur as a result of inadvertent intraneural injection during intramuscular administration. The purpose of this study was to characterize the neurotoxic effect of three commonly used antiemetic agents (promethazine, dimenhydrinate, and prochlorperazine) as compared to saline in the rat sciatic nerve model. Intrafascicular and extrafascicular injection as well as direct application of the antiemetic drugs were performed. Nerves were harvested at 2 weeks postoperatively for histology and morphometry, with an additional sacrifice point at 8 weeks for the intrafascicular injection group. Injection injuries caused by antiemetic drugs differed depending on the agent injected and the location of injection. Extrafascicular injection and direct application caused no damage. Intrafascicular injection caused diffuse axonal injury in the promethazine and dimenhydrinate groups, while prochlorperazine caused only focal injury. Regeneration was prominent at 8 weeks in all intrafascicular injection groups in this rat model. Prochlorperazine thus appears to be less neurotoxic when injected intraneurally and should preferentially be used for intramuscular injections.