Intramuscular Injection Of Botulinum Toxin Research Articles

Botulinum toxin is detrimental to repair of a chronic rotator cuff tear in a rabbit model.

Re-tear continues to be a problem after rotator cuff repair. Intramuscular botulinum toxin (Botox) injection can help optimize tension at the repair site to promote healing but could have an adverse effect on the degenerated muscle in a chronic tear. We hypothesized that Botox injection would improve repair characteristics without adverse effect on the muscle in a chronic rotator cuff tear model. The supraspinatus tendon of both shoulders in 14 rabbits underwent delayed repair 12 weeks after transection. One shoulder was treated with intramuscular Botox injection and the other with a saline control injection. Six weeks after repair, outcomes were based on biomechanics, histology, and magnetic resonance imaging. Botox-treated repairs were significantly weaker (2.64 N) than control repairs (5.51 N, p = 0.03). Eighty percent of Botox-treated repairs and 40% of control repairs healed with some partial defect. Fatty infiltration of the supraspinatus was present in all shoulders (Goutallier Grade 3 or 4) but was increased in the setting of Botox. This study provides additional support for the rabbit supraspinatus model of chronic cuff tear, showing consistent fatty infiltration. Contrary to our hypothesis, Botox had a negative effect on repair strength and might increase fatty infiltration.

Impact of Seasonal Variations on Spasticity Assessment and Treatment

BACKGROUND: Spasticity is treated using intramuscular botulinum toxin injections. Previous reports of worsening of spasticity in cold weather suggest that spasticity levels and botulinum toxin dose may both be influenced by seasonal temperature changes. AIMI: The aim of this study was to determine the effect of seasonal temperature variation on spasticity and botulinum toxin dosage. METHODS: Medical charts of 132 participants in 3 diagnostic groups: (1) stroke (n=60); (2) multiple sclerosis (n=34); and (3) cerebral palsy (n=38) receiving treatment in an outpatient spasticity clinic were reviewed. Age, sex, diagnosis, number of muscles injected, botulinum toxin dose, and spasticity (Modified Ashworth Scale) were collected for summer and winter. Spasticity and botulinum toxin dose were compared between summer and winter using separate paired t-tests for each diagnostic group. RESULTS: The spasticity level, botulinum toxin dosage, and total number of muscles in summer versus winter months were not significantly different ( p>0.05) in any diagnostic group. Conclusions: Seasonal temperature variations appear to have no effect on spasticity or botulinum toxin dosage. Performance of spasticity measurements in warm indoor environment may have negated the impact of seasonal temperature differences. Future studies should perform spasticity measurements in temperature controlled rooms to mimic seasonal variations.

Effect of muscle weakness and joint inflammation on the onset and progression of osteoarthritis in the rabbit knee

Interactions between mechanical and non-mechanical independent risk factors for the onset and progression of Osteoarthritis (OA) are poorly understood. Therefore, the goal of the present study was to investigate the invivo effects of muscle weakness, joint inflammation and the combination on the onset and progression of OA in a rabbit knee joint model. Thirty 1-year-old female New Zealand White rabbits (average 5.7kg, range 4.8-6.6kg) were divided into four groups with one limb randomly assigned to be the experimental side: (1) surgical denervation of the vastus lateralis (VL) muscle; (2) muscle weakness induced by intramuscular injection of Botulinum toxin A (BTX-A); (3) intraarticular injection with Carrageenan to induce a transient inflammatory reaction; (4) combination of Carrageenan and BTX-A injection. After 90days, cartilage histology of the articular surfaces were microscopically analyzed using the Osteoarthritis Research Society International (OARSI) histology scoring system. VL denervation resulted in significantly higher OARSI scores in the patellofemoral joint (group 1). BTX-A administration resulted in significant cartilage damage in all four compartments of the knee (group 2). Carrageenan did not cause significant cartilage damage. BTX-A combined with Carrageenan lead to severe cartilage damage in all four compartments. Muscle weakness lead to significant OA in the rabbit knee. A transient local inflammatory stimulus did not promote cartilage degradation nor did it enhance OA progression when combined with muscle weakness. These results are surprising and add to the literature the conclusion that acute inflammation is probably not an independent risk factor for OA in this rabbit model.

Therapeutic outcomes in patients with post-traumatic strabismus from a tertiary center in Chile

Purpose: Strabismus (heterotropia) is one of several possible complications of ocular traumatic injury. This condition is associated with a decreased quality of life. The purpose of this study is to present the functional outcomes of a series of 35 patients presenting with strabismus secondary to eye trauma. Methodology: Retrospective study. Treatments for each type of post-traumatic ocular lesion were categorized, which included conservative management by clinical observation; use of a lens with prismatic addition; intramuscular injection of botulinum toxin; or surgery. The strabismus conditions were evaluated prior to the treatment and six months after the last treatment had been received. The rate of therapeutic success, defined as ±10 PD (prism diopters) was assessed. Results: The orbital injuries that most commonly caused strabismus were found to be orbital fracture, penetrating eye injury and direct muscle trauma. All cases of direct muscle trauma received surgical treatment; 54% of orbital fractures resolved spontaneously during clinical observation, whereas 38% required surgery. Three cases of penetrating eye injury were observed and all were resolved surgically. The rate of therapeutic success was 88.57%. A single treatment was sufficient in 88.6% of all cases. Conclusions: Non-surgical therapeutic clinical observation is sufficient in a significant percentage of cases because a large number of patients tend to spontaneous recovery. Additional techniques, such as treatment with botulinum toxin, can play a useful complementary role. Surgical intervention, assessed on a case by case basis, also proved to be highly effective in the minority of cases where it was required.

Low dose PTH improves metaphyseal bone healing more when muscles are paralyzed

Stimulation of bone formation by PTH is related to mechanosensitivity. The response to PTH treatment in intact bone could therefore be blunted by unloading. We studied the effects of mechanical loading on the response to PTH treatment in bone healing. Most fractures occur in the metaphyses, therefor we used a model for metaphyseal bone injury.One hind leg of 20 male SD rats was unloaded via intramuscular botulinum toxin injections. Two weeks later, the proximal unloaded tibia had lost 78% of its trabecular contents. At this time-point, the rats received bilateral proximal tibiae screw implants. Ten of the 20 rats were given daily injections of 5μg/kg PTH (1–34). After two weeks of healing, screw fixation was measured by pull-out, and microCT of the distal femur cancellous compartment was performed. Pull-out force provided an estimate for cancellous bone formation after trauma.PTH more than doubled the pull-out force in the unloaded limbs (from 14 to 30N), but increased it by less than half in the loaded ones (from 30 to 44N). In relative terms, PTH had a stronger effect on pull-out force in unloaded bone than in loaded bone (p=0.03).The results suggest that PTH treatment for stimulation of bone healing does not require simultaneous mechanical stimulation.

Efficacy of Upper Limb Therapies for Unilateral Cerebral Palsy: A Meta-analysis

Children with unilateral cerebral palsy present with impaired upper limb (UL) function affecting independence, participation, and quality of life and require effective rehabilitation. This study aims to systematically review the efficacy of nonsurgical upper limb therapies for children with unilateral cerebral palsy. Medline, CINAHL (Cumulative Index to Nursing and Allied Health Literature), Embase, the Cochrane Central Register of Controlled Trials, and PubMed were searched to December 2012. Randomized controlled or comparison trials were included. Forty-two studies evaluating 113 UL therapy approaches (N = 1454 subjects) met the inclusion criteria. Moderate to strong effects favoring intramuscular injections of botulinum toxin A and occupational therapy (OT) to improve UL and individualized outcomes compared with OT alone were identified. Constraint-induced movement therapy achieved modest to strong treatment effects on improving movement quality and efficiency of the impaired UL compared with usual care. There were weak treatment effects for most outcomes when constraint therapy was compared with an equal dose (amount) of bimanual OT; both yielded similar improved outcomes. Newer interventions such as action observation training and mirror therapy should be viewed as experimental. There is modest evidence that intensive activity-based, goal-directed interventions (eg, constraint-induced movement therapy, bimanual training) are more effective than standard care in improving UL and individualized outcomes. There is little evidence to support block therapy alone as the dose of intervention is unlikely to be sufficient to lead to sustained changes in UL outcomes. There is strong evidence that goal-directed OT home programs are effective and could supplement hands-on direct therapy to achieve increased dose of intervention.

A Beautician's Dystonia: Long-Lasting Effect of Botulinum Toxin.

Treatment options for dystonia are not curative but symptomatic; the treatment of choice for focal dystonias is repeated botulinum toxin injections. Here, we present the case of a 46-year-old beautician with focal dystonia in her left hand that affected her ability to work. Pharmacological treatment with clonazepam and gabapentin failed to resolve her symptoms and was discontinued due to side effects (sleepiness, gastrointestinal disorders). Intramuscular injection of botulinum toxin (incobotulinumtoxinA, Xeomin) into the extensor digitorum communis (35 U), flexor carpi radialis (35 U), and flexor digitorum superficialis (30 U) muscles resulted in complete resolution of symptoms at clinical assessments at 1, 3, 6, and 10 months after the injections, confirmed by the results of surface electromyography 10 months after treatment. The patient was able to work again 1 month after treatment. No reinjection has been necessary at the last evaluation (12 months after treatment). In conclusion, botulinum toxin is an effective treatment for focal dystonia that can have long-lasting effects and can improve patients' ability to work and quality of life.

Is Adipocyte Differentiation the Default Lineage for Mesenchymal Stem/Progenitor Cells after Loss of Mechanical Loading? A Perspective from Space Flight and Model Systems

Mesenchymal stem/progenitor cells (MSC/MPC) are found in many tissues and fluids including bone marrow, adipose tissues, muscle, synovial membranes, synovial fluid, and blood. Such cells from different sources can proliferate and differentiate into different lineages (e.g. osteogenic, chondrogenic and adipogenic) after suitable stimulation. However, details regarding the regulation of MSC/MPC proliferation and differentiation status are still unclear and it is likely that regulation involves both biological and mechanical influences in the different environments. It has been noted that in humans and preclinical animal models that exposure to microgravity/space flight or prolonged bed rest (a surrogate for microgravity) can lead to infiltration of skeletal muscle and bone marrow with fat. Similarly, in preclinical models treated with multiple intramuscular injections of Botulinum Toxin A to induce muscle weakness and atrophy, there is also an infiltration of the muscle with fat. The origins and basis for these fat deposits are largely unknown, but there is a possibility that the altered mechanical and biological environments lead to dysregulation of MSC/MPC and progression to preferential differentiation towards the adipocyte lineage. Furthermore, loss of MSC regulatory control by either mechanical and/or biological factors may also contribute to their involvement in obesity development and progression. Thus, the utility of using MSC/MPC from some sources for tissue engineering purposes may be compromised and further research regarding optimal loading for tissue engineering purposes is likely warranted.

Treatment of Tourette syndrome.

Tourette's syndrome (TS) consists of chronic motor and phonic tics and characteristically begins in childhood. The tics can be disabling and commonly associated behavioral comorbities such as attention deficit hyperactivity disorder (ADHD) and obsessive-compulsive disorder (OCD), can also cause problems in daily functioning. The underlying etiology and neurobiology of TS remain unknown although genetic factors appear to be important, cortical control of basal ganglia motor function appears to be disturbed and neurochemical abnormalities, particularly involving dopamine neurotransmission, are likely present. The treatment of TS involves appropriate education and support. Tics can be treated with habit reversal cognitive behavioral therapy, medications (most commonly alpha agonists and antipsychotics), local intramuscular injections of botulinum toxin and some severe, refractory cases have responded to deep brain stimulation surgery (DBS). It is important to appropriately diagnose and treat comorbid behavioral disorders that are disrupting function. OCD can be treated with cognitive behavioral therapy, selective serotonin reuptake inhibitors, and atypical antipsychotics. DBS has become a treatment option for patients with disabling OCD despite other therapies. ADHD is treated with appropriate classroom accommodations, behavioral therapy, alpha agonists, atomoxetine or methylphenidate-containing stimulant drugs.

Pain assessment based on the localization technique in intramuscular injections of botulinum toxin in children

Pain assessment based on the localization technique in intramuscular injections of botulinum toxin in children

Analisi di minimizzazione dei costi della tossina botulinica di tipo A (Dysport®) nel trattamento della spasticità post-ictus in Italia

Stroke is the most frequent cause of acquired spastic paresis. Different studies have indicate that intramuscular injection of botulinum toxin A is an effective means of alleviating spasticity in stroke patients. We estimated the cost (cost minimization analysis, CMA) of two treatment strategies for spasticity following a stroke: physiotherapy only and botulinum toxin A plus physiotherapy. The sequence of medical interventions and health states in chronic spasticity following stroke was developed based on a Delphi Panel survey. The economic parameters were derived from direct medical costs incurred by the Italian National Health Service (NHS). The clinical parameters (severity of spasticity) were derived from a previous cost-effectiveness analysis. The mean cost of treatment was €7,376.57 for patient treated with botulinum toxin A plus physiotherapy and €9,452.25 for patient treated with physiotherapy only. The sensitivity analysis confirmed the results of the base case. Based on data from a Delphi Panel survey, we performed a cost minimization analysis focused on the use of physiotherapy only or botulinum toxin A plus physiotherapy for spasticity following a stroke. From the Italian NHS perspective, botulinum toxin A plus physiotherapy is a cost-saving strategy compared with physiotherapy only in the treatment of patients with spasticity following stroke.

Management of spasticity revisited

Spasticity is common after stroke and other neurological conditions and causes considerable limitations of movement, activities of daily living and participation. Interaction with other components of the upper motor neurone syndrome (UMNS) and the heterogeneity of patients' presentations together with limited tools for outcome measurement have hampered the production of randomised controlled trial data for management strategies. Specialist multi-disciplinary goal-centered management programmes are the mainstay of treatment. Pharmacological therapies have limited effect, and physical and positional management are crucial. Targeted intramuscular botulinum toxin injection is now the most popular pharmacological treatment. Intrathecal therapies also play a lesser role. A team approach and holistic assessment are essential to beneficial outcomes.

Effectiveness of botulinum toxin injection with and without needle electromyographic guidance for the treatment of spasticity in hemiplegic patients: a randomized controlled trial

Purpose: To compare the effects of botulinum toxin injection with and without needle electromyographic guidance for the treatment of spasticity. Method: A randomized controlled study was conducted in a tertiary university hospital. Twenty-seven adult hemiplegic patients with spasticity due to brain or spinal cord damage were included. Spastic muscles were injected with botulinum toxin with or without EMG guidance. The modified Ashworth scale and modified Barthel index in each patient pre- and post-injection were documented. Results: In group A, which consisted of 15 patients (55.55%), the injection was administered with needle electromyographic guidance, while in 12 patients (44.44%) of group B without electromyographic guidance with the use of anatomic landmarks only. The follow-up period was 3 months. At 3 weeks post-injection, spasticity was decreased (p < 0.05) in all patients and the mean (SD) reduction of spasticity was higher (p < 0.05) in group A (1.67 (0.5)) than group B (1.25 (0.46)). Similarly, the mean (SD) functional modified Barthel index improved statistically significantly (p < 0.001) post-injection (45.37 (8.43)) than pre-injection (54.07 (9.610), especially in group A (p < 0.05). Conclusion: The effectiveness of intramuscular botulinum toxin injection for the treatment of spasticity in hemiplegic patients is superior when performed with needle electromyographic guidance than without electromyography.Implications for RehabilitationIt is recommended that botulinum toxin muscle injections of hemiplegic limbs be performed with EMG guidanceMore spasticity reduction and functional improvement at 3 months post-injection was observed in patients injected with botulinum toxin by the use of combined EMG guidance and anatomic landmarksEMG guidance might also save amount of botulinum toxin due to less spasticity observed during injection than when injection is performed with anatomic landmarks only

Reduced gravitational loading does not account for the skeletal effect of botulinum toxin-induced muscle inhibition suggesting a direct effect of muscle on bone

Intramuscular injection of botulinum toxin (botox) into rodent hindlimbs has developed as a useful model for exploring muscle–bone interactions. Botox-induced muscle inhibition rapidly induces muscle atrophy and subsequent bone loss, with the latter hypothesized to result from reduced muscular loading of the skeleton. However, botox-induced muscle inhibition also reduces gravitational loading (as evident by reduced ground reaction forces during gait) which may account for its negative skeletal effects. The aim of this study was to investigate the skeletal effect of botox-induced muscle inhibition in cage control and tail suspended mice, with tail suspension being used to control for the reduced gravitational loading associated with botox. Female C57BL/6J mice were injected unilaterally with botox and contralaterally with vehicle, and subsequently exposed to tail suspension or normal cage activities for 6weeks. Botox-induced muscle inhibition combined with tail suspension had the largest detrimental effect on the skeleton, causing the least gains in midshaft tibial bone mass, cortical area and cortical thickness, greatest gains in midshaft tibial medullary area, and lowest proximal tibial trabecular bone volume fraction. These data indicate botox-induced muscle inhibition has skeletal effects over and above any effect it has in altering gravitational loading, suggesting that muscle has a direct effect on bone. This effect may be relevant in the development of strategies targeting musculoskeletal health.

Cervical Myelopathy in Patients With Athetoid Cerebral Palsy

Retrospective clinical study. To report the surgical outcomes of patients with cervical myelopathy associated with athetoid cerebral palsy and to assess whether a halo vest is necessary for postoperative external immobilization. Although a halo vest has remained the first choice for postoperative external immobilization of patients with cervical myelopathy associated with cerebral palsy, simplification of this method has been attempted in recent years. Studies focusing on postoperative external immobilization are rare. Since 2001, 20 patients underwent surgery with posterior instrumented fusion or posterior fixation and anterior decompression with fusion with a year or longer follow-up. Before 2004, all patients were given a halo vest for postoperative external immobilization. After 2004, halo vests were not used, and when abnormal involuntary neck movements were severe, an intramuscular injection of botulinum toxin was administered before and after surgery. Surgical outcomes, surgical methods and complications were compared between the group that used a halo vest and the group that did not use a halo vest. In the halo vest group, the average Japanese Orthopedic Association score was 6.9 points before surgery and 9.3 points at 1-year follow-up. The average recovery rate was 25.0%. In the group without halo vest use, the average Japanese Orthopedic Association score was 5.8 points before surgery and 9.9 points at 1-year follow-up. The average recovery rate was 35.7%. The group without halo vest use achieved outcomes equal to those achieved in the group with halo vest use. The frequency of complications was less without halo vest use than with halo vest use. No inferiority in clinical outcomes was seen if postoperative halo vest use was omitted. Progress in surgical instrumentation and injection of botulinum toxin may explain this result.

Efficacy of carbamazepine combined with botulinum toxin a in the treatment of blepharospasm and hemifacial spasm.

To observe the efficacy of the combined treatment of carbamazepine and botulinum toxin A for blepharospasm and hemifacial spasm. Fifty-eight patients with either blepharospasm or hemifacial spasm were randomly divided into treatment and control groups. In the treatment group, 30 patients were administered with local intramuscular injections of botulinum toxin A and oral carbamazepine 100 mg/time, 3 times a day for 60 days. Twenty-eight subjects in the control group underwent local intramuscular injections of botulinum toxin A only. After combined treatment, the complete remission rate was 90%, which was significantly higher than that of the of the control group (67.9%, P<0.05, X2=4.733). However, no statistical significance was noted regarding the duration of therapeutic effects between the treatment group (range 14~40 weeks; 19.2 weeks on average) and control group (range 12~36 weeks; 18 weeks on average). The combined therapy of carbamazepine and topical injections of botulinum toxin A had increased efficacy in the treatment of blepharospasm or hemifacial spasm, but had no significant effect in terms of the duration of the therapeutic effect.

Study on the interest of applying anesthetic cream before intramuscular botulinum toxin injections in children and adolescents with cerebral palsy

Study on the interest of applying anesthetic cream before intramuscular botulinum toxin injections in children and adolescents with cerebral palsy

Evaluation of the effects of botulinum toxin A injections when used to improve ease of care and comfort in children with cerebral palsy whom are non-ambulant: a double blind randomized controlled trial

BackgroundChildren with cerebral palsy (CP) whom are non-ambulant are at risk of reduced quality of life and poor health status. Severe spasticity leads to discomfort and pain. Carer burden for families is significant. This study aims to determine whether intramuscular injections of botulinum toxin A (BoNT-A) combined with a regime of standard therapy has a positive effect on care and comfort for children with CP whom are non-ambulant (GMFCS IV/V), compared with standard therapy alone (cycle I), and whether repeated injections with the same regime of adjunctive therapy results in greater benefits compared with a single injecting episode (cycle II). The regime of therapy will include serial casting, splinting and/or provision of orthoses, as indicated, combined with four sessions of goal directed occupational therapy or physiotherapy.Method/designThis study is a double blind randomized controlled trial. Forty participants will be recruited. In cycle I, participants will be randomized to either a treatment group who will receive BoNT-A injections into selected upper and/or lower limb muscles, or a control group who will undergo sham injections. Both groups will receive occupational therapy and /or physiotherapy following injections. Groups will be assessed at baseline then compared at 4 and 16 weeks following injections or sham control. Parents, treating clinicians and assessors will be masked to group allocation. In cycle II, all participants will undergo intramuscular BoNT-A injections to selected upper and/or lower limb muscles, followed by therapy.The primary outcome measure will be change in parent ratings in identified areas of concern for their child’s care and comfort, using the Canadian Occupational Performance Measure (COPM). Secondary measures will include the Care and Comfort Hypertonicity Scale (ease of care), the Cerebral Palsy Quality of Life Questionnaire (CP QoL–Child) (quality of life), the Caregiver Priorities and Child Health Index of Life with Disabilities Questionnaire (CPCHILD©) (health status) and the Paediatric Pain Profile (PPP) (pain). Adverse events will be carefully monitored by a clinician masked to group allocation.DiscussionThis paper outlines the theoretical basis, study hypotheses and outcome measures for a trial of BoNT-A injections and therapy for children with non-ambulant CP.Trial registrationAustralia New Zealand Clinical Trials Registry:N12609000360213

Can Botulinum Toxin Decrease Carer Burden in Long Term Care Residents With Upper Limb Spasticity? A Randomized Controlled Study

To evaluate whether botulinum toxin can decrease the burden for caregivers of long term care patients with severe upper limb spasticity. This was a double-blind placebo-controlled trial with a 24-week follow-up period. A 250-bed long term care hospital, the infirmary units of 3 regional hospitals, and 5 care and attention homes. Participants included 55 long term care patients with significant upper limb spasticity and difficulty in basic upper limb care. Patients were randomized into 2 groups that received either intramuscular botulinum toxin A or saline. The primary outcome measure was provided by the carer burden scale. Secondary outcomes included goal attainment scale, measure of spasticity by modified Ashworth score, passive range of movement for shoulder abduction, and elbow extension and finger extension. Pain was assessed using the Pain Assessment in Advanced Dementia Scale. A total of 55 patients (21 men; mean age = 69, SD =18) were recruited. At week 6 post-injection, 18 (60%) of 30 patients in the treatment group versus 2 (8%) of 25 patients in the control group had a significant 4-point reduction of carer burden scale (P < .001). There was also significant improvement in the goal attainment scale, as well as the modified Ashworth score, resting angle, and passive range of movement of the 3 regions (shoulder, elbow, and fingers) in the treatment group which persisted until week 24. There were also fewer spontaneous bone fractures after botulinum toxin injection, although this did not reach statistical significance. No significant difference in Pain Assessment in Advanced Dementia scale was found between the 2 groups. No serious botulinum toxin type A-related adverse effects were reported. Long term care patients who were treated for upper limb spasticity with intramuscular injections of botulinum toxin A had a significant decrease in the caregiver burden. The treatment was also associated with improved scores on patient-centered outcome measures.

Bupivacaine and botulinum toxin to treat comitant strabismus

To evaluate the change in ocular motility and muscle thickness measured with ultrasonography after intramuscular injection of bupivacaine and botulinum toxin A. Eight patients (five female) were enrolled to measure ocular motility prior and 1, 7, 30 and 180 days after one injection of 2 ml of 1.5% bupivacaine and 2.5 U of botulinum toxin A in agonist and antagonist muscles, respectively, of eight amblyopic eyes. Muscle thickness was measured prior and on days 1, 7 and 30 after injection using 10-MHz ultrasonography (eyelid technique). Mean change in alignment was 10 prism diopters after 180 days (n=6). An average increase of 1.01 mm in muscle thickness was observed after 30 days of bupivacaine injection and 0.28 mm increase was observed after botulinum toxin A injection, as measured by ultrasonography. Lateral rectus muscles injected with bupivacaine had a mean increase of 1.5 mm in muscle thickness. In this study, a change in ocular motility was observed after 180 days of intramuscular injection of bupivacaine and botulinum toxin in horizontal extraocular muscles. Overall, there was an increase of muscle thickness in both botulinum toxin A and bupivacaine injected muscles after 30 days of injection when measured by ultrasonography. This change was more pronounced on lateral rectus muscles after bupivacaine injection.