Neurotoxin Injections for Spasticity

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Introduction   

Spasticity is a common problem for individuals diagnosed with neurological disorders. It affects over 12 million people worldwide and can cause significant problems in mobility, speech, and daily functioning [1]. Developed in the 1970s, botulinum toxin as a medication to treat muscle spasticity was first used to treat ophthalmologic conditions, such as blepharospasm and strabismus. At the time of development, researchers theorized that the use of neurotoxin injections to treat spasticity could extend to skeletal muscles, but more research would be needed. Over time, the FDA approved neurotoxin administration for treating many musculoskeletal conditions, as well as for cosmetic use. During development, researchers Dr. Alan Scott and others such as Dr. Mitchell Brin and Dennis Honeychurch faced many barriers because the FDA was hesitant to approve the injection of the neurotoxin that causes botulism into humans for therapeutic use [2]. Since then, abundant research has shown the effectiveness and safety of neurotoxin injections to help manage muscle spasticity [1].  

Today, these medications are widely accepted as a standard treatment for many conditions, including spasticity [2], and they are FDA-approved for this purpose for individuals over two years old [3]. Nurses encounter many clients with neurological disorders that contribute to spasticity, and many of those clients are likely treated using neurotoxin injections. By gaining knowledge regarding neurotoxin injections for the treatment of spasticity, nurses can be more effective in caring for clients needing or receiving this therapy.  

Definitions 

• Botulinum Toxin: A neurotoxin produced by the bacterium Clostridium botulinum that causes botulism but can be purified and used for cosmetic and therapeutic medical purposes [4] 
• Hypertonia: a condition in which there is excessive muscle tone [4] 
• Neurotoxin: a poisonous substance that disrupts the function of the nervous system [4] 
• Spasticity: muscular hypertonicity with increased reflexes [4] 

What is Spasticity? 

Spasticity is an involuntary dysfunction of one or more muscle groups, causing them to contract all at once, and the affected muscles are resistant to relaxing. Usually, when the brain sends signals to the nerves, the nerves release acetylcholine, which transmits the message to the muscles to have them contract. For individuals with spasticity, the nerves are damaged, which causes an overwhelming volume of messages that are relayed to the muscles [5]. This can cause exaggerated muscle reflexes, motor weakness, slowed movement, loss of dexterity, and poor muscle control [6]. Spasticity can vary in severity, from mild tightness to uncontrollable and painful stiffness and spasms. Spasticity may be caused by several different conditions, including spinal cord injury, multiple sclerosis, cerebral palsy, stroke, brain injury, amyotrophic lateral sclerosis (ALS), hereditary spastic paraplegias, adrenoleukodystrophy, phenylketonuria, and Krabbe disease.  

Spasticity can involve hypertonia and clonus, a series of rapid muscle movements that may feel like a tremor and typically occur in the ankles. Spasticity may also involve involuntary crossing of the legs and muscle spasms. Contractures are a permanent condition affecting some people with spasticity. This permanent contraction of a muscle and tendon can cause stiffness and spasms and impact how a person is able to function. Clients experiencing spasticity may also have muscle, joint, and bone deformities due to the condition. Individuals with spasticity may have difficulty performing their daily activities and walking. They may experience sleep disturbances due to muscle tightness and spasms [7]. Over 12 million people worldwide experience spasticity [1]. Clients may refer to the condition as “tightness” or “stiffness” [6]. 

Typically, muscle movements are caused by contracting and relaxing muscles. Damage to the central nervous system can inhibit the usual function of these muscles, which makes voluntary movements difficult. Muscle spasticity is different from muscle rigidity. Muscle rigidity is due to basal ganglia issues, which makes muscle coordination challenging. This is often seen with conditions such as Parkinson’s disease. Muscle rigidity also equally impairs the muscles of a particular group, like around a joint. In spasticity, the increased muscle tone does not necessarily remain constant, and more rapid movements cause a stronger spasm of the muscle [7].  

Upon assessment, nurses may find high muscle tone in the shoulders, elbow, wrist, and finger flexors, forearm pronators, hip adductors, knee flexors and extensors, and the muscles controlling the ankles. A common finding is a “thumb in palm” feature, where excessive flexion and tone cause a clenched fist. When the nurse moves an affected limb, they will notice increased resistance with increased movement speed [6]. 

There are two scales that are typically used to measure and document spasticity in clients. The Modified Ashworth Scale (MAS) measures the intensity of muscle tone using a 0-4 scale. A score of 0 indicates no increased tone, while a score of 4 indicates that the muscle is rigid in flexion or extension. The Tardieu scale or modified Tardieu scale describes the level of resistance to muscle stretch that may occur. Using this scale, two parameters are observed to determine a rating for a specific stretching speed. The first parameter observed is the quality of muscle movement. A 0-4 scale is used to describe this observation, with a score of 0 indicating no resistance to movement and a score of 4 indicating clonus is present for ten or more seconds. The second parameter used is the angle of muscle reaction, which is measured at the minimum stretching position of the muscle for each joint, except for the hips, which are measured at rest [1]. Documenting these scales can allow the provider to determine the efficacy of the treatments and adjust the treatment plan as needed.  

Spasticity can cause multiple medical problems for clients who experience more severe forms of the disorder. Mobility challenges and involuntary movements can lead to skin breakdown and wounds. Severe spasticity can also cause bone fractures, joint dislocation, contractures, urinary tract infections, and chronic constipation. Many treatments for spasticity are available, including physical therapy, serial casting, occupational therapy, speech therapy, oral medications, and neurotoxin injections. They are often used in conjunction and can enhance outcomes [7].  

Use of Neurotoxin Injections for Spasticity 

Spasticity can be treated with botulinum toxin injections. Botulinum toxin is produced by the bacterium Clostridium botulinum, a spore-forming, gram-positive, anaerobic bacterium [3] commonly found on plants, in soil, in water, and in the gastrointestinal tracts of animals [8]. Through a complex manufacturing process, the toxin is isolated and purified for therapeutic use. The dosages of botulinum toxin used for clinical treatments are far lower than the amount that would cause botulism [9]. There are multiple subtypes of botulinum toxin. The type used for medical purposes is botulinum toxin type A, first used as a treatment for strabismus [8]. Onabotulinumtoxin A is FDA-approved to treat spasticity in the upper and lower extremities. Abobotulinumtoxin A and Incobotulinumtoxin A are FDA-approved for the treatment of upper extremity spasticity [11].  

Myobloc is a type B botulinum toxin, while the other brands are type A and more commonly used for therapeutic treatment [10]. Myobloc is not FDA-approved for treating spasticity in the upper and lower extremities. These toxins interfere with neural transmissions by blocking acetylcholine, the principal neurotransmitter at the neuromuscular junction [8]. Botulinum toxin is one of the most poisonous biological substances on earth, but it is also used to treat an increasing variety of medical conditions, including spasticity [8]. These isolated toxins are the same medication used for cosmetic purposes, such as reducing the appearance of wrinkles, but the doses and targeted muscles are different than what is used to treat spasticity [9].  

When botulinum toxin is injected into the intramuscular space, acetylcholine is blocked from fusing to the cell membranes, paralyzing the target muscle cells and weakening the muscle. This treatment’s therapeutic effect occurs 4-7 days after injection and lasts 2-3 months. Once the nerves sprout new terminals and synaptic contacts, the treatment must be repeated to maintain its therapeutic effects [8]. 

A benefit of using botulinum toxin injections to treat spasticity is that specific muscle groups can be targeted [7]. Botulinum toxin injection therapy is usually recommended for clients with spasticity limited to a few muscle groups, like upper or lower extremities. This treatment is also effective for clients with only a few specific muscles within a group that cause spasticity. The effects of the injections last 3-4 months, and only a tiny amount of the medication used reaches the circulatory system [5]. Clients who receive neurotoxin injections to treat spasticity may benefit from improved range of motion, better positioning of limbs, fewer spastic movements, improved gait, and decreased pain [10]. 

Case Study 

Logan is a 4-year-old client with cerebral palsy who was born at 23 weeks gestation. He has muscle spasticity in his lower extremities, making ambulation with a walker difficult. Logan’s doctor has recommended botulinum toxin injections to reduce the spasticity in his legs and improve his coordination for walking with assistance. Before the procedure, Logan’s mom asks the nurse, “Doesn’t this toxin cause botulism?” How can the nurse respond? 

The nurse confirms that, yes, this is the same neurotoxin that causes botulism. However, what is used is an isolated and purified form of the toxin, not the actual bacterium that produces it, and a much lower amount is used than what causes botulism. When the neurotoxin is injected into the muscle, it affects the nerve endings that communicate with the muscle, but only in that area. The body system is unaffected since the neurotoxin is not injected intravenously.  

Procedure 

Neurotoxin injections for spasticity are administered as an outpatient procedure in the clinic. There are three type A toxins and one type B toxin that are FDA-approved for this purpose. The type A toxins used are onabotulinumtoxin A, incobotulinumtoxin A, and abobotulinumtoxin A. The type B toxin that may be used is rimabotuinumtoxin B. Prior to the appointment, EMLA cream is applied to the injection sites to provide local anesthesia to the areas that will be injected. The EMLA cream is cleansed from the skin shortly before the injection occurs. The client is then positioned on the procedure table. A skin antimicrobial solution, such as alcohol, is used to clean the injection sites [6]. 

At this time, the provider may apply a numbing spray to the skin to ensure the procedure is painless for the client. A 27-gauge needle is used to inject the medicine [10]. The dosage depends on the size of the muscles, the severity of spasticity, and the client’s size. Typically, 25-200 units of Onabotulinumtoxin A are injected into each targeted muscle [6]. The larger the muscle group, the more injections will be needed to provide therapeutic effects [10]. If bleeding occurs during the procedure, a hematoma may form. Tamponade at the site can lessen the size of the bruising or even prevent it from appearing. Applying ice to the site if bleeding occurs can also be helpful [12]. 

The procedure is brief, and the client is observed for a short period. After the procedure, they can resume normal activities and routines. Sedation is not typically used for this procedure, but light restraints may be used for small children. Though the procedure is painless, they may be fearful at the sight of the needles used for the injections. Occasionally, a medication to help the client relax may be administered before the procedure. Occasionally, serial casting may be completed after the neurotoxin administration and is typically only used for injections at the ankle sites [10].  

Recent research has suggested that using electromyography, electrical stimulation, and ultrasound guidance produces more accurate injections than anatomical guidance alone [13]. 

Electromyography (EMG), which uses a small electrode needle to measure the electrical activity of the muscle, may also be used to guide medication administration. This helps identify the precise area of the muscle that should be treated [9]. Ultrasound, a less invasive alternative to EMG, may also be used to guide the provider administering the injections [14]. 

Safety 

Like any medical treatment or procedure, there are safety concerns that nurses should be aware of, though significant side effects from the administration of neurotoxins to treat spasticity are not expected [10]. Neurotoxin injections to treat spasticity are generally considered safe, with a high probability of benefits and a low probability of adverse effects [10]. Allergic reactions are possible, so nurses should verify the client’s list of known allergies. Individuals with multiple allergies are more likely to be allergic to the botulinum toxin [12].  

If the needle is misplaced during the procedure, the medication can inadvertently affect the wrong muscle. When unintended muscles are paralyzed by the toxin, functional issues can occur [12].  

Drug Interactions 

There are no known drug interactions for botulinum toxin injections, though anticoagulants, both pharmacological and herbal, can cause an increased risk for bleeding and bruising.  

Contraindications 

Clients with severe widespread spasticity and clients with permanent rigid muscle contractures are not candidates for the use of neurotoxin injections to reduce muscle tone. Other treatments, such as intrathecal baclofen, may be more appropriate for these clients [10]. Botulinum toxin is classified as a category C drug for pregnant women. It is usually not recommended since there are insufficient human studies to determine the effects on human fetuses. The manufacturer of botulinum toxins does not provide guidance for the use of botulinum toxin while breastfeeding. Neurotoxin injections are also approved for individuals older than 65, with studies suggesting no difference in safety issues between clients older and younger than 65. Botulinum toxin is contraindicated for individuals with keloidal scarring, botulinum toxin allergies, and amyotrophic lateralizing sclerosis myopathies (ALS, also known as Lou Gehrig’s disease) [3].  

Adverse Effects  

Over time, the body may create antibodies to the administered toxin. This is not dangerous for the client but can cause the treatment to become less effective. Long-term use of neurotoxins to reduce muscle spasticity can cause muscle atrophy, but this is reversed when the injections are discontinued [5]. Loss of bladder control, vision changes, and drooping eyelids can occur but are temporary [10]. 

One adverse effect that can occur is ecchymosis, or bruising, at the injection site. Applying ice at the intended injection site before the procedure can reduce the risk of bruising. Mild bruising occurs for 11-25% of clients, and hematoma can occasionally occur. If a hematoma occurs, antibiotics may be prescribed to reduce the risk of further adverse effects from infection. To reduce the risk of bruising, clients should not currently be taking anticoagulants or have any issues with coagulation. Herbal medications that may increase the risk for bruising include ginseng, ginkgo, and high doses of garlic. These side effects are consistent with any type of injections clients receive [12]. 

Pain is another adverse effect of neurotoxin injections. There is no pain specifically due to the medication, but pain from the needle injection is expected [10]. Localized pain can occur, and increased pain is often due to the incorrect needle size being used to administer the injections. Topical anesthetics and having the bevel of the needle up and injecting slowly can reduce pain. Some providers may choose to dilute the toxin with saline solution, which can help to minimize pain [12]. Child life specialists may provide distraction during the procedure [10].  

Infection at the injection site can occur when aseptic technique is not used for the procedure. Nurses should monitor for typical signs of infection, including fever, chills, and redness or tenderness at the injection site. Headaches can occur after the neurotoxin administration. While this is a common side effect, it is short-term and resolves within a few days. Occasionally, the headaches can last a few weeks and are treated with NSAIDs [12].  

Allergic reactions can cause edema, erythema at the injection site, diffuse erythema, urticaria, or anaphylactic shock. Erythema usually resolves within 24 hours and can be treated with antihistamines. Anaphylactic reactions require an emergency treatment with steroids and epinephrine, and the client should continue to be monitored [12].  

It is not uncommon for clients to experience flu-like symptoms and dry mouth after the administration of botulinum toxin. These side effects typically resolve within a few days. Nurses should advise clients who experience side effects to discuss them with their doctor, as dosage and site changes may help to relieve the side effects in the future [9]. 

Serious adverse effects can occur when there is a systemic spread of the botulinum toxin. This is not a common occurrence but is more likely to occur for clients using botulinum toxin injections for therapeutic effects, such as treating spasticity, than when it is used for cosmetic treatments. This is because the dosages used for therapeutic treatments are greater. Accidental intravenous injection of the toxin can contribute to serious complications. Serious adverse effects include unintended muscle weakness or paralysis, as well as dysarthria, dysphagia, dysphonia, and respiratory arrest. Dysarthria makes speech more difficult for the client, while dysphagia describes difficulty with swallowing. Dysphonia alters the client’s tone and quality of their voice. This condition is called botulism. The early signs of this complication include intense headaches and fatigue. Treatment depends on the severity of the case of botulism but may consist of neurotrophic drugs, antitoxin serum administration, symptomatic treatment, and respiratory support [12].  

Case Study 1 

Drake is a 27-year-old male with a congenital neurological disorder. He received a botulinum toxin injection in his upper extremities three days ago. His father calls the clinic and informs the nurse that Drake was fine after the procedure but he has developed a fever in the past 12 hours. He states that at one of the injection sites there is a large bruise and redness, and that it’s warm to the touch.  

• What do you think is going on? 

Drake likely has an infection at the injection site. While this is rare, it is possible. The nurse notifies the physician who administered the injections of the observations made by Drake’s father. The physician wants to see Drake in the clinic this afternoon and plans to prescribe antibiotics after confirming the findings with a physical exam. The nurse tells Drake’s father that this can be a side effect of any injection and informs Drake’s father of the plan.  

The Nurse’s Role  

Nurses are essential in the use of neurotoxin injections to manage spasticity. Nurses should be aware of which botulinum toxin is being used, the procedure for injection, and possible adverse effects. Nurses may also be necessary for positioning the client and assisting with the injection procedure. Observing for breaches in aseptic technique is one way nurses can contribute to client safety during the procedure. Botulinum toxin products must be stored and prepared according to manufacturer instructions. Nurses can help ensure that the medications used have been stored properly.  

The scope of practice for nurses regarding the injection of Neurotoxins as a procedure varies among states, but nurses trained to provide neurotoxin injections generally provide cosmetic treatments, not therapeutic treatments for spasticity. Nurses must check their state scope of practice guidelines to determine their role in the administration of neurotoxins.  

Prior authorization may be required to administer botulinum toxin, even when treating a condition such as spasticity [15]. Nurses may be responsible for gathering documentation to assist in requesting prior authorization.   

Documentation is essential for any medical procedure, but for neurotoxin injections documentation is especially important for insurance reimbursement. Medicare requires there to be clear and accurate documentation regarding the type of botulinum toxin used, the strength of the toxin, the diagnosis, a statement addressing other treatment methods that have been tried without success, the dosage of the injections, support for the use of electromyography if it is used, and a complete anatomic description of the sites that were injected. Medicare also requires documentation of the effectiveness of the injections. There must also be documentation regarding the portion of the drug that must be wasted. Medicare will cover the wasted portion since botulinum toxin has a short shelf-life, but the reason for the unavoidable waste must be clearly stated [16]. Nurses are essential in ensuring all necessary documentation is present.  

Nurses can encourage clients and their caregivers to set attainable goals for treatment. Goal Attainment Scaling helps to individualize the therapy by considering what the client and caregiver would consider a successful treatment [13]. Goal Attainment Scaling allows individualized goals to be measured on a standardized scale. Scores range from -2, which indicates “much less than expected,” to +2, which indicates “much more than expected.” A score of zero means the outcome was at the client’s expected level. This allows progress toward goals to be tracked and evaluated over time [17]. The healthcare team and the client should have conversations to discuss realistic goals. The goals of the physician and client can vary. A client may feel their treatment goal is achieved if they are able to sign their name, while the physician may not consider the treatment successful if they are unable to have more dexterity than that. The healthcare team and client should frequently reassess the goals and adjust them based on the treatment’s effectiveness and the client’s changing needs [13].  

In addition to facilitating communication between the physician, client, and caregivers, nurses can also encourage effective communication with other members of the healthcare team. The physical therapist should be notified of the injection schedule to maximize benefits through physical therapy and inform them of any changes they may need to make regarding casting and splinting [10]. 

Case Study 2 

The nurse is precepting a new nurse in the Neurophysiology clinic. The new nurse asks, “Why is it necessary to document details such as the amount of botulinum toxin wasted during the procedure if it’s not a controlled substance?” 

• Why do you think this is necessary? 

The nurse explains to the orienting nurse that careful and complete documentation is necessary for insurance reimbursement for the cost of the injection procedure, especially for clients insured through Medicare and Medicaid. The nurse further explains that because the shelf life of the toxin is short, the cost of the wasted medication is covered as long as documentation is clear. Failing to provide detailed and accurate documentation can cause reimbursement requests to be denied. Nurses play an integral part in the functioning of any clinic, and providing documentation that allows for reimbursement is one way nurses ensure the clinic can be financially stable and continue to provide care for clients.  

Client and Family Education 

Clients and their caregivers require specific education regarding neurotoxin injections for spasticity. The reason why the treatment is recommended should be reviewed and nurses should assess that the client or caregiver can verbalize their understanding. A review of the procedure is helpful for clients and caregivers to know what to expect on the day of the administration procedure [10]. If sedation is used for the procedure, nurses can educate caregivers on what to expect with the use of sedatives and specific adverse reactions to monitor [18]. Expectations for efficacy should also be communicated, as the effects of treatment may take several days to become noticeable and a few weeks for peak effect. The importance of maintaining the follow-up schedule should be emphasized, as providers will need to assess the effectiveness of the treatment and plan for subsequent treatments to enhance the effects of neurotoxin therapy. 

Nurses can also educate clients and caregivers that more frequent injections can increase the risk for neutralizing antibodies, decreasing the effectiveness of treatment over time [10]. Prior to the client returning home after the administration procedure, nurses should educate clients and their caregivers regarding symptoms to monitor that may indicate an adverse reaction, such as continued pain at the injection site, excessive bruising, unexpected muscle weakness, difficulty swallowing, and difficulty breathing [3]. The nurse should advise the client and caregiver that if the client experiences trouble swallowing, gagging, or trouble breathing, 911 should be called, as this indicates a potentially life-threatening emergency [18].  

Physical and Occupational therapy may be recommended to enhance the effects of the neurotoxin injections through stretching and prescribed daily exercises [5]. Nurses must emphasize the importance of complementary therapies to facilitate optimal outcomes.  

Case Study 3 

Vanessa is a 68-year-old female who is experiencing spasticity in her right upper extremity following a stroke. She has had difficulty regaining her ability to perform daily tasks since the spasticity makes voluntary muscle control difficult. At today’s clinic appointment, her physician recommended neurotoxin injections to treat the spasticity. 

• What is necessary for the nurse and physician to discuss with Vanessa? 

Vanessa will need to understand the risks of the procedure. While rare complications can occur, she will need to be informed of what they may be. Realistic expectations will need to be communicated to Vanessa. The neurotoxin injections are not expected to improve strength but may improve coordination if the spasticity can be reduced. A discussion of goals should occur. Vanessa says she would like to perform more self-hygiene activities independently, such as brushing her teeth. She would also like to be able to prepare simple meals for herself, like a bowl of cereal for breakfast or a cold sandwich for lunch. Vanessa also says she enjoys reading but has difficulty turning the pages due to spasticity.  

After discussing these goals, the nurse can explain how the goals will be evaluated using goal attainment scaling after treatment to help identify any changes that may need to be made in the treatment. EMLA cream will be used to numb the injection sites, so the nurse provides teaching on when and how to apply the cream. The nurse informs Vanessa that the results of the injections may take several days to be observed and a few weeks for them to reach their peak effectiveness. Also, the injections will need to be repeated in 3-4 months. The nurse advises Vanessa that it is imperative that she keep all follow-up appointments so progress can be monitored and treatments can be continued. The nurse reminds Vanessa that attending physical and occupational therapy appointments is beneficial in enhancing the effects of the injections. Finally, the nurse educates Vanessa on the signs and symptoms of adverse reactions that should be reported to the clinic following the procedure. The nurse reminds Vanessa that she can contact the clinic if she has further questions.  

Current and Upcoming Research 

Recent research regarding the use of neurotoxin injections to treat spasticity includes focusing on a goal-oriented approach. This client-centered approach considers how spasticity changes over time and the goals of the client and caregiver. Research continues by incorporating functional anatomy as a method to identify muscles that should be treated to maximize the benefits of neurotoxin therapy [19]. Ongoing discussion is needed among providers to discuss ineffective treatments. This can contribute to the conversation of neurotoxin use for spasticity by helping providers understand dosage needs, muscle choices for injections, and injection techniques. Research regarding guidelines for best practices continues in an effort to improve the efficacy of the treatment for all clients.  

Treatment intervals may also vary according to the underlying diagnosis and the client’s needs. More research is necessary to help identify treatment intervals for different conditions to help clients have a more consistent therapeutic outcome rather than what may feel like a rollercoaster of effectiveness as injections are administered and the effects lessen over time. Research is being conducted to determine if small-bore needles cause damage to the neurotoxin and whether larger-bore needles might be more appropriate for use. Dilution studies are also being conducted to determine if this impacts the effects of the medication [13].  

Conclusion

Muscle spasticity affects a significant portion of the global population, and neurotoxin injections can improve the quality of life of these clients. Neurotoxin injection to treat spasticity is generally considered to be a safe procedure with few if any, side effects. By knowing that spasticity is a neuromuscular disorder caused by the inappropriate release of chemical neurotransmitters, nurses can better understand how neurotoxins work to reduce the impact of the disorder. While rare, side adverse events, such as infection and misplaced injections, can occur. Nurses can be instrumental in monitoring for these complications and educating clients and their families on what symptoms may indicate a problem.  

Nurses can more effectively participate in the administration procedure by being knowledgeable about which neurotoxin is being used, what documentation is necessary, and how to help improve client outcomes through Goal Attainment Scaling. Client and family education is a vital part of neurotoxin injection therapy. Nurses contribute to positive outcomes by ensuring clients and their caregivers understand what to expect during and after the procedure. Continued research is necessary to improve the benefits of neurotoxin injections, and nurses must continue to increase their knowledge regarding changes in best practices.  

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