Muscle spasms and spasticity constitute a significant problem in patients with spinal cord injury, interfering with rehabilitation and leading to impairments in quality of life in addition to medical complications. Administration of intrathecal baclofen (ITB) is indicated when spasticity continues to produce a clinical disability despite trials of oral treatments and other alternatives in patients who have functional goals and/or pain without contractures. Severe spasticity of spinal origin has been shown to respond dramatically to long-term ITB when used in appropriate patients with spasticity.
Key points
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Spasticity and spasms are serious complications for many patients with spinal cord injury (SCI), as they both indicate an imbalance in the mechanisms that regulate reflex motor activity at the level of the spinal cord.
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Muscle spasms and spasticity constitute a significant problem, interfering with rehabilitation and leading to impairments in quality of life in addition to medical complications.
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Intrathecal baclofen (ITB) may be an effective option to consider in patients who cannot tolerate the adverse effects of high-dose oral baclofen.
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ITB administration is indicated when spasticity continues to produce a clinical disability despite trials of oral treatments and other alternatives in patients who have functional goals and/or pain without contractures.
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Intrathecal administration achieves high concentrations of the drug in the spinal cord with small dosages, thus reducing the incidence of central nervous system side effects. In addition, it allows for flexible dosing patterns to suit an individual patient’s lifestyle.
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The 2 major risks of ITB involve symptoms related to overdose or withdrawal; the latter is more important because of the associated severe effects on clinical status and the possibility of death, but is responsive to rapid treatment.
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Severe spasticity of spinal origin has been shown to respond dramatically to the long-term intrathecal administration of baclofen when it is used in appropriate patients with spasticity.
Introduction
Chronic, intractable spasticity is a major health problem for patients with spinal cord injury (SCI), and can cause significant disability and impairments in quality of life. Undesired muscle spasms and increased motor tone often make activities of daily living, transfers, self-care, and even sitting comfortably difficult or near impossible for patients with both complete and incomplete lesions. Using a database of self-reported secondary medical problems in recently injured SCI patients, 53% reported spasticity as the most disabling complication, followed by pain and pressure ulcers. In a survey of 500 long-standing SCI patients, spasticity was the second most reported complication after urinary tract infections, and was found to occur much more frequently in SCI with Frankel grades of B or C, and more so in incomplete tetraplegics than in paraplegics.
Baclofen, the administration of which is primarily indicated for the spasticity of spinal origin, was first introduced for clinical use in Europe in the 1960s. Although oral baclofen continues to be used successfully to treat spasticity, when given intrathecally it has a more potent effect, requiring approximately one-hundredth of the oral dose, although this ratio varies greatly among patients. The development of implantable pump and catheter drug-delivery systems has allowed for the continuous infusion of baclofen into the intrathecal space, and remains an effective method of controlling rigidity and spasticity of spinal origin in appropriately selected patients.
Introduction
Chronic, intractable spasticity is a major health problem for patients with spinal cord injury (SCI), and can cause significant disability and impairments in quality of life. Undesired muscle spasms and increased motor tone often make activities of daily living, transfers, self-care, and even sitting comfortably difficult or near impossible for patients with both complete and incomplete lesions. Using a database of self-reported secondary medical problems in recently injured SCI patients, 53% reported spasticity as the most disabling complication, followed by pain and pressure ulcers. In a survey of 500 long-standing SCI patients, spasticity was the second most reported complication after urinary tract infections, and was found to occur much more frequently in SCI with Frankel grades of B or C, and more so in incomplete tetraplegics than in paraplegics.
Baclofen, the administration of which is primarily indicated for the spasticity of spinal origin, was first introduced for clinical use in Europe in the 1960s. Although oral baclofen continues to be used successfully to treat spasticity, when given intrathecally it has a more potent effect, requiring approximately one-hundredth of the oral dose, although this ratio varies greatly among patients. The development of implantable pump and catheter drug-delivery systems has allowed for the continuous infusion of baclofen into the intrathecal space, and remains an effective method of controlling rigidity and spasticity of spinal origin in appropriately selected patients.
Definition of spasticity and spasms
Spasticity is a state of sustained, increased muscle contractility that can occur in many diseases of central origin such as stroke, cerebral palsy, multiple sclerosis, and amyotrophic lateral sclerosis. Clinically it is defined as a motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with exaggerated tendon jerks, resulting from hyperexcitability of the stretch reflex, as one component of the upper motor neuron syndrome. It is a combination of clinical signs characterized by increased muscle tone with or without the presence of clonus and muscle spasms, abnormal spinal reflexes, and increased resistance to passive movement.
Muscle spasms are episodes of involuntary motor contractions that occur following a lesion of the ascending motor pathway. These spasms are often painful, and can lead to serious complications such as decubitus ulcers, falls and fractures, and respiratory compromise.
The original Ashworth scale, which is referred to in many clinical studies ( Table 1 ), is a simple 5-point Likert scale in which the observer’s subjective opinion of the patient’s resting muscle tone ranges from “normal” at the lowest grade to “rigid” at the highest. This original scale was revised to form the modified Ashworth scale ( Table 2 ), which is the one most commonly used today in the clinical setting, by adjusting the lowest number from 0 to 1 and the highest from 4 to 5. There was also the addition of a category between 1 and 2, with 1 indicating a “catch” at the joint’s end range of motion and 1+ indicating a “catch” closer to the midpoint of the joint’s range of motion.
| Score | Definition |
|---|---|
| 0 | No increase in muscle tone |
| 1 | Slight increase in muscle tone, manifested by a catch and release |
| 2 | More marked increase in muscle tone through most of the range of motion, but affected limb is easily moved |
| 3 | Considerable increase in muscle tone; passive movement difficult |
| 4 | Limb rigid in flexion or extension |
| Score | Definition |
|---|---|
| 0 | No increase in tone |
| 1 | Slight increase in muscle tone, manifested by a catch and release, or by minimal resistance at the end of the range of motion (ROM) when the affected part(s) is moved into flexion and extension |
| 1+ | Slight increase in muscle tone, manifested by a catheter, followed by minimal resistance throughout the remainder (less than half) of the ROM |
| 2 | More marked increase in muscle tone through most of the ROM, but affected part(s) easily moved |
| 3 | Considerable increase in muscle tone, passive movement difficult |
| 4 | Affected part(s) rigid in flexion or extension |
Another method of assessing spasticity is the Penn Spasm Frequency score ( Table 3 ), which is an ordinal ranking of the patient-reported frequency of leg spasms per day and per hour. A major limitation of this is that the frequency of spasms can be affected by activity level, and it does not take into account the length of each spasm.
| Score | Criteria |
|---|---|
| 0 | None |
| 1 | No spontaneous spasms; vigorous sensory and motor stimulation results in spasms |
| 2 | Occasional spontaneous spasms occurring less than once per hour |
| 3 | Greater than 1 but less than 10 spontaneous spasms per hour |
| 4 | Greater than 10 spontaneous spasms per hour |
The incidence of spasticity in SCI patients
Spasticity is a prevalent issue for patients with SCI, and becomes more so with increasing time after injury and resolution of spinal shock. Problematic spasticity occurs in 40% to 60% of patients with SCI and multiple sclerosis, which results in a significant impact on activities of daily living and patient independence. Its treatment must be based on individualized clinical decisions by the physician in conjunction with the patient and family or caretaker.
Maynard and colleagues reviewed 2 major epidemiologic studies in patients after traumatic SCI, exploring the incidence and severity of spasticity development in addition to the incidence of spasticity treatment among these patients. The investigators found that spasticity development and treatment are common but not inevitable sequelae of SCI, with the incidence of spasticity being higher among cervical and upper thoracic rather than lower thoracic and lumbosacral levels of injury. This finding may be due to primarily upper motor neuron damage to the spinal cord at the cervical and upper thoracic levels of injury, in contrast to lower motor neuron damage to the conus medullaris or cauda equina at the lower thoracic and lumbosacral levels. In addition, although the relationship between spasticity and level of injury must be taken into consideration, grouping patients by the presence of quadriplegia versus paraplegia is likely inappropriate. When investigating the incidence of and treatment of spasticity, multiple studies have found that spasticity is more common and more severe in patients with Frankel grade B and C lesions as opposed to grade A or D, and, by the same token, more common in patients with motor incomplete lesions than with motor complete lesions.
When to treat spasticity
The first step in the management of all problematic spasticity is to identify, address, and treat any remediable causes and factors (ie, urinary tract infection [UTI], impacted stool, pressure sore, ingrown toenail, and so forth). If such measures are ineffective then it is appropriate to pursue treatment until a therapeutic response is obtained.
The successful management of spasticity can be a therapeutic challenge, as its clinical presentation is highly variable among patients. Thus, the health care provider must assess each individual independently to determine whether spasticity is proving advantageous rather than disadvantageous.
To do this one must first establish whether there is a functional problem caused by the spasticity, and determine the related goals of treatment for the patient and/or caregiver. Despite common belief, the effects of spasticity might not always be negative. For example, spasticity can stabilize weakened legs, allowing a patient to stand or transfer and have improved bed mobility. Spasticity can also be a functionally helpful factor by being protective against skeletal muscle atrophy, indirectly aiding in functional independence and ambulation, and decreasing the incidence of fracture. Moreover, spasticity has been reported to increase glucose uptake and thereby reduce the risk for diabetes in those with SCI. The goal of functional improvement must therefore consider the balance of treatment effects.
Treatment options available for spasticity
Various pharmacologic interventions are available to manage spasticity following SCI. The treatment approach to spasticity usually relies on a combination of physical modalities and therapies, such as stretching to promote relaxation, mechanical bracing, and the use of transcutaneous electrical nerve stimulation, in addition to medications used as monotherapy or in conjunction with the physical modalities.
Several oral agents are available that target increased muscle tone. A Cochrane systematic review was conducted to assess the effectiveness and safety of several drugs with antispastic effects, such as baclofen, dantrolene, tizanidine, gabapentin, clonidine, and diazepam, which are commonly used as a first-line treatment. Of these drugs only dantrolene has a peripherally acting mechanism of action. Another peripherally acting, but longer-lasting, treatment option is botulinum toxin type A (Botox), which is used to treat focal spasticity or localized spasms. Phenol is less commonly used nowadays, but when the patient reaches a maximum dose of Botox and still needs injections in other sites, it is considered. The other drugs, which are primarily centrally acting, thus predispose to greater side effects. Adverse effects of baclofen ( Table 4 ) appear to be dose related and usually appear at doses greater than 60 mg/d, with the rate of medication discontinuation ranging from between 4% and 27%.
| Symptom | Range of Percentage of Patients Affected |
|---|---|
| Weakness | 0.8–68.7 |
| Somnolence | 7–70 |
| Vertigo | 4.5–13 |
| Headache | 1.5–17 |
| Nausea | 1.7–24 |
| Vomiting | 2–10 |
| Depression | 2–19 |
| Dry mouth | 4.7–21.7 |
| Bladder symptoms | 7.6–11.5 |
Studies have shown that patients with spasticity resulting from SCI generally tend to have a more favorable response to baclofen than those with spasticity of cerebral origin, with significant improvements seen with oral baclofen alone ( Table 5 ). Most patients with spasticity are generally treated according to a protocol whereby baclofen, with or without diazepam, is often the first step in management followed by other drugs such as tizanidine or Botox for localized symptoms. However, there is no unified supporting evidence for this commonly used therapeutic approach, and often it is used at the sole discretion of the treating physician’s experience and judgment.
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