This chapter focuses on the clinical diagnosis, pathophysiology, and physiatric management of spasticity and contractures.

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  Spasticity is an involuntary velocity-dependent increase in muscle tone, a component of upper motor neuron syndrome.

  
  
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  Contractures are a loss of full active and passive range of motion in a limb that can be due to limitations imposed by the joint, muscle, or soft tissue.

  
  
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  Spasticity and contractures are significant contributors to disability.

  
  
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  Clinical measurement of spasticity includes the Modified Ashworth and Tardieu scales.

  
  
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  Spasticity can be treated systemically with oral medications such as baclofen and tizanidine and with an intrathecal baclofen pump. Botulinum toxin and other neurolytic injections are used for localized treatment.

  
  
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  Prevention is critical for contracture management. Once they occur, contractures can be managed with rehabilitation modalities, including stretching, proper positioning, and splinting.

  
  
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  Once a contracture has developed, surgical release may be required.

Spasticity

Lance et al defined spasticity as a “motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with exaggerated tendon jerk, resulting from hyper-excitability of the stretch reflex.”¹ While valuable, this definition omits common clinical manifestations of spasticity. For example, clonus and flexor withdrawal spasms seen with spasticity arising from spinal cord injury are not encompassed by the Lance definition. Although a number of alternative definitions have been proposed, no universally accepted definition has yet been established.²

Spasticity is a common finding in central nervous system (CNS) injury as a feature of the upper motor neuron (UMN) syndrome. This syndrome, addressed in more detail in other chapters, is defined as injury to the motor neurons in the brain or their connecting pathways leading to the (lower) motor neurons in the anterior horn of the spinal cord. Damage to any portion of this pathway results in a characteristic set of clinical signs and symptoms.³ These signs include clonus, flexor spasms, and hyperactive tendon reflexes from excessive or inappropriate muscle activity (Fig. 56–1). Spasticity has become a term that encompasses all these features.⁴ The majority of positive UMN symptoms arise from reflexes that result from abnormal processing of the sensory feedback from the periphery such as pain, cutaneous stimulation, and muscle stretch.⁴ Stretch reflexes refer to proprioceptive reflexes that are either tonic, from a sustained stretch, as in the case of clonus, or phasic, from a short stretch, as in the case of deep tendon reflexes.⁴ Examples of the nociceptive reflexes are flexor and extensor spasms and the Babinski sign, a familiar cutaneous reflex.⁴

Dystonia and Spastic Dystonia

It is important to contrast spasticity with dystonia, a phenomenon that has some similar clinical manifestations but with different mechanisms and etiologies. Dystonia is a movement disorder characterized by involuntary, repetitive, and patterned muscle contractions that can be tonic or episodic in nature, often causing abnormal postures or motion that is twisting, flexing, extending, or squeezing in nature (e.g., blepharospasm or torticollis).⁵ While spasticity as a component of the UMN syndrome will often have an identifiable lesion or lesions, dystonic patients usually have no clearly defined brain lesion as the cause of their movements, although in some cases causative factors may be identified.⁶ Despite the lack of a clear anatomic lesion, physiologic studies have localized functional abnormalities in the rostral brainstem and/or basal ganglia with observations that damage to these areas can result in dystonia.⁵

Dystonias can be focal or generalized and can be inherited, occur sporadically, or be secondary to specific causes such as brain lesions, metabolic or neurodegenerative disorders, toxins, or even some medications.⁵ While dystonia is usually attributed to a dysfunctional extrapyramidal system, rarely, it can occur after an acute peripheral injury as well, a phenomenon that is not seen with spasticity.⁶ The increased muscle tone, involuntary nature of the disease, and resulting abnormal postures seen in dystonia, such as that in poststroke dystonia, can be mischaracterized as spasticity.⁷

Spastic dystonia is a clinical entity that represents the overlap between spasticity and dystonia.⁸ It is an involuntary, stretch-sensitive, tonic muscle contraction.⁸ The stretch-sensitive aspect of spastic dystonia refers to the eletromyographic (EMG)–proven increase in muscle activity with phasic stretch and the observation that maintaining tonic stretch for several seconds inhibits spastic dystonia (decrease in EMG activity in the affected muscle) and thus improves the ability to rest muscle.⁸ Denny and Brown provided a similar definition when they called the tonic contracture leading to hemiplegic posture (shoulder adduction and flexor bias in wrist, elbow, and fingers) spastic dystonia.⁹

Spastic dystonia is commonly seen in individuals after traumatic brain injury but not those with spinal cord injury.¹⁰ Denny and Brown’s studies in monkeys provided a potential explanation for this finding. Despite severing of the dorsal roots in the monkeys, a persistence of the tonic contraction with spastic dystonia was described.⁹ This finding indicated that spastic dystonia, while sensitive to stretch and length like spasticity, occurs independently of spinal reflexes.^8,10 Treatments that are typically effective for spasticity, such as baclofen, are commonly but not uniformly effective for dystonia. Some therapies, such as botulinum toxin injections, are useful for spasticity, dystonia, and spastic dystonia.^8,10

Contractures

Spasticity may result in contracture formation. A contracture is defined as the loss of full active and passive range of motion in a limb that results from limitations imposed by the joint, muscle, and/or soft tissue.¹¹ Usually contractures occur due to periarticular connective tissue restriction involving muscles, tendons, ligaments, and joint capsule.¹² These types of contractures are not mutually exclusive and frequently occur together. Contracture can occur as a result of prolonged immobility of the limb and/or a lack of weight bearing in the lower limbs.¹³ Spasticity, dystrophic myopathies, neurologic disorders, trauma, burns, and generally any illness with resulting immobility place a patient at a high risk of developing contracture.^13,14

The focus of this chapter is spasticity and contractures in adults, but it is important to be aware that spasticity and contractures are a significant cause of morbidity in the pediatric population; cerebral palsy is the most common cause of pediatric spasticity.¹⁵ While many of the management and diagnostic principles are similar, this chapter focuses on adult patients.

A wide variety of diagnoses causing UMN syndromes can lead to spasticity, with the most common being stroke, traumatic brain injury, multiple sclerosis, spinal cord injury, cerebral palsy, and motor neuron diseases (Table 56–1). There is incomplete information regarding the incidence of spasticity in the population as a whole, but data are available regarding the more common disease states.

A review by Wissel et al found that the prevalence of poststroke spasticity reported in published papers was highly variable, ranging from 4% to 42.6%.¹⁶ This review also analyzed the time course of the development of poststroke spasticity and found that 4 to 27% were affected “early” (defined as 1–4 weeks poststroke), 19% to 26.7% were “post-acute” (1–3 months poststroke), and 17% to 42.6% were affected in the chronic phase (>3 months poststroke).¹⁶ Another study by Wallmark et al analyzed the prevalence of spasticity after aneurysmal subarachnoid hemorrhage (SAH).¹⁷ They reported the prevalence of spasticity after SAH as approximately 20% and found no difference in the prevalence of spasticity from a subarachnoid hemorrhage compared with other types of stroke.¹⁷ Thibault et al studied spasticity in patients with disorders of consciousness from brain injury.¹⁸ Of the 65 patients they studied, 40 had traumatic etiology, with 89% of these traumatic brain injury patients with some spasticity (Modified Ashworth Scale [MAS] ≥ 1), including 39 patients with severe spasticity (MAS ≥ 3).¹⁹

Other studies have looked at the epidemiology of spasticity following traumatic spinal cord injury.²⁰ Maynard et al performed two studies, the first of which analyzed the occurrence of spasticity for 96 subjects at a single spinal cord injury center.²¹ The authors found that 67% of subjects developed spasticity by discharge, with 37% of the patients requiring medication.²¹ They also found that spasticity occurred with a higher frequency in those with cervical and upper thoracic injuries compared with those with lower thoracic and lumbosacral levels of injury.²¹ Maynard et al’s second study analyzed 466 patients at 13 spinal cord injury centers and found that 26% received antispasticity treatment by discharge.²¹ In both studies, the percentage of patients requiring spasticity treatment on follow-up increased, from 37% to 49% in the former and from 26% to 46% in the latter study.²¹ Hagen reports that spasticity usually manifests 2 to 6 months after injury, with up to 70% of patients eventually developing spasticity.²²

Pozzili found that up to 80% of patients with multiple sclerosis (MS) experience spasticity of varying severity over the course of their disease.²³ Patti and Villa reported the prevalence of spasticity as greater than 50% in 200 MS patients younger than age 35.²⁴

Contractures may occur secondary to a wide variety of pathologies. Fergusson et al performed a systematic literature review of all epidemiologic studies of joint contractures encompassing a wide variety of etiologies.¹⁶ We focus on contractures resulting from neurologic disorders in this discussion, with contractures caused by burns or trauma covered in their respective chapters.

Studies have shown variable rates of contracture formation in different populations. O’Dwyer et al found that one-half of the stroke patients they studied developed muscle contractures within 13 months of their stroke, with the earliest developing contracture 2 months poststroke.⁷ Sackley et al recorded a 60% contracture rate in 122 stroke patients,²⁵ and Pinedo and de la Billa found a contracture rate of 23% in 73 patients with hemiplegic stroke.²⁶ Singer et al found a contracture rate of 16.2% in 105 moderate to severe brain injury patients,²⁷ Pohl and Mehrholz reported that 56% of fifty patients with severe cerebral damage had a contracture in at least one shoulder,²⁸ and Yarkonoy and Sahgal reported a contracture incidence of 84% in 75 patients with craniocerebral trauma with a positive correlation between the duration of coma and the presence of contractures.²⁹ Vogel et al studied 216 patients with pediatric-onset spinal cord injuries and found that 23% had hip contractures, 16% had ankle contracture, and 7% had elbow contractures.³⁰ Interestingly, Vogel et al found that different types of contractures were associated with injuries of different severity; hip contractures were associated with more complete injuries on an ASIA examination and elbow contractures with less complete injuries.³⁰

Spasticity

Spasticity results from the loss of descending inhibition of spinal cord reflex arcs as well as loss of cortical inhibition on the postural centers contained within the vestibular nuclei and reticular formation³¹ (Fig. 56–2). UMN lesions that disrupt the inhibitory and excitatory pathways of the CNS may result in disinhibition of the anterior horn cells and their associated spinal reflexes.¹⁰ Experimental animals with damage to the corticospinal tract have improvement in spasticity when lesions are created in the vestibular nuclei or after sectioning of the dorsal roots.³¹ This suggests that spasticity may represent an overall increase in the spinal cord reflexes secondary to a loss of cerebral inhibition.³¹

The two mechanisms at work in the pathophysiology of spasticity are the spinal mechanism with resulting change in the function of spinal neurons and the cerebral mechanism encompassing supraspinal and suprasegmental mechanisms.³² These two mechanisms indicate that spasticity is caused either by hypersensitivity of the reflex arc due to changes in the spinal cord or by the loss of descending inhibition from damage to the supraspinal CNS resulting in the manifestation of abnormal impulses.³³ It is the presence of these two mechanisms that is believed to underlie the difference between spinal spasticity and cerebral spasticity. The “clasp knife phenomenon,” for example, is more prominent in spinal spasticity and describes the sudden disappearance of the velocity-dependent increase in resistance to passive stretch resulting in the affected limb moving akin to the opening of a clasp knife.⁶² Other differences include more prominent clonus in spinal spasticity and more frequent flexor withdrawal spasms when compared with individuals with spasticity of cerebral origin.

Immediately after injury to the motor portion of the CNS, there is paralysis, flaccidity, and gradual muscle shortening.^4,8 Within several weeks of the injury, neural plasticity contributes to muscle overactivity and abnormal spinal reflex response to peripheral inputs.⁸ This neural rearrangement occurs in the form of sprouting by interneuronal endings at the segmental spinal levels to take the place of the degenerated descending fibers.¹⁹ The different components of spasticity occur because of disinhibition of existing normal reflexes.⁴ Clonus, for example, occurs as a result of a disinhibited or hyperactive phasic stretch reflex that in nonpathologic states is a normal deep tendon reflex.⁴ Flexor spasms, by contrast, arise as a result of the disinhibited normal nociceptive reflex.⁴ A painful stimulus to the foot, for example, results in reflexive ankle dorsiflexion, hip flexion, and knee flexion for the homeostatic withdrawal of the limb from a painful stimulus.⁴ The disinhibition of this reflex results in flexor spasms in response to painful stimuli.^4,34

Contractures

Contracture formation occurs along a pathway that begins with muscle unloading when immobilized, followed by atrophy, loss of sarcomeres, and accumulation of connective tissue and fat in the muscle tissue.³⁴ Immobilization in a shortened position results in muscle unloading, found in animal studies to correlate with the rate of muscle atrophy.³⁴ In addition, immobilization also causes decreased muscle fiber diameter, reduces the capacity to synthesize proteins, and leads to an overall reduction in muscle volume.³⁴ Maintenance of the muscles in a shortened position then leads to the loss of sarcomeres; this does not occur in patients who are immobilized with the joint in a neutral position.³⁴ The remaining sarcomeres adapt to their shortened resting position and overlap optimally to potentiate maximal tension at the immobilized length.³⁴ The next step from immobility to contracture formation is quantitative and qualitative changes in the intramuscular connective tissue.³⁵ There is an increase in the ratio of collagen to muscle fiber tissue with an increase in the number of perpendicularly oriented collagen fibers.³⁴ Another observation, especially in patients with chronic hemiplegia, is that the skeletal muscles on the paretic side have increased fat content relative to the nonparetic side, with fat accumulation in the tendons of the paretic muscles; this occurs with both flaccid and spastic paresis.³⁵

As with any clinical examination, evaluation of the patient should begin as the patient enters the examination room. If he or she is ambulatory, the patient’s entrance affords an opportunity to evaluate gait. A scissoring gait, for example, generally indicates spasticity of the hip adductors resulting in a crossing over of the medial thighs.³⁶ Another example of pathologic gait would be circumduction in an individual with ankle dorsiflexion weakness and plantarflexion spasticity and/or contracture.³⁷ Inadequate dorsiflexion can contribute to falls and injury.³⁷

In nonambulatory patients, evaluation of the patient begins with noting the patient’s posture in his or her wheelchair. Limb posture, such as maintaining the elbow in a flexed position, may provide evidence of spasticity. In hemiplegic individuals, it is common to observe a combination of internal rotation and adduction at the shoulder, flexion of the elbow, pronation of the forearm, and flexion of the wrist and fingers.

A thorough skin examination is essential in individuals with spasticity. Contracture and/or spasticity can result in an extremity or body part maintained in a position that keeps it in contact with the skin of another body part, affording little opportunity for cleaning and creating a risk of maceration, infection, and ultimately, the formation of pressure ulcers. A detailed neurologic examination and musculoskeletal examination should be conducted of all four limbs, including deep tendon reflexes, abnormal reflexes (e.g., Babinski’s and Hoffman’s signs), sensation, strength and motor control, muscle tone, muscle bulk/atrophy, and range of motion. Many neurologic conditions are unilateral (e.g., stroke) or asymmetrical (e.g., traumatic brain injury, multiple sclerosis), and side-to-side comparison is always warranted.

When examining a limb for spasticity, the proximal and distal joints should be ranged both actively and passively. The clinician should also observe and palpate for muscle spasm with joint movement, evaluate for clonus with rapid and slow stretching of the joint, and be aware that spasticity frequently is accompanied by some degree of muscle contracture, especially over time.³⁸ There are several clinical scales that may be useful to quantify the degree and type of spasticity found on examination.

The Modified Ashworth Scale

The Modified Ashworth Scale (MAS) is the most commonly used clinical scale to measure hypertonic or spastic muscle. The scale ranges from 0 to 4, with the muscle acting across the joint rated based on what point during flexion or extension resistance or a catch is noted. During rapid elbow flexion, for example, the triceps should relax. If the triceps is hypertonic, the examiner will have difficulty passively flexing the elbow; the degree and point at which resistance or a catch is encountered are what allows the examiner to rate spasticity in the muscle on this scale. A score of 0 indicates no resistance to passive movement, with a 4 indicating a rigid joint. A score of 1 on the MAS indicates resistance at the end of the movement, with a 1+ indicating resistance at more of the range of motion than a 1 but still involving less than half the total range of the joint. A 2 indicates resistance or a catch throughout more than half or most of the range of motion, with a three indicating difficult passive movement (Table 56–2).

Tardieu Scale

Criticism of the MAS includes the fact that it does not distinguish between neural and soft tissue contributions to spasticity.³⁵ In 1954, Tardieu et al developed a clinical scale that was later modified by Held and Peierrot-Deseilligny and further changed by Boyd and Graham, resulting in the Modified Tardieu Scale (MTS; Table 56–3).³⁵ It differs from the MAS by taking into account resistance to passive movement at both slow and fast speeds, allowing for measurement of the “spasticity angle,” which represents the dynamic or neural component of spasticity.³⁵ This angle is the difference between the angle at which resistance is first encountered with rapid movement (R1) and the angle that reflects the maximum range of the joint with a slow muscle stretch (R2). The MTS also includes a “Quality of Muscle Reaction,” which is scored 0–5 (some score it 0–4), with 0 indicating no resistance to passive range pf motion (ROM) and 5 indicating that the joint is immobile. This testing is done at three velocities; V1, or as slow as possible; V2, or the speed of the limb falling under gravity; and V3, which is as fast as possible.³⁵

Penn Spasm Frequency Scale

The Penn Spasm Frequency Scale does not directly measure spasticity but allows the clinician to enumerate the number of spasms an individual experiences (Table 56–4). The scale ranges from 0 to 4, with 0 indicating no spasms and 4 indicating spasms that occur spontaneously more than ten times an hour. A score of 1 indicates that spasms occur only with stimulation. A 2 on the scale indicates that spasms are occurring less than once an hour, and a 3 means that spasms are occurring between one and ten times an hour.