Spasticity: Cerebral Palsy and Traumatic Brain Injury

Cerebral Palsy

Cerebral palsy and traumatic brain injury are upper motor neuron central nervous system diseases that result in decreased function, muscle imbalances, and malpositioning of the upper limb. Cerebral palsy is often related to hypoxic ischemic encephalopathy (HIE) when an infant’s brain is deprived of adequate blood flow secondary to a hypoxic-ischemic event during the prenatal, intrapartum, or postnatal period. HIE requires immediate intervention and affects 20 out of every 1000 full term births, and is even higher in premature births, affecting 60% of all live, premature births. HIE caused by asphyxia is the leading cause of infant fatalities in the United States, as well as the primary source of severe impairments. The clinical manifestations of HIE are broad, and may include developmental delays, epilepsy, cognitive issues, motor skill delays, and neurodevelopment delays. The true severity of HIE generally cannot be fully determined until the baby reaches 3 to 4 years of age. A commonplace end result of a HIE in infancy is cerebral palsy with varying degrees of severity.

The etiology of an HIE event, occurring before, during, or after the baby is born, are several. HIE during pregnancy has risk factors including maternal diabetes with vascular disease, decreased placental circulation, preeclampsia, cardiac disease, infections of the fetus, drug and alcohol abuse, severe fetal anemia, and lung malformations. HIE during the birth has risk factors including excessive bleeding from the placenta, low maternal blood pressure, umbilical cord rupture, prolonged late stages of labor, abnormal fetal position, and rupture of the placenta or the uterus. HIE during the postpartum period has risk factors including premature babies, severe cardiac or pulmonary disease, infections (sepsis and meningitis), low neonatal blood pressure, brain or skull trauma, and congenital brain malformations.

Cerebral palsy is an irreversible and nonprogressive brain injury. Although the brain insult itself does not change, the sequela of the brain injury varies over time, and may include progressive muscular fibrosis, joint contracture, limb length differences, osteopenia, and/or muscle atrophy. The brain injury that occurs as part of an HIE event is based on the blood supply pattern in the motor cortex; characteristic patterns of brain injury from the middle cerebral artery in the motor cortex lead to characteristic patterns of upper motor neuron dysfunction. The most common patterns of upper motor neuron spasticity lead to muscle imbalances within the upper extremity, with resultant shoulder internal rotation, elbow flexion, forearm pronation, wrist flexion, finger flexion, intrinsic spasticity, and thumb-in-palm deformity. ^,

Traumatic Brain Injury

Traumatic brain injury (TBI) is a leading cause of disability and death in the United States. An estimated 1.5 million Americans sustain a TBI annually, and about 50,000 of these people die. ^, Brain tumors, vascular malformations, and infection are less common causes of TBI. One-third of TBI survivors still require assistance with activities of daily living 1 year following injury. Most TBIs occur in individuals who are less than 45 years old at the time of TBI; those who survive have a normal life span. The enormous lifetime costs of TBI were estimated to be $56 billion in the United States in 1995. ^,

Following TBI, the Glasgow Outcome Scale is frequently used to predict the ultimate outcome. Patients with lower scores have a substantially higher incidence of severe sequelae. Age at time of injury and duration of coma are also important determinants of neurologic outcome. Brainstem involvement, as indicated by the presence of decerebrate or decorticate posturing, has a poor prognosis.

The brain-injured patient often has residual limb deformities, including spasticity, movement disorders, contracture, and muscle imbalance similar but not equivalent to cerebral palsy. Spastic deformities in the upper extremity after TBI most often also result in characteristic patterns of shoulder internal rotation, elbow flexion, forearm pronation, wrist flexion, finger flexion, intrinsic spasticity, and thumb-in-palm deformity. Because of the similar patterns of deformities, cerebral palsy (CP) and TBI will be discussed together in this chapter, although we will primarily focus on CP.

Bodily Impairment

Bodily impairment is defined by the WHO-ICF as a problem with body function or structure and is measured by physical examination. Physical examination of the spastic upper extremity includes both a motor and sensory evaluation of the upper extremity. Motor evaluation includes active range of motion, passive range of motion, strength, and grading of spasticity. Sensory evaluation includes two-point and stereognosis testing.

Motor examination requires experience, a relaxed clinical atmosphere, repeated examinations, and a team approach, as spasticity and functional use can vary by time of day, effort, stress, and environment. The resting position of the limbs is noted. The assessment should include the legacy measures of range of motion and strength of the shoulder, elbow, forearm, wrist, fingers, and thumb. Passive range of motion of all joints is documented, particularly noting the presence or absence of joint contractures. A joint contracture with limited passive movement will obviously limit active motion. Active range of motion and muscle strength of all involved and potential donor muscles for transfer is measured. Manual muscle testing (MMT) can be utilized in older children, adolescents, and adults. In addition to MMT, dynamometry for grip and pinch strength can be measured and compared with established norms for children as young as 6 years old.

Patterns of muscle firing and movement patterns also need to be assessed. CP can cause spasticity, dystonia, or flaccidity in varying patterns of involvement (see Video 32.1, Video 32.2 ). Many patients have a combination of movement patterns. Spastic involvement of a muscle is often coupled with flaccid involvement of its antagonist, potentiating the deformity from imbalance. Spastic patterns are diagnosed with hyperreflexia and clonus, which requires documentation. Muscle spasticity can be overcome by applying gentle sustained resistance to the spastic force. The most common grading systems for spasticity are the Modified Tardieu Scale and the Modified Ashworth Scale ( Table 32.1 ). Inspection for potential hygiene problems should include the axilla, antecubital fossa, volar wrist flexion crease, palm, and interdigital spaces.

Range of Motion

Preoperative evaluation to determine whether a muscle is a suitable donor for tendon transfer is useful. Methods include observation during active range of motion while performing functional tasks along with palpation of the muscle during voluntary firing. Muscles that exhibit considerable spasticity will produce the antagonist (opposite) position if used as a donor for tendon transfer. Muscles that exhibit considerable dystonia will produce unpredictable pattern of activity if used as a donor for tendon transfer. Muscles that are best suited for tendon transfer exhibit phasic patterns of firing, without considerable spasticity or dystonia.

For individuals who have a central nervous system insult that has affected the motor cortex, impairment of the sensory cortex is common, highlighting the interplay of impaired sensory and motor function. Assessment of sensory function varies with the patient’s age and cognitive ability. Stereognosis testing is the most sensitive sensory modality to test in the CP population. Stereognosis testing involves presenting familiar objects to the patient behind a screen for the child to identify with sensation only ( Fig. 32.1 ). In the hemiplegic child, the dominant hand is tested as well to ensure the child has the cognitive and verbal skills to understand and complete the test. An extra set of objects or pictures of the objects can be incorporated when testing younger children to make sure they know the names of the objects. Stereognosis can be tested with two or three simple objects such as a coin, poker chip, paperclip, or key. The complete test includes 12 standardized objects ( Table 32.2 ) that include similar and dissimilar objects. Previously, poor sensibility was listed as a contraindication to surgery ; however this dictum is no longer valid, as sensory deficiencies are present in nearly all children with CP. ^, Furthermore, sensibility has been reported to change over time or after surgical intervention, which may represent plasticity of the sensory cortex.

Additionally, the physical examination should also include other potential manifestations of the child’s central nervous system insult, such as cognitive impairments, balance, and lower extremity involvement. The child’s intellectual or cognitive impairments are difficult to assess in an office visit. Asking the child to follow voluntary commands and inquiring about the child’s school level along with participation in normal or specialized classroom provides a general baseline. Lower extremity involvement with hemiplegia, triplegia, or quadriplegia is also part of coordination of the overall care of the child.

Surgical Toolbox

The surgical techniques performed fall into four main categories: (1) soft tissue releases (tendon lengthening, myotomy); (2) tendon transfer; (3) bone or joint (osteotomy, fusion); and (4) neurectomy (selective and hyperselective).

As outlined in Table 32.5 , each of these surgical techniques can be applied sequentially to each anatomic area of the upper limb: shoulder, elbow, forearm, wrist, fingers, and thumb.

Soft tissue release with muscle-tendon lengthening is performed using one of four methods ( Fig. 32.2 ). The first method is a Z-plasty of the tendon and suturing the cut ends together in an elongated state. A second method is fractional lengthening whereby the muscle-tendon junction is identified. The tendon is isolated along its origin from the muscle. A tendinous segment is identified that has muscle on both sides of the tendon. The tendon is incised, leaving the muscle intact on both sides of the cut. The respective part (e.g., elbow or wrist) is stretched, elongating the cut ends of the tendon within the substance of the muscle. No suturing is required. The third method involves releasing the origin of the muscle and allowing it to slide in a distal direction during stretching of the limb. The last method is a myotomy that completely releases the muscle.

The particular lengthening technique utilized depends on numerous factors including the anatomy of the muscle-tendon unit, the length required, and the surgeon preference. For example, there are certain muscles that have short muscle tendon units (e.g., biceps muscle) and are not amenable to fractional lengthening. In addition, if substantial lengthening is required, fractional lengthening would exceed the length of the muscle-tendon junction, resulting in discontinuity between the muscle and tendon. Lastly, certain muscles are amendable to release of the origin and allowing the muscles to slide in a distal direction (e.g., flexor pronator mass and thenar muscles).

Hierarchy of Upper Limb Function

Proximal muscle stability and control is mandatory for hand function. Evaluation of the upper limb requires synthesis of the assessment of each anatomic segment of the limb. The spastic shoulder is usually positioned in internal rotation and adduction. The shoulder must be stable and well positioned, allowing the arm, forearm, and hand to function. With reference to the elbow, flexor spasticity is commonplace. In mild hemiparesis, this yields elbow flexion posturing during walking and times of excitement. In more severe cases, a myostatic contracture develops that limits elbow extension. The forearm, referred to as “the forgotten joint,” is, however, a frequent source of discontentment. The common forearm position is spastic pronation that is initially supple (dynamic) and develops a myostatic contracture over time. Excessive pronation impedes supinations activities, such as feeding, carrying a tray, obtaining soap from a dispenser, catching a ball, and wiping one’s buttocks. Tendon releases and transfers can improve forearm position (discussed below). Surgical management tends to focus on the wrist flexion with a variety of options available. The management of the spastic wrist and hand in CP follows the concepts of “hierarchy of hand function” or the “reconstruction ladder” ( Table 32.6 ).

The pivotal fundamental movement is wrist extension, which yields tenodesis for grip as the fingers flex into the palm and tenodesis for lateral pinch as the thumb adducts against the index finger. Wrist extension also aligns the finger flexors along Blix’s length-tension curve for maximum active grip. The second most essential movement is lateral pinch, which is necessary to perform numerous activities of daily living. Most daily activities are performed using lateral pinch, such as holding an object, turning a key, or using a fork. The third essential motion is grasp, which allows the holding of objects. The fourth and last movement is digital opening for object acquisition. The reason to place this function lowest on the ladder is that wrist flexion yields passive digital opening, which is often adequate for object procurement. In addition, synchronous digital opening is difficult to achieve via surgery as metacarpophalangeal joint extension requires both extrinsic function (extensor digitorum communis, extensor indicis proprius, and extensor digiti quinti) and intrinsic function (interphalangeal joint extension with interossei and lumbricals). Providing a comprehensive plan of all involved joints is necessary, as outlined in Table 32.5 .

Shoulder Reconstruction

The spastic shoulder is usually positioned in internal rotation and adduction. The child may be bothered by the posture and the inability to access his or her axilla. Severe internal rotation and adduction can make the axilla inaccessible, leading to stench and intertriginous infections. Treatment requires release of the offending spastic muscles based upon the clinical examination. The potential culprit spastic muscles include the pectoralis major and subscapularis. However, additional muscles such as the latissimus dorsi and teres major can contribute to the position. Clinical examination can often discern the most spastic muscles. These muscles can be treated by lengthening or release depending on their anatomy. For example, a tight spastic pectoralis major can be addressed by simple fractional lengthening via a small incision, as there is ample muscle-tendon junction on its undersurface. In contrast, the subscapularis requires a more extensive deltopectoral approach with release of the upper tendinous portion. The goal is to provide ample access to the axilla. The procedure is performed via a deltopectoral approach extended into the axilla. The deltopectoral approach allows access to the pectoralis major and the subscapularis. The approach can be extended through the axilla if the latissimus dorsi and teres major are contributing. Following surgery, the arm is positioned in an abduction pillow for 3 weeks followed by passive range of motion.

The shoulder can also be positioned in excessive external rotation ( Fig. 32.3 ). This awkward position can negate the child in a wheelchair from entering through a doorway. The offending muscle(s) are usually the infraspinatus, teres minor, and/or posterior deltoid. These muscles can be released from their insertions to lessen the shoulder external rotation. If the contracture is fixed and severe, a shoulder derotation osteotomy can be performed. This has been an effective treatment in the adult with fixed shoulder external rotation deformities. The muscles can also be denervated by selective neurectomy of their motor nerve ( Case Study 32.1 ).

FLOAT NOT FOUND