Spastic Cerebral Palsy

Spastic CP is the most common type, comprising about 70% of cases. It may be further subdivided according to the pattern of limb involvement. Spastic diplegia primarily involves the lower limbs and may be symmetric or asymmetric (see Figure 77-1). Parents often give a history of “tiptoeing” even when walking holding on to furniture. Spastic hemiparesis involves the upper and lower limb on one side, usually with the upper extremity more affected than the lower (see Figure 77-1). Parents may report early handedness (before 2 years) or that the child did not support his or her weight as well on the affected side when crawling. Spastic quadriparesis evenly involves all four limbs (see Figure 77-1).

In the clinical history, patients with spastic CP are more likely to have been at risk for a cortical brain injury. Certain types of spastic CP are more highly associated with certain risks for brain injury. Children with spastic diplegia have likely had injury to both cerebral hemispheres; this most often is periventricular leukomalacia related to premature birth. Children with spastic hemiparesis more likely had unilateral injury, such as prenatal or perinatal stroke. Risk factors for stroke, such as a family history of hypercoagulability, should be assessed. Children with spastic quadriparesis may be the most severely affected. Global brain injury has often occurred, and there is a higher rate of associated cognitive impairment, epilepsy, and other disabilities.

Spastic CP is characterized on physical examination by signs of an upper motor neuron syndrome, indicating a CNS process. On observation, the clinician may see a characteristic pattern in spastic limbs (Figure 77-2). Affected upper extremities have a tendency toward flexion at the elbow and wrist, with pronation of the forearm and fingers kept closed or fisted. Affected hips are adducted and are “scissored” in extreme cases. There is partial flexion at the knees and plantarflexion at the ankles. Torticollis and truncal hyperextension or twisting may also be present. After inspection, the clinician may perform passive range of motion, revealing increased tone in the affected limb. Typical of spasticity is “velocity dependence, meaning resistance increases with more rapid passive movement. In some cases, a spastic “catch” may be elicited in a limb with passive joint extension in which the increase in tone is momentarily reduced. Tone may also be increased in states of stress or excitement and decreased in sleep. In long-standing or severe cases, range of motion may be limited by secondary joint contractures, which typically evolve later in infancy or childhood. Strength may be intact, although this varies, and an element of weakness and motor fatigue is common. Reflex testing reveals hyperreflexia. This is the result of a hyperexcitable stretch reflex and in extreme forms presents as clonus. Extensor plantar responses (i.e., Babinski’s sign) may be present on the affected side. Children with spastic CP may experience difficulties with fine motor movements (e.g., sequential finger movements) or in isolated effortful movements. In mild cases, this may appear as “clumsiness” with easy fatigability. Observation of gait is helpful both in recognizing the pattern of involvement and in assessing functional impairment.

Figure 77-2 Characteristic pattern in spastic limbs.

Dyskinetic Cerebral Palsy

Dyskinetic CP comprises about 15% of CP. Involuntary movements interfering with voluntary motor function are characteristic. Dyskinetic CP may be further divided by primary movement type into choreoathetoid CP and dystonic CP (Figure 77-3). Choreoathetoid movements have a smooth, fluctuating dancelike quality (chorea) and a writhing or wriggling quality (athetosis) in the distal extremities. Dystonia is abnormal sustained movement or posturing in a repetitive, patterned fashion. Although dystonias are also quite common in spastic CP, dystonic CP refers to the case in which dystonia is the primary feature. Even in retrospect, dyskinetic CP may not be noticed until after age 2 or 3 years because infants without CP have some degree of choreoathetoid movement. The movement disorder in dyskinetic CP reflects injury to the basal ganglia. Clinical history should explore risk factors for such injury, including hyperbilirubinemia or hypoxic ischemic injury at term or postnatally. Children with dyskinetic CP are often described as having “fluctuating tone.” This reflects involuntary, often sustained muscle contraction that may be mistaken for intermittent spasticity. The physical examination should include observation of involuntary movements, recognizing that multiple movement types may be present. Sustained posture (e.g., extension of the arms) or distraction may elicit involuntary movements. Serial assessments of tone may be necessary to characterize whether spasticity is also present.

Figure 77-3 Dyskinetic cerebral palsy.

Ataxic Cerebral Palsy

Ataxic CP comprises about 5% of cases. Slow, jerky, uncoordinated movements characterize ataxic CP. Ataxia may be apparent in gait, titubation, or speech. In some cases, it may be elicited by complex motor tasks, such as rapid alternating hand movements or tandem gait. For some children, there is an associated global hypotonia. Ataxic CP may only be diagnosed after other causes of incoordination have been ruled out, such as weakness, movement disorder, and spasticity. Ataxic CP is often diagnosed later than the other subtypes because of the subtlety of symptoms in toddlers. This possibility should be kept in mind when considering “benign hypotonia” in infants.

Oromotor Dysfunction

Oromotor dysfunction can affect communication, nutritional intake, and control of secretions. Speech therapy is used to facilitate communication and to help with oromotor training. Occupational therapy may facilitate oral nutritional intake. In some cases, a gastrostomy may provide a safer, more efficient means of providing medications and nutrition to the child.

Drooling is a very common problem for children with CP. Therapies can train and reinforce improved swallowing of saliva for some children. Oral medications may also be used to decrease saliva production. These are largely anticholinergics, including glycopyrrolate, hydroxyzine, and scopolamine. Injection of botulinum toxin into the salivary gland may also decrease saliva production. There are conflicting data regarding the comparative efficacy of oral medication versus botulinum toxin injection. In refractory cases, partial surgical resection may also be performed. However, this can cause irreversible symptoms of dry mouth and affect dentition, so should be used only after other therapies have failed. There is an increased risk of dental issues when such oromotor concerns are present.

Spasticity

A cornerstone of symptomatic treatment for CP is spasticity management. Improving spasticity can facilitate motor function. This would be the case, for instance, when improved ankle flexion facilitates ambulation for a child with spastic diplegia. In other cases, spasticity management is needed to facilitate caregiving. An example is a child with spastic quadriparesis whose positioning, dressing, and changing become much easier as limb flexion and adduction decrease. Finally, improvements in spasticity may postpone or preclude later orthopedic procedures and joint contractures.

The first step in spasticity management is detailed assessment of the involved muscle groups and the degree of spasticity in each. The modified Ashworth Scale is a grading from 0 (no increased tone) to 4 (rigid) that quantifies the subjective assessment. A quantitative record of spasticity may help track subtle responses to treatment that are gradual over time. The functional impairment the patient and family identify should guide the targets of spasticity management. If spasticity is present but causes no functional limitation, treatment need not be as aggressive.

When spasticity is focal, limited to a few muscle groups, injectable botulinum toxin can be particularly helpful. Botulinum toxin blocks neuromuscular transmission and thus relieves spasticity by partially weakening the targeted muscle. Evidence has supported its efficacy in quantitative measures of spasticity, particularly in the lower extremities, although there is conflicting evidence regarding longer term functional impact. Injections must be repeated every 3 to 8 months and should be done in conjunction with physical therapy (PT), which has a synergistic benefit. A more permanent effect is seen with phenol or ethanol injection, which causes chemodenervation of the targeted muscle.

For global spasticity, oral medications may be used. These include benzodiazepines, baclofen, tizanidine, and dantrolene. Benzodiazepines are systemic sedatives acting on GABA (γ-aminobutyric acid) in the CNS. Diazepam is among the most commonly used. Baclofen likewise works through GABA pathways but through a different mechanism. Tizanidine is an α-adrenergic medication that has been used widely but has no published evidence supporting its use in children. In each of these medications, sedation is a common adverse effect. Children with truncal low tone or drooling may also have a worsening of these symptoms. Frequently, adverse effects limit oral medications’ usefulness for treatment of spasticity and argues for slow titration. Dantrolene acts directly upon muscle and thus does not have associated sedation. However, a potentially fatal hepatotoxicity has been associated with dantrolene, thus limiting its use. When baclofen is effective but associated sedation is limiting, intrathecal baclofen is an option. Intrathecal baclofen may be infused into the cerebrospinal fluid through a surgically placed pump and catheter terminating in the T10 region of the spinal cord. A single test dose infused through a standard lumbar puncture is performed initially to demonstrate benefit. Although this avoids cognitive sedation, pump-related difficulties may occur in 20% to 50% of children.

In some cases, surgical options target spasticity. This includes selective dorsal rhizotomy (SDR). SDR is partial transection of the dorsal lumbosacral spinal roots, interrupting sensory input to selected levels of the spinal cord, which in turn diminishes the motor output at that level. This is most useful for children with spasticity in the lower extremities who are old enough to have achieved a stable gait. Tendon release is another common surgical intervention, which decreases the mechanical tension across a joint that contributes to spasticity.

Finally, PT and occupation therapy (OT) are established components of spasticity management programs despite uncertainty as to the best regimen. PT focuses primarily upon lower limb motor impairment and ambulation issues, and OT addresses mainly upper limb and fine motor concerns. In many cases, a trained professional initiates this therapy and teaches parents exercises to continue at home. These customized regimens seek to build strength, maintain range of motion, reduce excessive muscle tone, and improve motor function. Caregivers should understand that medication and surgical interventions are to be used in conjunction with physical therapy, not as substitutes. Speech therapy (ST) is used to address oromotor and speech-related issues, as previously described.

Persuant to a U.S. federal law, all states are required to have an “early intervention” program for at-risk infants and children from birth to 3 years old, with screening and delivery of PT, OT, ST services usually in the home setting. At age 3 years, a transition to a local school-based system occurs. Physicians need to be aware of these services and promote them for patients with CP and other developmental disorders.

Dyskinesias

The movement disorder of dyskinetic CP is particularly difficult to treat. In some cases, chorea responds to chronic benzodiazepine administration, although again this is limited by sedation. Haloperidol has been used with success in some cases, but rigorous evidence for use in children with CP is lacking. Likewise, valproic acid use has been reported, but data regarding use in children outside of epilepsy are lacking.

For dyskinetic CP with dystonia as the primary feature, trihexyphenidyl will provide some relief, but not for all children. Injectable botulinum toxin is an option for focal symptoms, such as cervical dystonia. Intrathecal baclofen may also provide some benefit in patients with combined spastic and dyskinetic (primarily dystonic) CP.

Alternative and Complementary Therapies

It is helpful to become familiar with alternative and complementary therapies families may explore. Examples include conductive education, hyperbaric oxygen, and stem cell infusion. Unfortunately, over the past 25 years, there have been fewer than a dozen randomized controlled trials of alternative or complementary treatments for children with CP. Some have had limited evidence of benefit in case series or select populations but not enough to support an overall benefit. As such, treatments must be considered individually for physiologic plausibility, potential benefits, potential harms, and the cost and energy required.

Pain

Musculoskeletal aches from limited joint mobility are not unusual among children with CP. Painful muscle spasms occur when abrupt spastic contractions occur, usually in the severe spastic diplegic, quadriplegic, and dystonic forms of CP. These spasms often respond to the pharmacologic interventions mentioned above, especially benzodiazepines and intrathecal baclofen (if frequent).