Features of CP
Because cerebral palsy is a diagnosis of movement and posture, people who have cerebral palsy will have one or more of the following movement disorders.
Abnormal muscle tone – Muscle tone is the amount of activity in a muscle when you are not trying to move, or how much the muscle is “on”. In cerebral palsy, sometimes muscle tone is higher than normal (hypertonia) and sometimes muscle tone is lower than normal (hypotonia). Normal movement requires just the right amount of muscle tone to hold you up, without so much tone that it interferes with movement. The brain sends many signals through the spinal cord to the muscles. In the unaffected person, any unwanted signals are quieted, or inhibited by the brain, so the muscles are have just the right amount of tone needed. In hypertonia, the damaged part of the brain cannot inhibit these signals. The result is unwanted muscle activity. The most common kind of unwanted muscle activity in cerebral palsy is called spasticity. In hypotonia, there are fewer signals to the muscles, resulting in floppy muscles.
Spasticity – is hypertonia that is defined as velocity-dependent resistance to movement, which means the faster a joint, such as an elbow, is straightened, the tighter, or more spastic, the muscle feels. Spasticity may change with posture, position or effort. It may be mild and only appear during strenuous activity or it may be present all the time. Moderate or severe spasticity may hinder movement and function and can make muscles and joints tight, leading to contractures.
Rigidity – is resistance to movement regardless of the speed or direction of the passive movement. Muscles that have rigidity feel heavy and like “a lead pipe” when they are moved passively. Rigidity is typically not seen in cases of cerebral palsy caused by prematurity; however it is a common feature in cerebral palsy caused by anoxia, such as in near drowning.
Hypotonia – is lower than normal tone, creating muscles that are “floppy”. Hypotonia may be seen in young infants with some forms of cerebral palsy, with spasticity or hypertonia manifesting as the child develops.
Involuntary movements – may take many forms and are usually the result of injury or damage to the basal ganglia. The basal ganglia is a group of structures in the brain that communicates with the voluntary motor cortex and modifies the quality and quantity of movement. Damage to the basal ganglia can result in diminished movement (such as is seen in Parkinson’s disease) or excessive, involuntary movements, such as is seen in cerebral palsy. A general term for abnormal involuntary movement is dyskinesia. Examples of dyskinesia are dystonia, athetosis and chorea.
Dystonia – is involuntary, sustained, or intermittent muscle contractions that cause twisting and repetitive movements, abnormal postures or both.1 Muscle tone typically fluctuates, varying from normal or hypotonia to extreme hypertonia. Dystonic movements can be precipitated or worsened by attempts to move and can vary according to emotional state.2 Dystonia can occur in the eyes, mouth neck, trunk arms or legs.
Athetosis – is slow, involuntary writhing movement of face and extremities. It often occurs with chorea, and is called choreo-athetosis.
Chorea – is brief, irregular jerking movements that most commonly begin in the shoulders, neck, trunk and face.
Weakness is common in cerebral palsy but is not always easily detected. Spasticity may mask weakness, making it difficult to fully assess. Treatments that take away spasticity, such as an intrathecal baclofen pump or a selective posterior rhizotomy, often reveal underlying weakness. Weakness may be present in conjunction with spasticity and may manifest itself in gait deviations or difficulty performing activities of daily living. A physical or occupational therapist may identify muscle weakness and develop an individualized program to increase muscle strength.
Impaired motor control
This is the inability to recruit muscles with normal precision, speed or timing. Normally, muscle movement can occur in any direction, in any joint, without unwanted movement in adjacent joints. This is called selective movement. In cerebral palsy, the injury to the brain interferes with selective control. When selective control is impaired, movement occurs synergystically. Synergistic movement is when motion at one joint, such as the ankle, cannot occur without movement at another joint, such as the knee. Impaired motor control may interfere with functions such as walking or holding a pencil.
Balance is a complex response to gravity and movement involving many different parts of the brain. It is the coordination of incoming sensory information that is processed to allow for controlled, purposeful motor output. Falling may be the result of poor balance due to an injury to the brain that controls posture, the inability to respond to changes in surrounding or terrain , or it may be caused by tripping over a foot that gets in the way. A thorough evaluation by an experienced practitioner is necessary to determine the source of poor balance and if any intervention can improve balance and function.
When a joint, such as an elbow or knee, cannot move through its normal range of motion, it is said to have a contracture. Spasticity can cause muscles to be tight and develop contractures. Contractures may limit a person’s ability to sit in chair, stand up straight or open a hand. Conventional treatments are available to stretch the joint and treat contractures.
Perceptual motor dysfunction
This is when there is a problem interpreting what is seen. Visual acuity, or the clarity of vision, may be unaffected. Visual skills that may be affected include discriminating contrast or color, depth perception, object discrimination or identifying shapes, visual memory or the ability to locate or focus on one object.
All newborn babies have primitve reflexes. These are stereotypical, or predictable movements that occur when the infant is placed in a specific position. Common primitive reflexes occur when an infant is held upright or his or her head is moved. These reflexes are necessary in early infancy to facilitate development of sucking and head control; however, they are normally integrated, or disappear, at various stages during the first year. In cerebral palsy there may be a delay in this integration, and the child may have difficulty moving out of primitive reflex patterns. In some cases, the reflexes persist into adolescence and adulthood. Some reflexes may be helpful, such as a primitive flexion or extensor pattern that stabilizes a joint in a purposeful manner. Some reflexes, however, interfere with positioning and function, such as rolling, standing or walking.
Problems with eating and talking are often referred to as oral-motor dysfunction. During early development, parents may notice that their baby may not be able to suck on a pacifier or take a bottle due to muscle weakness in and around the mouth. The ability to suck, swallow, and breathe during breast or bottle-feeding may be influenced by either weakness or tightness of the supporting muscles. As an older child, eating solid foods may be challenging if the mouth is influenced by abnormal tone. In these cases, safety with swallowing can be compromised. Coughing or choking on liquids may suggest oral-motor dysfunction, as these are often the most difficult for patients with swallowing dysfunction to manage. Oral-motor dysfunction may lead to problems managing saliva, which can result in drooling or coughing.
Optimal nutrition is important for everyone to maintain good health and well being. For children, good nutrition is essential to help them achieve their full potential for growth and development. Some people with cerebral palsy may face special nutrition-related challenges. A thorough assessment by a qualified nutritionist or dietician is needed to determine the cause of these problems and to develop an appropriate treatment plan. The most common nutritional problems include:
- Difficulty chewing or swallowing foods, which may result in inadequate nutritional intake
- Poor weight gain and poor growth (in children) or difficulty managing weight
- Excessive weight gain
- Increased risk for osteoporosis because of low calcium and vitamin D intake or medications which interfere with their absorption
The strength of bones is determined by looking at bone mineral density (BMD) of one or more bones. BMD is measured using a dual-energy X-ray absorptiometry (DEXA ) scan, which is like an x-ray. Everyone’s bones become less dense, or have lower BMD, as they age. Low BMD can increase the risk of developing a fracture, or breaking a bone following minimal force or trauma. BMD can be compared to two normative measures – a “T-score”, which is the BMD of “young, normal adults” of the same gender and a “Z-score”, which is the expected BMD for a person’s age and gender. According to the National Osteoporosis Foundation and the World Health Organization, in post-menopausal women and men over the age of 50, osteopenia is a BMD between 1.0 and 2.5 standard deviations below that of a “young normal” adult (T-score between -1.0 and -2.5). Osteoporosis is when there is a BMD that is 2.5 standard deviations or more below that of a “young normal” adult (T-score at or below -2.5). Possible causes of poor bone health in children and adults with cerebral palsy include a diet lacking in calcium and vitamin D, immobility, lack of weight bearing, medications such as anti-convulsants and an impairment of the endocrine system.
While low BMD has been detected in both children and adults with cerebral palsy, standards do not exist for the diagnosis of osteopenia or osteoporosis in children because their bones are still growing. It is recommended that all children have adequate calcium and vitamin D intake, either through diet or supplements. Researchers are still investigating all of the mechanisms and treatments for osteoporosis in children and adults with cerebral palsy, as the risk that any individual developing a fracture differs.
1. Sanger TD, Delgado MR, Gaebler-Spira D, et al: Classification and definitions of disorders caused by hypertonia in childhood. Pediatrics 2003;111:89-97.
2. Delgado MR, Albright AL: Movement disorders in children: definitions, classifications, and grading systems. J of Child Neurology 2003;S1-S8.