Cerebral Palsy

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Diagnosis

Typically, doctors diagnose cerebral palsy (CP) in infants by testing their motor skills and thoroughly analyzing their medical history. A medical history, diagnostic tests, and regular check-ups may be required to confirm the diagnosis of CP or to eliminate the possibility of other disorders.

Unnaturally soft, relaxed, or floppy muscle tone is called hypotonia; muscle tone that is stiff or rigid is called hypertonia. Some infants with CP have hypotonia in the first 2 or 3 months of life and then develop hypertonia. They also might develop an unusual posture or favor one side of the body.

A newborn held on its back and tilted so its legs are above its head will automatically respond with the Moro reflex, extending its arms in a gesture that resembles an embrace. This reflex usually disappears after about 6 months. Infants with cerebral palsy often retain it for an abnormally long period.

Signs of hand preference are also observed. When an object is held in front and to the side, infants usually do not display a tendency to use either the right or left hand. This is normal during the first 12 months of life. Infants with spastic hemiplegia, however, often develop hand preference early, indicating one side of their body is stronger than the other.

The physician will look for other conditions that can be linked to CP, such as seizures, mental impairment, and vision or hearing problems.

Intelligence tests often are administered to a child with CP to evaluate mental impairment, but the results can be misleading and there is a risk of underestimating intelligence. For instance, a child with movement, sensation, or speech problems associated with CP would have difficulty performing well on such tests.

Differential Diagnosis
If motor skills decline over time there may be genetic disease, muscle or metabolic disorder, or tumor in the nervous system, either coexistent or instead of CP. The physician must rule out other disorders that cause movement problems, identify any coexisting disorder, and determine if the condition is changing.

An electroencephalogram (EEG) traces electrical activity in the brain and can reveal patterns that suggest a seizure disorder.

Electromyography (EMG) and nerve conduction velocity (NCV) studies may be performed when a nerve or muscle disorder is suspected. These tests, which can be used in combination, are often referred to as EMG/NCV studies. NCV is administered before EMG and measures the speed at which nerves transmit electrical signals.

During NCV, electrodes are placed on the skin over a nerve that supplies a specific muscle or muscle group. A mild, brief electrical stimulus is delivered through the electrode and the response of the muscle is detected, amplified, and displayed. The strength of the signal is also measured. Neurological conditions can cause the NCV to slow down or to be slower on one side of the body.

EMG measures nerve impulses within the muscles. Tiny electrodes are placed in the muscles in the arms and legs and the electronic responses are observed using an instrument that displays movement of an electric current (oscilloscope). As muscles contract, they emit a weak electrical signal that can be detected, amplified, and tracked, providing information about how well the muscles are working.

Lab tests
Chromosome analysis may be performed to identify a genetic anomaly (e.g., Down syndrome) when abnormalities in features or organ systems are present.

Thyroid function tests may reveal low levels of thyroid hormone, which can produce several congenital defects and severe mental retardation.

A high level of ammonia in the blood (hyperammonemia) is toxic to the central nervous system (i.e., brain and spinal cord). A deficiency in any of the enzymes involved in breaking down amino acids can cause hyperammonemia. This may be due to a liver disorder or a defect in metabolism.

Imaging tests
Imaging tests are helpful in diagnosing hydrocephalus, structural abnormalities, and tumors. This information can help the physician assess the child's long-term prognosis.

Magnetic resonance imaging (MRI scan) uses a magnetic field and radio waves to create pictures of the internal structures of the brain. This study is performed on older children. It defines abnormalities of white matter and motor cortex more clearly than other methods.

Computed tomography (CT scan) can show congenital malformations, hemorrhage, and periventricular leukomalacia in infants.

Ultrasound uses the echoes of sound waves projected into the body to form a picture called a sonogram. It is often used in infants before the bones of the skull harden and close to detect cysts and abnormal structures in the brain.

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