Cerebral palsy is a non-progressive central motor dysfunction caused by brain injury from various causes, often accompanied by mental retardation, seizures and speech disorders. However, there are many types of cerebral palsy and complex clinical manifestations, which may lead to misdiagnosis, and several diseases that are easily misdiagnosed as cerebral palsy are briefly described as follows.
1.Ketonuria phenylpropionate
Phenylpropionic acid ketonuria is a common amino acid metabolic disease, which belongs to autosomal recessive genetic disease.
It is mainly due to the defect of phenylalanine hydroxylase (PAH) in the liver, which cannot change phenylalanine (PA) into tyrosine, resulting in the accumulation of PA and its metabolites in the body, causing a series of functional abnormalities. Diffuse cerebral cortical atrophy can be seen. Early diagnosis can prevent brain damage, and screening in the neonatal period is mostly done by bacterial inhibition to measure PA levels in the blood, while screening in older infants can be done by urine ferric chloride test. After a positive screening test, biochemical quantification of blood PA and tyrosine is required for confirmation. In normal individuals, the plasma PA concentration is 0.06-0.18 mmol/L, while in affected children it can be consistently above 1.22 mmol (20 mg/dL), and the blood tyrosine is normal or slightly low.
The differentiation point with cerebral palsy is the progressive course of the disease, blood biochemistry and amino acid analysis abnormalities, early treatment with low phenylalanine diet can make the intellectual development close to normal.
2. Central neurospongiform degeneration
It is autosomal recessive. There is aspartate acyltransferase deficiency in fibroblasts. The pathological changes are mainly seen in the white matter of the brain, filled with cystic spaces containing fluid, like a sponge.
The child is normal at birth, but begins to show mental retardation, hypotonia, and optic nerve atrophy from 2 to 4 months after birth. At 6 months after birth, there is a marked progressive increase in head circumference, followed by seizures, progressive increase in muscle tone, and choreoathetosis. Cerebrospinal fluid is normal. Most deaths occur within 5 years of age.
The difference with cerebral palsy is the progressive neurological decline, giant head sign, optic nerve atrophy, and cystic changes in the white matter of the brain on CT and MRI. Biochemical tests show an increase in N-acetylaspartate in the urine. There is no effective treatment for this disease.
3. Acute transverse myelitis
Characterized by acute onset of spinal cord dysfunction. There are necrotic lesions in the gray and white matter of the spinal cord with congestion and edema and cellular infiltration.
The disease is often preceded by viral infections, such as measles, chickenpox, and influenza virus. Most of the cases have an acute onset and initially present with pain or sensory abnormalities in the lower extremities or trunk, followed by weakness of the lower extremities, sphincter dysfunction, incontinence, and loss of sensation below the level of the affected section. In the early stage of the disease, the muscle tone of the lower extremity is reduced and the Achilles tendon reflex disappears. MRI may show edema and enlargement at the level of the lesion. The prognosis is good in most cases due to viral infection. In cerebral palsy, there is no sensory or bowel disorder and the cerebrospinal fluid is normal.
4.Rheumatic chorea
The typical symptoms are involuntary movements of the whole body or some muscles, with the most movements of the limbs. Frowning, shoulder shrugging, eye closure and neck contraction may also occur. The movements are mostly bilateral or limited to one side, intensifying during excitement or concentration, and disappearing after sleep. The muscle strength and sensation are often not impaired. It usually appears 2-6 months after streptococcal infection and usually lasts for 1 to 3 months.
The differentiation point with cerebral palsy is the late onset of the disease, with rheumatic activity, self-limiting course, no intellectual and other motor disorders.
5.Twisting dystonia
It is a relatively common group of extrapyramidal disorders. It can be autosomal dominant or recessive or X-linked inheritance. Neurobiochemical examination reveals abnormal distribution of neurotransmitters in the brain.
The disease is characterized by continuous involuntary contraction of both active and antagonistic muscles at the onset of active movement, resulting in a specific torsional posture or position. The disease is chronic and progressive, and the age of onset varies according to the genetic type, and the early symptoms usually begin with symptoms of dystonia in a restricted position. In the dominant type, the early symptoms are mostly abnormal postures of the medial muscles, especially the oblique neck, and in some cases, twisted postures of the trunk or pelvic muscles are the main feature. In the recessive type, the first manifestation is abnormal gait or hand posture of one lower limb, inversion of the foot position when walking, difficulty in writing, and finally progressing to generalized dystonia. The differentiation from cerebral palsy is a family history of the disease. The patient has a normal perinatal period, no mental retardation, no convulsive seizures, no cone bundle signs, and no sensory impairment.
6. Progressive spinal muscular atrophy
It is an autosomal recessive disease, caused by the degeneration of the anterior horn cells of the spinal cord and the motor nucleus of the brainstem secondary to the atrophy of nerve roots and muscles, most children are born with normal activities, and symptoms appear only at 3-6 months of age or later. The trunk, scapular girdle, pelvic girdle and lower extremities are symmetrically weak, with the proximal end being more severe. The disease progresses to complete flaccid paralysis and may involve respiratory muscles and lead to death. Electromyography showed mostly normal nerve conduction velocity and reduced motor potential, suggesting neurogenic damage. Muscle biopsy shows significant muscle atrophy and neurodegeneration.
The disease generally has normal intelligence and disappearance of tendon reflexes, and the EMG and muscle biopsy are abnormal.
7. Benign congenital muscle relaxation
Some of the muscle groups have strong movements, but they start to stand and walk only at the age of 2-5 years, and half of them are similar to normal children at the age of 8-9 years. The muscle biopsy and electromyography are normal, the intelligence is normal, and the prognosis is good.
In summary, there are many diseases that need to be differentiated from cerebral palsy, so we should pay attention to exclude other diseases to avoid misdiagnosis when the diagnosis is not clear.