Overview
The disease is a familial, autosomal recessive condition involving degenerative lesions of the posterior spinal cord and cerebellum, often accompanied by cardiac damage, diabetes mellitus, skeletal deformities, and other non-neurologic damage. The most common age of onset is adolescence, and both sexes are affected, with symptoms progressively worsening, and individual cases developing after adulthood. In some cases, the onset of symptoms occurs after adulthood. The age of onset of the disease in the same family is approximately the same, but the severity of the disease varies.
Causes
The disease is an inherited disorder caused by a defect in the FRDA gene located on the long arm of chromosome 9 (9q13-21.1). Pathologic changes are visible to the naked eye as a thinner-than-normal spinal cord with prominent thoracic segments and mild cerebellar atrophy. The histologic changes in the spinal cord were characterized by degenerative changes in the posterior cord, lateral corticospinal tracts, and cerebellar tracts of the spinal cord. The lesions of the posterior cord of the spinal cord were obvious, accompanied by extensive gliosis. The cerebellar cortex and dentate nucleus and cerebellar peduncles are less affected, and the pontine bridges and medulla may be wrinkled, with no obvious changes in the cerebral cortex. Spinal cord lesions are more severe in the lower part of the spinal cord and gradually decrease closer to the medulla oblongata.
Symptoms
Symptoms are gradual, usually 8 to 15 years old with insidious onset, occasionally seen in infants and those who start after 50 years of age, the most common symptom is ataxia of both lower limbs, unsteady gait, waddling gait, commonly used upper limb swinging compensatory maintenance of body balance. The unsteadiness of standing and swaying is not necessarily aggravated by eye closure. Ataxia of the trunk and upper limbs also occurs later, with scribbling or even inability to write. There may be tremors of the limbs and head, or involuntary movements such as chorea. Most patients have nystagmus, which is more horizontal and less vertical and rotational. Speech disorders are also characteristic of this disease, with slow, monotonous and slurred speech, or intermittent and explosive, or excessively slow and elongated articulation, sometimes with excessive urgency. Calf tendon reflexes are absent. Upper limb reflexes are present in the early stages and may disappear in the later stages. The metatarsal reflexes are often extensor. Damage to the pyramidal tract may also increase muscle tone, and the ataxic gait may change to a spastic gait. Occasionally, there is lightning-like pain in the limbs, but there is no objective superficial sensory impairment, and the positional and tremor senses are dulled or lost, with the lower limbs being the most important. There may also be retinal pigmentation and optic nerve atrophy. There may be ptosis, abnormal pupillary reflexes and paralysis of the eye muscles. Occasionally, there are hearing and vestibular dysfunction and dysphagia. The disease may have disorders of the vegetative nervous system, tachycardia, nausea, vomiting, hypothermia, diabetes, sexual dysfunction, and sphincter dysfunction. Skeletal changes are scoliosis, bowed feet, and clubfoot. Cardiac changes are heart enlargement, heart murmurs, and EKG (electrocardiogram tracing) abnormalities. Heart valve disease, myocardial dystrophy, heart block and heart failure may be the cause of sudden death in this disease.
Examination
The results of imaging studies are valuable in the diagnosis of this disease:
1. X-rays of the corresponding parts of the body are altered in the case of scoliosis with bowed feet.
2. MRI of the head is valuable in confirming the diagnosis of the disease.
3. Genetic testing, FRDA gene testing found that the FRDA gene, intron 18, GAA repeats more than 66 times.
Diagnosis
The first symptoms of this disease are mostly ataxia of the trunk and limbs, loss of tendon reflexes, deep sensory deficits and positive pathological reflexes, occasional optic atrophy, neurodeafness, mild dementia, and skeletal deformities are also one of the characteristics of this disease. If there are typical symptoms of posterior cord, lateral cord and cerebellum, skeletal system deformities, cardiac organic damage, etc., the diagnosis can be confirmed. Combined with relevant imaging and abnormal amplification of FRDA gene GAA, the diagnosis can be made.
Treatment
There is no specific treatment at present, but supportive therapy is given to mild cases, and tendon transfer, lengthening surgery, and joint fusion surgery can be performed to correct foot deformity.
Prognosis
The prognosis is poor, and the age of death ranges from 21 to 69 years. The cause of death is 90% heart disease and 10% complications of diabetes mellitus.