Spinal amyotrophies: causes, symptoms, diagnosis, treatment

Amyotrophy is a group of hereditary neurological diseases characterized by skeletal muscle damage due to the progressive degeneration of the neurons of the anterior horns of the spinal cord and motor nuclei of the brainstem. Manifestations can begin in infancy or childhood. They vary depending on the type and may include hypotension; hypoflexia; violation of sucking, swallowing and breathing; in severe cases, early death. The diagnosis is based on genetic testing. Treatment of spinal amyotrophies is symptomatic.

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Causes of spinal amyotrophies

Spinal amyotrophy usually occurs as a result of autosomal recessive mutations in a single genetic locus on the short arm of chromosome 5, leading to a homozygous deletion. There are 4 main types.

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Symptoms of spinal amyotrophies

Spinal amyotrophy type I (Verdnig-Hoffmann's disease) manifests itself at the age of about 6 months. Muscular hypotension (often noticeable at birth), hyporeflexia, fasciculation of the tongue and severe difficulties in sucking, swallowing and breathing are noted. Death comes from stopping breathing in the first year of life in 95% of cases, all die by 4 years.

Spinal amyotrophy of type II (intermediate). Symptoms usually appear at the 3rd to 15th month of life. Children can not walk or crawl, less than 25% are able to sit. Develops flaccid paralysis and fasciculation, which in young children is difficult to identify. Deep tendon reflexes are absent, dysphagia is possible. The disease often leads to death at an early age from respiratory complications. However, the progression of the disease can suddenly stop, but the persistent weakness and high risk of severe scoliosis and its complications persist.

Spinal amyotrophy of type III (Kugelberg-Welander disease) usually occurs between the ages of 15 months and 19 years. Symptoms, as in type I, but the disease progresses more slowly, and the duration of life is longer (sometimes normal). Some family cases are secondary to enzyme defects (eg, hexosaminidase deficiency). Symmetrical weakness and weight loss, starting with the quadriceps muscle and flexors, gradually spread distal, becoming most pronounced on the legs. Later, the hands are amazed. Life expectancy depends on the development of respiratory complications.

Spinal amyotrophy type IV can be inherited by a recessive, dominant or X-linked type, debuting in adults (30-60 years) with primary weakness and weight loss of proximal muscles and slowly progressing. This disease is difficult to distinguish from amyotrophic lateral sclerosis, affecting mainly the lower motoneurons.

Diagnosis of spinal amyotrophies

EMG is necessary with the determination of the speed of nerve conduction, including studies of muscles innervated by cranial nerves. The speed of the exercise is normal, but the affected muscles, the involvement of which is often not clinically obvious, behave as denervated. The exact diagnosis is made using genetic testing, which identifies a causal mutation in 95% of cases. Sometimes a muscle biopsy is taken. Serum enzymes (eg, creatine kinase, aldolase) can be slightly elevated. Diagnostically informative amniocentesis.

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Treatment of spinal amyotrophies

Specific treatment is not. With the cessation of progression or slow development of the disease, physiotherapy, corset and special adaptations help (in terms of preventing the development of scoliosis and contractures). Adaptive orthopedic devices open up opportunities for independence and self-care when eating, writing or working on the computer.