How Does Spinal Muscle Atrophy Present?

Discussion Muscle tone is the slight tension that is felt in a muscle when it is voluntarily relaxed. It can be assessed by asking the patient to relax and then taking the muscles through a range of motion such as moving the wrists, forearm and upper arm. Muscle strength is the muscle’s force against active resistance. Impaired strength is called weakness or paresis. There are 5 levels of muscle strength. Hypotonia can occur with or without weakness. Decreased fetal movements in utero, persistent hypotonia and difficulty feeding are more consistent with congenital rather than an acquired hypotonia. Common treatable conditions such as hypothyroidism, electrolyte abnormalities and metabolic problems can often be ruled in or out relatively quickly. A differential diagnosis of hypotonia with and without muscle weakness can be found here. A differential diagnosis of hypotonia in infants can be found here. Learning Point Spinal muscle atrophy (SMA) was first described in the 19th century and is an autosomal dominant neuromuscular disease caused by a deletion or mutation in the motor neuron 1 gene on chromosome 5q13. It causes anterior horn cell loss in the spinal column and brain stem with progressive symmetric proximal muscle weakness. Patients also present with respiratory and orthopaedic problems. Hypotonia, decreased or absent deep tendon reflexes, muscle fasciculations and muscle contractions can also occur. The gene frequency is 1 in 40-70 in the general population but ...
Source: PediatricEducation.org - Category: Pediatrics Authors: Tags: Uncategorized Source Type: news