I frequently tell parents and friends that the Internet has a great deal of good medical information, considerable misinformation, as well as incomplete information. This was clearly shown when I put "Benign Hypotonia" into Google. I was astounded to find information from the National Institute of Neurological Disorders and Stroke that was both incomplete and totally lacking in any discussion about muscle diseases, as the possible cause of hypotonia. There was no mention of a muscle biopsy, which is the most important test to diagnose the majority of the muscle diseases. There was no also no mention of genetic testing, family history, or any laboratory tests. Instead, it was the usual CT scans, MRIs, EMGs and EEGs. I wonder what neurologists would do without these tests?
The problem is that most neurologists do not have any or even minimal training about neuromuscular disorders. They also do not learn how to read muscle biopsies, unless they train in a neuromuscular center. The muscle diseases that can cause hypotonia are mostly in the Congenital Myopathy group. These include Central Core disease, Fibre-type Disproportion, (about which there are different opinions), Minicore disease, Nemaline Myopathy, and Myotubular Myopathy. Central Core disease is particularly important to diagnose because of the anesthetic problems that can be associated with it. Spinal muscular atrophy can also manifest as hypotonia in a newborn or infant. This is also an important diagnosis to make, particularly for genetic counseling and prognosis. Cerebral palsy can present as hypotonia in the early months and is also an important distinction to make from other neuromuscular disorders.
Image copyright: Laineys Repertoire, flickr,
Article last time updated on 04.11.2016.