Muscle & nerve
-
A young woman presented with facial myokymia in association with dermatomyositis. There was no evidence of peripheral neuropathy. ⋯ Myokymia and dermatomyositis both responded to immunosuppressive treatment. The presence of antibodies to voltage-gated potassium channels and the association with dermatomyositis indicated an autoimmune cause for myokymia, which may have been due to reversible peripheral nerve hyperexcitability.
-
Decrement of the compound muscle action potential (CMAP) during 10-HZ repetitive nerve stimulation is thought to be an unusual finding in dominant myotonia congenita, and has not previously been reported in patients with the genetically verified disorder. It was the purpose of the present study to elucidate the relation between decrement and CLCN1 mutation type in myotonia congenita. Decrement and genotypes were studied in eight Danish families with myotonia congenita. ⋯ Three novel CLCN1 mutations (two dominant and one recessive) were found segregating with the Thomsen/Becker phenotypes. In families with the novel dominant mutations M128V and E193K, decrement was absent in all family members tested. In conclusion, CMAP decrement may be pronounced in dominant myotonia congenita, and the presence of decrement is related to mutation type.
-
The underlying mechanism of the water-immersion skin wrinkling test, which is used as a test of sympathetic nerve function, remains elusive. We investigated changes of blood circulation in the hand occurring with water-immersion wrinkling by measuring the velocity of ulnar and digital artery blood flow, and of digit skin blood flow, in healthy subjects before and during wrinkling. ⋯ Our data show that water-immersion wrinkling is a function of digit pulp vasoconstriction. This test of sympathetic function can now be quantified using parameters of blood flow velocity, enabling its more widespread and accurate use.
-
The cricopharyngeus (CP) is a striated muscle sphincter situated at the pharyngoesophageal junction. The upper esophageal sphincter is comprised of the striated CP muscle and nonmuscular components at the level of the cricoid cartilage. This review describes the basic anatomy and physiology of the CP muscle, its central and peripheral relationship, methods of investigating it, and electrophysiological properties related to deglutition. ⋯ The CP sphincter muscle is tonically contracted at rest and relaxes during swallowing, belching, and vomiting. Electromyography (EMG) of the CP sphincter muscle has been undertaken frequently in a variety of subhuman species with the aim of understanding deglutition, whereas it has seldom been reported in healthy human subjects and patients. Increased knowledge of the physiology and anatomy of the human CP sphincter muscle is not only important scientifically but is necessary for advancing the diagnosis and treatment of oropharyngeal dysphagia, for which neurological causes are responsible in 80% of cases.