An 11-month-old girl presented with episodic severe stridor from birth, often resulting in cyanosis. Her parents had noted recurrent unilateral ptosis. Later she developed spasms of her hands during exercise. Psychomotor development was normal. Neurologic examination showed generalized hypertonia. Cerebral MRI excluded a Chiari malformation. Laryngoscopy under general anesthesia showed no abnor...

A 35 year old woman with clinical features of hyperkalaemic periodic paralysis confirmed on provocative exercise testing was investigated. DNA sequence analysis of the gene for the alpha-subunit of the skeletal muscle voltage gated sodium channel (SCN4A) on chromosome 17q23 identified a point mutation at nucleotide position 2188. This results in a threonine to methionine substitution at amino a...

Neuromyotonia is a heterogeneous group of genetic and autoimmune channelopathies resulting in hyperexcitability of peripheral nerves. We report an unusual case of neuromyotonia, which to our knowledge has not been previously described. The patient developed intermittent attacks of severe painful muscle stiffness accompanied by sweating, myokymia and raised serum creatine kinase. Genetic analysi...

A 38-year-old man was diagnosed, at the age of 18, with SCN4A-negative hyperkalaemic periodic paralysis. The diagnosis remained unchanged until his 8-year-old daughter suffered an exercise-induced syncope. Her EKG showed a polymorphic ventricular tachycardia. Patient’s hands and feet, previously overlooked, became “neurologically” relevant since they were characteristic of Andersen-Tawil syndro...

Familial hypokalemic periodic paralysis is an autosomal-dominant channelopathy characterized by episodic muscle weakness with hypokalemia. The respiratory and cardiac muscles typically remain unaffected, but we report an atypical case of a family with hypokalemic periodic paralysis in which the affected members presented with frequent respiratory insufficiency during severe attacks. Molecular a...

Neurology S. L. Venance, K. Jurkat-Rott, F. Lehmann-Horn and R. Tawil SCN4A-associated hypokalemic periodic paralysis merits a trial of acetazolamide This information is current as of November 24, 2007 http://www.neurology.org/cgi/content/full/63/10/1977 located on the World Wide Web at: The online version of this article, along with updated information and services, is All rights reserved. Pri...