A rare neuromuscular disorder with onset usually in late childhood or early adulthood, characterized by intermittent or continuous widespread involuntary muscle contractions; FASCICULATION; hyporeflexia; MUSCLE CRAMP; MUSCLE WEAKNESS; HYPERHIDROSIS; TACHYCARDIA; and MYOKYMIA. Involvement of pharyngeal or laryngeal muscles may interfere with speech and breathing. The continuous motor activity persists during sleep and general anesthesia (distinguishing this condition from STIFF-PERSON SYNDROME). Familial and acquired (primarily autoimmune) forms have been reported. (From Ann NY Acad Sci 1998 May 13;841:482-496; Adams et al., Principles of Neurology, 6th ed, p1491)
Also Known As:
Neuromyotonia; Isaacs-Mertens Syndrome; Pseudomyotonia; Acquired Neuromyotonia; Continuous Muscle Activity Syndrome; Gamstorp-Wohlfart Syndrome; Isaacs' Syndrome; Myokymia, Myotonia, Muscle Wasting, And Hyperhidrosis; Pseudomyotonia Syndrome of Isaacs; Quantal Squander; Syndrome of Continuous Muscle Activity; Continuous Myokymia; Continuous Myokymias; Gamstorp Wohlfart Syndrome; Isaac Syndrome; Isaacs Mertens Syndrome; Isaacs Pseudomyotonia Syndrome; Myokymias, Continuous; Neuromyotonia, Acquired; Myokymia, Continuous