title: The generator site in acquired autoimmune neuromyotonia.
abstract: OBJECTIVE
  To investigate the origin of ectopic activity in neuromyotonia (NMT).
  
  
  METHODS
  We studied two patients. In addition to routine studies, we tested synchronicity of spontaneous discharges in different motor units in simultaneous recordings made with two needle electrodes in the first dorsal interosseus muscle. Time-locked fasciculations in these double recordings would represent abnormal ectopic activity initiated in a nerve trunk with ephaptic stimulation of a nearby axon. In patient 1, this research protocol was applied once, 15years after regular intravenous immunoglobulin (IvIg) treatment. Patient 2 was investigated before and 1year after IvIg.
  
  
  RESULTS
  Both patients improved after IVIg, mirrored by a striking decrease in the amount of spontaneous activity on electromyography. Moreover, our technique did not detect synchronous spontaneous activity (time-locked fasciculations) on the second assessment, although this was predominant before treatment in patient 2.
  
  
  CONCLUSIONS
  In NMT, abnormal discharges originate both in distal axonal branches and in more proximal segments. It appears that IvIg is more effective in blocking antibody activity in proximal axonal segments, perhaps related to factors such as blood-nerve barrier, temperature or differing ion channel distributions.
  
  
  CONCLUSIONS
  Treatment effects can shed light on the origin of abnormal activity in NMT.
authors.affiliation: Institute of Physiology Unit, Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Portugal; Department of Neurology, Department of Neurosciences and Mental Health, Hospital de Santa Maria, Centro Hospitalar Lisboa Norte, Portugal.
authors.forename: Miguel Oliveira
authors.initials: MO
authors.lastname: Santos
authors.affiliation: Institute of Physiology Unit, Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Portugal; Departments of Neurology and Neuroscience, Barts and the London School of Medicine, Queen Mary University of London, United Kingdom.
authors.forename: Michael
authors.initials: M
authors.lastname: Swash
authors.affiliation: Institute of Physiology Unit, Instituto de Medicina Molecular, Faculty of Medicine, University of Lisbon, Portugal; Department of Neurology, Department of Neurosciences and Mental Health, Hospital de Santa Maria, Centro Hospitalar Lisboa Norte, Portugal. Electronic address: mamedemg@mail.telepac.pt.
authors.forename: Mamede
authors.initials: M
authors.lastname: de Carvalho
mesh_terms: D000368:Aged; D001327:Autoimmune Diseases / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D004576:Electromyography; D019054:Evoked Potentials, Motor; D005207:Fasciculation; D006801:Humans; D007136:Immunoglobulins / Q000008:administration & dosage / Q000627:therapeutic use; D020386:Isaacs Syndrome / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation* / Q000503:physiopathology
chemical_list: D007136:Immunoglobulins
keywords: Fasciculation potentials; Hyperexcitability; Intravenous immunoglobulin; Myokymic discharges; Neuromyotonia