title: Level of consciousness as a conditioning factor of F wave generation in stroke patients.
abstract: OBJECTIVE
  The current study aimed to investigate whether the level of consciousness influenced the F wave generation, as an independent factor.
  
  
  METHODS
  Forty three patients with acute stroke were divided according to their level of consciousness in two groups; to those with Glasgow scale (GCS) score 3-7 indicating coma (group I) and those with GCS score 8-15 (group II). A series of 40 electrical stimuli were delivered to the ulnar nerve bilaterally in order to obtain F waves. The following variables were estimated and then compared between groups: F persistence, F wave latency, amplitude and duration. All studies were performed within 3 days from the onset of the stroke symptoms.
  
  
  RESULTS
  The main finding to emerge was the significantly reduced F wave persistence in the group of patients with low GCS score as opposed to patients allocated in the group with GCS score 8-15. This result is referred to F waves obtained from both the affected and unaffected limb. F wave minimum latency was also prolonged in the group with low GCS score, whilst the comparison of all other F wave variables revealed no significant differences between groups I and II. F wave persistence measurements did not differ between the affected and unaffected sides. Stroke location and type (ischemic or hemorrhagic) were not associated with alterations of F wave measurements.
  
  
  CONCLUSIONS
  Our results on stroke patients suggest that generation of F waves, expressed by the F wave persistence is associated with the level of consciousness.
  
  
  CONCLUSIONS
  F wave study may be useful as an objective measure in documenting the severity of consciousness impairment.
authors.affiliation: Department of Neurology, University of Patras Medical School, P.O. Box 1045, 26504 Rion-Patras, Greece. echroni@yahoo.com
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Chroni
authors.forename: George
authors.initials: G
authors.lastname: Katsoulas
authors.forename: Andreas A
authors.initials: AA
authors.lastname: Argyriou
authors.forename: George C
authors.initials: GC
authors.lastname: Sakellaropoulos
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Polychronopoulos
authors.forename: George
authors.initials: G
authors.lastname: Nikiforidis
mesh_terms: D000200:Action Potentials / Q000502:physiology / Q000528:radiation effects; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D003243:Consciousness; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D008297:Male; D008875:Middle Aged; D009431:Neural Conduction / Q000502:physiology* / Q000528:radiation effects; D011446:Prospective Studies; D011930:Reaction Time / Q000528:radiation effects; D018709:Statistics, Nonparametric; D020521:Stroke / Q000145:classification / Q000503:physiopathology*; D014474:Unconsciousness / Q000503:physiopathology