title: Relationship between the states of spinal impact injuries and magnetically evoked EMGs in rats.
abstract: The relationship between the states of spinal impact injuries and magnetically evoked electromyograms (EMGs) were studied in rats. Impact injuries to the spinal cord were induced at a depth of 0.25-2.0 mm by insertion of a cylinder tip measuring 2 mm in diameter into the lumbar vertebrae L1-L2. Magnetically induced electromyograms for the brain and lumbar vertebrae L4-L5 were recorded from the tibialis anticus and the gastrocnemius muscles. H-reflex was not induced by the spinal cord injury (SCI) at a depth of 0.25 mm, although motor evoked potential (MEP) was observed. Continuous waves following the M-response were observed in the SCI at a depth of 0.25 mm. Elevation of the threshold, reduction of its latency and decrease in amplitude of the M-responses were observed at an injury depth of 0.5 mm or deeper. With SCI magnitude from mild (0.5 mm depth) to severe (1.0 mm depth), the amplitudes of the M-response were decreased, and the latency of the M-response was shorter than that of the control. The F-response was accelerated in severe SCI. Our results indicated that there was a relationship between extensive injury legions and the H-reflex F- and M-responses in magnetically evoked EMGs. Magnetically evoked EMGs are useful for monitoring the states of SCI.
authors.affiliation: Department of Physiology, Kinki University School of Medicine, Osaka, Japan. kchiba@med.kindai.ac.jp
authors.forename: A
authors.initials: A
authors.lastname: Chiba
authors.forename: S
authors.initials: S
authors.lastname: Hiruma
authors.forename: S
authors.initials: S
authors.lastname: Hashimoto
authors.forename: M
authors.initials: M
authors.lastname: Inase
mesh_terms: D000818:Animals; D004576:Electromyography / Q000379:methods; D019054:Evoked Potentials, Motor / Q000502:physiology*; D008161:Lumbosacral Region; D008280:Magnetics; D018482:Muscle, Skeletal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D014949:Wounds, Nonpenetrating / Q000503:physiopathology*