title: Medium-latency reflex response elicited from the flexor carpi radialis by radial nerve stimulation.
abstract: The H reflex obtained from the flexor carpi radialis muscle by median nerve stimulation is a well-known monosynaptic reflex. However, the origin of the late responses is still contentious. Radial nerve stimulation was performed through the spiral groove, and EMG recording was obtained from the flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles. An M response followed by an F response was achieved from the ECR by radial nerve stimulation; the antagonistic FCR muscle elicited a late response. A total of 25 cases were included in this study. In 22 of these cases, a response with a latency of 40.97 ± 5.35 ms was obtained from the FCR by radial nerve stimulation. When extension of the hand was restricted, the response disappeared in five of nine cases. Application of cold markedly suppressed the response and prolonged the latency of the FCR medium-latency reflex response (FCR-MLR). Oral tizanidine considerably suppressed the FCR-MLR response. Two out of eight cases did not exhibit any response. No response could be recorded from a patient with complete amputation of the right hand. The FCR-MLR is the reflex caused by stretching of the FCR muscle from radial nerve stimulation, and it is greatly influenced by group II afferents.
authors.affiliation: Department of Neurology, Akdeniz University Hospital, B Block, Antalya, Turkey. uysalh@akdeniz.edu.tr
authors.forename: Hilmi
authors.initials: H
authors.lastname: Uysal
authors.forename: Ferah
authors.initials: F
authors.lastname: Kızılay
authors.forename: Sirin Erkaya
authors.initials: SE
authors.lastname: Inel
authors.forename: Hakan
authors.initials: H
authors.lastname: Özen
authors.forename: Gökhan
authors.initials: G
authors.lastname: Pek
mesh_terms: D000328:Adult; D003000:Clonidine / Q000031:analogs & derivatives / Q000494:pharmacology; D004558:Electric Stimulation; D005260:Female; D006181:H-Reflex / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009125:Muscle Relaxants, Central / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000294:innervation / Q000502:physiology*; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology*; D011826:Radial Nerve / Q000187:drug effects / Q000502:physiology*; D012026:Reflex, Stretch / Q000187:drug effects / Q000502:physiology*; D014953:Wrist / Q000294:innervation / Q000502:physiology
chemical_list: D009125:Muscle Relaxants, Central; C023754:tizanidine; D003000:Clonidine