Abstract
Electromyographic single motor unit recordings were used to study the axonal refractory period of 28 accessory nerve innervated motor units in young normal subjects and 10 reinnervated motor units in elderly subjects. The refractory period was measured after a conditioning antidromic propagated nerve impulse and after a conditioning electrical nerve stimulus delivered through the same electrode as the test stimulus. The refractory period after a propagated impulse was 1.83 +/- 0.26 ms when test stimulus strength was 10% above the axonal threshold at rest and 0.88 +/- 0.26 ms when test stimulus strength was 100% above threshold. Corresponding data after an electrical stimulus were 2.38 +/- 0.32 ms and 1.28 +/- 0.22 ms. The difference between the methods was partially due to the effect of stimulus spread when the refractory period was measured after an antidromic propagated nerve impulse. Different properties of the nerve fibre membrane and the surrounding tissues after a propagated nerve impulse and after an electrical stimulus might also contribute. For further studies of motor unit pathology both methods seem equally reliable when proper normal data are available.
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Adrian E. D. The recovery process of excitable tissues: Part II. J Physiol. 1921 Aug 3;55(3-4):193–225. doi: 10.1113/jphysiol.1921.sp001963. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Borg J. Axonal refractory period of single short toe extensor motor units in neuropathies and neuromuscular diseases. J Neurol Neurosurg Psychiatry. 1981 Dec;44(12):1136–1140. doi: 10.1136/jnnp.44.12.1136. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Borg J. Effects of prior activity on the conduction in single motor units in man. J Neurol Neurosurg Psychiatry. 1983 Apr;46(4):317–321. doi: 10.1136/jnnp.46.4.317. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Borg J., Grimby L., Hannerz J. Axonal conduction velocity and voluntary discharge properties of individual short toe extensor motor units in man. J Physiol. 1978 Apr;277:143–152. doi: 10.1113/jphysiol.1978.sp012266. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Borg J. Properties of single motor units of the extensor digitorum brevis in elderly humans. Muscle Nerve. 1981 Sep-Oct;4(5):429–434. doi: 10.1002/mus.880040513. [DOI] [PubMed] [Google Scholar]
- GILLIATT R. W., WILLISON R. G. The refractory and supernormal periods of the human median nerve. J Neurol Neurosurg Psychiatry. 1963 Apr;26:136–147. doi: 10.1136/jnnp.26.2.136. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Illis L. S., Sedgwick E. M., Tallis R. C. Spinal cord stimulation in multiple sclerosis: clinical results. J Neurol Neurosurg Psychiatry. 1980 Jan;43(1):1–14. doi: 10.1136/jnnp.43.1.1. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kimura J. A method for estimating the refractory period of motor fibers in the human peripheral nerve. J Neurol Sci. 1976 Aug;28(4):485–490. doi: 10.1016/0022-510x(76)90119-2. [DOI] [PubMed] [Google Scholar]
- Lowitzsch K., Hopf H. C. Refraktärperiode und Ubermittlung frequenter Reizserien im gemischten peripheren Nerven des Menschen. J Neurol Sci. 1972 Nov;17(3):255–270. doi: 10.1016/0022-510x(72)90031-7. [DOI] [PubMed] [Google Scholar]
- Paintal A. S. Effects of temperature on conduction in single vagal and saphenous myelinated nerve fibres of the cat. J Physiol. 1965 Sep;180(1):20–49. [PMC free article] [PubMed] [Google Scholar]