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. 2000 May;68(5):581–588. doi: 10.1136/jnnp.68.5.581

Monitoring of head injury by myotatic reflex evaluation

J Cozens 1, S Miller 1, I Chambers 1, A Mendelow 1
PMCID: PMC1736921  PMID: 10766887

Abstract

OBJECTIVES—(1) To establish the feasibility of myotatic reflex measurement in patients with head injury. (2) To test the hypothesis that cerebral dysfunction after head injury causes myotatic reflex abnormalities through disordered descending control. These objectives arise from a proposal to use reflex measurements in monitoring patients with head injury.
METHODS—The phasic stretch reflex of biceps brachii was elicited by a servo-positioned tendon hammer. Antagonist inhibition was evoked by vibration to the triceps. Using surface EMG, the amplitude of the unconditioned biceps reflex and percentage antagonist inhibition were measured. After standardisation in 16 normal adult subjects, the technique was applied to 36 patients with head injury across the range of severity. Objective (1) was addressed by attempting a measurement on each patient without therapeutic paralysis; three patients were also measured under partial paralysis. Objective (2) was addressed by preceding each of the 36 unparalysed measurements with an assessment of cerebral function using the Glasgow coma scale (GCS); rank correlation was employed to test a null hypothesis that GCS and reflex indices are unrelated.
RESULTS—In normal subjects, unconditioned reflex amplitude exhibited a positive skew requiring logarithmic transformation. Antagonist inhibition had a prolonged time course suggesting presynaptic mechanisms; subsequent measurements were standardised at 80 ms conditioning test interval (index termed "TI80").
 Measurements were obtained on all patients, even under therapeutic paralysis (objective (1)). The unconditioned reflex was absent in most patients with GCS less than 5; otherwise it varied little across the patient group. TI80 fell progressively with lower GCS, although patients' individual GCS could not be inferred from single measurements. Both reflex indices correlated with GCS (p<0.01), thereby dismissing the null hypothesis (objective (2)).
CONCLUSION—Cerebral dysfunction in head injury is reflected in myotatic reflex abnormalities which can be measured at the bedside. With greater reproducibility, reflex measurements may assist monitoring of patients with head injury.



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Selected References

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  1. Burke D., Hagbarth K. E., Löfstedt L., Wallin B. G. The responses of human muscle spindle endings to vibration of non-contracting muscles. J Physiol. 1976 Oct;261(3):673–693. doi: 10.1113/jphysiol.1976.sp011580. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Cordo P., Gandevia S. C., Hales J. P., Burke D., Laird G. Force and displacement-controlled tendon vibration in humans. Electroencephalogr Clin Neurophysiol. 1993 Feb;89(1):45–53. doi: 10.1016/0168-5597(93)90084-3. [DOI] [PubMed] [Google Scholar]
  3. Cowan J. M., Day B. L., Marsden C., Rothwell J. C. The effect of percutaneous motor cortex stimulation on H reflexes in muscles of the arm and leg in intact man. J Physiol. 1986 Aug;377:333–347. doi: 10.1113/jphysiol.1986.sp016190. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Crone C., Nielsen J. Methodological implications of the post activation depression of the soleus H-reflex in man. Exp Brain Res. 1989;78(1):28–32. doi: 10.1007/BF00230683. [DOI] [PubMed] [Google Scholar]
  5. Hultborn H., Meunier S., Morin C., Pierrot-Deseilligny E. Assessing changes in presynaptic inhibition of I a fibres: a study in man and the cat. J Physiol. 1987 Aug;389:729–756. doi: 10.1113/jphysiol.1987.sp016680. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Iles J. F. Evidence for cutaneous and corticospinal modulation of presynaptic inhibition of Ia afferents from the human lower limb. J Physiol. 1996 Feb 15;491(Pt 1):197–207. doi: 10.1113/jphysiol.1996.sp021207. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Iles J. F., Pisini J. V. Vestibular-evoked postural reactions in man and modulation of transmission in spinal reflex pathways. J Physiol. 1992 Sep;455:407–424. doi: 10.1113/jphysiol.1992.sp019308. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Jankowska E. Interneuronal relay in spinal pathways from proprioceptors. Prog Neurobiol. 1992;38(4):335–378. doi: 10.1016/0301-0082(92)90024-9. [DOI] [PubMed] [Google Scholar]
  9. Kane N. M., Curry S. H., Butler S. R., Cummins B. H. Electrophysiological indicator of awakening from coma. Lancet. 1993 Mar 13;341(8846):688–688. doi: 10.1016/0140-6736(93)90453-n. [DOI] [PubMed] [Google Scholar]
  10. Karam D. B. Tendon reflex latencies in the upper extremity. Arch Phys Med Rehabil. 1977 Jul;58(7):306–308. [PubMed] [Google Scholar]
  11. Katz R., Penicaud A., Rossi A. Reciprocal Ia inhibition between elbow flexors and extensors in the human. J Physiol. 1991 Jun;437:269–286. doi: 10.1113/jphysiol.1991.sp018595. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Lee C. M. Train-of-4 quantitation of competitive neuromuscular block. Anesth Analg. 1975 Sep-Oct;54(5):649–653. doi: 10.1213/00000539-197509000-00021. [DOI] [PubMed] [Google Scholar]
  13. Ommaya A. K. Head injury mechanisms and the concept of preventive management: a review and critical synthesis. J Neurotrauma. 1995 Aug;12(4):527–546. doi: 10.1089/neu.1995.12.527. [DOI] [PubMed] [Google Scholar]
  14. Rothwell J. C., Thompson P. D., Day B. L., Boyd S., Marsden C. D. Stimulation of the human motor cortex through the scalp. Exp Physiol. 1991 Mar;76(2):159–200. doi: 10.1113/expphysiol.1991.sp003485. [DOI] [PubMed] [Google Scholar]
  15. Roujas F., Gaillard M. Le moniteur de fonction cérébrale. Limites et intérêts. Agressologie. 1989 Nov-Dec;30(11-12):597–599. [PubMed] [Google Scholar]
  16. Schieppati M. The Hoffmann reflex: a means of assessing spinal reflex excitability and its descending control in man. Prog Neurobiol. 1987;28(4):345–376. doi: 10.1016/0301-0082(87)90007-4. [DOI] [PubMed] [Google Scholar]
  17. Stam J., van Crevel H. Measurement of tendon reflexes by surface electromyography in normal subjects. J Neurol. 1989 May;236(4):231–237. doi: 10.1007/BF00314505. [DOI] [PubMed] [Google Scholar]
  18. Tarkka I. M., Hayes K. C. Characteristics of the triceps brachii tendon reflex in man. Am J Phys Med. 1983 Feb;62(1):1–11. [PubMed] [Google Scholar]
  19. Teasdale G., Jennett B. Assessment of coma and impaired consciousness. A practical scale. Lancet. 1974 Jul 13;2(7872):81–84. doi: 10.1016/s0140-6736(74)91639-0. [DOI] [PubMed] [Google Scholar]

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