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Autonomic Testing

What is it?​

Taking a blood pressure might be common practice, but how a clinician takes your blood pressure could matter! Blood pressure (BP) is the force that propels oxygen-rich blood to all parts of the body. Measurement of BP is one of the most frequently performed clinical procedures in health care practices today.

autonomic-testing

Why is it important?

While most healthcare providers take BP only in a seated position, body position changes have been researched and seen to make physiological changes in the human body (1,4), consequently reflecting brain function.

autonomic-testing

How does it work?

The autonomic nervous system, made up of the sympathetic (SNS) and parasympathetic nervous (PNS) systems, is responsible for the regulation and integration of internal organs’ functions, specifically with SNS being a key factor in BP control through specialized receptors called baroreceptors. During postural changes, such as going from sitting, to lying on your back (supine), to standing, feedback loops increase firing to sympathetic nerves ultimately changing BP (6-9). More specifically, however, we can correlate different body positions and BP regulation with the vestibular system, located in the inner ear, and primarily associated with balance, equilibrium, orientation and navigation (8,10) through the vestibulo-sympathetic reflex (VSR). This reflex is particularly important in preventing a drop in BP due to the organs of the vestibular system (otoliths and semicircular canals) having the ability to sense motion with respect to gravity within milliseconds, consequently firing the VSR for activation of the cardiovascular system; with the ultimate goal of maintaining a stable BP during position change (4, 8, 10-20).

Autonomic-testing

The vestibular system, because of its involvement with balance, equilibrium, and navigation (8,10), also has immense associations and connections with areas of the brain such as, frontal lobes (executive planning/motor planning), cerebellum (fine/coordinated movements), and posterior parietal cortex (spatial orientation) (4, 8, 10-20). Therefore, it makes sense that dysfunction in this reflex, feedback loop, or association/integrating areas may have a significant difference in BP from side to side, or in different positions, that could result in feelings of dizziness, lightheadedness, nausea, or syncope.

How does it help?

The C3 Logix tests include tablet-based applications of standard paper and pencil tests: Trail Making A, Trail Making B, and Digit Symbol Matching, assessing psychomotor and visual processing speeds (8), simple and choice reaction time tests, assessing single stimuli reaction times as well as “choice” reaction times when choosing between two simultaneous stimuli (9), and a Standard Assessment of Cognition, assessing orientation, concentration, immediate and delayed memory. Upon completion, a compiled score is assigned to each section and can be used to detect any subtle deviations compared against normative data (1).

References

  1. Armstrong RS (2002) Nurses’ knowledge of error in blood pressure measurement technique. International Journal of Nursing Practice 8, 118-126.

  2. McKay DW, Campbell NRC, Parab LS, Chockalingam A & Fodar JG (1990) Clinical Assessment of Blood Pressure. Journal of Human Hypertension 4, 639-645.

  3. Bailey H & Bauer JH (1993) Review of common error in the indirect measurement of blood pressure. Sphygmomanometry. Archives of Internal Medicine 153, 2741-2748.

  4. Norman RC, Campbell MD & Donald (1999) Accurate blood pressure measurement. Why does it matter? Canadian Medical Association Journal 10, 277-279.

  5. Freeman, R. et al. Consensus statement on the definition of orthostatic hypotension, neurally mediated syncope and the postural tachycardia syndrome. Clin. Auton. Res.21, 69–72 (2011).

  6. Prusiński A, Rozentryt P. Odruchy autonomiczne. In: Traczyk WZ, editor. Diagnostyka czynnościowa człowieka [Polish]Warszawa: Fizjologia stosowana. PZWL; 1999. pp. 213–27

  7. Trzebski A. Autonomiczny układ nerwowy i mięśni gładkie. In: Traczyk WZ, Trzebski A, editors. Fizjologia człowieka z elementami fizjologii stosowanej i klinicznej [Polish] Warszawa: PZWL; 2001. pp. 508–88.

  8. Yates, B. J., Bolton, P. S. & Macefield, V. G. Vestibulo-sympathetic responses. Compr. Physiol. 4,851–887 (2014).

  9. Abboud, F. M. & Thames, M. Interaction of cardiovascular reflexes in circulatory control. In Shepherd J. T., Abboud F. M. editors. Handbook of Physiology Section 2: Circulation Volume III: Peripheral Circulation and Organ Blood Flow, Part 2.(Bethesa, MD: American Physiological Society, 1983).

  10. Yates, B. J. Vestibular influences on the autonomic nervous system. Ann. N. Y. Acad. Sci.781,458–473 (1996).

  11. Ishikawa, T. & Miyazawa, T. Sympathetic responses evoked by vestibular stimulation and their interactions with somato-sympathetic reflexes. J Aut. Nerv Syst 1,243–254 (1980)

  12. Uchino, Y., Kudo, N., Tsuda, K. & Iwamura, Y. Vestibular inhibition of sympathetic nerve activities. Brain Res. 22, 195–206 (1970).

  13. Kerman, I. A. & Yates, B. J. Regional and functional differences in the distribution of vestibulosympathetic reflexes. Am. J. Physiol. 275, R824–R835 (1998)

  14. Yates, B. J., Yamagata, Y. & Bolton, P. S. The ventrolateral medulla of the cat mediates vestibulosympathetic reflexes. Brain Res. 552, 265–272 (1991).

  15. Yates, B. J. & Miller, A. D. Physiological evidence that the vestibular system participates in autonomic and respiratory control. J Vestib Res 8, 17–25 (1998).

  16. Yates, B. J. & Miller, A. D. Properties of sympathetic reflexes elicited by natural vestibular stimulation: implications for cardiovascular control. J. Neurophysiol. 71, 2087–92 (1994).

  17. Yates, B. J., Jakus, J. & Miller, A. D. Vestibular effects on respiratory outflow in the decerebrate cat. Brain Res. 629, 209–217 (1993).

  18. Jian, B. J., Cotter, L. A., Emanuel, B. A., Cass, S. P. & Yates, B. J. Effects of bilateral vestibular lesions on orthostatic tolerance in awake cats. J. Appl. Physiol. 86, 1552–1560 (1999).

  19. Cohen, B. et al Sinusoidal galvanic vestibular stimulation (sGVS) induces a vasovagal response in the rat. Exp. Brain Res. 210,45–55 (2011)

  20. Tang, P. C. & Gernandt, B. E. Autonomic responses to vestibular stimulation. Exp. Neurol. 24, 558–578 (1969).

  21. Appenzeller O, Goss JE. Autonomic deficits in Parkinson's syndrome. Arch Neurol. 1971; 24:50–57. [PubMed]

  22. Bannister R, Oppenheimer DR. Degenerative disease of the nervous system. Brain. 1972; 95:457–74. [PubMed]

  23. Sharpey-Schafer EP, Taylor PJ. Absent circulatory reflexes in diabetic neuritis. Lancet. 1960; 1:559–62.[PubMed]

  24. Bannister R. Chronic autonomic failure with postural hypotension. Lancet. 1979; 2:404–6. [PubMed]

  25. Edis AJ, Shepherd JT. Autonomic control of the peripheral vascular system. Arch Intern Med. 1970; 125:716–24. [PubMed]

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