Cognitive motor dissociation in patients with chronic disorders of consciousness: a literature review

Cover Page

Cite item

Full Text


Chronic disorders of consciousness include several conditions that differ significantly in both clinical and neurophysiological features. As medical technology continues to develop, the differential diagnosis of disorders of consciousness extends beyond purely clinical work. Nevertheless, all types of consciousness disorders are united by varying degrees of dissociation between wakefulness, cognitive and motor activity. The external similarity and minimal differences in clinical symptoms in unresponsive patients may hide different morphofunctional variants of this condition. In particular, use of electroencephalography and functional magnetic re- sonance imaging techniques allows us to detect covert consciousness in some clinically unresponsive patients. Based on various estimates, this phenomenon occurs in 5–15% of all cases. A special instance of covert consciousness is cognitive motor dissociation (CMD), defined as activation of cortical motor centers, recorded using neurophysiological techniques, in response to a corresponding instruction to perform a movement without its visible performance. Some researchers believe that detection of CMD indicates a more favourable prognosis for the subsequent restoration of consciousness, rather than its absence. The aim of this review is to examine CMD and its potential significance for outcomes in patients with chronic disorders of consciousness.

About the authors

Vladimir A. Belkin

Clinical Institute of the Brain

Author for correspondence.
ORCID iD: 0000-0002-4043-743X

neurologist, Intensive care unit

Russian Federation, 623702, Berezovsky, Sverdlovsk Region, Russia, Shilovsky str., 28. build. 6

Kseniya A. Ilina

Research Center of Neurology

ORCID iD: 0000-0002-3014-4350

neurologist, Department of anesthesiology and intensive care

Russian Federation, Moscow

Yulia V. Ryabinkina

Research Center of Neurology

ORCID iD: 0000-0001-8576-9983

D. Sci. (Med.), Head, Department of anesthesiology and intensive care

Russian Federation, Moscow


  1. Zasler N.D. Terminology in evolution: caveats, conundrums and controversies. NeuroRehabilitation. 2004;19(4):285–892. doi: 10.3233/NRE-2004-19404. PMID: 15671582.
  2. Gosseries O., Zasler N.D., Laureys S. Recent advances in disorders of consciousness: focus on the diagnosis. Brain Inj. 2014;28(9):1141–1150. doi: 10.3109/02699052.2014.920522. PMID: 25099018.
  3. Zasler N.D., Aloisi M., Contrada M., Formisano R. Disorders of consciousness terminology: history, evolution and future directions. Brain Inj. 2019;33(13-14):1684–1689. doi: 10.1080/02699052.2019.1656821. PMID: 31498704.
  4. Giacino J.T., Ashwal S., Childs N. et al. The minimally conscious state: definition and diagnostic criteria. Neurology. 2002;12(58):349–353. doi: 10.1212/WNL.58.3.349. PMID: 11839831.
  5. Fins J.J., Bernat J.L. Ethical, palliative, and policy considerations in disorders of consciousness. Neurology. 2018;91(10):471–475. doi: 10.1212/WNL.0000000000005927. PMID: 30089621.
  6. Gosseries O., Bruno M.A., Chatelle C. et al. Disorders of consciousness: what’s in a name? NeuroRehabilitation. 2011;28(1):3–14. doi: 10.3233/NRE-2011-0625. PMID: 21335671.
  7. Bruno M.A., Vanhaudenhuyse A., Thibaut A. et al. From unresponsive wakefulness to minimally conscious PLUS and functional locked-in syndromes: recent advances in our understanding of disorders of consciousness. J Neurol. 2011;258:1373–1384. doi: 10.1007/s00415-011-6114-x. PMID: 2167419.
  8. Belkin V.A. Review of the American Congress of Rehabilitation Medicine (ACRM) clinical recommendations for the diagnosis and treatment of patients with chronic im-pairment of consciousness. Farmateka. 2019;26(3):14–19. doi: 10.18565/pharmateca.2019.3.14-19. (In Russ.)
  9. Schnakers C., Perrin F., Schabus M. et al. Detecting consciousness in a total locked-in syndrome: an active event-related paradigm. Neurocase. 2009;15(4):271–277. doi: 10.1080/13554790902724904. PMID: 19241281.
  10. Bardin J.C., Fins J.J., Katz D.I. et al. Dissociations between behavioral and functional magnetic resonance imaging-based evaluations of cognitive function after brain in-jury. Brain. 2011;134(Pt 3):769–782. doi: 10.1093/brain/awr005. PMID: 21354974.
  11. Naci L., Sinai L., Owen A.M. Detecting and interpreting conscious experiences in behaviorally non-responsive patients. Neuroimage. 2015;145(Pt B):304–313. doi: 10.1016/j.neuroimage.2015.11.059. PMID: 26679327.
  12. Rohaut B., Eliseyev A., Claassen J. Uncovering consciousness in unresponsive ICU patients: technical, medical and ethical considerations. Crit Care. 2019;23(1):78. doi: 10.1186/s13054-019-2370-4. PMID: 30850022.
  13. Owen A.M., Coleman M.R., Boly M. et al. Detecting awareness in the vege-tative state. Science. 2006;313:1402–1402. doi: 10.1126/science.1130197. PMID: 18591475.
  14. Fernández-Espejo D., Owen A.M. Detecting awareness after severe brain injury. Nat Rev Neurosci. 2013;14(11):801–809. doi: 10.1038/nrn3608. PMID: 24088810.
  15. Fernández-Espejo D., Rossit S., Owen A.M. A thalamocortical mechanism for the absence of overt motor behavior in covertly aware patients. JAMA Neurol. 2015;72(12):1442–1450. doi: 10.1001/jamaneurol.2015.2614. PMID: 26501399.
  16. Parent A., Hazrati L.N. Functional anatomy of the basal ganglia. I. The cortico-basal ganglia-thalamo-cortical loop. Brain Res Brain Res Rev. 1995;20(1):91–127. doi: 10.1016/0165-0173(94)00007-C. PMID: 7711769.
  17. Schiff N.D. Cognitive motor dissociation following severe brain injuries. JAMA Neurol. doi: 10.1001/jamaneurol.2015.2899. PMID: 26502348.
  18. Laureys S., Schiff N.D. Coma and consciousness: paradigms (re)framed by neuroimaging. Neuroimage. 2012;61(2):478–491. doi: 10.1016/j.neuroimage.2011.12.041. PMID: 22227888.
  19. Fins J.J. Rights come to mind: brain injury, ethics, and the struggle for consciousness. New York: Cambridge University Press; 2015. doi: 10.1017/CBO9781139051279.
  20. Monti M.M., Vanhaudenhuyse A., Coleman M.R. et al. Willful modulation of brain activity in disorders of consciousness. N Engl J Med. 2010b;362(7):579–589. doi: 10.1056/NEJMoa0905370. PMID: 20130250.
  21. Forgacs P.B., Conte M.M., Fridman E.A. et al. Preservation of electroence-phalographic organization in patients with impaired consciousness and imaging-based evidence of command-following. Ann Neurol. 2014;76(6):869–879. doi: 10.1002/ana.24283. PMID: 25270034.
  22. Kondziella D., Friberg C.K., Frokjaer V.G. et al. Preserved consciousness in vegetative and minimal conscious states: systematic review and meta-analysis. J Neurol Neuro-surg Psychiary. 2016;87(5):485–492. DOI: 10.1136/ jnnp-2015-310958. PMID: 26139551.
  23. Edlow B., Fins J.J. Assessment of covert consciousness in the intensive care unit: clinical and ethical considerations. J Head Trauma Rehabil. 2018;33(6):424–434. doi: 10.1097/HTR.0000000000000448. PMID: 30395042.
  24. Iazeva E.G., Legostaeva L.A., Zimin A.A. et al. A Russian validation study of the Coma Recovery Scale-Revised (CRS-R). Brain Inj. 2019;33(2):218–225. doi: 10.1080/02699052.2018.1539248. PMID: 30388893.
  25. Claassen J., Doyle K., Matory A. et al. Detection of brain activation in unresponsive patients with acute brain injury. N Engl J Med. 2019; 380(26):2497–2505. doi: 10.1056/NEJMoa1812757. PMID: 31242361.
  26. Curley W.H., Forgacs P.B., Voss H.U. et al. Characterization of EEG signals revealing covert cognition in the injured brain. Brain. 2018;141(5):1404–1421. doi: 10.1093/brain/awy070. PMID: 29562312.
  27. Cruse D., Chennu S., Chatelle C. et al. Bedside detection of awareness in the vegetative state: a cohort study. Lancet. 2011;378(9809):2088–2094. doi: 10.1016/S0140-6736(11)61224-5. PMID: 22078855.
  28. Giacino J.T., Edlow B. Covert consciousness in the intensive care unit. Trends Neurosci. 2019;42(12):844–847. doi: 10.1016/j.tins.2019.08.011. PMID: 3151497.
  29. Jöhr J., Halimi F., Pasquier J. et al. Recovery in cognitive motor dissociation after severe brain injury: a cohort study. PLoS One. 2020;15(2):e0228474. doi: 10.1371/journal.pone.0228474. PMID: 32023323.
  30. Skibsted A.P., Amiri M., Fisher P.M. et al. Consciousness in Neurocritical Care Cohort Study using fMRI and EEG (CONNECT-ME): protocol for a longitudinal prospective study and a tertiary clinical care service. Front Neurol. 2018;9:1012. doi: 10.3389/fneur.2018.01012. PMID: 30542319.
  31. Reitsma J.B., Rutjes A.W., Khan K.S. et al. A review of solutions for diagnostic accuracy studies with an imperfect or missing reference standard. J Clin Epidemiol. 2009;62(8):797–806. doi: 10.1016/j.jclinepi.2009.02.005. PMID: 19447581.
  32. Van Erp W.S., Lavrijsen J.C., van de Laar F.A. et al. The vegetative state/unresponsive wakefulness syndrome: a systematic review of prevalence studies. Eur J Neurol. 2014;21:1361– 1368. doi: 10.1111/ene.12483. PMID: 25039901.
  33. Schnakers C., Vanhaudenhuyse A., Giacino J. et al. Diagnostic accuracy of the vegetative and minimally conscious state: clinical consensus versus standar-dized neurobe-havioral assessment. BMC Neurol. 2009;9:35 doi: 10.1186/1471-2377-9-35. PMID: 19622138.
  34. Brefel-Courbon C., Payoux P., Ory F. et al. Clinical and imaging evidence of zolpidem effect in hypoxic encephalopathy. Ann Neurol. 2007;62:102–105. doi: 10.1002/ana.21110. PMID: 17357126.
  35. Thengone D.J., Voss H.U., Fridman E.A., Schiff N.D. Local changes in network structure contribute to late communication recovery after severe brain injury. Sci Trans Med. 2016;8(368):368re5. doi: 10.1126/scitranslmed.aaf6113. PMID: 27928029.

Supplementary files

Supplementary Files

Copyright (c) 2021 Belkin V.A., Ilina K.A., Ryabinkina Y.V.

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

СМИ зарегистрировано Федеральной службой по надзору в сфере связи, информационных технологий и массовых коммуникаций (Роскомнадзор).
Регистрационный номер и дата принятия решения о регистрации СМИ: серия ПИ № ФС 77-83204 от 12.05.2022.

This website uses cookies

You consent to our cookies if you continue to use our website.

About Cookies