Pain Without Consciousness? Rethinking pain-suffering in Disorders of Consciousness
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Abstract
Disorders of consciousness (DoC) are a challenge for understanding pain and suffering, as they are complex subjective experiences involving multiple neural networks. Neurophysiological studies and neuroimaging suggest that some patients in a vegetative state may experience pain, and those with covert consciousness are more likely to perceive it. However, these patients are often ignored by medical staff because they cannot express it. This narrative review addresses recent neuroscientific research on pain in these patients, highlighting the need to reconsider it in clinical practice. In the context of diagnostic and prognostic uncertainty, it is crucial to deepen and establish ethical frameworks to ensure respect for the autonomy and well-being of there patients, addressing the bioethical dilemmas derived from the uso of neurotechnologies in patients who cannot express consent.
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References
1. Multi-Society Task Force on PVS. Medical aspects of the persistent vegetative state. New England Journal of Medicine. 1994; 330(21):1499–508.
2. Multi-Society Task Force on PVS. Medical Aspects of the Persistent Vegetative State. Prognosis for Recovery. New England Journal of Medicine [Internet]. 1994 [citado 1 de mayo de 2023]; 330(22):1572–9. Disponible en: https://www.nejm.org/doi/full/10.1056/NEJM199406023302206
3. Giacino JT, Ashwal ; S, Childs ; N, Cranford ; R, Jennett ; B, Katz ; D I. The Minimally Conscious State. Definition and diagnostic criteria. American Academy of Neurology. 2002; 58:349–53.
4. Laureys S, Berré J, Goldman S. Cerebral Function in Coma, Vegetative State, Minimally Conscious State, Locked-in Syndrome, and Brain Death. Yearbook of Intensive Care and Emergency Medicine 2001 [Internet]. 2001 [citado 26 de abril de 2023]; 386–96. Disponible en: https://doi.10.1007/978-3-642-59467-0_33
5. Demertzi A, Soddu A, Laureys S. Consciousness supporting networks. Curr Opin Neurobiol [Internet]. 2013 [citado 26 de abril de 2023]; 23(2):239–44. Disponible en: https://doi.10.1016/J.CONB.2012.12.003
6. Laureys S, Faymonville ME, Degueldre C, Fiore G Del, Damas P, Lambermont B. Auditory processing in the vegetative state. Brain. 2000; 123:1589–601.
7. Laureys S, Faymonville ME, Peigneux P, Damas P, Lambermont B, Del Fiore G. Cortical Processing of Noxious Somatosensory Stimuli in the Persistent Vegetati- ve State. Neuroimage. 2002; 17(2):732–41.
8. Owen AM, Coleman MR, Boly M, Davis MH, Laureys S, Pickard JD. Detecting awareness in the vegetative state. Science (1979) [Internet]. 2006 [citado 28 de marzo de 2024]; 313(5792):1402. Disponible en: https://doi.10.1126/science.1130197
9. Monti MM, Vanhaudenhuyse A, Coleman MR, Boly M, Pickard JD, Tshibanda L. Willful Modulation of Brain Activity in Disorders of Consciousness. New England Journal of Medicine [Internet]. 2010 [citado 28 de marzo de 2024]; 362(7):579–89. Disponible en: https://doi.10.1056/nejmoa0905370
10. Peterson A, Owen AM, Karlawish J. Alive inside. Bioethics [Internet]. 2020 [citado 28 de marzo de 2024]; 34(3):295–305. Disponible en: https://doi.10.1111/bioe.12678
11. Laureys S, Celesia GG, Cohadon F, Lavrijsen J, León-Carrión J, Sannita WG. Unresponsive wakefulness syndrome: A new name for the vegetative state or apallic syndrome. BMC Med. 2010 ;8.
12. Luppi AI, Cain J, Spindler LRB, Górska UJ, Toker D, Hudson AE. Mechanisms Underlying Disorders of Consciousness: Bridging Gaps to Move Toward an Inte- grated Translational Science. Neurocrit Care [Internet]. 2021 [citado 28 de marzo de 2024]; 35:37–54. Disponible en: https://doi.10.1007/s12028-021-01281-6
13. Ramos KM, Grady C, Greely HT, Chiong W, Eberwine J, Farahany NA. The NIH BRAIN Initiative: Integrating Neuroethics and Neuroscience [Internet]. Neuron. Cell Press; 2019 [citado 28 de marzo de 2024]; 101:394–8. Disponible en: https://doi.10.1016/j.neuron.2019.01.024
14. Giacino JT, Katz DI, Schiff ND, Whyte J, Ashman EJ, Ashwal S. Practice Guideline Update Recommendations Summary: Disorders of Consciousness. Arch Phys Med Rehabil [Internet]. 2018 [citado 28 de marzo de 2024]; 99(9):1699–709. Disponible en: https://doi.10.1016/j.apmr.2018.07.001
15. Kondziella D, Bender A, Diserens K, van Erp W, Estraneo A, Formisano R. Euro- pean Academy of Neurology guideline on the diagnosis of coma and other disorders of consciousness. Eur J Neurol [Internet]. 2020 [citado 28 de marzo de 2024]; 27(5):741–56. Disponible en: https://doi.10.1111/ene.14151
16. Comanducci A, Boly M, Claassen J, De Lucia M, Gibson RM, Juan E. Clinical and advanced neurophysiology in the prognostic and diagnostic evaluation of disorders of consciousness: review of an IFCN-endorsed expert group [Internet]. Clinical Neurophysiology. Elsevier Ireland Ltd; 2020 [citado 28 de marzo de 2024]; 131:2736–65. Disponible en: https://doi.10.1016/j.clinph.2020.07.015
17. Pan J, Xie Q, Qin P, Chen Y, He Y, Huang H. Prognosis for patients with cognitive motor dissociation identified by brain-computer interface. Brain [Internet]. 2020 [citado 28 de marzo de 2024]; 143(3):1177–89. Disponible en: https://doi.10.1093/brain/awaa056
18. Edlow BL, Claassen J, Suarez JI. Common data elements for disorders of consciousness. Neurocrit Care [Internet]. 2024 [citado 28 de marzo de 2024]. Disponible en: https://doi.10.1007/s12028-023-01931-x
19. IASP Revises Its Definition of Pain for the First Time Since 1979 [Internet]. [citado 26 de abril de 2024]. Disponible en: https://www.iasppain.org/wp-content/uploads/2022/04/revised-definition-flysheet_R2-1-1-1.pdf
20. Raja SN, Carr DB, Cohen M, Finnerup NB, Flor H, Gibson S. The Revised IASP definition of pain: concepts, challenges, and compromises HHS Public Access. Pain [Internet]. 2020 [citado 26 de abril de 2024]; 161(9):1976–82. Disponible en: https://www.iasp-pain.org/wp-content/uploads/2022/04/revised-definition-flys-heet_R2-1-1-1.pdf
21. Zasler ND, Formisano R, Aloisi M. Pain in Persons with Disorders of Consciousness [Internet]. Brain Sciences. MDPI; 2022 [citado 23 de mayo de 2024]. Disponible en: http://10.3390/brainsci12030300
22. Bueno-Gómez N. Conceptualizing suffering and pain. Philosophy, Ethics, and Humanities in Medicine [Internet]. 2017 [citado 10 de mayo de 2024]; 12(7):2–11. Disponible en: 10.1186/s13010-017-0049-5
23. Scarponi F, Tinelli G. Disturbi di coscienza: approccio riabilitativo al dolore. Disorders of consciousness: Rehabilitative perspective in management of pain. Il Fisioterapista. 2018; 2:11–5.
24. Lukas A, Barber JB, Johnson P, Gibson SJ. Observer-rated pain assessment instruments improve both the detection of pain and the evaluation of pain intensity in people with dementia. European Journal of Pain [Internet]. 2013 [citado 9 de mayo de 2024]; 17(10):1558–68. Disponible en: https://onlinelibrary.wiley.com/doi/full/10.1002/j.1532-2149.2013.00336.x
25. Herr K, Bjoro K, Decker S. Tools for assessment of pain in nonverbal older adults with dementia: A state-of-the-science review. J Pain Symptom Manage [Internet]. 2006 [citado 9 de mayo de 2024]; 31(2):170–92. Disponible en: 10.1016/J. JPAINSYMMAN.2005.07.001
26. Herr K. Pain assessment strategies in older patients. Journal of Pain [Internet]. 2011 [citado 9 de mayo de 2024]; 12(3 SUPPL.):S3. Disponible en: 10.1016/J. JPAIN.2010.11.011
27. Bartolo M, Chiò A, Ferrari S, Tassorelli C, Tamburin S, Avenali M. Assessing and treating pain in movement disorders, amyotrophic lateral sclerosis, severe acquired brain injury, disorders of consciousness, dementia, oncology and neuroinfectivology: Evidence and recommendations from the Italian Consensus Conference on Pain in Neurorehabilitation. European Journal of Physical and Rehabilitation Medicine; 2016.
28. Schnakers C, Chatelle C, Vanhaudenhuyse A, Majerus S, Ledoux D, Boly M. The Nociception Coma Scale: A new tool to assess nociception in disorders of consciousness. Pain [Internet]. 2010; 148(2). Disponible en: https://journals.lww.com/pain/fulltext/2010/02000/the_nociception_coma_scale__a_new_tool_to_assess.9.aspx
29. Guldenmund P, Stender J, Heine L, Laureys S. Mindsight: Diagnostics in disorders of consciousness [Internet]. Vol. 2012, Critical Care Research and Practice. 2012 [citado 31 de mayo de 2024]. Disponible en: 10.1155/2012/624724
30. Chatelle C, Thibaut A, Bruno MA, Boly M, Bernard C, Hustinx R. Nociception coma scale-revised scores correlate with metabolism in the anterior cingulate cortex. Neurorehabil Neural Repair [Internet]. 2014 [citado 30 de mayo de 2024]; 28(2):149–52. Disponible en: 10.1177/1545968313503220
31. Sattin D, Schnakers C, Pagani M, Arenare F, Devalle G, Giunco F. Evidence of altered pressure pain thresholds in persons with disorders of consciousness as measured by the Nociception Coma Scale–Italian version. Neuropsychol Rehabil [Internet]. 2018 [citado 31 de mayo de 2024]; 28(8):1295–310. Disponible en: 10.1080/09602011.2017.1290532
32. Bonin EAC, Lejeune N, Szymkowicz E, Bonhomme V, Martial C, Gosseries O. Assessment and management of pain/nociception in patients with disorders of consciousness or locked-in syndrome: A narrative review [Internet]. Frontiers in Systems Neuroscience. Frontiers Media. 2023 [citado 31 de mayo de 2024]. Disponible en: 10.3389/fnsys.2023.1112206
33. Naro A, Russo M, Leo A, Rifici C, Pollicino P, Bramanti P. Cortical responsiveness to nociceptive stimuli in patients with chronic disorders of consciousness: Do c-fiber laser evoked potentials have a role? PLoS One [Internet]. 2015 [citado 1 de junio de 2024]; 10(12). Disponible en: 10.1371/journal.pone.0144713
34. Calabrò RS, Pignolo L, Müller-Eising C, Naro A. Pain perception in disorder of consciousness: A scoping review on current knowledge, clinical applications, and future perspective [Internet]. Brain Sciences. MDPI AG; 2021 [citado 1 de junio de 2024]. Disponible en: 10.3390/brainsci11050665
35. De Ridder D, Adhia D, Vanneste S. The anatomy of pain and suffering in the brain and its clinical implications. Neurosci Biobehav Rev [Internet]. 2021 [citado 10 de mayo de 2024]; 130:125–46. Disponible en: 10.1016/j.neubiorev.2021.08.013
36. Riganello F, Macrì S, Alleva E, Petrini C, Soddu A, Leòn-Carriòn J. Pain perception in unresponsive wakefulness syndrome may challenge the interruption of artificial nutrition and hydration: Neuroethics in action [Internet]. Vol. 7, Frontiers in Neurology. Frontiers Media. 2016 [citado 8 de junio de 2024]. Disponible en: 10.3389/fneur.2016.00202
37. Pistoia F, Sacco S, Stewart J, Sarà M, Carolei A. Disorders of consciousness: Painless or painful conditions?-evidence from neuroimaging studies [Internet]. Brain Sciences. MDPI AG; 2016 [citado 5 de junio de 2024]. Disponible en: 10.3390/brainsci6040047
38. Calabrò RS, Pignolo L, Müller-Eising C, Naro A. Pain perception in disorder of consciousness: A scoping review on current knowledge, clinical applications, and future perspective [Internet]. Brain Sciences. MDPI AG; 2021 [citado 31 de mayo de 2024]. Disponible en: 10.3390/brainsci11050665
39. Chatelle C, Majerus S, Whyte J, Laureys S, Schnakers C. A sensitive scale to assess nociceptive pain in patients with disorders of consciousness. Journal of Neurology, Neurosurgery & Psychiatry [Internet]. 2012; 83(12):1233–7. Dis- ponible en: https://dx.doi.org/10.1136/jnnp-2012-302987
40. Cortese MD, Arcuri F, Nemirovsky IE, Lucca LF, Tonin P, Soddu A. Nociceptive Response Is a Possible Marker of Evolution in the Level of Consciousness in Unresponsive Wakefulness Syndrome Patients. Front Neurosci [Internet]. 2021 [ci- tao 11 de junio de 2024]; 15. Disponible en: 10.3389/fnins.2021.771505
41. Chatelle C, Hauger SL, Martial C, Becker F, Eifert B, Boering D. Assessment of Nociception and Pain in Participants in an Unresponsive or Minimally Conscious State After Acquired Brain Injury: The Relation Between the Coma Recovery Scale–Revised and the Nociception Coma Scale–Revised. Arch Phys Med Rehabil [Internet]. 2018 [citado 23 de mayo de 2024]; 99(9):1755–62. Disponible en: 10.1016/j.apmr.2018.03.009
42. Formisano R, Contrada M, Aloisi M, Ferri G, Schiattone S, Iosa M. Neuropsychological Rehabilitation. 2020 [citado 11 de junio de 2024]: 1893–2904 Nociception Coma Scale with personalized painful stimulation versus standard stimulus in non-communicative patients with disorders of consciousness. Disponible en: 10.1080/09602011.2019.1614464
43. Lee IS, Necka EA, Atlas LY. Distinguishing pain from nociception, salience, and arousal: How autonomic nervous system activity can improve neuroimaging tests of specificity. Neuroimage [Internet]. 2020 [citado 17 de junio de 2024]; 204:116254. Disponible en: 10.1016/J.NEUROIMAGE.2019.116254
44. Riganello F, Tonin P, Soddu A. I Feel! Therefore, I Am from Pain to Consciousness in DOC Patients. Int J Mol Sci [Internet]. 2023 [citado 17 de junio de 2024]; 24(11825). Disponible en: 10.3390/ijms241411825
45. Devalle G, Castiglioni P, Arienti C, Abbate C, Mazzucchi A, Agnello L. Cardio-respiratory autonomic responses to nociceptive stimuli in patients with disorders of consciousness. PLoS One [Internet]. 2018 [citado 3 de junio de 2024]; 13(9). Disponible en: 10.1371/journal.pone.0201921
46. Calabrò RS, Naro A, Manuli A, Leo A, De Luca R, Lo Buono V. Pain perception in patients with chronic disorders of consciousness: What can limbic system tell us? Clinical Neurophysiology [Internet]. 2017 [citado 10 de junio de 2024]; 128(3):454– 62. Disponible en: 10.1016/J.CLINPH.2016.12.011
47. Boly M, Faymonville ME, Schnakers C, Peigneux P, Lambermont B, Phillips C. Perception of pain in the minimally conscious state with PET activation: an observational study. www.thelancet.com/neurology [Internet]. 2008 [citado 22 de junio de 2024]; 7:1013–20. Disponible en: www.thelancet.com/neurology
48. Markl A, Yu T, Vogel D, M€ Uller F, Kotchoubey B, Lang S. Brain processing of pain in patients with unresponsive wakefulness syndrome. Brain Behav [Internet]. 2013 [citado 22 de junio de 2024]; 3(2):95–103. Disponible en: 10.1016/S1474
49. National Library of Medicine [Internet]. 2025 [citado 26 de marzo de 2025]. Disorder of Consciousness | Card Results | ClinicalTrials.gov. Disponible en: https://clinicaltrials.gov/search?cond=Disorder%20of%20Consciousness
50. Amadio J, Bi GQ, Boshears PF, Carter A, Devor A, Doya K. Neuroethics Ques- tions to Guide Ethical Research in the International Brain Initiatives [Internet]. Vol. 100, Neuron. Cell Press; 2018 [citado 28 de marzo de 2024]:19–36. Disponible en: https://doi.10.1016/j.neuron.2018.09.021
51. Young MJ, Bodien YG, Edlow BL. Ethical Considerations in Clinical Trials for Disorders of Consciousness. Brain Sci [Internet]. 2022 [citado 24 de marzo de 2024]; 12(2). Disponible en: 10.3390/brainsci12020211
52. Young MJ, Bodien YG, Giacino JT, Fins JJ, Truog RD, Hochberg LR. The neuroethics of disorders of consciousness: A brief history of evolving ideas. Brain [Internet]. 2021 [citado 28 de marzo de 2024]; 144(11):3291–310. Disponible en: https://doi.10.1093/brain/awab290
53. Peterson A, Mintz K, Owen AM. Unlocking the Voices of Patients with Severe Brain Injury. Neuroethics [Internet]. 2022 [citado 6 de abril de 2025]; 15(1). Disponible en: https:/doi.10.1007/s12152-022-09492-0
54. Declaración de Helsinki de la AMM – Principios éticos para las investigaciones médicas con participantes humanos –WMA– The World Medical Association [Internet]. [citado 27 de marzo de 2025]. Disponible en: https://www.wma.net/es/policies-post/declaracion-de-helsinki-de-la-amm-principios-eticos-para-las-investigaciones-medicas-en-seres-humanos/?utm_source=chatgpt.com
55. Huerta-Chávez V, Rivera-Tello S, Ramos-Loyo J. Los Potenciales Relacionados a Eventos (PREs): una técnica para estudiar el funcionamiento del cerebro durante el procesamiento de información: Event-Related Potentials (ERPs): a technique to study brain functioning during information processing. e-CUCBA [Internet]. 2022 [citado 3 de abril de 2025]; (19):183–94. Disponible en: http://e-cucba.cucba.udg.mx/index.php/e-Cucba/article/view/278
56. Alonso-Valerdi LM, Arreola-Villarruel MA, Argüello-García J. eBrain computer-interfaces: Conceptualization, redesign challenges and social impact. Revista Mexicana de Ingeniería Biomédica [Internet]. 2019 [citado 28 de marzo de 2024]; 40(3). Disponible en: https://doi.10.17488/RMIB.40.3.8