Pain in prolonged disorders of consciousness: Laser evoked potentials findings in patients with vegetative and minimally conscious states

Tommaso, Marina de; Navarro, Jorge; Ricci, Katia; Lorenzo, Marta; Lanzillotti, Crocifissa; Colonna, Fabio; Resta, M.; Lancioni, Giulio E.; Livrea, Paolo

doi:10.3109/02699052.2013.775507

Cited by 38 publications

(34 citation statements)

References 34 publications

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“…PICO questions 1–3 refer to clinical standard (resting state) EEG, PICO questions 4–6 to consciousness paradigms, including high‐density EEG, TMS‐EEG and evoked potentials. Thirty publications were included for final analysis . PICO 1 Can visual analysis of clinical standard EEG differentiate coma and VS/UWS from MCS? …”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

European Academy of Neurology guideline on the diagnosis of coma and other disorders of consciousness

Kondziella

Bender

Diserens

et al. 2020

Euro J of Neurology

488

392

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Section: Resultsmentioning

confidence: 99%

“…Fourteen studies with 1298 patients were eligible for inclusion . The relative risk for detection of signs of covert consciousness with cognitive evoked potentials compared to clinical examination was 1.49 (95% CI 1.27–1.75; P < 0.0001).…”

Section: Resultsmentioning

confidence: 99%

European Academy of Neurology guideline on the diagnosis of coma and other disorders of consciousness

Kondziella

Bender

Diserens

et al. 2020

Euro J of Neurology

488

392

View full text Add to dashboard Cite

show abstract

“…In addition, and of special concern, healthy volunteers may not necessarily be able to cooperate in active paradigms; for instance, in one study, only 9 (75%) of 12 healthy controls produced EEG data that could be classified significantly above chance 48. As to EEG-based paradigms, it seems important to be aware that the absence of some ERPs does not exclude the presence of others;47 that the latency of ERPs can be increased and their amplitude decreased;28 and that serial ERP testing may reveal inconsistent results 30. Notably, the stability of auditory information processing in VS and MCS patients, for example, as indicated by a preserved P300 response, is the prerequisite for other even more demanding tasks and cognitive potentials 30.…”

Section: Discussionmentioning

confidence: 99%

Preserved consciousness in vegetative and minimal conscious states: systematic review and meta-analysis

Kondziella

Friberg

Frøkjær

et al. 2015

J Neurol Neurosurg Psychiatry

238

219

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Active, passive and resting state paradigms using functional MRI (fMRI) or EEG may reveal consciousness in the vegetative (VS) and the minimal conscious state (MCS). A meta-analysis was performed to assess the prevalence of preserved consciousness in VS and MCS as revealed by fMRI and EEG, including command following (active paradigms), cortical functional connectivity elicited by external stimuli (passive paradigms) and default mode networks (resting state). Studies were selected from multiple indexing databases until February 2015 and evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2. 37 studies were identified, including 1041 patients (mean age 43 years, range 16-89; male/female 2.1:1; 39.5% traumatic brain injuries). MCS patients were more likely than VS patients to follow commands during active paradigms (32% vs 14%; OR 2.85 (95% CI 1.90 to 4.27; p<0.0001)) and to show preserved functional cortical connectivity during passive paradigms (55% vs 26%; OR 3.53 (95% CI 2.49 to 4.99; p<0.0001)). Passive paradigms suggested preserved consciousness more often than active paradigms (38% vs 24%; OR 1.98 (95% CI 1.54 to 2.54; p<0.0001)). Data on resting state paradigms were insufficient for statistical evaluation. In conclusion, active paradigms may underestimate the degree of consciousness as compared to passive paradigms. While MCS patients show signs of preserved consciousness more frequently in both paradigms, roughly 15% of patients with a clinical diagnosis of VS are able to follow commands by modifying their brain activity. However, there remain important limitations at the single-subject level; for example, patients from both categories may show command following despite negative passive paradigms.

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“…Thus, the authors proposed the analysis of the brain’s global functional connectivity as a potentially useful tool for reliably differentiating between UWS/VS and MCS [57]. Finally, other studies investigated pain perception in patients with DOCs by implementing specific neurophysiological approaches mainly based on the use of laser-evoked potentials [58,59,60,61,62,63,64,65]. The most comprehensive results came from a study investigating the presence of both the Aδ-fiber and the C-fiber laser evoked potentials as a marker of a residual cortical pain processing [62].…”

Section: Emerging Neuroimaging Evidence About the Experience Of Pamentioning

confidence: 99%

Disorders of Consciousness: Painless or Painful Conditions?—Evidence from Neuroimaging Studies

et al. 2016

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The experience of pain in disorders of consciousness is still debated. Neuroimaging studies, using functional Magnetic Resonance Imaging (fMRI), Positron Emission Tomography (PET), multichannel electroencephalography (EEG) and laser-evoked potentials, suggest that the perception of pain increases with the level of consciousness. Brain activation in response to noxious stimuli has been observed in patients with unresponsive wakefulness syndrome (UWS), which is also referred to as a vegetative state (VS), as well as those in a minimally conscious state (MCS). However, all of these techniques suggest that pain-related brain activation patterns of patients in MCS more closely resemble those of healthy subjects. This is further supported by fMRI findings showing a much greater functional connectivity within the structures of the so-called pain matrix in MCS as compared to UWS/VS patients. Nonetheless, when interpreting the results, a distinction is necessary between autonomic responses to potentially harmful stimuli and conscious experience of the unpleasantness of pain. Even more so if we consider that the degree of residual functioning and cortical connectivity necessary for the somatosensory, affective and cognitive-evaluative components of pain processing are not yet clear. Although procedurally challenging, the particular value of the aforementioned techniques in the assessment of pain in disorders of consciousness has been clearly demonstrated. The study of pain-related brain activation and functioning can contribute to a better understanding of the networks underlying pain perception while addressing clinical and ethical questions concerning patient care. Further development of technology and methods should aim to increase the availability of neuroimaging, objective assessment of functional connectivity and analysis at the level of individual cases as well as group comparisons. This will enable neuroimaging to truly become a clinical tool to reliably investigate pain in severely brain-injured patients as well as an asset for research.

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Pain in prolonged disorders of consciousness: Laser evoked potentials findings in patients with vegetative and minimally conscious states

Abstract: The results may suggest that high relevant stimuli may be processed even in patients with severe brain damage. Larger series and multimodal approaches may contribute to confirm that cortical arousal toward pain salience may be a primary function for life persistence.

Cited by 38 publications

References 34 publications

European Academy of Neurology guideline on the diagnosis of coma and other disorders of consciousness

European Academy of Neurology guideline on the diagnosis of coma and other disorders of consciousness

Preserved consciousness in vegetative and minimal conscious states: systematic review and meta-analysis

Disorders of Consciousness: Painless or Painful Conditions?—Evidence from Neuroimaging Studies

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