Disorders of Consciousness

Educational Objectives

The goal of this program is to improve management of disorders of consciousness. After hearing and assimilating this program, the clinician will be better able to:

1. Differentiate the locked-in state of consciousness from the comatose state.
2. Use diagnostic modalities to identify patients with cognitive motor dissociation.

Summary

Assessment of consciousness: a study comparing the Glasgow Coma Scale (GCS) and the Coma Recovery Scale (CRS), which evaluates auditory, motor, and oral motor function, found a 40% increase in consciousness detection with CRS; patients in a minimally conscious state demonstrated better clinical outcomes compared with patients in a vegetative state at 12 mo; achieving this level of recovery is a long-term process which poses challenges in care

Etiology: mortality in traumatic brain injury (TBI) ranges from 40% to 50%; however, a study by Turgeon et al (2011) found that 70% of mortality was due to withdrawal of life sustaining support (WLST), and 50% of withdrawals happened within 3 days; Vlachos et al (2023) performed a retrospective analysis of patients with cardiac arrest and found that WLST accounted for 59% of deaths; 16% of the patients that were withdrawn upon would have been predicted to have a functionally favorable survival according to their prognostic model

Disorders of consciousness: fully recovered/conscious patients has preserved motor and cognitive function; patients in comas have highly compromised cognitive and motor function; patients in a locked-in state have fully intact cognitive function, but have functional problems in motor representation of that cognitive function, and are not able to interact with the outside world; minimally conscious patients are emerging from coma and have some level of interaction with the world, but not to the level of full cognitive recovery; patients with cognitive motor dissociation (CMD) exhibit some level of cognitive function but lack the motor ability to express that cognition externally; unlike patients in a locked-in state who may demonstrate preserved cognition through actions like blinking, patients with CMD lack motor responses; cognitive impairment is coupled with a deficit in motor function

Owen et al (2006): functional magnetic resonance imaging (fMRI) was used to demonstrate preserved conscious awareness in a patient 26 yr of age who was in a car accident and fulfilled the criteria for a diagnosis of vegetative state; the patient was asked to imagine playing tennis or moving around the home and activated predicted cortical areas in a manner indistinguishable from that of healthy volunteers

Brain function assessment: electroencephalography (EEG) is primarily used for detecting seizures and assessing the background activity of the brain to guide appropriate interventions; EEG recordings may provide insights into cortical functioning based on the frequency patterns of brain waves; various categories or spectra have been developed to analyze frequency patterns and evaluate cortical function

Claassen et al (2019): compared healthy patients with patients with CMD and patients who were comatose; the comatose group was instructed to perform a hand-opening or hand-closing task while their EEG was recorded; the EEG patterns were compared with the patterns of a healthy cohort using a machine learning algorithm; patients whose brain wave patterns resembled patterns of healthy controls were identified as having CMD; this approach provides a bedside technique for identifying patients with CMD (which was previously detectable only through fMRI imaging); a follow-up study found that CMD patients were found to have a high rate of good functional recovery up to 12 mo compared with patients in comas, in addition to a shorter time to improved recovery

Guidelines from the European Academy of Neurology: emphasize the value of advanced diagnostic tools such as high-density EEG, positron emission tomography (PET) scans, and fMRI in providing a detailed assessment of patients with coma and related disorders; integration of clinical rating scales, observation of voluntary eye movements, EEG-based techniques, and functional neuroimaging into a comprehensive diagnostic approach is recommended

Physiology of coma: involves various structural injuries, eg, bihemispheric injury, bilateral thalamic injury, brainstem injury (particularly in the midbrain and pons); toxic metabolic insults may lead to widespread neuronal dysfunction; emerging evidence suggests that coma and consciousness are circuit-based problems; the mesiocircuit model illustrates complex interactions among different brain structures crucial for consciousness; disconnections among circuits may lead to impaired consciousness; using EEG paradigms, CMD patients exhibit distinct brain activity patterns compared with comatose patients; investigating the functional and structural differences between groups may offer insights into the underlying mechanisms of CMD and coma

Franzova et al (2023): conducted a retrospective analysis to investigate structural injuries in patients with CMD and patients in a comatose state; distinct injury patterns unique to each patient group were identified with machine learning techniques; patients with thalamic injury were more likely to be comatose; patients with brainstem injuries tended to exhibit coma; bicortical injury emerged as a predictive factor for CMD and coma; researchers focused on EEG coherence when examining patients with CMD and comatose patients with cortical injuries; coherence measures the synchronization of different parts of the cortex; higher coherence indicates better communication within the cortex; patients with CMD exhibited greater cortical coherence compared with patients in comas

Future therapies: efforts to find effective treatments for consciousness disorders, including pharmacological and surgical interventions, have produced limited success; pinpointing the location of brain injury is crucial for development of new treatments

Readings

Claassen J, Doyle K, Matory A, et al. Detection of brain activation in unresponsive patients with acute brain injury. N Engl J Med. 2019 Jun 27;380(26):2497-2505. doi: 10.1056/NEJMoa1812757; Franzova E, Shen Q, Doyle K, et al. Injury patterns associated with cognitive motor dissociation. Brain. 2023 Nov 2;146(11):4645-4658. doi: 10.1093/brain/awad197; Kondziella D, Bender A, Diserens K, et al; EAN Panel on Coma, Disorders of Consciousness. European Academy of Neurology guideline on the diagnosis of coma and other disorders of consciousness. Eur J Neurol. 2020 May;27(5):741-756. doi: 10.1111/ene.14151; Paunet T, Mariano-Goulart D, Deverdun J, et al. Functional PET neuroimaging in consciousness evaluation: study protocol. Diagnostics (Basel). 2023 Jun 10;13(12):2026. doi: 10.3390/diagnostics13122026; Vlachos S, Rubenfeld G, Menon D, et al. Early and late withdrawal of life-sustaining treatment after out-of-hospital cardiac arrest in the United Kingdom: Institutional variation and association with hospital mortality. Resuscitation. 2023 Dec;193:109956. doi: 10.1016/j.resuscitation.2023.109956; Wang J, Hu X, Hu Z, Sun Z, Laureys S, Di H. The misdiagnosis of prolonged disorders of consciousness by a clinical consensus compared with repeated coma-recovery scale-revised assessment. BMC Neurol. 2020;20(1):343. Published 2020 Sep 12. doi:10.1186/s12883-020-01924-9.

Disclosures

For this program, members of the faculty and planning committee reported nothing relevant to disclose.

Acknowledgements

Dr. Franzova was recorded at Jefferson Neurocritical Care Symposium, held February 3, 2024, in Philadelphia, PA, and presented by Thomas Jefferson University. For information on upcoming CME activities from this presenter, please visit https://Jefferson.edu. Audio Digest thanks the speakers and Thomas Jefferson University for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0.75 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0.75 CE contact hours.

Lecture ID:

NE150903

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.

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