Ep. 179: Language and communication impairment after coma

00:00:00: Welcome to EANcast, your weekly source for education, research and updates from the European Academy of Neurology.

00:00:15: Hello and welcome to the EANcast Weekly Neurology.

00:00:19: My name is Alfonso Magiacano.

00:00:22: I am a psychologist and a researcher working on neuroreplication of severe acquired brain injuries at Fundazione Dogniochi in Florence and Sant'Angelo di Rombardi in Italy.

00:00:34: In today's episode, we'll explore a fascinating and complex topic, the language and communication impairments after coma.

00:00:44: Our guest today is Dr.

00:00:46: Charlotte Nubine, neuropsychologist and speech therapist at the Coma Science Group, the University of Liege in Belgium.

00:00:53: Her research focuses on disentangling the relationship between the language processing and consciousness in patients recovering from severe brain injury.

00:01:04: Sharlene, welcome and thank you so much for joining us today.

00:01:09: Thank you Alfonso.

00:01:11: Let's start with the basics.

00:01:13: Many patients who emerge from a coma may still present disorders of consciousness, such as the vegetative state or the minimally conscious state.

00:01:24: Sharlene, could you briefly explain what these conditions are and what distinguishes one from the other?

00:01:32: Well, disorders of consciousness are conditions in which patients' awareness of themselves or their environment is impaired or absent after a severe brain injury.

00:01:46: Coma itself is a state of complete unconsciousness lasting more than one hour in which patients can't be aroused and don't open their eyes even to stimuli.

00:01:58: When patients start opening their eyes, they enter a non-responsive wakefulness syndrome where there is no other sign of consciousness.

00:02:08: If the letters show reproducible behaviors such as following a moving object with their eyes or performing simple motor actions like grabbing a bedsheet, they are classified as minimally conscious state minus.

00:02:25: Compared to the minimally conscious state minus in the minimally conscious state plus, patients also demonstrate some language-based behaviors like responding to simple verbal comments or attempting yes-no communication.

00:02:40: Finally, they can use these responses consistently or functionally use objects and then they are considered to be emerging from the minimally conscious states.

00:02:55: But besides, some patients may appear unresponsive at the bedside, yet show volitional brain activity on EEG or fMRI when asked to imagine performing specific activities or movements.

00:03:10: And in this case, they are considered as having a cognitive motor dissociation.

00:03:15: So, in accurate diagnosis of these disorders seems to be absolutely crucial, but for prognosis and for treatment planning.

00:03:26: But why is this diagnostic accuracy so important and how can comorbidities such as sensory, motor or language impairments complicate the clinical picture?

00:03:42: Well indeed getting the diagnosis right is crucial both for prognosis and treatment planning.

00:03:49: Well, maybe first, mortality and recovery chances differ drastically depending on whether a patient is diagnosed as unresponsive with Ness syndrome or a minimally conscious state just one month after injury.

00:04:03: For example, mortality is really halved in minimally conscious state and the likelihood of functional recovery is also significantly higher.

00:04:13: A second point is that the diagnosis gets treatment.

00:04:17: Some brain stimulation techniques, whether invasive or non-invasive, seem effective in minimally conscious state, but not in the unresponsive workfulness syndrome.

00:04:28: And third, ethically, diagnosis affects decisions about life-sustaining treatment.

00:04:36: A survey study showed that healthcare professionals are generally more accepting of withdrawing treatments in chronic and responsive workfulness syndrome than minimally conscious states.

00:04:51: And however, comorbidities complicate this picture.

00:04:55: As you said, motor paralysis, sensory deficits, or language impairments like aphasia can prevent patients from showing purposeful responses.

00:05:05: and without a careful assessment, these patients may be misclassified as unresponsive even if some awareness is preserved, emphasizing the importance of thorough multimodal assessments.

00:05:20: So one major issue in this context seems to be aphasia or language impairment.

00:05:27: Could you help us understand how aphasia can interfere with the assessment of consciousness?

00:05:34: In other words, How do we avoid mistaking a patient's inability to communicate for a lack of awareness?

00:05:43: Yes indeed, aphasia is particularly challenging because patients may understand very little of what is asked even if they are conscious.

00:05:51: Studies have shown that receptive aphasia involving comprehension difficulties can prevent them from following comments during behavioral, EEG and fMRI assessments.

00:06:04: A first study with post-stroke conscious aphasic patients showed that more than half of those with global aphasia were mistakenly classified as minimally conscious when using standard behavioral scales.

00:06:18: And a second study based on EHE recently demonstrated that brain responses to motor comments were also much weaker in aphasic patients.

00:06:31: So in short, inability to communicate doesn't equal lack of awareness and clinicians must account for language deficits to avoid misdiagnosis.

00:06:42: So when it comes to the assessment, is it actually possible to evaluate specific language components in patients with disorders of consciousness in the same way we might do with conscious, phasic patients?

00:06:57: And if so... What kinds of clinical or experimental tools are available for this purpose?

00:07:05: Evaluating specific language functions in post-commetose patients is possible, but far more complex than in conscious aphasic patients.

00:07:14: Behavioral responses are often minimal, so traditional aphasia tests can't be used reliably.

00:07:22: At the clinical level, tools like the brief evaluation of receptive aphasia, the PERA, assess language via I guess responses, asking patients to look at the correct picture when a word or sentence is presented.

00:07:40: So this allows differentiation of language deficits even in minimally conscious patients.

00:07:45: and once basic communication returns, conventional tools for stroke patients like the Mississippi aphasia screening test can help further refine language profiles.

00:07:58: Now, at the experimental level, EEG and fMRI can detect language processing without requiring behavior.

00:08:06: For instance, EEG markers like the N-Fourhundred Wave revives semantic processing.

00:08:13: And fMRI studies also show activation in language areas during passive listening.

00:08:20: Combining behavioral and neurophysiological assessments gives the most complete a picture of residual language abilities.

00:08:28: in brief.

00:08:31: Then language and communication abilities are often considered side on better cognitive recovery.

00:08:39: But would you say that the recovery of language functions can also serve as a prognostic marker for overall consciousness recovery on all limited outcomes?

00:08:51: Yes, language recovery is more than a functional milestone and can predict overall consciousness recovery.

00:08:58: Even subtle language processing after a coma correlates with better outcomes.

00:09:04: So for example, one study measured EEG brain responses in patients who couldn't follow commands while listening to streams of words forming simple phrases.

00:09:16: And those whose brains tracked the rhythm and structure of sentences more strongly were also more likely to recover at functional level several months later.

00:09:32: And in another study, patients with the same level of consciousness but with higher communication abilities as measured by the functional communication measures.

00:09:42: also had a better outcome.

00:09:45: So this suggests that language can return before full consciousness and its monitoring may provide valuable prognostic insights.

00:09:57: So, Sharlaine, from a speech therapy perspective, working with post-comatose patients must be incredible challenging.

00:10:06: But what are the main pitfalls or difficulties that speech therapists face in this area?

00:10:12: And what are future direction or promising approaches that do you see emerging in this field?

00:10:21: Well, thank you for this question, Alfonso.

00:10:25: Speech therapy in postcometerous patients is extremely challenging indeed.

00:10:30: For four main reasons that have been reported in our recent survey study.

00:10:37: First, there are patient-related difficulties, which include fluctuating lateness, medical instability, limited cooperation or motor and cognitive impairments.

00:10:51: Agitation or resistance can further disrupt therapy and complex medical needs like tracheotomy care require specialized skills as well.

00:11:02: Secondly, family involvement is essential but also complicated.

00:11:06: relatives may be distressed or have expectations that don't match reality requiring careful communication with them.

00:11:15: Multidisciplinary teams also face hurdles, such as unclear oral definitions, insufficient collaboration and gaps.

00:11:23: in no-lage about brain injury and individualized care.

00:11:28: And finally, resource limitations, such as lack of standardized guidelines, limited training and inadequate tools pose ongoing challenges.

00:11:39: And looking forward... Promising approaches include tailored assessment tools, standardized rehabilitation protocols and multidisciplinary training, as well as technologies like eye tracking or neuroimaging to detect residual language in patients with disorders of consciousness.

00:12:02: Thank you, Sherline.

00:12:03: And to close with a more philosophical but scientifically interesting question, is it possible to have language without consciousness?

00:12:12: For instance, do experimental or neuroimaging studies suggest that some degree of unconscious language processing might persist even when a word is absent?

00:12:26: Yes, well, by assessing residual language in post-commit to patients, I actually faced difficulties in dissociating language from disorders of consciousness partly because there is no clear boundary between the two functions in healthy cognition.

00:12:45: And looking at the literature, I found that some language processing can occur even without full consciousness.

00:12:54: So neuroimaging and experimental studies show that high-level processes like sentence integration require awareness, but lower-level processes such as phonetic discrimination or simple lexicosemantic processing can persist in unconsciousness.

00:13:14: And as our clinical observations also suggest that certain language functions can reemerge before full consciousness, there seems to be a complex and partially independent relationship between the two functions.

00:13:30: So while reflective, meaningful language requires awareness, the brain can still process some linguistic information unconsciously.

00:13:41: And this has real clinical relevance, for example, considering a behaviorally unresponsive patient who still shows residual high-level language processing in passive listening tasks.

00:13:55: This was a truly fascinating discussion, Shatlan.

00:13:58: Thank you for sharing your insight and your research with us today.

00:14:03: But before we wrap up, could you summarize one or two key tech home messages for our listeners?

00:14:10: Perhaps something clinicians should keep in mind when assessing or treating patients of their own.

00:14:18: Well, yes, I say first that inaccurate assessment requires combining behavioral observation and neurophysiological tours, and it guides prognosis therapy and decision making.

00:14:32: Secondly, understanding residual language and communication in post-commetose patients gives us a window into their cognitive recovery trajectory.

00:14:45: And finally, even when behavioral responses are absent, the brain may still process language at a basic or higher level, which has both clinical and ethical implications.

00:15:03: Thank you again, Shetland, for joining us and for your valuable contribution.

00:15:08: And thank you to all our listeners for tuning into the EIN Cast Weekly Neurology.

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