Auditory Processing in DOC Patients

Hierarchical Auditory Processing in Disorders of Consciousness: From Basic Deviance Detection to Semantic Integration

This prospective observational study investigates whether electroencephalography (EEG) can improve the differentiation between unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS) in patients with severe acquired brain injury. The study further examines the association between EEG markers of auditory processing and long-term functional outcome at 12 months.

Accurate classification of disorders of consciousness remains challenging in neurological early rehabilitation. Behavioral assessment is the clinical standard, yet misclassification persists, particularly in patients with severe motor impairment or fluctuating arousal. Neurophysiological measures may provide complementary information beyond observable behavior.

This study applies event-related potential (ERP) paradigms during bedside EEG recording to assess hierarchical levels of auditory processing in patients with disorders of consciousness in the subacute phase after brain injury. The paradigms are designed to detect neural responses reflecting basic auditory discrimination as well as higher-order cognitive processing.

The primary objective is to determine the highest neurophysiologically detectable level of auditory processing and to examine whether it differs between clinically defined consciousness groups. Secondary objectives include evaluating the relationship between EEG-derived markers and standardized behavioral assessments, as well as assessing the prognostic value of EEG findings for functional outcome one year after admission.

The study aims to clarify the diagnostic and prognostic relevance of EEG-based measures in routine neurorehabilitation settings.

Inclusion Criteria:

• Presence of a disorder of consciousness (Unresponsive Wakefulness Syndrome [UWS] or Minimally Conscious State [MCS]), classified using the Coma Recovery Scale-Revised (CRS-R) based on three assessments conducted on at least two separate days
• Age between 18 and 80 years
• Written informed consent provided by the patient's legal representative
• Preserved brainstem auditory evoked potentials (BAEPs) on at least one side

Exclusion Criteria:

• Ongoing sedation at the time of EEG assessment
• Current treatment with medications known to significantly affect cortical functional state, including barbiturates, neuroleptics (antipsychotics), antiepileptic drugs, benzodiazepines, or comparable agents
• Colonization with multidrug-resistant organisms requiring isolation precautions (e.g., 4MRGN)
• Pregnancy
• Impaired language comprehension (e.g., insufficient German language proficiency or aphasia)
• Temporal bone fractures or severe infratentorial brain injury associated with unilateral or bilateral absence of auditory evoked potentials (AEPs)
• Bilateral hearing impairment or deafness, or presence of a cochlear implant
• Scalp wounds or conditions preventing placement of an EEG electrode cap