Unconsciousness or unresponsiveness in Akinetic Mutism? Insights from a multimodal longitudinal exploration.

The clinical assessment of patients with disorders of consciousness (DoC) relies on the observation of behavioral responses to standardized sensory stimulation. However, several medical comorbidities may directly impair the production of reproducible and appropriate responses, thus reducing the sensitivity of behavior-based diagnoses. One such comorbidity is Akinetic Mutism (AM), a rare neurological syndrome characterized by the inability to initiate volitional motor responses, sometimes associated with clinical presentations that overlap with those of DoC. In this paper, we describe the case of a patient with large bilateral mesial frontal lesions, showing prolonged behavioral unresponsiveness and severe disorganization of electroencephalographic (EEG) background, compatible with a vegetative state/unresponsive wakefulness syndrome (VS/UWS). By applying an unprecedented multimodal battery of advanced imaging and electrophysiology-based techniques (AIE) encompassing spontaneous EEG, evoked potentials, event-related potentials, transcranial magnetic stimulation combined with EEG, and structural and functional MRI, we provide: (i) a demonstration of the preservation of consciousness despite unresponsiveness in the context of complete AM, (ii) a plausible neurophysiological explanation for behavioral unresponsiveness and its subsequent recovery during rehabilitation stay, and (iii) novel insights into the relationships between DoC, AM, and parkinsonism. The present case offers proof-of-principle evidence supporting the clinical utility of a multimodal hierarchical workflow that combines AIEs to detect covert signs of consciousness in unresponsive patients.