Covert cortical processing (CCP) is a newly recognized state of consciousness characterized by intact association cortex responses to environmental stimuli in the absence of behavioral evidence of stimulus processing. Historically, clinical evaluation of unresponsive patients following brain injury relied on behavioral assessments, but advances in neuroimaging and electrophysiologic techniques now allow clinicians to detect covert brain activity, including functional MRI (fMRI), electroencephalography (EEG), transcranial magnetic stimulation-EEG (TMS-EEG), and positron emission tomography (PET). These techniques enable the classification of patients based on covert brain activity, leading to new diagnostic categories such as cognitive-motor dissociation (CMD) and CCP. CCP is a spectrum of association cortex responses ranging from rudimentary to complex, and is not a monotonic state. It is crucial to refine diagnostic criteria and integrate these findings into clinical practice to better understand and treat patients with disorders of consciousness (DoC). The emergence of covert brain activity has prompted a reevaluation of traditional diagnostic categories, highlighting the need for more nuanced approaches to assess consciousness. Studies have shown that patients previously classified as vegetative state (VS) may exhibit covert processing of stimuli, indicating the presence of consciousness. The perturbational complexity index (PCI), which measures neural complexity, has shown promise in distinguishing conscious and unconscious states, particularly in patients with brain injury. PCI is a promising tool for assessing brain complexity and may provide a more accurate measure of consciousness. However, further research is needed to explore the relationship between CCP and PCI, as well as to determine the clinical implications of these findings. The integration of these findings into clinical practice is essential for improving the diagnosis and treatment of patients with disorders of consciousness.Covert cortical processing (CCP) is a newly recognized state of consciousness characterized by intact association cortex responses to environmental stimuli in the absence of behavioral evidence of stimulus processing. Historically, clinical evaluation of unresponsive patients following brain injury relied on behavioral assessments, but advances in neuroimaging and electrophysiologic techniques now allow clinicians to detect covert brain activity, including functional MRI (fMRI), electroencephalography (EEG), transcranial magnetic stimulation-EEG (TMS-EEG), and positron emission tomography (PET). These techniques enable the classification of patients based on covert brain activity, leading to new diagnostic categories such as cognitive-motor dissociation (CMD) and CCP. CCP is a spectrum of association cortex responses ranging from rudimentary to complex, and is not a monotonic state. It is crucial to refine diagnostic criteria and integrate these findings into clinical practice to better understand and treat patients with disorders of consciousness (DoC). The emergence of covert brain activity has prompted a reevaluation of traditional diagnostic categories, highlighting the need for more nuanced approaches to assess consciousness. Studies have shown that patients previously classified as vegetative state (VS) may exhibit covert processing of stimuli, indicating the presence of consciousness. The perturbational complexity index (PCI), which measures neural complexity, has shown promise in distinguishing conscious and unconscious states, particularly in patients with brain injury. PCI is a promising tool for assessing brain complexity and may provide a more accurate measure of consciousness. However, further research is needed to explore the relationship between CCP and PCI, as well as to determine the clinical implications of these findings. The integration of these findings into clinical practice is essential for improving the diagnosis and treatment of patients with disorders of consciousness.