Patients admitted to the ICU often have a primary brain condition (status epilepticus, head trauma, intracranial hemorrhage, etc.) and generally require sedation and analgesia. This results in brain dynamics different from that observed in conscious patients. Therefore, diagnosing brain damage in these patients can be very complicated. This diagnosis, however, is important, because establishing a correct treatment as quickly as possible is essential to improve the patient’s outcome. Furthermore, these patients have a very high probability of epileptic seizures and often require brain monitoring for extended periods (even longer than a week). Therefore, the use of qEEG is especially important in these patients. In addition, we will see how the use of numerical tools helps in the diagnosis and definition of epileptic seizures and in identifying the brain response to external stimuli, in this case to music, which can be useful in the development of neurorehabilitation methods.