Lay summary – Mitochondria are tiny structures inside cells that help produce the energy the brain needs to work properly. After a traumatic brain injury, mitochondria may stop working as they should, which can make it harder for brain cells to recover. This study aimed to compare two ways of identifying mitochondrial dysfunction in people with acute traumatic brain injury. One approach uses existing criteria based on cerebral microdialysis, a method that measures chemicals in the brain. The other uses a newer approach that combines information from different types of brain monitoring. Comparing these methods may help researchers and clinicians better understand when the injured brain is struggling to produce enough energy and how this relates to other signs of brain health.