Invasive Multimodality Brain Monitoring

Coma reduces the sensitivity of the neurologic examination to ongoing secondary brain injury. Multimodality monitoring (MMM) consists of an array of diagnostic tools frequently used in a critical care setting that are designed to optimize central nervous system physiology and detect secondary injury at its earliest manifestation. Intracranial pressure (ICP) and cerebral perfusion pressure (CPP) monitoring is the cornerstone of MMM. The partial pressure of oxygen in brain parenchyma (PbtO(2)) and cerebral blood flow (CBF) sensors allow for precise determination of the adequacy of cerebral perfusion. The status of cerebral autoregulatory control can be evaluated by plotting PbtO(2) and CBF against CPP, and by calculating the pressure reactivity index (PRx). Tools such as intracranial electroencephalography (EEG) and continuous video EEG improve the rate of seizure detection. Microdialysis provides evidence of the metabolic consequences of central nervous system pathology and can be used to ensure adequate glucose supply, detect ischemia (which manifests as lactate/pyruvate elevation), and monitor for downstream signatures of tissue injury (glutamate and glycerol elevation). MMM sensors can be inserted via multilumen bolts and require data aggregation and display systems to allow for real-time visualization. Taken together, these devices and the physiologic relationships that they reveal can unlock powerful information about the cause and treatment of coma.