[Vegetative State: Difficulty in Identifying Consciousness and Predicting Outcome]

Area of Science:

• Neuroscience
• Neurology
• Medical Imaging

Background:

• Vegetative state (VS) presents challenges in predicting consciousness recovery.
• Existing neuroimaging and neurophysiological methods offer insights into brain function in VS patients.
• Understanding residual brain activity is key to prognostication.

Purpose of the Study:

• To review and analyze neurovisualization and neurophysiological methods for predicting consciousness recovery in VS.
• To evaluate the sensitivity and specificity of Positron Emission Tomography (PET) with FDG and functional Magnetic Resonance Imaging (fMRI).
• To discuss the role of neurophysiological tests like EEG, TMS, and EP.

Main Methods:

• Literature review of studies applying neurovisualization (PET, fMRI) and neurophysiological tests.
• Analysis of fMRI's ability to assess brain activity at rest and in response to stimuli.
• Evaluation of neurophysiological tests for accessibility and effectiveness.

Main Results:

• PET with FDG shows higher sensitivity than fMRI in detecting consciousness signs.
• fMRI with an active paradigm offers higher specificity, but its absence doesn't rule out prognosis.
• Neurophysiological tests are accessible and effective in evaluating residual functional activity.

Conclusions:

• Neurovisualization and neurophysiological tests reflect residual brain activity in VS, crucial for predicting outcomes.
• Consciousness recovery correlates with restored thalamocortical tract function, indirectly assessed by these methods.
• A unified pathophysiological concept for brain function in VS is lacking; authors propose a 'stable pathological states' concept.