Current evaluation of unconscious patients is limited and based on exhibited behaviour. The difficulty in evaluation is derived from the fact that this type of diagnosis depends on the patient’s ability to perform motor functions, and inability to perform motor functions does not necessarily imply lack of consciousness. Therefore, there may be patients with residual cognitive abilities that are missed using the existing clinical tests. Functional imaging opens possibilities of direct assessment of brain abilities without depending on behvioural measures.
Novel papers published in the past few years demonstrate that fMRI can identify brain activity in unconscious patients. Following these papers, in late 2010 we have started performing clinical tests to identify signs of awareness in unconscious patients. The tests are based on the tests used in these groundbreaking papers. We test for brain reaction to auditory stimuli, as well as reaction to more complex stimuli such as language and the patient’s name. In addition, we test the patient’s ability to perform conscious action. We request the patient to imagine something – hum a song, imagine an image, imagine engaging in sports, and imagine navigation. Using the MRI we can see whether the patient has performed the task or not. Identifying a corresponding response to the task indicates comprehension of language and task performing capabilities. We also use those novel methods in evaluating patients receiving a novel regenerative drug (RPh201).
It is important to note the limitations of this test. While positive results do supply information regarding patient’s condition, nothing can be inferred from negative ones. The test reflects patients’ awareness during the limited time they are inside the magnet. It is possible that during that time patients were tired, unfocused, or unmotivated. Additionally, uncontrolled movements of the patients during scanning are common and significant motion decreases the reliability of the results. Our experience from the first 11 patients was published in the Journal of Neurological Sciences.
It is important to state that this stage, consciousness evaluation using fMRI is a pure diagnostic tool, and its therapeutic implications of results are unclear.
The test’s complexity requires a preliminary meeting with the patient’s family, to match the test to the patient. To make an appointment, contact the neurological clinic nurse, 02-6778437 (fMRI clinic).