An fMRI Study of Patients with Severe Brain Injury

S. Andrew Josephson, MD

Disclosures

AccessMedicine from McGraw-Hill 

After severe brain injury, some unfortunate patients are left in a state of wakefulness with eyes open, but without any signs of awareness; the term “vegetative state” is used to describe these patients. Other patients are able to show inconsistent signs of awareness but still cannot communicate effectively and are said to be in a “minimally conscious state.” These diagnoses to date have been based solely on a detailed clinical examination. A recent study (Monti et al, 2010) aimed to examine whether the use of functional MRI (fMRI) could lead to reclassification of some of these patients and be used as a means to establish communication between these neurologically devastated patients and their caregivers.

The authors studied 54 patients with severe brain injury, 23 in the vegetative state and 31 in a minimally conscious state. After verifying their fMRI methods on 16 normal subjects, the brain-injured patients were asked to perform a motor task, imagining playing tennis, as well as a spatial imagery task, imagining navigating the streets of their city or walking from room to room in their house. The authors examined the fMRI data to see if areas of the brain involved in motor and spatial imagery were activated in these patients appropriately during these tasks as they would be in normal individuals.

Of the 54 patients, 5 were indeed able to willfully modulate their brain activity with activation of the supplementary motor area during the tennis task (5 of 5) and activation of the parahippocampal gyrus (4 of 5) during the spatial navigation task. All 5 of these patients had a traumatic brain injury as the etiology of their neurologic injury, and 4 of the 5 had previously been classified as in a vegetative state. When the authors returned to the bedside, three were found to have some signs of awareness and therefore more appropriately classified as in a minimally conscious state; however, the other two had no signs of such awareness on clinical examination despite the fMRI findings.

The authors found that only 1 of the 5 patients could use this technique as a means of communication. They asked the subject to answer simple yes/no autobiographical questions (“Is your name Fred?”) by imagining the motor task as “yes” or the sensory task as “no.” In this way, examination of the fMRI areas of activation could be used to gauge the patient’s answers, which were found to be autobiographically correct. In this patient, no other clinical means of communication at the bedside could be established.

This interesting study demonstrates that a small number of patients thought to be in a vegetative state through bedside testing may indeed actually be in a minimally conscious state. This distinction, while important from a classification and research standpoint, really means little to families and patients with severe neurologic injury looking for meaningful signs of interaction with the outside world. However, the methods of communication established with one single patient using fMRI are an important advance and could pave the way for future studies to determine if sophisticated imaging techniques of the brain would allow for simple communication in a small minority of these patients, allowing families to communicate with their loved ones on some level.

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