Patients react immediately when the ILN is stimulated in this manner: they open their eyes, their pupils dilate, they make meaningless sounds, their blood pressure increases and their EEG activity desynchronizes. This arousal reaction by itself is not of therapeutic utility and does not predict recovery. But the long-term effect of such stimulation was encouraging: eight of 21 patients transitioned from the unresponsive VS to the more communicative MCS condition, and the five MCS patients who were stimulated emerged from their bedridden state, with four of them able to enjoy life back at home. Because Yamamoto exclusively targeted therapy to between three and six months after the patient’s injury, however, most likely at least some of these patients would have recovered spontaneously, even without intervention.
Furthermore, it is doubtful that any type of DBS could be beneficial to the most severely affected patients, such as those in permanent VS. As a historical note, Schiavo was enrolled in one of these earlier brain-stimulation trials, but to no avail.
A recent judicious case study of a single MCS patient, however, directly demonstrated the usefulness of DBS. It was carried out by a multi-institutional team of neurologists, neurosurgeons, neuroscientists and an ethicist assembled by Nicholas D. Schiff of the Weill Cornell Medical College in New York City, Joseph T. Giacino and Kathleen Kalmar of the JFK Johnson Rehabilitation Institute in Edison, N.J., and the Cleveland Clinic in Ohio. The 38-year-old patient suffered severe brain trauma from an assault. After some initial improvement, his condition stabilized and did not change substantially over the next six years. The individual had the characteristic pattern of MCS: minimum motor control, mainly voluntary eye movements, and, infrequently, single words or other vocalizations; he could not even eat by mouth.
After implanting two electrodes in the anterior parts of the left and right ILN of the patient’s thalami and after a two-month postoperative recovery period, the patient went through 11 months of on-and-off DBS therapy. The outcome was a remarkable improvement in the man’s awareness and motor control. When the DBS is turned on, the patient can make hand and arm movements and can chew and swallow his own food, a major step in improving his quality of life. Most dramatically, he can communicate via gestures, words and, at times, short sentences. Some of these activities depend on ongoing electrical stimulation, implying a direct causal effect of DBS on cognitive and motor skills. Furthermore, the almost one-year-long DBS therapy has ameliorated the overall functionality of the patient’s brain because some of the beneficial effects persist even when DBS is turned off. In other words, the treatment has both sustained short-term benefits as well as slowly accumulated long-term carryover effects.
One successful intervention is not a proven therapy, nor a cure for MCS, as Schiff and his colleagues caution. MCS is a very diverse syndrome, and whether any improvement occurs, and on what timescale, will depend on a host of factors, such as severity and distribution of the injury, overall condition of the patient, and so on. But if the improvement is replicated, it shows that advances in the basic neurosciences, combined with the appropriate prosthetic technology, might restore motor functions and the mechanisms supporting awareness in the brain.
This article was originally published with the title Reviving Consciousness.