A Minimally Conscious Patient Suddenly 'Awakens,' Thanks to a Common Depressant

A sadly short-lived reemergence from life experienced through a pinhole.

Dec 14 2014, 8:07pm

Image: Wiki

​The doctors weren't expecting that the small dose of a common anti-anxiety drug called midazolam would do anything more than lightly sedate their patient for a CT scan—as intended. But said patient, who had been in a minimally-conscious state for two years following a motorcycle accident-caused brain injury, quite suddenly began to interact and converse, just out of the blue. He chatted up the anesthesiologist, talked to his aunt via cellphone, and congratulated his brother on a recent graduation.

Then, the patient reverted, just as suddenly returning to a near-vegetative existence, a relationship with the world through a pinhole of awareness and interactivity.

This "awakening," which occurred in a hospital in Pisa, Italy, ​is described by a team of neuroscientists in the current issue of Restorative Neurology and Neuroscience. Following the event, the team attempted to duplicate it using the same drug. Again, the patient began to converse and interact, "appropriately" following both behavioral and verbal commands. The patient had no memory of the accident and no awareness of his current status. Normal life might as well have been yesterday.

As the drug wore off, the patient again receded.

With help from EEG recordings, the neuroscientists have so far focused on activity in two regions of the brain: the task-positive network and the linguistic network. "Our attention has focused on these two particular networks because we believe that their functional improvement has substantially contributed to determine the awakening reaction presented by our patient," they write in the current paper.

"The task-positive network, in fact, has to deal with the ability to cope with and solve cognitive tasks that require explicit behavioral responses, while the linguistic one deals with language comprehension and production," the neuroscientists explain.

Image: Maria Chiara Carboncinia et al

"Awakenings" like this aren't unheard of. Researchers have had some previous success with other benzodiazepines (depressants in the same general family as Xanax) as well as the stimulant amantadine, which is sometimes used to treat Parkinson's disease. The patient in question hadn't responded to any of them.

So, why midazolam? It has to do with brain wave frequencies, possibly. The "power spectrum" of these frequencies is biased in different ways in minimally-conscious or catatonic patients; the peak frequency for this particular patient is around 7 Hz. Midazolam appears to smooth the power spectrum out, limiting the harmful bias.

What all of this means for treating minimally-conscious states in general remains to be seen, but the Italian group offers it as at least something that might be tried in other patients, particularly those sharing a similar peak power spectrum frequency.

"These patients may be candidates for a continued treatment with oral benzodiazepines," the team concludes, "or, theoretically, for a more aggressive protocol, such as the continuous intravenous infusion of midazolam, which is commonly practiced in the intensive care unit to interrupt a [prolonged epileptic seizure."