Pain in Minimally Conscious Adults
NEW YORK, October 8 (Reuters Health)—A study of brain activity using highly sensitive PET scans suggested that individuals in a minimally conscious state can perceive pain and, therefore, should receive analgesic drugs.
Each year in the United States alone, more than 200,000 individuals sustain serious brain injuries that leave them with significant neurologic damage. Close to half of those patients will permanently lose the ability to live and function on their own.
Some brain-damaged individuals persist for years in what is called a “vegetative” state, showing no evidence that they are aware of the external world. Existing a step up from vegetative patients are the “minimally conscious” individuals who display occasional, inconsistent signs of consciousness.
The current study, which is reported in the November Lancet Neurology, looked at minimally conscious patients, as well as those in a persistent vegetative state.
“The biggest finding is how these minimally conscious patients’ brains respond to pain in a way very similar to your and my brain and how very different this is from what we saw in vegetative state patients, even if at the bedside the clinical examination of these ... patients is very, very similar,” senior author Dr. Steven Laureys told Reuters Health.
Dr. Laureys, a researcher with the University of Liège in Belgium, said that his team’s study is the first to use PET “to directly measure the brain’s response to potentially painful stimuli ... in minimally conscious patients who, by definition, cannot tell us if it hurts.”
The study included five minimally conscious patients, 15 in a persistent vegetative state, and 15 healthy comparison subjects. The brain response to painful electrical stimulation of a nerve in the hand was assessed with PET scans.
The authors found that brain responses to pain in the minimally conscious group were very similar to those seen in the healthy group. The responses in the vegetative state group, by contrast, were much weaker.
“In my view, our scanning results should be interpreted as strong evidence in favor of preserved perception of pain and hence should prompt clinicians to use painkillers even if patients cannot tell us they feel pain,” Dr. Laureys said.
Lancet Neurol. 2008;7(11):1013-1020.
REM Sleep Disorder in Parkinson’s Disease Points to Degenerative Pattern
NEW YORK, October 15 (Reuters Health)—REM sleep behavior disorder (RBD) in patients with Parkinson’s disease is associated with specific motor features, Canadian researchers reported in the October issue of the Journal of Neurology, Neurosurgery, and Psychiatry.
“Our study emphasizes that Parkinson’s disease, rather than being a uniform entity, can vary considerably between individuals,” lead investigator Dr. Ron B. Postuma told Reuters Health. “RBD may point to a subtype of ‘diffuse’ Parkinson’s disease that has more nonmotor manifestations, more cognitive impairment, less tremor, and less responsiveness to dopamine medications.”
Dr. Postuma of McGill University, Montreal, and colleagues used polysomnography to evaluate 36 Parkinson’s disease patients for RBD. The condition was defined as the absence of atonia during REM sleep, with a history of potentially harmful motor manifestations or complex motor behaviors seen on the sleep lab videotape recording during REM sleep. The team found that 21 of the patients had RBD while the others did not.
The RBD group was less likely to be tremor predominant (14% vs 53%), and less of their Unified Parkinson Disease Rating Scale score was accounted for by tremor (8.2% vs 19.0%). They also had a greater frequency of falls (38% vs 7%) and a significantly lower response to their medication.
Dr. Postuma and colleagues surmised that Parkinson’s disease patients with RBD “may have a different underlying pattern of neurodegeneration” than patients without RBD.
“We will continue to follow these patients over time, so that prognostic features and disease progression can be assessed prospectively,” the researchers said.
J Neurol Neurosurg Psychiatry. 2008;79(10):1117-1121.
Low Cystatin C Levels May Increase Alzheimer’s Disease Risk
NEW YORK, October 17 (Reuters Health)—The results of a study published in the September 30 issue of Neurology suggest that a low level of cystatin C may be a risk factor for the development of Alzheimer’s disease in elderly men.
“Cystatin C is an endogenous cysteine inhibitor, produced by nearly all human cells and available in all body fluids,” Dr. Johan Sundelöf, of Uppsala University, Sweden, and colleagues wrote. “During the past decade, experimental, genetic, and clinical data have suggested that cystatin C activity in the brain may protect against the development of Alzheimer’s disease by inhibition of β-amyloid aggregation, one of the pathologic hallmarks of the disease.”
The researchers examined the association between serum levels of cystatin C and the development of Alzheimer’s disease in a group of 1,230 men in their early 70s, who were reassessed when they were about 77 years old.