Greater risk with mild TBI
Overall, the association was stronger for mild TBI than for moderate to severe TBI. This, said Dr. Leng, might be because of differences in the brain injury mechanism.
Mild TBI often involves repetitive concussive or subconcussive injuries, such as sports injuries or blast injury among active-duty military personnel. This type of injury is more likely to cause diffuse axonal injury and inflammation, whereas moderate or severe TBI is often attributable to a direct blow with more focal but severe damage, explained Dr. Leng.
She noted that veterans with mild TBI were more likely to have a psychiatric condition, but because the study controlled for such conditions, this doesn’t fully explain the stronger association between mild TBI and sleep disorders.
Further studies are needed to sort out the exact mechanisms, she said.
The association between TBI and risk for sleep disorders was reduced somewhat but was still moderate in an analysis that excluded patients who developed a sleep disorder within 2 years of a brain injury.
This analysis, said Dr. Leng, helped ensure that the sleep disorder developed after the brain injury.
The researchers could not examine the trajectory of sleep problems, so it’s not clear whether sleep problems worsen or get better over time, said Dr. Leng.
Because PTSD also leads to sleep problems, the researchers thought that having both PTSD and TBI might increase the risk for sleep problems. “But actually we found the association was pretty similar in those with, and without, PTSD, so that was kind of contrary to our hypothesis,” she said.
The new results underline the need for more screening for sleep disorders among patients with TBI, both in the short term and the long term, said Dr. Leng. “Clinicians should ask TBI patients about their sleep, and they should follow that up,” she said.
She added that long-term sleep disorders can affect a patient’s health and can lead to psychiatric problems and neurodegenerative diseases.
Depending on the type of sleep disorder, there are a number of possible treatments. For example, for patients with sleep apnea, continuous positive airway pressure treatment may be considered.
‘Outstanding’ research
Commenting for this news organization, Frank Conidi, MD, director, Florida Center for Headache and Sports Neurology; CEO, Brainsport, Team Neurologist, the Florida Panthers of the National Hockey League; and past president, Florida Society of Neurology, said the study is “by far” the largest to investigate the correlation between sleep disorders and head trauma.
The design and outcome measures “were well thought out,” and the researchers “did an outstanding job in sorting through and analyzing the data,” said Dr. Conidi.
He added that he was particularly impressed with how the researchers addressed PTSD, which is highly prevalent among veterans with head trauma and is known to affect sleep.
The new results “solidify what those of us who see individuals with TBI have observed over the years: that there is a higher incidence of all types of sleep disorders” in individuals with a TBI, said Dr. Conidi.
However, he questioned the study’s use of guidelines to classify the various types of head trauma. These guidelines, he said, “are based on loss of consciousness, which we have started to move away from when classifying TBI.”
In addition, Dr. Conidi said he “would have loved to have seen” some correlation with neuroimaging studies, such as those used to assess subdural hematoma, epidural hematoma, subarachnoid hemorrhage, and diffuse axonal injury, but that this “could be an impetus for future studies.”
In “a perfect world,” all patients with a TBI would undergo a polysomnography study in a sleep laboratory, but insurance companies now rarely cover such studies and have attempted to have clinicians shift to home sleep studies, said Dr. Conidi. “These are marginal at best for screening for sleep disorders,” he noted.
At his centers, every TBI patient is screened for sleep disorders and, whenever possible, undergoes formal evaluation in the sleep lab, he added.
The study was supported by the U.S. Army Medical Research and Material Command and the U.S. Department of Veterans Affairs. Dr. Leng and Dr. Conidi have disclosed no relevant financial relationships.
A version of this article first appeared on Medscape.com.