毎日平均18人の退役兵士が自殺／米国 軍隊 イラク・アフガニスタン
Veterans can have seizures decades after a head injury, study finds
It's unclear what can trigger the post-traumatic epilepsy, which can hit up to 35 years after a penetrating head wound. The long-term study looks at Vietnam veterans.
By Jeannine Stein, Los Angeles Times
July 20, 2010
Soldiers who suffered brain injuries can develop seizures decades ― as long as 35 years ― after the initial injury, researchers have found.
A study published Tuesday in the journal Neurology found that among a group of 199 Vietnam veterans, about 13% developed post-traumatic epilepsy more than 14 years after they had suffered a penetrating head wound, such as a gunshot injury or shrapnel that entered brain tissue. Penetrating head injuries are generally linked with a higher risk for epilepsy than other types of head injuries, such as concussions.
Among the veterans, who are part of a long-term investigation called the Vietnam Head Injury Study, the overall rate of post-traumatic epilepsy was about 44%, consistent with similar military groups.
It is unclear what's responsible for the triggering of seizures so many years after a penetrating head injury, said study coauthor Jordan Grafman, chief of the Cognitive Neuroscience Section of the National Institute of Neurological Disorders and Stroke in Bethesda, Md.
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"There are all sorts of things that can contribute to a [late-onset] seizure, including sleep deprivation, excessive drinking and other kinds of illnesses," Grafman said.
The study showed that soldiers who retained pieces of metal in their brains were at heightened risk for seizures, as were those with larger brain lesions (these also predicted a higher frequency of seizures).
The researchers also looked to see if there was a link between seizure risk and a gene known to be involved in neuronal plasticity (the ease with which brain cells can change or repair their patterns of connections), but found no association. Still, Grafman hasn't ruled out a genetic component: "We all recover from brain injuries differently, and we may find that in some cases those differences are genetic."
The study also found that some vets who had developed post-traumatic epilepsy experienced worsening of seizures over the years. In the most recent year that the study participants reported their seizures, a quarter had simple partial seizures ― during which people stay alert and can recall what happened ― that had progressed into generalized seizures, which can trigger a loss of consciousness.
The seizures occurred despite the fact that more than 88% of those with post-traumatic epilepsy were on anticonvulsant medication.
Cognitive decline later in life was also seen among some of the veterans with seizure disorders. This was assessed by comparing past scores on the Armed Forces Qualification Test (which is given to potential soldiers to measure mental ability) to more recent ones.
"You can have an injury and get better, but with time, people don't always do as well as they should," said Dr. Gerald Grant, associate professor of neurosurgery at Duke University in Durham, N.C., and a former Air Force neurosurgeon. "It shows us that this is a chronic disease."
It is unclear how the study relates to combatants returning from Iraq and Afghanistan today, the authors said. The Vietnam veterans in the study suffered from penetrating brain injuries, which are rarer in soldiers fighting in the current conflicts because helmets have improved. Today, closed-head injuries (where the brain is not penetrated) are more common, in part because of the helmet improvements and partly because of a change in the weaponry used in modern warfare.
Nonetheless, Grafman said, the study underscores the importance of long-term follow-up for military civilians who have suffered traumatic brain injuries.
"It's clear that this is lifelong," he said.
Copyright (c) 2010, The Los Angeles Times
Neurology. 2010 Jul 20;75(3):224-9.
Correlates of posttraumatic epilepsy 35 years following combat brain injury.
Raymont V, Salazar AM, Lipsky R, Goldman D, Tasick G, Grafman J.
National Institute of Neurological Disorders and Stroke, Building 10, Room 7D43, MSC 1440, Bethesda, MD 20892-1440 firstname.lastname@example.org.
BACKGROUND: The Vietnam Head Injury Study (VHIS) is a prospective, longitudinal follow-up of 1,221 Vietnam War veterans with mostly penetrating head injuries (PHIs). The high prevalence (45%-53%) of posttraumatic epilepsy (PTE) in this unique cohort makes it valuable for study. METHODS: A standardized multidisciplinary neurologic, cognitive, behavioral, and brain imaging evaluation was conducted on 199 VHIS veterans plus uninjured controls, some 30 to 35 years after injury, as part of phase 3 of this study. RESULTS: The prevalence of seizures (87 patients, 43.7%) was similar to that found during phase 2 evaluations 20 years earlier, but 11 of 87 (12.6%) reported very late onset of PTE after phase 2 (more than 14 years after injury). Those patients were not different from patients with earlier-onset PTE in any of the measures studied. Within the phase 3 cohort, the most common seizure type last experienced was complex partial seizures (31.0%), with increasing frequency after injury. Of subjects with PTE, 88% were receiving anticonvulsants. Left parietal lobe lesions and retained ferric metal fragments were associated with PTE in a logistic regression model. Total brain volume loss predicted seizure frequency. CONCLUSIONS: Patients with PHI carry a high risk of PTE decades after their injury, and so require long-term medical follow-up. Lesion location, lesion size, and lesion type were predictors of PTE.
PMID: 20644150 [PubMed - in process]
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