The risk of stroke is significantly elevated among traumatic brain injury patients in the first 5 years after injury, particularly during the first 3 months and if it involved a skull fracture, Taiwanese researchers reported July 28 in Stroke.
"To the best of our knowledge, this is the first study to demonstrate that TBI [traumatic brain injury] is a potential risk factor for subsequent stroke," wrote Yi-Hua Chen, Ph.D., and her coauthors from Taipei (Taiwan) Medical University.
Noting that other studies have identified neurological disorders, epilepsy, psychiatric diseases, and other morbidities that occur during the years after a TBI, the authors wrote that this study "leads the way in identifying stroke as an additional neurological problem that may arise following TBI."
Because of the large number of people who have TBI and stroke, the study results have important clinical implications in managing patients with TBI, including "more intensive medical monitoring, support, and intervention" after a TBI – particularly during the first few months or years – and the need to educate families about the early signs and symptoms of stroke in patients who have had a TBI.
Medical professionals "should also be aware of the need to provide early neuroimaging examination ... for suspected stroke patients, particularly those with a history of TBI," Dr. Chen and her colleagues added.
Using records from a health insurance database, they identified about 23,000 adults who had received ambulatory or inpatient care for a diagnosis of TBI between 2001 and 2003 and almost 70,000 patients who did not have a TBI. They matched patients from the groups for sex, age, and year they received the index use of health care. The patients were followed for 5 years. Overall, their mean age was almost 42 years and a little over half were men. People who had had a stroke diagnosis previously were excluded (Stroke 2011 July 28 [doi:10.1161/STROKEAHA.111.620112]).
Stroke rates were significantly higher among those who had had a TBI across the three different time periods that the investigators evaluated. During the first 3 months, strokes occurred more often in TBI patients than among individuals in the comparison group (2.91% vs. 0.30%, respectively). Over 1 year, 4.17% of those with a TBI had a stroke, compared with 0.96% of control group patients. In a 5-year period, 8.20% of those with a TBI had a stroke vs. 3.89% of those in the comparison group.
After adjusting for certain comorbidities, regions of residence, and sociodemographic features, the risk of a stroke after a TBI was about tenfold greater over the first 3 months, almost 5 times greater over 1 year, and about two times greater over the 5-year follow-up.
The authors also found that the stroke risk was "more pronounced" among those who had a fractured skull, compared with the control group overall: The risk of stroke was almost 20-fold greater over 3 months, about 8 times greater over 1 year, and about three and a half times greater over 5 years. Those with a TBI were at a greater risk of having all subtypes of a stroke during the 5-year follow-up period.
They described the possible mechanism behind the increased risk of stroke after a TBI as "vague" and pointed out that more studies were needed to determine the mechanism. But they speculated about several possibilities, including damage to the cerebrovascular system disturbing the blood supply to the brain, leakage of blood caused partly by bleeding from an artery, as well as increased intracranial pressure and blood pressure that occur after TBI.
The authors had no disclosures.