Epilepsy Risk Lasts Years After Traumatic Brain Injury

Allison Gandey

February 24, 2009

February 24, 2009 — The risk for epilepsy is particular high shortly after brain injury, but can last more than a decade — even for mild head trauma, researchers warn.

In a report published online February 20 in the Lancet, investigators show that the risk for epilepsy increased about 2-fold after a mild head injury and rose 7-fold after a severe injury.

"We were particular surprised by the long-lasting increased risk after traumatic brain injury, which we find has important clinical implications both for diagnosis and preventive treatment," lead author Jakob Christensen, MD, from Aarhus University Hospital, in Denmark, told Medscape Neurology & Neurosurgery.

It should be accepted as the reference study in the field.

In an accompanying comment, Simon Shorvon, MD, and Aidan Neligan, MD, from the University College London Institute of Neurology and the National Hospital for Neurology and Neurosurgery, in the United Kingdom, say the study is a commendable size and is complete with an advanced statistical design. "As such," they write, "it should be accepted as the reference study in the field."

The population-based cohort study was of more than 1.5 million people born in Denmark. Data were from the Danish national hospital register, and researchers found that more than 78,500 people had at least 1 head injury. More than 17,400 had epilepsy, and of these, 1017 had a head injury before diagnosis.

The researchers found an increase in the risk for epilepsy after mild and particularly severe brain injury and after skull fracture, with risk persisting more than 10 years after the index injury.

Increased Risk for Epilepsy

Brain Injury Relative Risk 95% CI
Mild 2.22 2.07 – 2.38
Severe 7.40 6.16 – 8.89
Skull fracture 2.17 1.73 – 2.71

Increased Epilepsy Risk More Than 10 Years After Injury

Brain Injury Relative Risk 95% CI
Mild 1.51 1.24 – 1.85
Severe 4.29 2.04 – 9.00
Skull fracture 2.06 1.37 – 3.11

The increased risk for epilepsy was even more pronounced in people older than 15 years of age. In these cases, mild injury increased the risk by 3.5 times and severe injury by more than 12 times.

Patients with a family history of epilepsy were at an even higher risk — almost 6 times for mild injury and 10 times for severe injury. Women also had a slightly higher risk than men.

"These are new findings, which we find very interesting and surprising," Dr. Christensen said.

An estimated 40% to 50% of hospitalizations for traumatic brain injuries are related to traffic collisions. Another 20% to 25% are attributed to falls, 8% to 10% to firearms and assaults, and the remainder to other causes such as sporting injuries.

Hard to Diagnose

"Survival has increased after high-impact trauma," Dr. Christensen explained. This is likely due to improved acute treatment, but many of these patients are at increased risk for epilepsy, which may be hard to diagnose, and physicians will need to be aware of this increased risk, he said.

Dr. Christensen pointed out that his group's work lacked direct clinical information. "Critics will most likely note the register-based approach. However, the major strengths of this study are the size and the complete follow-up, which make up for some of the shortcomings mentioned above."

Traumatic brain injury is a significant risk indicator for epilepsy many years after injury, the investigators conclude. "Drug treatment after brain injury with the aim of preventing posttraumatic epilepsy has been discouraging, but our data suggest a long time interval for potential, preventive treatment of high-risk patients."

The researchers have disclosed no relevant financial relationships. The editorialists also declare no conflict of interest.

Lancet. Published online February 20, 2009. Abstract Abstract

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