Nov. 20, 2006 -- The scenario is one of the most frightening in the current war-on-terror. Terrorists release toxic gas weapons on a subway or train or maybe at a shopping mall or sporting event. Within seconds dozens of people are near death, suffering from seizures, paralysis and respiratory arrest. Hundreds or thousands more people survive the ordeal, but suffer from long-term disabilities.
Unfortunately, for those who survive, only a rapid infusion of an antidote may prevent long-term effects of these nerve agents. Nerve agents are toxic chemicals that attack a person's nervous system. The most feared complication from nerve agent exposure is seizures, says Jaideep Kapur, M.D., Ph.D., associate professor of neurology at the University of Virginia School of Medicine.
In many cases, these seizures last minutes to hours, a condition known as status epilepticus. Approximately 20 percent of all people who develop the condition die and the majority of those who survive suffer some amount of brain damage.
Kapur recently received a 5-year, $2.3 million grant from National Institute of Neurological Disorders and Stroke to develop treatments for nerve agent-induced seizures.
"We can give antidotes to soldiers in the field before they go into combat which protects them from some nerve agents. But in a terrorist attack, it can take precious time to respond to the incident and to administer any antidote. By the time the seizures start, it's too late for any current treatments," Kapur says.
The first step in the process of developing the treatments will be to better understand how the nerve agents cause seizures. Kapur says there is an increase in the brain's output of glutamate when a person is exposed to nerve agents. He says excess glutamate can causes seizures. One way to treat the seizures may be to counteract the increased levels of glutamate with the same chemicals a person naturally uses to keep the balance in their brain.
Some people who suffer from status epilepticus that is not cause by nerve agents respond to some available drug therapies. Kapur says one goal of his grant is to improve the efficacy of these drugs to improve their success rates.
While most people think of chemical weapons being used in World War I, their use on the world stage has been far more recent. Seizures were observed in humans exposed to nerve agents in the Iran-Iraq War from 1980 to 1988 and the 1995 Tokyo subway attack, in which sarin gas was released on several lines, killing 12 people and injuring more than 1,000.