The layers of thin tissue that cover your brain are called meninges. An infection in these tissues is called meningitis. When your brain becomes inflamed or infected, the problem is called encephalitis. If both the meninges and the brain appear to be involved, the condition is called meningoencephalitis.
Some cases of meningitis and encephalitis are caused by bacteria, fungi, and other types of germs. But many are caused by viruses, and many kinds of viruses can be to blame.
About 10 percent of cases of encephalitis are caused by the herpes simplex virus. This may involve herpes simplex virus type 1 (HSV1), the virus that also causes cold sores. In fact, most cases of herpes encephalitis are caused by HSV1. The disease may also be caused by herpes virus type 2 (HSV2). This virus can be spread by sexual contact or from an infected mother to her baby during childbirth. HSV1 infection can also be sexually transmitted to the genital area.
If you have viral meningitis, symptoms may include fever, light sensitivity, headache, and a stiff neck. If you have other symptoms, such as confusion, seizures, sleepiness, or a focal neurologic deficit—a nerve function problem that affects a specific area—these may suggest that your brain is also affected, and your doctor may diagnose it as meningoencephalitis.
Encephalitis involving herpes is a medical emergency. It needs to be promptly diagnosed and treated. This disease is fatal in a third or more of cases when it is not treated. Many people who survive it have long-term problems afterward.
These are possible symptoms of meningoencephalitis:
Sensitivity to light
Trouble thinking clearly
If your doctor thinks you may have herpes meningoencephalitis, you will probably need to have a lumbar puncture (spinal tap). This allows your doctor to take a sample of your spinal fluid. Cells and other substances in this fluid may give your doctor important clues. Your doctor may want to create images of your brain using a CT or MRI scan. He or she may also do a test called an EEG to measure your brain waves. This involves placing electrodes onto your scalp.
If doctors think that a newborn has herpes encephalitis resulting from infection with HSV2 while passing through the birth canal, they may check samples of the baby's blood and spinal fluid.
Your doctor may treat you with an antiviral medication called acyclovir. You may need to take this medicine through an intravenous line for 10 to 14 days. Doctors may also give you medicine to reduce swelling in the brain and to treat or prevent seizures.
Doctors may treat babies with this disease with acyclovir for several weeks.
Ways to avoid infections from herpes viruses include:
Abstain from sex or have only one sex partner who has been tested for the virus and isn't infected.
Use a latex condom, which can reduce—but not entirely prevent—the risk of infection.
Avoid kissing people with cold sore blisters. It's important to keep in mind that most people have already been infected with HSV1 virus by the time they're 20 years old. If you've already been infected, the virus goes dormant inside your body except during outbreaks.
Some pregnant women who have had genital herpes outbreaks may want to have their babies delivered by cesarean section. This may prevent meningoencephalitis in newborns.
People with severe cases may have long-term brain damage. They may have trouble thinking, controlling their body, and hearing, seeing, or speaking. They may need to take medicines for a long time, and they may require long-term care.