Rasmussen's Encephalitis


What is Rasmussen's Encephalitis?

Rasmussen’s encephalitis is a chronic inflammation of the brain which progresses in severity over time. The inflammation typically affects one side of the brain, or cerebral hemisphere, and causes severe episodes of epileptic activity including chronic, focal seizures. People affected with Rasmussen’s encephalitis may experience permanent brain damage, loss of motor skill and mental deterioration as a result of the chronic inflammation of the brain. The condition is very rare with an estimated 200-500 cases worldwide, and it typically affects children between the ages of 2-10.

The inflammation association with Rasmussen’s encephalitis is thought to get progressively worse, peak and then subside, leaving stable function but permanent brain damage.


The symptoms of Rasmussen’s encephalitis vary from patient to patient, but focal, near continuous seizures are the most common sign. Seizures tend to present in rapid contractions and relaxations of the arms, legs and face continuously and rhythmically. As a result of the inflammation and epileptic activity, additional effects will present including paralysis of one side of the body (typically the opposite side of where the inflammation of the brain is occurring), perhaps signaling permanent brain damage. Symptoms may include:

  • Near continuous focal seizures
  • Weakness or paralysis on one side of the body
  • Cognitive deterioration


While the exact cause of Rasmussen’s encephalitis is unknown, two theories are currently being investigated.

  • Autoimmune disorder theory: One theory is that Rasmussen’s encephalitis is an autoimmune disorder, where the body mistakenly attacks its own tissue. Antibodies, which are part of the normal immune system trained to fight off infection and viruses, short circuit and attack healthy tissue.
  • Infection: Another theory is that Rasmussen’s encephalitis is a result of an unknown virus entering the brain such as influenza, measles or cytomegalovirus.


If Rasmussen’s encephalitis is suspected, a detailed evaluation by a neurologist will be necessary. The neurologist and clinical team will conduct a detailed review of the patient’s medical history along with a neurological evaluation. During the neurological evaluation, an MRI, CT scan and/or EEG may be conducted. The MRI will produce a detailed map of the brain and the EEG will track the electronic activity in the brain to determine if the activity is characteristic of Rasmussen’s encephalitis.

  • MRI: An MRI uses large magnets, radio waves and a computer to produce a map of the brain.
  • CT scan: This test uses a series of X-rays and a computer to create images of the inside of the body. A CT scan shows more detail than a regular X-ray.
  • EEG: This test records the brain's electrical activity through sticky pads (electrodes) attached to the scalp.


Treatment for Rasmussen’s encephalitis is often palliative, helping the patient live the best life possible with the condition, although medication and surgery may be appropriate in some cases.

  • Medication: Most seizure medication has proven ineffective at controlling the effects of Rasmussen’s encephalitis. However, autoimmune medications may be tried to slow down brain damage including steroids, immunoglobulin and tacrolimus.
  • Surgery: Surgery to treat Rasmussen’s encephalitis may be an option. Currently, a cerebral hemispherectomy is the only surgery option available which requires a removal of part of the brain. This type of surgery may leave the patient with permanent motor and cognitive impairment. Deciding if surgery is the right option often involves weighing the current effects of the disease versus the effects of surgery. 

Additional resources

To learn more about the Epilepsy Center at Texas Children’s Hospital and to inquire about admissions and patient candidates, please contact 832-822-0959.