Doctors have discovered the apparent cause of the seizure that sent Massachusetts Sen. Ted Kennedy to the hospital, and the news isn't good. The long-serving senator has a malignant brain tumor, his doctors say.

The Associated Press reports that the tumor is located in the left parietal lobe of Kennedy's brain, and has been identified as a malignant glioma. This is a general category of tumor, and an early diagnosis; a more specific identification is typically made after further testing. According to the National Cancer Institute, "Malignant gliomas are the most common primary brain tumor, accounting for more than half of the ... malignant brain tumors diagnosed each year in the United States ... The outlook for patients with malignant gliomas is poor. Median survival for patients with moderately severe malignant gliomas is three to five years. For patients with the most severe, aggressive form of malignant glioma, median survival is less than a year."

The Kennedy generation that included brothers John F. Kennedy, Robert F. Kennedy and Ted Kennedy was made up of nine children in total. Ted Kennedy is one of just three still living.