Neurosyphilis is a disease of the coverings of the brain, the brain itself, or the spinal cord. It can occur in people with syphilis, especially if they are left untreated. Causes Neurosyphilis is caused by Treponema pallidum. This is the bacteria that causes syphilis. Neurosyphilis usually occurs about 10 to 20 years after a person is first infected with syphilis. Not everyone who has syphilis develops this complication. There are four different forms of neurosyphilis: Asymptomatic (most common form) General paresis Meningovascular Tabes dorsalis