A developmental venous anomaly is an unusual arrangement of small veins in the brain or spinal cord. It's a condition you are born with.

Arteriovenous malformations is the abnormal formation of veins and arteries. It can develop in the fetus or newborn baby.

Pneumocystis pneumonia or PCP is a fungal infection in 1 or both lungs. It is common in people who have a weak immune system, such as people who have AIDS.

Opportunistic infections that other people might fight off easily could make you really sick if you have HIV. Getting one or more of these opportunistic infections could mean that your HIV has advanced to AIDS.

HIV affects the brain and nervous system and can cause dementia.

The skull base offers support from the bottom. Think of it as the floor of the skull, where the brain sits. Tumors can form at the base of the skull.

Lymphadenitis is an infection in one or more lymph nodes. The lymph nodes help filter bacteria, viruses, and other unwanted material from the body.

Vascular dementia is caused by decreased blood flow to brain tissue causing signs of dementia. Read on for details about this condition.

A look at the 2 vaccines designed to help prevent meningococcal disease in preteens, teens, and young adults: MenACWY and MenB.

A cerebral cavernous malformation (CCM) is a collection of small blood vessels (capillaries) in the central nervous system that is enlarged and irregular in structure. In CCM, the walls of the capillaries are thinner than normal, less elastic, and likely to leak. Cavernous malformations can happen anywhere in the body. They most commonly cause symptoms when they are found in the brain and spinal cord.