In-depth

Acute lymphocytic leukemia

Acute lymphocytic leukemia is a type of leukemia that affects immature white blood cells. It's the most common cancer in children and adolescents.

Acute myelogenous leukemia (AML)

Acute myelogenous leukemia (AML), a form of cancer that affects the blood cells, is the most common type of leukemia.

Anthrax

Anthrax is a deadly bacterial illness that normally affects animals. But in rare instances, humans can contract the disease.

Ataxia

Ataxia describes lack of muscle coordination while performing voluntary movements. A sign of an underlying condition, ataxia can affect any part of your body.

Brain aneurysm

A brain aneurysm is a bulge in an artery in the brain. A ruptured aneurysm causes bleeding in the brain and potentially fatal cell damage.

Coma

Coma is often a complication from a severe brain injury that leaves a person unconscious and unresponsive. Many people recover from this condition.

Cough headaches

Cough headaches — so named because they're triggered by coughing — are sometimes harmless, but they may be a symptom of a serious condition.

Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease is a rare cause of dementia that progresses rapidly once symptoms develop.

Dysarthria

Dysarthria is a speech disorder caused by an inability to control or coordinate the muscles used for speaking.

Encephalitis

Encephalitis is inflammation of the brain usually caused by a viral infection. Severe cases can cause brain damage, even death.

Exercise headaches

You know exercise is good for you. But did you know that exertion can leave you with a pounding headache?

Febrile seizure

Although febrile seizures can be frightening for parents and children, they're generally harmless. Most occur after a sudden fever spike, usually due to an infection.

Guillain-Barre syndrome

Guillain-Barre syndrome may cause severe weakness, numbness or paralysis — starting in the extremities and often spreading throughout the entire body.

Headaches in children

Children of all ages experience headaches, but the causes aren't all the same. Here's how to help your child.

Legionnaires' disease

Legionnaires' disease, a severe form of pneumonia, is caused by bacteria that can live in water in air conditioning systems, showers and spas.

Meningitis

Fever, headache and stiff neck are common signs and symptoms of meningitis — an infection of the membranes and fluid surrounding the brain and spinal cord.

Migraine

A migraine isn't an ordinary headache. In addition to severe head pain, it can cause nausea, vomiting, and extreme sensitivity to light and sound.

Naegleria infection

Summertime freshwater swimming may put you at risk of this rare but often fatal infection. Learn more about your risks and how to protect yourself.

Neck pain

Although often eased with simple techniques at home, neck pain can sometimes be a symptom of a more serious problem requiring medical treatment.

Paraneoplastic syndromes of the nervous system

Paraneoplastic syndromes of the nervous system are cancer-related disorders that can cause a broad spectrum of neurological impairments.

Pseudotumor cerebri

Pseudotumor cerebri — Comprehensive overview covers symptoms, causes, treatment of increased pressure inside the skull.

Reye's syndrome

Reye's syndrome is a rare but serious condition linked to giving children aspirin to treat viral infections.

Sex headaches

Sex headaches are usually nothing to worry about. But they can sometimes be associated with bleeding problems inside and around the brain.

Thunderclap headaches

Thunderclap headaches strike suddenly. Immediate medical attention is essential. Some thunderclap headaches signal a life-threatening condition.

Transverse myelitis

Transverse myelitis — inflammation of the insulating material that covers nerve cells in your spine (myelin) — causes pain, muscle weakness and other problems.

West Nile virus

West Nile virus infection usually resolves on its own, but occasionally it can be serious.

Mar. 20, 2012