Definition and Overview

A cerebral abscess is a serious medical condition characterised by the collection of pus in the brain. It puts abnormal pressure on delicate brain tissue and causes the brain to swell. This can result in permanent brain damage. The infection can also disrupt blood flow to the brain. If the blood flow is cut off, the patient will have a stroke. For this reason, a cerebral abscess is treated as a medical emergency.

The condition can develop if:

  • An infection in the lung, heart, or abdomen travels to the brain through the bloodstream.

  • An infection in the head area, such as a sinus or an ear infection, spreads to the brain.

  • Pathogens enter the brain through an open wound. The open wound can be caused by head trauma or brain surgery.

A cerebral abscess can progress quickly. But when caught early, it can be adequately treated with medications or surgery.

Causes of Condition

A cerebral abscess can develop if pathogens find their way to the brain and cause an infection. They can enter the brain either through an open wound in the head or the bloodstream. The body’s immune system reacts to this infection by sending more white blood cells to the area. This immune response results in irritation and inflammation.

The condition can affect any person of any age. However, some have a higher-than-average risk than others. These include people with congenital heart disease. People with meningitis and a weak immune system are also at risk. When a person has a weak immune system, his or her body’s ability to fight pathogens is compromised. The immune system may weaken due to certain medical conditions and medicines. These include immunosuppressant drugs that are used to limit the activity of the immune system to prevent it from attacking healthy cells and tissues. However, by suppressing the immune system, patients become more prone to infections. Older people also usually have a weaker immune system when compared to younger individuals. A previous injury or surgery also increases a person’s risk of infection.

Other risk factors are certain birth defects that allow infections to easily reach the brain through the intestine or teeth. An example is a heart defect called tetralogy of Fallot.

Key Symptoms

People with a cerebral abscess may present with different symptoms. This depends on the size and location of the abscess in the brain. These symptoms include vomiting, confusion, and headaches. Patients may also suffer from fatigue and fever brought on by the infection. In severe cases, patients find it difficult to communicate and understand speech. They also usually take an unusually long time to respond to questions and struggle to focus. Other symptoms include a stiff neck, loss of muscle function, decreased sensations, and changes in vision. If there is too much intracranial pressure, patients can go into a coma.

In very young children, the condition can cause their fontanelle (the soft spot on top of the baby’s head) to bulge. It can also cause limb spasticity.

Who to See and Types of Treatments Available

Diagnosing cerebral abscess can take time because its symptoms are similar to many diseases and illnesses. It is helpful for doctors to know right away if the patient has:

  • A recent history of infection or has recently undergone surgery.

  • Recently travelled to a developing country.

  • A weak immune system.

It is also important for doctors to know when the symptoms first appeared. If a cerebral abscess is suspected, patients are referred to a brain specialist or neurologist.

The condition is diagnosed using the following tests and procedures:

  • Blood tests - Blood tests are used to measure the levels of WBCs in the patient’s body. The body produces more WBCs when it is fighting infections and illnesses.

  • Chest x-ray - A chest x-ray is used to determine if the condition is caused by a lung infection.

  • Imaging tests - An MRI and a CT scan are used to obtain clear images of the brain. When compared to x-rays, they produce more detailed information, particularly of soft tissues and blood vessels. Thus, they allow doctors to accurately diagnose the condition as well as monitor the effectiveness of treatment. They are the reasons why the number of fatalities from brain abscess has substantially decreased in the last few decades.

  • Electroencephalogram (EEG) - This test is used to detect any abnormality in the brain’s electrical activity.

  • Needle biopsy - This procedure is used to take a small amount of pus from the abscess for analysis. It is performed using a CT scan.

A cerebral abscess can be treated with medications, aspiration, or surgery. If the abscess is caught early, it can be treated with intravenous antibiotics. Medications are also used if:

  • Surgery is too risky for the patient.

  • The abscess is located deep inside the brain.

  • The patient has meningitis, an infection that affects the brain’s protective membranes.

  • The patient has hydrocephalus.

  • The patient has several abscesses.

If the size of the abscess is at least 2cm, it is aspirated and its content is drained out. The procedure involves drilling a small hole into the skull to gain access to the abscess. If the condition does not respond well to medications and aspiration, surgery becomes an option. This requires surgeons to remove a small piece of the skull. This helps relieve intracranial pressure and allows the doctors to treat the abscess directly. Once the abscess has been treated, the part of the skull that has been removed is replaced with a bone graft.

Surgery is the last treatment option because of its risks. Some of these risks are life-threatening. These include the formation of blood clot in the brain. Blood clots can obstruct or totally cut off the flow of blood to the brain. This can lead to a stroke. Other risks include headaches that can last for several months, a stiff jaw, and recurrent infections. The replacement bone can also move out of place and delay healing.

Patients who have undergone brain surgery have to recover and stay in the hospital for several weeks. They will be monitored for any signs of complications and to ensure that the surgical site is healing properly.

References:

  • Brouwer, MC; Coutinho, JM; van de Beek, D (Mar 4, 2014). “Clinical characteristics and outcome of brain abscess: systematic review and meta-analysis.”. Neurology. 82 (9): 806–13.

  • Nath A, Berger J. Brain abscess and parameningeal infections. In: Goldman L, Schafer AI, eds. Cecil Medicine . 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 421.

  • Tunkel AR. Brain abscess. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases . 7th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2009:chap 88.

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