Brain abscess is defined as a localized suppurative area within the brain. It is rare but serious infection mainly caused by bacteria and sometimes by other pathogens such as viruses and fungi. The pathogen may enter into the brain directly from a penetrating skull injury or may pass into the brain from other part of the body. It may also spread through blood. More often the bacteria reach brain parenchyma from infection in paranasal sinuses, middle ear infection, or the mastoid process.
After reaching the brain, it may take 2 to 3 weeks for the pathogen to form an abscess.Usually the onset is gradual but in people with compromised immune system it may have an acute onset. As the abscess expands in size it increases intracranial pressure leading to symptoms of intense headache, fever, vomiting, hemiparesis, facial palsy, etc.
The diagnosis of brain abscess is established with the help of CT scan, MRI studies. Treatment of brain abscess requires appropriate antibiotics and surgical drainage. Mortality from brain abscess is around 30 to 60 percent. From patients who recover, at least half of them may suffer from some neurological problems.
Causes And Risk Factors For Brain Abscess
Brain abscess is commonly caused by bacteria and virus infection.The pathogens can enter into the body and in the brain through 3 routes.
- From another infected area in the body. Example (sinusitis, mastoiditis, etc).
- Penetrating injury on skull which also includes neurosurgical procedures. Infection can either spread through skull bone as in case of osteomyelitis of skull bone.
- Almost one third of brain abscess occur through hematogenous route. It means the spread is through blood. Bacterial endocarditis (infection of heart) and pyogenic infection of lung (lung abscess) or diseases of lungs such as bronchiectesis can lead to abscess in brain.
- Another important predisposing factor for development of brain abscess is suppression of immune system.
Following are the risk factors for development of brain abscess:
- Patient suffering from sinusitis and middle ear infection.
- Congenital cyanotic heart disease.
- Compromised immune state as in HIV and AIDS.
- Person taking chemotherapy or immunosuppressant drugs.
- Injury on head or fracture of skull.
- Infection on face and scalp.
- Tooth and jaw infection.
Signs And Symptoms Of Brain Abscess
The symptoms of brain abscess may develop after several weeks. However, sometimes they may appear suddenly especially in immune-compromised patient. The symptoms include:
- Increased irritability and confusion.
- Weakness of muscles.
- Change in vision because of papilloedema.
- Irritation from exposure to light.
- Alteration of mental status.
- Facial palsy
- Stiffness of neck
- Change in behavior
- Poor appetite
In infants and children most of the above symptoms are same. But there may be some additional symptoms that are not present in adults.
- The fontanelles are swollen and bulge out. These are soft spots on the head.
- Crying with high pitch.
- Spasticity of hands and legs.
Treatment Options For Brain Abscess
Brain abscess is diagnosed with the help of CT scan and MRI of brain. Blood test will reveal rise in white blood cell count due to bacterial infection. Treatment of brain drainage needs proper medications and surgical drainage of the abscess. Broad spectrum antibiotics are necessary for treating the condition. Antibiotic selected must be able to penetrate deep inside the capsule of brain abscess. In some cases anticonvulsant medicines are also used to control seizures.
Surgical drainage is necessary to reduce the increased intracranial pressure in brain. Pus is aspirated through burr hole incision. But sometimes surgical excision of the abscess may be necessary if the capsule gets filled up repeated with pus despite repeated aspiration.