Vasculitis (or angiitis) refers to inflammation of a blood vessel. Primary CNS Vasculitis results from an auto-immune attack on the blood vessels supplying the brain and spinal cord. Such inflammation results in the blockage of these vessels, and thus stops the flow of blood to parts of the brain or spinal cord. Cessation of blood flow to an area of tissue is known as ischemia. The result of vasculitis is that both the blood vessel wall and the tissue that blood vessel supplies will die.
What causes CNS vasculitis?
The underlying cause of CNS vasculitis is poorly understood. However, it is widely accepted that an autoimmune mechanism is responsible for the disease. When the body detects foreign pathogens it directs antibodies against them. These antibodies bind to the foreign organisms (or antigens) and form antigen-antibody complexes. During the development of CNS vasculitis these complexes are deposited in the walls of certain blood vessels supplying the brain and spinal cord. This deposition results in the release of chemicals which attract defensive white blood cells to the vessel wall. These white cells infiltrate the vessel wall, ingest the antigen-antibody complexes, and release enzymes which damage the vessel wall. The end result is the inflammation and death of the blood vessel, and the death secondarily of the tissue that the vessel no longer supplies.
What symptoms are associated with CNS vasculitis?
The symptoms associated with CNS vasculitis are varied. However, many patients with this disorder follow a similar clinical course. Patients usually develop headaches as an initial symptom. This may be accompanied by changes in the patients mental status. These symptoms are then followed by weakness over parts of the body, seizures, ataxia (an inability to smoothly coordinate muscle movements), or even coma. In fact, it is not uncommon for a patient to exhibit the signs of a stroke.
How is CNS vasculitis diagnosed?
Vasculitis which is limited to the central nervous system is rare and the diagnosis of this disease is difficult. The following techniques are employed to help establish a diagnosis:
Measurement of the erythrocyte sedimentation rate, which is nonspecific but indicative of an ongoing inflammatory process.
Detection of inflammation in the cerebrospinal fluid (CSF). This is performed by a lumbar puncture (or spinal tap). A needle is inserted into the small of the back to recover CSF, which circulates around the spinal cord. Levels of protein are elevated in 85% of patients with CNS vasculitis.
Magnetic Resonance Imaging (MRI) almost always detects evidence of widespread small vessel infarcts, or unusual p[atterns of enhancements resulting from inflammation and breakdown of the blood-brain barrier.
Cerebral angiography, which is an x-ray examination of blood vessels supplying the brain after the patient has been injected with a dye. This test may demonstrate irregularities of the cerebral arteries, known as "beading."
Even with the use of these measures, a definitive diagnosis of CNS vasculitis cannot be established without a brain biopsy. This procedure involves removing a small piece of the brain for examination under a microscope. This is the only way to definitively ascertain a diagnosis of CNS vasculitis. The other methods are used as supportive evidence.
How is CNS vasculitis treated in a neuro-ICU?
A neuro-ICU is specialized to treat critically-ill neurologic patients, including patients with severe CNS vasculitis. Patients with severe depression of level of consciousness (stupor or coma) may require intubation and placement on a respirator. The administration of corticosteroids such as dexamethasone can improve the condition of patients with this disorder. Patients with severe brain swelling or increased intracranial pressure may require placement of an intracranial pressure monitor. Other treatments to reduce the auto-immune attack on the blood vessels of the brain may include plasmapheresis (removal of proteins including antibodies from the bloodstream), and immunosuppression with drugs such as cyclophosphamide. Because the suppression of the immune system can result in a number of side effects the patient's overall medical status is carefully monitored by the intensive care unit.