CSF oligoclonal banding

Alternative names

Cerebrospinal fluid - immunofixation

Definition

CSF oligoclonal banding is a test performed on cerebrospinal fluid (CSF). CSF is a clear fluid that circulates in the space surrounding the spinal cord and brain. The CSF contains substances that may be markers for disease. Oligoclonal bands are immunoglobulins that suggest inflammation of the central nervous system. The presence of oligoclonal bands may be a sign of multiple sclerosis.

How the test is performed

A lumbar puncture (spinal tap) is performed and the fluid is sent to the laboratory for analysis.

How the test will feel

Patients will be asked to either sit up or lie down on their sides with the back parallel to the bed and the chin tucked under and the legs curled in the fetal position. The healthcare provider will use the bony protrusions of the hip to determine the most appropriate location to remove fluid. This is usually at what is known as the L3-L4 vertebral level.

Subsequently iodine will be used to clean off the area and a sterile sheet will be draped over the surrounding area. In infants and small children, EMLA cream, a local anesthetic cream will be used to numb the skin and will be applied about 1 hour prior to the procedure. In adults, lidocaine will be injected under the skin initially, and then deeper such that tissue beneath the skin will also be numbed.

A thin 20-gauge needle will then be inserted into the interspace between the vertebra. Depending on how much subcutaneous tissue there is, this may require shallow or deeper penetration of the needle. There may be an audible "pop" when the needle penetrates the dura (membrane that surrounds the spinal cord and encases the fluid). At that point there will be fluid flowing out of the needle and this will be collected in plastic containers. Under normal circumstances, the opening pressure will be measured with a manometer and then about 20-30 cc of spinal fluid will be collected and sent for evaluation under the microscope.

Under experienced hands there should not be any pain. There may be a feeling of pressure when the needle is inserted but with appropriate anesthetic, this should not hurt. Occasionally, some people may feel numbness shooting down the leg. This may be due to irritation of a nerve root.

The needle is withdrawn, the sensation subsides and is not permanent. Following the procedure, the patient is advised to remain lying down for an hour or two to prevent low-pressure headaches. The entire procedure takes approximately 20 minutes.

Why the test is performed

This test helps confirm the diagnosis of multiple sclerosis (MS) however, it is not specific for this disease. The presence of oligoclonal bands in the CSF must be interpreted in the context of clinical findings and other laboratory results.