When diagnosing disorders and diseases of the brain and spinal cord a doctor may decide to order a patient to go through a lumbar puncture procedure, otherwise known as a spinal tap. This is done by inserting a needle into the lower back and removing cerebrospinal fluid. A blood culture is performed. All of this is done in a sterile environment. Lumbar punctures are used on infants, children, adults and the elderly according to need.
Lumbar punctures show anything from cancer cells to blood in the brain and spinal cord. One of the tests is to determine pressure. Normal lower back pressure in adults ranges between eighty to one hundred and eighty or two hundred millimeters of fluid. In children the range is between thirty to sixty. Should lumbar punctures show anything greater then a patient may undergo treatment in relieving the pressure. What this also tells the doctor is that there may be swelling or bleeding in the brain. Other reasons for abnormal pressure include stroke, an infection, or other serious disease.
During the tests the appearance of the cerebrospinal fluid (CSF) is examined. Normal cerebrospinal fluid is clear without color. During a spinal tap blood can appear in the fluid. This might be a symptom of a brain or spinal cord hemorrhage. In some cases it is caused by the needle unintentionally poking a blood vessel. Samples are again taken. If later lumbar punctures show a decrease in red blood cells then it was a blood vessel, but if the fluid may undergo a change from red, yellow and finally a brownish color. Cloudy cerebrospinal fluid is an indicator of infection, such as meningitis.
Further lumbar punctures show the level of protein, cell counts and glucose are visible in the CSF. Bacteria, fungus and other organisms are a sign of disease or infection. High protein and glucose could be a sign of diabetes, but not always. High protein is seen in patients with tumors, infection, injuries, and cancer, among other possibilities. Bacterial meningitis can be a cause for low glucose and high white cell count results.
A lumbar puncture is not done if other tests show signs of a tumor or cancer. However, follow up tests may be ordered to check on the patient’s progress.
In many cases lumbar punctures show nothing foreign in the cerebrospinal fluid and the doctor may order other tests if the patient is still suffering discomfort. Patients should consult with their doctors. Don’t be afraid to ask questions about procedure, what tests will be involved, and what to expect.