Risks

Though lumbar punctures are generally recognized as safe, they do carry some risks. These include:

• Post-lumbar puncture headache. Around 25% of people who have undergone a lumbar puncture develop a headache afterward due to a leak of fluid into nearby tissues.

  The headache typically starts several hours up to two days after the procedure and may be accompanied by nausea, vomiting and dizziness. The headaches are usually present when sitting or standing and resolve after lying down. Post-lumbar puncture headaches can last from a few hours to a week or more.

• Back discomfort or pain. You may feel pain or tenderness in your lower back after the procedure. The pain might radiate down the back of your legs.
• Bleeding. Bleeding may occur near the puncture site or, rarely, into the epidural space.

• Brainstem herniation. Increased pressure within the skull (intracranial), due to a brain tumor or other space-occupying lesion, can lead to compression of the brainstem after a sample of cerebrospinal fluid is removed.

  A computerized tomography (CT) scan or MRI prior to a lumbar puncture can be obtained to determine if there is evidence of a space-occupying lesion that results in increased intracranial pressure. This complication is rare.