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Harvard Medical School
You will need to sign a consent form, which is generally required when the procedure is done outside of an emergency situation. Tell your doctor ahead of time if you have ever had an allergic reaction to lidocaine or the numbing medicine used at the dentist's office.
Doctors routinely do a physical examination and in some cases order a CT scan of the brain before recommending a lumbar puncture. The CT scan is performed when doctors suspect a medical problem that could put you at risk for movement of the brain during the procedure, a very rare but serious complication.