Collection of the cerebrospinal fluid (CSF) that bathes the brain and spinal cord has become a common procedure in HD clinical trials, both observational and interventional. During this procedure, a thin needle is inserted into the lower back to reach a fluid-filled space, and a small sample is drawn.
The CSF is an important source of biomarkers — substances that can be measured to better understand the progression of HD or the effects of a therapeutic. Lumbar puncture has become increasingly common in both observational and interventional HD trials, but misconceptions about the process can deter participation.
Here we explore some myths and truths about the procedure, which has evolved significantly in recent years to increase speed and comfort, and decrease the risk of side effects.
Myth:
A lumbar puncture is extremely painful.
Truth: Before CSF is drawn, the healthcare provider applies a local anesthetic using a very fine needle. Most people only feel a small pinch from the small anesthetic needle then a burn and pressure as the local anesthetic is given. There may be some pressure or discomfort from the actual spinal needle insertion.
Myth:
The procedure requires a giant needle.
Truth: The “atraumatic” needle used for lumbar punctures is about as thin as a fingernail and designed to minimize tissue damage and reduce the risk of headaches afterwards.
Myth:
Everyone gets a bad headache after a lumbar puncture.
Truth: Using an atraumatic needle, less than 5% of people who undergo lumbar puncture experience a headache. Smaller needles and good hydration can minimize the risk. In very rare cases when the headache is extreme and doesn’t resolve in a week or so, this can indicate a small leak in the CSF, and a highly effective procedure called a “blood patch” can be performed to help seal it.
Myth:
Lumbar punctures are dangerous and can have very serious side effects like paralysis.
Truth: A very thin needle is guided into the space between bones of the low back, below where the spinal cord ends, where there is no risk of nerve damage. Outdated consent forms may refer to worst-case scenarios, but the most common side effects are local discomfort from the needle and headache. Data from large studies in people with neurodegenerative diseases suggests that serious complications from lumbar puncture are extremely rare.
Myth:
A lumbar puncture takes a long time, and afterwards you have to lie flat for hours and you’ll be out of commission for days.
Truth: From start to finish, the actual lumbar puncture should take less than 20 minutes and can take as little as 5 minutes. Including prep and recovery, the entire process takes around 30 minutes. Old-school practice used to require long periods of remaining flat, but today, most people are encouraged to get up and move around immediately after the procedure. In fact, it’s now believed that fast mobilization afterwards can reduce side effects like headache. Most people resume normal activities within 24 hours, and avoiding intense activities is recommended. Most people feel back-to-normal very quickly!
Myth:
HD providers don’t have the training to perform lumbar punctures.
Truth: Lumbar punctures have become very common for diagnosing or monitoring many conditions. The procedure is simple and represents a core clinical skill taught in many fields, including neurology. It has also become quite common in clinical trials, and HD trial sponsors (companies developing drugs) support additional training and practice if needed.
In summary, lumbar punctures are commonly used in clinical studies and clinical trials. The procedure should be quick and relatively painless if done properly and by experienced hands. The fluid we are able to obtain is critical to advancing our understanding of HD and the development of new therapeutics.