Myelogram

A myelogram is a medical imaging test that uses a special dye and X-rays or a computed tomography (CT) scan to create detailed pictures of your spinal canal. This test helps doctors see problems with your spinal cord, nerve roots, and the surrounding tissues, especially when other imaging methods like MRI are not suitable or clear enough.

What is Myelogram?

A myelogram is a diagnostic imaging procedure that uses a contrast agent (dye) injected into the fluid around your spinal cord, combined with X-rays or a CT scan. This special dye helps highlight your spinal cord, nerve roots, and the protective membranes (meninges) that surround them. The goal is to identify issues within the spinal canal that might be causing symptoms.

This test provides detailed images of your spinal canal, which is the space inside your spine that holds your spinal cord and nerve roots. The contrast dye makes these structures show up more clearly on the X-ray or CT images. This allows doctors to detect abnormalities that might not be visible on standard X-rays. A myelogram is often performed when other imaging tests, such as a magnetic resonance imaging (MRI) scan or a regular computed tomography (CT) scan, cannot be done or have not provided enough information. For example, some people cannot have an MRI due to implanted medical devices like pacemakers. The procedure involves a lumbar puncture, also known as a spinal tap, to inject the dye.

Why it's ordered

Doctors order a myelogram to find the cause of symptoms like severe back pain, numbness, or weakness that may be related to problems in the spinal canal. It helps identify conditions affecting the spinal cord, nerve roots, and surrounding structures, such as herniated discs, spinal stenosis, and tumors. This test is particularly useful when other imaging methods are inconclusive or contraindicated.

A myelogram can help diagnose several conditions that affect the spine and nervous system. These include a herniated disc, which occurs when the soft cushion between your vertebrae (spinal bones) bulges out and presses on nerves. It can also detect spinal stenosis, a narrowing of the spinal canal that puts pressure on the spinal cord or nerves. This test is also used to find spinal tumors, which are abnormal growths that can compress the spinal cord or nerve roots. Additionally, a myelogram can help identify inflammation, bone spurs, or other structural problems within the spinal canal that might be causing pain or neurological symptoms. Your doctor will discuss if a myelogram is the most appropriate test for your specific condition.

How to prepare

Preparing for a myelogram involves discussing your medical history, medications, and allergies with your doctor. You will likely need to stop certain medications, especially blood thinners, for a few days before the procedure. You will also be asked to fast for several hours beforehand and arrange for someone to drive you home, as you cannot drive yourself after the test.

Before your myelogram, it is crucial to tell your doctor about all medications you are taking, including over-the-counter drugs, supplements, and herbal remedies. You must specifically mention any blood thinners, such as aspirin, warfarin (Coumadin), or clopidogrel (Plavix), as these may need to be stopped several days before the test to reduce the risk of bleeding. Always follow your doctor's specific instructions regarding medication adjustments. Inform your doctor about any allergies you have, especially to iodine, contrast dyes, or local anesthetics. Also, tell them if you are pregnant or suspect you might be, or if you have kidney problems, diabetes, or a history of seizures. You will typically be asked not to eat or drink anything for a few hours before the procedure. It is also important to arrange for a responsible adult to drive you home, as you may feel drowsy or dizzy afterward and should not operate a vehicle.

What to expect during

During a myelogram, you will lie on an X-ray table while a doctor cleans your lower back and injects a local anesthetic to numb the area. A thin needle is then inserted into your spinal canal to inject the contrast dye. You might feel some pressure or a brief stinging sensation. X-ray or CT images are taken as the dye moves through your spinal fluid, sometimes requiring the table to be tilted.

The procedure usually takes about 30 to 60 minutes. After the local anesthetic takes effect, the doctor will carefully insert a needle into the space around your spinal cord, typically in your lower back. A small amount of cerebrospinal fluid (CSF), the fluid that surrounds your brain and spinal cord, may be removed for testing, and then the contrast dye is injected. Once the dye is injected, you may be asked to change positions or the X-ray table may be tilted. This helps the dye flow to different areas of your spinal canal, allowing for comprehensive imaging. You might feel a sensation of warmth or pressure during this part of the test. The doctor will take a series of X-rays or perform a CT scan to capture detailed images of your spinal cord and nerve roots as the dye outlines them.

Understanding your results

After a myelogram, a radiologist, a doctor specializing in medical imaging, will analyze the images and send a report to your referring clinician. Your clinician will then discuss the findings with you, explaining what the results mean in the context of your symptoms and medical history. Results are generally described as normal if no abnormalities are found, or abnormal if conditions like herniated discs, tumors, or spinal stenosis are identified.

A normal myelogram result means that the radiologist did not find any blockages, compressions, or other structural problems in your spinal canal. This suggests that your symptoms may be caused by something other than the conditions a myelogram is designed to detect, or that the problem is not severe enough to be visible on the images. An abnormal myelogram result indicates that the images show an issue within your spinal canal. This could include a herniated disc pressing on a nerve, a narrowing of the spinal canal (spinal stenosis), a spinal tumor, or inflammation. Your clinician will interpret these findings alongside your symptoms, physical examination, and other test results to develop a diagnosis and discuss potential treatment options. It is important to remember that the radiologist's report is just one piece of information, and your clinician will provide the full picture.

Risks

While generally safe, a myelogram carries some risks, with the most common being a headache, which can sometimes be severe and last for several days. Other potential risks include nausea, vomiting, dizziness, and allergic reactions to the contrast dye. Rarely, more serious complications such as infection, bleeding, nerve damage, or seizures can occur. Your doctor will discuss these risks with you before the procedure.

The most common side effect after a myelogram is a headache, which occurs in about 1 in 10 people (10%) and can range from mild to severe. This headache is often caused by a small leak of cerebrospinal fluid (CSF) from the injection site. Lying flat and drinking plenty of fluids after the procedure can help reduce the risk and severity of these headaches. Other less common side effects include nausea, vomiting, and dizziness. Allergic reactions to the contrast dye are also possible, ranging from mild symptoms like hives to more severe reactions like difficulty breathing, though these are rare. Very rarely, serious complications such as infection at the injection site, bleeding into the spinal canal, temporary nerve damage, or seizures can occur. Your medical team will monitor you closely for any signs of these complications.

Frequently asked questions

How long does a myelogram take?

The myelogram procedure itself usually takes about 30 to 60 minutes. However, you should plan for a longer visit to the clinic or hospital, as preparation time, recovery, and observation afterward will add to the total duration. You will typically need to lie flat for several hours after the test.

Will a myelogram hurt?

You will receive a local anesthetic to numb the area where the needle is inserted, so you should not feel sharp pain during the injection. You might feel some pressure or a brief stinging sensation as the needle is placed. Some people experience mild discomfort or a headache afterward, which can be managed with medication.

Can I eat or drink before a myelogram?

No, you will typically be asked to fast for several hours before your myelogram. This means you should not eat or drink anything, including water, for a specific period before the test. Your doctor or the imaging center will provide you with exact instructions regarding fasting.

What should I do after a myelogram?

After a myelogram, you will usually need to lie flat for 4 to 6 hours to help prevent a headache. It's important to drink plenty of fluids to help flush the contrast dye from your system and reduce the risk of headache. Avoid strenuous activity for at least 24 hours, and have someone drive you home.

Are there alternatives to a myelogram?

Yes, often magnetic resonance imaging (MRI) or a standard computed tomography (CT) scan can provide similar information without the need for contrast injection into the spinal canal. A myelogram is typically ordered when MRI is not possible (e.g., due to metal implants) or when previous imaging has not provided a clear diagnosis.

When can I resume normal activities after a myelogram?

You should avoid strenuous activities, heavy lifting, and bending for at least 24 to 48 hours after a myelogram. Your doctor will give you specific instructions based on your individual recovery. Most people can resume light activities the day after the procedure, but it's important to listen to your body and your doctor's advice.

Sources

• MedlinePlus — Myelogram
• Mayo Clinic — Myelogram
• Cochrane Library — Myelogram