Dorsal Root Entry Zone (DREZ) for Facial Pain

What is Dorsal Root Entry Zone (DREZ)?

The DREZ procedure is an operation for patients who have nerve pain that do not respond to medications. This type of pain is often called chronic, intractable pain. The DREZ procedure can be used for facial pain such as post-herpetic neuralgia, tic douloureux, trigeminal neuralgia, deafferentation pain (anesthesia dolorosa), atypical facial pain, and intractable pain syndromes secondary to ancer/craniofacial surgery/trauma.

When you feel pain from parts of your face and head, the pain signals travel along a pathway to the brain. This is a sensory tract called the sensory trigeminal pathway. In order for you to sense the pain, the signal must travel from your face through three landmarks to reach the sensory cortex of your brain.

First, the receptors in your skin sense pain and send this signal into the trigeminal ganglion. From here, the pain signal travels through the trigeminal nucleus caudalis in the brainstem. The signal continues up to the thalamus, which projects this signal to the sensory cortex of your brain and you feel pain.

This surgery targets the dorsal root entry zone (DREZ) of the trigeminal nucleus caudalis in the brainstem. When this pain pathway is blocked with the DREZ procedure, the pain signal cannot reach the brain and decreases the processing of pain.

Nucleus caudalis DREZ lesioning and related anatomic structures. Multiple lesion sites are shown, however only one is needed for trigeminal pain.

nucleus caudalis drez


nucleus caudalis drez


What is the goal?

The goal of a DREZ procedure is to relieve facial pain (by lesioning the nucleus caudalis) that is unresponsive to medical treatment and is not appropriate for other types of surgical treatment.

What happens before surgery?

You will receive paperwork from Dr. Lad’s office and from the Department of Surgery with instructions and reminders regarding preparation to make before you have surgery. You will also have pre-anesthesia testing to make sure you are healthy enough to undergo the surgery. The anesthesiology team caring for you on the day of surgery will meet with you to review your medical history and answer any questions you may have. Dr. Lad will also visit you before the surgery to review the procedure and complete any necessary evaluations.

What happens during surgery?

A nurse will start your IV fluids and give you a medication to make sure you are comfortable. Once in the operating room, monitoring devices will be attached for your safety (blood pressure cuff, ECG, etc). In addition, the nerves are continuously monitored throughout the procedure to perform it as safely as possible, including the nerves controlling strength and hearing. Dorsal Root Entry Zone requires general anesthesia which means this is done in the operating room with you completely asleep and the anesthesiologist monitoring you throughout the operation. You will be placed in a Mayfield head clamp and there will be small incisions in the temple area. The surgeon makes an incision at the top of the neck, locates the nucleus of the trigeminal nerve using a laminectomy, and then use a custom electrode to interrupt the nerve signal. The goal of the lesion is to stop the pain without causing dense numbness or injury to the nerve's motor function. The operation will last approximately 3-5 hours.

What happens after Surgery?

Once the surgery is complete, you will be transferred to the recovery room. You will be closely monitored here by specially trained nurses. Dr. Lad will then explain the results to your family in the waiting room and you will be transferred to the Intensive Care Unit.
Usually you will spend one night in the Neurosciences Intensive Care Unit (ICU). The following day you will be moved out of the ICU to a regular private room. On the first day after surgery, you will usually be allowed to get out of bed and have food and liquid. On the second or third day postoperatively, you will be discharged after you have been evaluated by physical therapy.

How do I take care of myself after surgery?

You will receive post-operative information from Dr. Lad’s office and from the Department of Surgery.

Results of DREZ surgery, in terms of pain relief and incidence of complications, vary significantly from person to person. You will need to continue all preoperative pain medication. These will be slowly decreased by the physician who started them. Staples/sutures are removed 10 to 14 days after surgery. If you have any questions about what activities are safe or not safe, ask your surgeon.

What are the risks of surgery?

In up to 40% of operated patients, complications include changes in sensation observed in parts of the body, clumsiness and fatigue, and difficulty ambulating.

DREZ is an invasive procedure, and while safe in expert hands, does have potential rare/infrequent risks, including:


Cerebrospinal fluid leak

Stroke or hemorrhage (very rare)



Difficulty with balance

If at any time following your DREZ you notice:

Redness, swelling, drainage or foul odor from the surgical site

Excessive bleeding

Increase in pain at the surgical site

Fever of 101⁰F or higher with any of the above symptoms




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