Facet blocks

Facet joints (also known as zygopophyseal joints or z-joints) are the small joints that connect vertebral bodies to each other. These joints can be stressed during extreme motions (e.g. whip-lash injury). They can have torn joint capsules all the way to fractures. With time they can develop arthritis and cause pain just like arthritic and traumatized knee and hip joints.
 

Here is a picture from Allaboutbackpain.com:

Here are some more pictures from Coloradospineinstitute.com.

Presentation

Patients with facet joint problems in the low back will present with low back pain. This pain usually does not radiate down past the knee. Depending on the studies anywhere from 20 to 50% of low back pain is caused by the facet joints (with the other main culprits being the discs and the sacro-iliac joints).

Patient with facet joint problems in the neck will present with neck and shoulder pain. The higher the pain-generating facet joint level, the higher in the neck will the corresponding painful area be.

This link will lead you to the facet trainer which shows the painful area depending on the painful facet joint in the neck.

The pain generated by facet joints will be aggravated by flexion-extension and also to some degree with rotation.

If a facet joint develops severe spurring (facet hypertrophy) it can narrow the foramen that is the opening for the nerve root that leaves the spinal cord. In this case it can cause pain shooting all the way down to the fingers and toes (sciatica). In this case the patient's complaint is similar to disc prolapse and sciatica.
 

Imaging

X-rays, CT sccans and MRI's of the spine may show varying changes in the facet joints ranging from normal appearing joints to severe hypertrophy (bone spurs) and fractures and displacements. Even a facet joint that looks relatively normal on imaging studies can cause pain.
 

Diagnosis

The diagnosis starts with the patient's description of the accident/trauma, the location and radiation of the pain and aggravating and relieving factors. Physical examination shows usually limited range of motion in the affected part of the spine with significant tenderness over the facet joints.
 

Treatment

In the past many pain physicians would inject local anesthetic and steroids into the respective facet joints. This would usually provide the patient with a couple of weeks of relief. In the last 10 years a new technique has been introduced that does not involve the injection of steroids and that provides for longer relief. The new technique involves the destruction of the nerve that supplies the facet joint (medial nerve branch) using radiofrequency to heat the tip of an insulated probe.

The current diagnosis and treatment consists of a two-step approach.

Step 1: Establishing the diagnosis by injecting under fluoroscopy a very small amount of local anesthetic (usually 0.5 ml) close to the spot where the nerve that supplies the facet joint is located. This may be done on multiple levels and sides. In a positive test the pain will diminish by at least 50% during the duration of effect of the local anesthetic (from 30 minutes to up to a couple of hours). In a negative test there will not be any significant improvement in pain. Many practitioners will do two test injections with the local anesthetic before proceeding to step 2.

Step 2: If there is over 50% reduction of pain in the affected area for the duration of effect of the numbing medication, then the patient will be scheduled on a different day for the radio-frequency ablation of those nerves (medial branches). The radio-frequency ablation (burning of the nerve) is done in 5 steps:
a. Positioning of the insulated radio-frequncy probes to the location of the medial nerve branches.
b. Stimulation of the probes at 50 Hz (50 impulses per second). This is called the sensory test to ensure that the patient does not feel any sensation anywhere else. Most patients will describe this part as tingling or pressure.
c. Stimulation of the probes at 2 Hz. This is called the motor test and it is performed to ensure that the probe will not heat any adjacent nerve roots.. Most patients will feel a thumping in their backs or necks with the muscles twitching at a rate of twice a second. If there is any muscle twitching going all the way down to the arm or the leg then the probe has to be re-positioned.
d. After satisfactory positioning of the probes most practitioners will inject a very small amount of numbing medication to make the actual burning less painful.
e. After all these steps the radio-frequency ablation is performed at about 80Celcius for about 90 seconds. Some practitioners may deviate by 10-20% with the temperature and the duration depending on their experience. Some will run 2 cycles of burning.
 

Procedure in detail

The diagnostic and therapeutic facet joint interventions are done as outpatient procedures using fluoroscopy. The placement of the needles has to be so precise that any "blind" placement without the use of live X-ray (fluoroscopy) is not possible. Most patients will receive mild sedation during these procedures. It is very important that the patient is not fully asleep as feedbcak by the patient is imperative especially for the testing before the ablation.
 

Duration of pain relief:

Most patients will be sore for a day or two from having the needles in their necks or backs. After that most will have significant pain relief from 3 to 9 months. Despite the heating of the nerve, it slowly recovers over the ensuing months and regenerates causing the same pain as before again.
 

Repetition:

The procedure can be repeated when the pain is severe enough due to the regeneration of the medial nerve branch.

We will post pictures of these procedures here very soon.

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Copyright © 2007 Pain Specialists of Texas. Last modified: 12/04/07