Monday, July 5, 2010

Facet pain: Prevalence, diagnosis & features

Clinical examination is not an efficient method of diagnosis of spine pain!!!

Pain emanating from various structures of the spine is a major cause of chronic pain problems. Linton et al estimated the prevalence of spinal pain in the general population as 66%, with 44% of patients reporting pain in the cervical region, 56% in the lumbar region, and 15% in the thoracic region. Manchikanti et al reported similar results. Despite the high prevalence of spinal pain, it has been suggested that a specific etiology of back pain can be diagnosed in only about 15% of patients with certainty based on clinical examination alone (2).

Prevalence of facet joint pain & Z joint pain:
In the 1990s precision diagnostic blocks were developed, including facet joint blocks, provocative discography, and sacroiliac joint blocks. Facet joints have been implicated as a cause of chronic spinal pain in 15% to 45% of patients with chronic low back pain, 48% of patients with thoracic pain, and 54% to 67% of patients with chronic neck pain (2).

Out of 500 screened patients by Manchikanti et al (2004) the prevalence of facet joint pain in patients with chronic cervical spine pain was 55%, with thoracic spine pain was 42%, and in with lumbar spine pain was 31%.

Based on the literature, in the United States, in patients without disc herniation, lumbar facet joints account for 30% of the cases of chronic low back pain, sacroiliac joints account for less than 10% of these cases, and discogenic pain accounts for 25% of the patients (1).

Based on the literature available in the United States, cervical facet joints account for 40% to 50% of cases of chronic neck pain without disc herniation, while discogenic pain accounts for approximately 20% of the patients (1).

The Z (zygapophysial) joint pain:
Facet joints are entertained first in spine pain diagnosis because of their commonality as a source of chronic low back pain followed by sacroiliac joint & disc as the last step (1).

Bogduk noted that a reductionist approach to chronic low back pain requires an anatomical diagnosis. Bogduk identified 4 factors necessary for any structure to be deemed a cause of back pain:

1. nerve supply to the structure
2. ability of the structure to cause pain similar to that seen clinically in normal volunteers
3. structure's susceptibility to painful diseases or injuries
4. demonstration that the structure can be a source of pain in patients using diagnostic techniques of known reliability and validity

The facet or zygapophysial joints of the spine are well innervated by the medial branches of the dorsal rami. Facet joints have been shown capable of causing pain in the neck, upper and mid back, and low back with pain referred to the head or upper extremity, chest wall, and lower extremity in normal volunteers. They also have been shown to be a source of pain in patients with chronic spinal pain using diagnostic techniques of known reliability and validity. Conversely, the reliability of physical examination & medical imaging provides little useful data in identifying facet joint pain diagnosis.
Summary of symptoms of facet pain may include the following:

1. Acute episodes of lumbar and cervical facet joint pain are typically intermittent, generally unpredictable, and occur a few times per month or per year.
2. Most patients will have a persisting point tenderness overlying the inflamed facet joints and some degree of loss in the spinal muscle flexibility (called guarding).
3. Typically, there will be more discomfort while leaning backward than while leaning forward.
4. Low back pain from the facet joints often radiates down into the buttocks and down the back of the upper leg. The pain is rarely present in the front of the leg, or rarely radiates below the knee or into the foot, as pain from a disc herniation often does.
5. Similarly, cervical facet joint problems may radiate pain locally or into the shoulders or upper back, and rarely radiate in the front or down an arm or into the fingers as a herniated disc might.

References: 1. Manchikanti L et al; Pain Physician. 2009 Jul-Aug; 12(4):E225-64. (An algorithmic approach for clinical management of chronic spinal pain.) 2. Manchikanti L et al; BMC Musculoskeletal Disorders 2004, 5:15doi:10.1186/1471-2474-5-15. (Prevalence of facet joint pain in chronic spinal pain of cervical, thoracic, and lumbar regions.)

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