Lower back pain is one of the common symptoms observed in United States following upper respiratory tract infection. Eighty percent (80%) of the adult population suffer with lower back pain at least once in lifetime. Lower Back Discogenic Pain or Lumbar Discogenic Pain (LDP) is the cause of low back pain in 39% of the patients. Discogenic Pain is one of the most common cause of lower back pain. Chronic lower back pain is also caused by bulge disk, disk herniation, and facet joint disease. Lower Back Discogenic Pain or Lumbar Discogenic Pain is observed in all age group and socio-economical class. Lower Back Discogenic Pain is caused by structural abnormalities of the thickness of the disc also known as degenerative disk disease. Lower Back Discogenic Pain or Lumbar Discogenic Pain caused by degenerative disk disease is not associated with disk herniation, disc fragments, or bulge disc.
Disc consists of peripheral circular annulus and central nucleus pulposus. Outer third of annulus has high density of nerves and blood vessels. Trauma or strain of the disc often results in mild to moderate inflammation around the damaged outer portion of the disc. Inflammation causes irritation of nerves in outer layer of annulus. Nerve irritation caused by chemicals produced in inflammation induces lumbar discogenic pain. Discogenic pain may not be associated with obvious anatomical or radiological changes of the disc as observed in X-ray and MRI. Radiological abnormalities of disc are observed in only 20% of the discogenic pain.
Causes Of Lower Back Discogenic Pain Or Lumbar Discogenic Pain
Discogenic pain is caused by irritation of the pain receptors and nerve fibers located over the outer layer of the annulus portion of the disc. Nerves are exposed as a result of disc degeneration, end plate injury, and inflammation of the disc. Lower Back Discogenic Pain or Lumbar Discogenic Pain is caused by inflammation and damage of disc end plate.1 The Following are the Causes of Lower Back Discogenic Pain or Lumbar Discogenic Pain-
Risk Factors Of Degenerative Disc Diseases Are As Follows-
Structural Changes Of Disc Resulting In Early Degeneration-
- Abnormal Intervertebral Disc Composition- Weak chemical and biological composition.
- Metabolic Changes In The Disc- Causes rapid wear and tear in few patients.
- Abnormal Disc Stresses- Caused by manual work or occupational posture reduces water content of the disc and induces process of disc degeneration in few patients.
Inflammatory Disc Disease3–
- Discitis is inflammatory condition of the disc caused by disc infection. Discitis is extremely painful and eventually results in severe thinning of the disc.
End Plate Injury-
- Minor injury of annular portion of the disc following fall, automobile accident and work accident can induce discogenic pain. End plate injury may be caused by tear or fracture of annular disc plate. End plate tear, fracture or traumatic disc inflammation always appears normal in radiological studies.
- Level of interleukin-1 (IL-1), IL-6, and IL-8- is higher in patients suffering with degenerative disc disease causing discogenic pain.3
Symptoms And Signs Of Lower Back Discogenic Pain Or Lumbar Discogenic Pain
Symptoms of Discogenic Back Pain-
Age- Between 30 and older.
- Location- Persistent lower back pain.
- Radicular or Nerve Root Pain Or Root Symptoms- Absent.
- Pain is increased on bending forward or lateral movements.
- Paravertebral muscle spasm often present with discogenic pain. Persistent muscle spasm results in aching and fatigue of lower back muscles.
Signs Of Discogenic Back Pain –
- Also known as McKenzie Assessment. Patient is advised to move in lateral direction. Lateral movement of the lower back induces pain in central column of the back.
- Lateral movement shifts nucleus pulposus towards injured disc and increases pressure, resulting in severe pain.
Investigations For Lower Back Discogenic Pain Or Lumbar Discogenic Pain
- No evidence of bulged disk, disk herniation or disc fragmentation observed.
- Thinning of Disc- degeneration or thinning of disc is observed in older patients.
- Traumatic Back Injury-
- MRI immediately following accident- Normal
- Follow up MRI after few weeks- Disc thinning or degeneration may be observed.
- MRI Findings Of Injured Annulus- Brighter or variable signal from injured area of annulus (High Intensity Zone- HIZ) are compared with normal signal of annulus. Study is reliable and need high intensity MRI signals.
Bony Vibration Test (BVT)-
Blunt electric vibrator is placed against the spine of lower back.
- Test causes either increase pain from mild to severe or
- Asymptomatic patient feels severe pain during vibration test.
Discography Test- 3 mL of Dye is injected in disc under aseptic condition in operating room.
- Dye injection provokes severe discogenic pain.
- Pain is not observed in adjacent normal disc during discography test.
- Post discography CAT scan and X-ray study- shows presence of disk herniation and ruptured disc.
- Disc Shape- Shows changes of disc shape.
Ultrasound Imaging Of Intervertebral Discs
- Density changes and structural changes of the disc are seen better with ultrasound imaging
- Density changes are observed at injured or inflamed section of the disc
- Ultrasound is a more sensitive test than photo MRI in diagnosis of discogenic pain.
High-Sensitivity C- Reactive Protein
- High-sensitivity C-reactive protein (hsCRP)- presence of hsCRP suggest low-grade inflammatory disease.
Treatment Of Lower Back Discogenic Pain Or Lumbar Discogenic Pain
Anti-Inflammatory Medications for Discogenic Back Pain-
- NSAIDs are often effective in treating inflammation of the disc causing discogenic pain.
Cortisone Injection For Discogenic Back Pain
- Caudal or epidural corticosteroid injection is effective in treating pain and inflammation.
Physical Therapy (PT) For Discogenic Back Pain
- Physical Therapy assists in improving blood flow to disc resulting in symptomatic relief and rapid healing of traumatic disc inflammation.
Surgery For Discogenic Back Pain-
Intradiscal Electrothermal Treatment (IDET)
- Surgical procedure is performed to cauterize the disc nerves by using heated coil.
Transdiscal Radiofrequency, Biacuplasty4
- The procedure involves placement of radiofrequency needle and nerve ablation using radiofrequency heat within the disk at the peripheral annular area.
Lateral Interbody Fusion5
- Lateral Interbody Fusion is less invasive and less extensive than spinal fusion surgery.
Disc Replacement Cages
- Disease disk is surgically removed and disc is replaced with cages or artificial disc.
- Spinal fusion surgery involves placing of rods and plate to fuse 2 or more vertebrae.
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