Degenerative disc disease

Degenerative disc disease refers to a variety of pathologies involving displacement of disc material into the spinal canal, such as protrusion, herniation, and sequestration. Degenerative disc disease results in mechanical compression of either the spinal cord or a nerve root. The most common symptoms of disc disease are radicular pain in the dermatome of the compressed nerve root, muscle weakness, and loss of deep tendon reflexes in the indicator muscles. The location of the lesion can often be determined using the patient's neurological deficits. In most cases of lumbosacral disc disease, L5 nerve compression is present, which leads to reduced sensitivity in the lateral leg, dorsum of the foot, and weakness in extending the big toe. A protruded/herniated disc on MRI confirms the diagnosis. Conus medullaris syndrome and cauda equina syndrome are severe forms of disc herniation that may present with paresis, sensory deficits, and urinary and bowel incontinence. They require urgent decompression via surgical intervention. Most spinal disc herniations, however, can be treated conservatively with analgesia and by maintaining physical activity.

• Disc protrusion: protrusion of the vertebral disc nucleus pulposus through the annulus fibrosus
• Disc herniation: (disc extrusion or disc prolapse): complete herniation of the nucleus pulposus through a tear in the anulus fibrosus
• Disc sequestration: extrusion of the nucleus pulposus and separation of a fragment of the disc

• Age: most common at 30–50 years
• Sex: ♂ > ♀ ^[1]
• Approx. 80% of all Americans suffer from significant back pain at some point in their lives. ^[2]
• Disc herniation is the cause of back pain in roughly 5% of cases.
  • Cervical and thoracic disc herniations: rare
  • Lumbosacral disc herniation
    • L5–S1 (most common site)
    • L4–L5 (second most common site)

Epidemiological data refers to the US, unless otherwise specified.

• The intervertebral disc consists of a dense outer ring (annulus fibrosus) and a gelatinous core (nucleus pulposus).
  • These structures work together as a shock absorber by distributing high axial pressure evenly onto the cover plates and base units of the vertebral bodies.
  • High pressure on the vertebral discs leads to fluid loss, and as a result, body height decreases physiologically by 1–2 cm during the day.
• Compression, tension, shear, and torque stresses on the spinal disc → degenerative changes (e.g., dehydration, annular tear) → disc protrusion or herniation through the annulus fibrosus into the central canal → adjacent nerve root impingement → sensorimotoric deficits in affected nerve root
• Intervertebral discs usually protrude/herniate posterolaterally, as the posterior longitudinal ligament is thinner than the anterior longitudinal ligament.
• Usually, the affected nerve root is the one below the level of disc herniation (e.g., L4–L5 disc herniation leads to L5 radiculopathy).

General clinical features

• Acute onset of severe back pain
  • Stabbing or resembling electric shock (most commonly of the lower back, called lumbago)
  • Radiates to the legs (sciatic pain) or the arms
• Paresthesia of affected dermatome
• Muscle weakness and atrophy
• Loss of deep tendon reflexes in the indicator muscles
• Pain increases with pressure (e.g., from coughing or sneezing)
• Short walks and changing position reduces the pain

A sudden decrease in pain concomitant with an increase in the degree of paralysis can be a warning sign of neuronal death.

Common radiculopathies

Spinal cord compression

• Definition: occurs when the spinal cord is compressed by a lesion such as a tumor, fracture, or ruptured disc
• Etiology
  • Acute onset (within minutes to hours): vertebral fracture, acute disc herniation, hematoma
  • Insidious onset
    • Abscess, primary tumor, metastasis: days to weeks
    • Slow-growing primary tumors, degenerative spine changes (e.g., spondylosis): months to years
• Clinical features: depend on the location of the spinal compression
  • Common features: back pain, radicular pain (follows dermatomal distribution of affected nerve), and neurological deficits below the level of the lesion (first sensory abnormalities, followed by motor and/or bladder/bowel dysfunction)
  • Incomplete spinal cord syndromes: cauda equina syndrome and conus medullaris syndrome
  • Patients may develop symptoms of isolated cauda equina syndrome, isolated conus medullaris syndrome, or a combination of the two.
  • Considered a medical emergency
• Treatment
  • Immediate management
    • IV glucocorticoids; : reduce pain, swelling, and inflammation → immediate decompression; bridge time until surgery can be performed
    • Opioids for further pain control if necessary
  • Surgical management: definitive treatment
    • Decompression surgery
    • Stabilization surgery
  • Radiation therapy: indicated if tumor is inoperable and following surgery; controls local tumor growth and significantly reduces pain

Other types of degenerative disc disease

Conus medullaris syndrome and cauda equina syndrome are medical emergencies requiring immediate surgical intervention.

References:^[5][6]

• Physical examination (reflexes, motor strength, sensory deficits)
• Straight leg-raising maneuvers
  • Straight leg raise test (Lasegue sign): straight leg of patient is raised → ↑ pain in the ipsilateral leg with radiation to the motor or sensory area of the affected nerve root
  • Bragard sign: straight leg of patient is raised → ↑ pain in the ipsilateral leg → leg is lowered to just below this point → ankle is dorsiflexed → reproduction of pain
  • Crossed straight leg raise test: opposite straight leg of patient is raised → increased pain in contralateral leg with radiation into the motor/sensory area of the affected nerve root
• Spurling maneuver (neck compression test)
  • Used for diagnosis of cervical spine radiculopathy
  • Forward flexion , tilting, and rotation of the neck towards the affected side and application of downward pressure to the head → reproduction of pain or paresthesia with radiation to the motor/sensory area of the affected nerve root
• MRI
  • To confirm diagnosis
  • Disc degeneration: sclerosed, dehydrated disc that is hypointense on T2-weighted images
  • Disc prolapse/herniation: herniation of disc tissue with surrounding edema
• CT-myelogram
  • If MRI is unavailable or cannot be conducted
  • Better for analysis of bone structure (e.g. prior to surgery)
• Plain radiographs: to exclude other pathologies (e.g., spine tumors, instabilities); preoperatively

See “Acute back pain” for details on the distinguishing characteristics and management of the underlying etiology.

• Musculoskeletal
  • Muscle strain (most common cause)
  • Spinal stenosis
  • Spinal disc herniation
  • Degenerative spondylolisthesis
  • Vertebral fractures
• Neurological: spinal cord compression, cauda equina syndrome, conus medullaris syndrome, spinal epidural hematoma
• Malignancy: bone metastases (extradural metastatic lesions) n
• Infections: spinal epidural abscess, vertebral osteomyelitis
• Inflammatory: ankylosing spondylitis, reactive arthritis, psoriatic arthritis

• Referred pain: acute pancreatitis, ureteric stone, abdominal aortic aneurysm, aortic dissection

Acute spinal cord compression is a surgical emergency. Obtain immediate MRI or CT myelography, give IV steroids for malignant compression, and decompress the cord (e.g., with surgery) as soon as possible!

The differential diagnoses listed here are not exhaustive.

Conservative treatment

• Physiotherapy with exercises strengthening the back
• No bed rest, but continuation of daily activities
• Local heat
• Analgesics (e.g., NSAIDs)
• Periradicular therapy (PRT): CT-navigated injection of a local anesthetic (e.g., ropivacaine) and glucocorticoids at the intervertebral foramen to reduce inflammation and edema at the affected nerve root

Up to 80% of all disc herniations are self-limiting and usually resolve within 4 weeks.

Surgical treatment

• Emergency indications
  • Significant or progressive neurological deficits
  • Bladder or bowel incontinence
  • Cauda equina syndrome/conus medullaris syndrome
• Elective indications: massive radicular pain which cannot be relieved by conservative and/or medical treatment
• Procedure: microsurgical intervention with nerve decompression
  • Access: windowing of the ligamentum flavum as a dorsal limitation of the spinal canal
  • Aim: removal of prolapsed disc material and potential sequestration
• Surgical complications
  • Damage of large prevertebral blood vessels (rare)
  • Post-dissection syndrome/postnucleotomy syndrome: persistent back pain, radicular pain, and paresthesia in approx. 5% of patients after disc surgery due to scarring, vertebral instability, or arachnoid adhesions to nerve roots.

1. Wang Y-XJ, Griffith JF, Zeng X-J, et al. Prevalence and Sex Difference of Lumbar Disc Space Narrowing in Elderly Chinese Men and Women: Osteoporotic Fractures in Men (Hong Kong) and Osteoporotic Fractures in Women (Hong Kong) Studies. Arthritis & Rheumatism. 2013; 65 (4): p.1004-1010. doi: 10.1002/art.37857 . | Open in Read by QxMD
2. Freburger JK, Holmes GM, Agans RP, et al. The rising prevalence of chronic low back pain.. Arch Intern Med. 2009; 169 (3): p.251-8. doi: 10.1001/archinternmed.2008.543 . | Open in Read by QxMD
3. Bhandutia AK, Winek NC, Tomycz ND, Altman DT. Traumatic Conus Medullaris Syndrome. JBJS Case Connector. 2016; 6 (2): p.e38. doi: 10.2106/jbjs.cc.15.00208 . | Open in Read by QxMD
4. Brouwers E, van de Meent H, Curt A, Starremans B, Hosman A, Bartels R. Definitions of traumatic conus medullaris and cauda equina syndrome: a systematic literature review. Spinal Cord. 2017; 55 (10): p.886-890. doi: 10.1038/sc.2017.54 . | Open in Read by QxMD
5. Eisen A, Aminoff MJ, Wilterdink JL. Anatomy and Localization of Spinal Cord Disorders. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/anatomy-and-localization-of-spinal-cord-disorders.Last updated: November 18, 2015. Accessed: July 11, 2017.
6. Schiff D, Brown P, Shaffrey ME, DeAngelis LM, Eichler AF, Savarese DMF. Treatment and Prognosis of Neoplastic Epidural Spinal Cord Compression, including Cauda Equina Syndrome. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/treatment-and-prognosis-of-neoplastic-epidural-spinal-cord-compression-including-cauda-equina-syndrome.Last updated: June 27, 2017. Accessed: September 14, 2017.