• Clinical science

Degenerative disc disease (Spinal disc herniation)

Abstract

Degenerative disc disease refers to a variety of pathologies with displacement of disc material into the spinal canal, such as protrusion, herniation, and sequestration. Degenerative disc disease results in mechanical compression on 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 by the patient's neurological deficits. In most cases of lumbar 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. MRI confirms the diagnosis by showing the protruded/herniated disc. Conus medullaris syndrome and cauda equina syndromes 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.

Definition

Epidemiology

  • Age: most common at 30–50 years
  • >
  • Approximately 80% of all Americans suffer from significant back pain at some point in their lives
    • About 5% of back pain is a consequence of disc herniation
      • Lumbar disc herniations
        • L5–S1 (most common site)
        • L4–L5 (second most common site)
      • Cervical and thoracic disc herniations are rare

References:[1][2]

Epidemiological data refers to the US, unless otherwise specified.

Pathophysiology

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

Sensory deficits Motor deficits Reduction of reflexes
C3/4 radiculopathy
  • Shoulder and neck area
C5 radiculopathy
  • Anterior shoulder
C6 radiculopathy
  • From upper lateral elbow over radial forearm up to thumb and radial side of index finger
C7 radiculopathy
  • Palmar: fingers II–IV (II ulnar half, III entirely, IV radial half)
  • Dorsal: medial forearm up to fingers II–IV (II ulnar half, III entirely, IV radial half)
  • Triceps and wrist flexors, finger extensors
C8 radiculopathy
  • Dorsal forearm up to dorsal and palmar area of fingers IV (ulnar half)
  • Finger flexors
L3 radiculopathy
  • Anterior lateral area of the thigh (stretching diagonally from thigh to upper area of the medial knee)
L4 radiculopathy
  • Extending from distal lateral thigh area over patella up to inner side of lower leg
  • Motor deficit: tibialis anterior muscle (foot dorsiflexion) difficulty heel walking
  • Patellar
L5 radiculopathy
  • Dorsolateral thigh, lateral side of the knee, anterolateral lower leg, dorsum of foot, big toe
S1 radiculopathy
  • Lateral foot

References:[2][3]

Subtypes and variants

Spinal cord compression

  • Definition: occurs when the spinal cord is compressed by a lesion such as a tumor, fracture, or ruptured disk
  • 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
  • Treatment
    1. Immediate management
    2. Surgical management: definitive treatment
      • Decompression surgery
      • Stabilization surgery
    3. Radiation therapy: indicated if tumor is inoperable and following surgery; controls local tumor growth and significantly reduces pain
Etiology Onset Pain Motor symptoms Sensory symptoms Urogenital and rectal symptoms
Conus medullaris syndrome
  • Sudden bilateral onset
  • Lower back pain
  • Less severe radicular pain
Cauda equina syndrome
  • Damage to or compression of the cauda equina with nerve fibers of L3–S5 (below L2)
    • Large posteromedial disc herniation, trauma, or tumors
  • Gradual unilateral onset
  • Severe radicular pain
  • Saddle block anesthesia (may be asymmetric)
  • Asymmetric, unilateral numbness and/or paresthesia in lower limb dermatomes

Conus medullaris syndrome and cauda equina syndrome are medical emergencies requiring immediate surgical intervention!
References:[3][4][5][6][7]

Diagnostics

  • Physical examination (reflexes, motor strength, sensory deficits)
  • Straight leg-raising maneuvers
    • Straight leg raise test (Lasegue's 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.
    • 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's 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

References:[1][2]

Differential diagnoses

Differential diagnoses of low back pain

Common etiologies Typical features Diagnostics Therapy
Musculoskeletal Muscle strain (most common cause of lower back pain)
  • Acute back pain and paravertebral stiffness and difficulty bending after physical exertion (e.g., heavy lifting)
  • No loss of sensory or motor function
  • Straight leg raise test negative
  • Percussion: tenderness over lumbar spine
  • Negative straight leg-raising maneuvers
Spinal stenosis
  • Conservative
    • NSAIDs
    • Physiotherapy
    • Epidural steroid injections
  • Surgery if conservative therapy fails
Spinal disc herniation
  • Unilateral radicular pain, dermatome referred (usually L5/S1 with positive straight-leg raise test)
  • Paresthesia and muscle weakness
  • MRI: shows disc herniation
  • Conservative
    • Activity continuation, no bed rest
    • NSAIDs
  • Surgical decompression: in case of severe/progressive neurologic deficits
Degenerative spondylolisthesis
  • Older age
  • Possibly radicular syndromes, spinal claudication
  • Lateral x-ray of the spine
  • Conservative
    • Physiotherapy
    • Orthotic braces
    • Steroid/anesthetic injections for radicular pain
  • Surgery if conservative treatment not efficient
    • Vertebral fusion
    • Decompression of the spine
Vertebral fractures
  • History of injury
  • Local pain on pressure, percussion, and compression
  • X-ray,CT
  • MRI for detecting spinal cord lesions
Malignancy

Bone metastases (extradural metastatic lesions)

Less commonly: intramedullary tumors (e.g., multiple myeloma, ependymomas, astrocytomas, metastases) and intradural-extramedullary (e.g., meningiomas, nerve sheath tumors)

  • MRI (urgent if spinal compression is suspected)
Infectious Spinal epidural abscess
Inflammatory Ankylosing spondylitis
  • Pain mostly at rest
  • Improves with activity
  • Physical therapy
  • NSAIDs
  • DMARDs in chronic cases
  • In severe cases surgery
Reactive arthritis
Psoriatic arthritis
Others Abdominal aortic aneurysm
  • Pulsatile abdominal mass
  • Bruit on auscultation
  • Ultrasound (also for follow-up)
  • CT (in case of rupture)
  • Open or endoscopic grafting (tube or Y-prosthesis)
Cauda equina syndrome
  • MRI
  • Surgical decompression
Spinal epidural hematoma
  • MRI with and without gadolinium : to demonstrate hematoma and underlying pathology
  • Surgical decompression to avoid permanent neurologic dysfunction (laminectomy and evacuation of blood)

Acute spinal cord compression is a medical emergency. Conduct an MRI or CT myelography immediately and decompress the cord via IV steroids and/or surgery as soon as possible!

The differential diagnoses listed here are not exhaustive.

Treatment

Conservative treatment

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

Surgical treatment

  • Emergency indications
  • 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.

References:[1]