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Degenerative disc disease

Last updated: January 19, 2021

Summary

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.

Definition

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

Anatomy and types of disc herniation Thoracic spine and costovertebral anatomy Costovertebral joints and ligaments

Epidemiology

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.

Pathophysiology

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).

Clinical features

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.

Dermatome map

Common radiculopathies

Overview of radiculopathies
Radiculopathy	Level of lesion	Sensory deficits	Motor deficits	Reduction of reflexes
C3/4 radiculopathy	C2–C4	Shoulder and neck area	Scapular winging	None
C5 radiculopathy	C4–C5	Anterior shoulder	Biceps and deltoid	Biceps reflex
C6 radiculopathy	C5–C6	From upper lateral elbow over radial forearm up to thumb and radial side of index finger	Biceps and wrist extensors	Biceps Brachioradialis reflex
C7 radiculopathy	C6–C7	Palmar: fingers II–IV (II ulnar half, III entirely, IV radial half) Dorsal: medial forearm up to fingers II–IV	Triceps and wrist flexors, finger extensors	Triceps reflex
C8 radiculopathy	C7–C8	Dorsal forearm up to dorsal and palmar area of fingers IV (ulnar half) and V, hypothenar eminence	Finger flexors	None
L3 radiculopathy	L2–L3	Anterior lateral area of the thigh (stretching diagonally from thigh to upper area of the medial knee)	Hip flexion	Adductor reflex Patellar reflex
L4 radiculopathy	L3–L4	Extending from distal anterolateral thigh area over patella up to inner side of lower leg	Knee extension	Patellar reflex
L5 radiculopathy	L4–L5	Lateral sides of thigh and knee, anterolateral lower leg, dorsum of foot, big toe	Tibialis anterior muscle (foot dorsiflexion) → difficulty heel walking (foot drop) Extensor hallucis longus muscle (first toe dorsiflexion)	Posterior tibial reflex (medial hamstring)
S1 radiculopathy	L5–S1	Dorsolateral thigh, dorsolateral lower leg, lateral foot	Peroneus longus and brevis muscle (foot eversion) and gastrocnemius muscle (foot plantarflexion) → difficulty toe walking	Achilles reflex Lateral hamstring reflex
S2 radiculopathy, S3 radiculopathy, S4 radiculopathy	S1–S4	Posterior aspect of thigh and lower leg (S2), perineum (S3–S4), perianal (S4)	None	Bulbocavernosus reflex Perineal reflex

Disc herniation and nerve root compression

Subtypes and variants

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

Overview of conus medullaris syndrome and cauda equina syndrome
Syndrome	Etiology	Onset	Pain	Motor symptoms	Sensory symptoms	Urogenital and rectal symptoms
Conus medullaris syndrome	Damage to the spinal cord segments T12–L2 (conus medullaris), which are situated at the level of L1 vertebra ^[3]^[4] Spinal tumors Trauma (e.g., vertebral fracture, spondylolisthesis)	Sudden, bilateral	Lower back pain Less severe radicular pain	Symmetric, hyperreflexic distal paresis of lower limbs, possibly fasciculations Achilles reflex may be absent	Symmetric, bilateral perianal numbness Sensory dissociation	Early onset of bladder and fecal incontinence Erectile dysfunction
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	Severe radicular pain	Asymmetric, areflexic, flaccid paresis of the legs Muscle atrophy	Saddle anesthesia: lack of sensitivity in the dermatomes S3–S5, affecting the areas around the anus, genitalia, and inner thighs (may be asymmetric) Asymmetric, unilateral numbness and/or paresthesia in lower limb dermatomes	Late onset of urinary retention Change in bowel habits due to loss of anal sphincter control Decreased rectal tone or bulbocavernosus reflex Erectile dysfunction

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

References:^[5]^[6]

Diagnostics

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

Straight leg raise tests Kernig sign Cervical radiculopathy and myelopathy Disc herniation of C2/3 Degenerative disc disease with disc extrusion Disc herniation C5–6 Spinal disc herniation Spinal disc herniation with migration 1/3

Differential diagnoses

Differential diagnoses of low back pain

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	Early mobilization NSAIDs and muscle relaxants Prevention: correct lifting of heavy items
	Muscle strain (most common cause of lower back pain)
	Spinal stenosis	In older patients Pain in buttocks and legs (neuropathic claudication; improves with bending forward)	X-ray: degenerative spine changes MRI: confirmatory test (nerve compression)	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	Surgical stabilization of the spine (e.g., kyphoplasty) Cord decompression
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)	History of cancer (e.g., lung cancer, breast cancer, prostate cancer, melanoma) Advanced age Pain worse at night Spinal cord compression Local spinal pain, may radiate to the shoulder and neck (common in spinal metastases) Brown-Séquard syndrome is a common initial finding in patients with spinal metastatic lesions.	MRI (urgent if spinal compression is suspected)	Surgery Radiation therapy In case of spinal cord compression: high-dose corticosteroids as soon as possible followed by definitive management
Infectious	Spinal epidural abscess	Point tenderness Fever and chills Spinal cord compression Risk factors: IV drug use Diabetes Invasive procedures (e.g., removal of an epidural catheter) Alcohol use disorder Immunosuppression	Urgent MRI Culture of blood, CSF, abscess contents (gained through aspiration) to identify the causative pathogen (Staphylococcus aureus (∼ 65% of cases)	Empiric antibiotic therapy Surgical drainage and decompression
Inflammatory	Ankylosing spondylitis	Pain mostly at rest Improves with activity	HLA-B27 present	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	Asymmetric, areflexic, flaccid paresis of the legs Bladder, bowel incontinence, saddle anesthesia	MRI	Surgical decompression
	Spinal epidural hematoma	♂ > ♀ (4:1) Bimodal distribution (peaks during childhood and between age 40–50 years) Spontaneous or traumatic (e.g., following lumbar puncture, pulling epidural catheter) bleeding Risk factors Thrombocytopenia Bleeding diathesis Anticoagulation Vascular malformations Acute spinal cord compression Back pain, lower extremity weakness and numbness, hyporeflexia	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.

Lumbar spondylosis Spinal epidural hematoma Degenerative and inflammatory lesions of the spine

The differential diagnoses listed here are not exhaustive.

Treatment

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.

Retroperitoneal hemorrhage from the left common iliac artery Bleeding from the common iliac artery

References

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
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
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
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
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.
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.