Disc is consisting of outer tough fibrous annulus and inner soft nucleus pulposus. The disc bulge is the abnormality of the disc that results when nucleus pulposus bulges into outer fibrous annulus. The problem of disc bulge is diagnosed when inner soft nucleus pulposus is protrudes in to the outer intact fibrous covering (fibrous annulus) to form a bulge. The protrusion of the nucleolus pulposus causes thinning of the outer capsule. The bulge or protrusion of disc consists of thin intact outer fibrous annulus and soft inner nucleus pulposus. The disc bulges into spinal foramina and spinal canal. Small disc bulge is often asymptomatic. Large disc bulge protrusion causes spinal stenosis and foraminal stenosis. The large disc bulge into spinal canal causes narrowing of spinal canal resulting in spinal canal narrowing or stenosis. Similarly, protrusion or bulge of disc into spinal foramina causes narrowing of foramina or foraminal stenosis. Foraminal narrowing causes pinch nerve pain in neck, chest wall, abdominal dermatome and lower leg. Pinch nerve pain is also known as radicular pain. Radicular pain spreads over, neck, shoulder and upper extremity.
Herniation of the disc is protrusion of nucleolus pulposus through the rupture capsule of the disc and is one of the common problems of herniated disc.(1) The nucleolus pulposus is extruded outside disc capsule and often irregular in shape and in few cases pieces of herniated disc floats in cerebrospinal fluid or epidural space. Herniated disc causes spinal and foraminal stenosis as described in disc bulge. The herniation of disc causes inflammation of the capsule and surface of the disc. The inflame tissue causes excessive secretion of prostaglandin. Prostaglandin irritates the spinal nerve resulting in neurogenic or radicular pain, which travels along the pathway of the nerve.
Characteristic of the pain is similar like disc pain. Though minor to moderate size bulge disc may be painless. In contrast herniated disc always causes severe radicular pain.
Degenerative Disc Disease
The degenerative disc disease (DDD) of is common among elderly patients. The degeneration of disc results in thinning of the disc. The thinning of the disc narrows foramina resulting foraminal stenosis. In few cases vertebral bones around the foramina and spinal canal forms protrusion of sharp bones known as bone spurs or osteophytes. Protrusion of osteophytes in narrowed foramina or spinal canal causes irritation or pinch of spinal nerve resulting in radicular pain. Degenerative disc disease is also associated with facet joint arthritis. The radicular pain is often associated with facet joint pain. Radicular pain runs along the nerve, while facet joint pain mostly localized over back. Discogenic pain caused by DDD is always felt over the back and side of the vertebral column.
Cervical, mid or lower back discitis is an inflammatory disease of the disc.(2) Discitis results in thinning of the disc. The inflammatory discitis causes secretion of inflammatory chemicals, which irritates the nerve to disc resulting in severe pain. The thinning of the disc causes foraminal stenosis and radicular pain. Discitis is more common in lumbar disc.
Symptoms and Signs Caused By Disc Abnormalities And Diseases
Chronic Pain- Disc diseases irritates or pinches the spinal nerve or tiny branches of nerves passing to disc. Thus disc disease causes either radicular and discogenic pain.
Discogenic pain- Discogenic pain is caused by chemical irritation of nerve, which is supplying sensory nerve to disc. The chemical irritation is caused prostaglandin, which is over-secreted by abnormal disc capsule. Discogenic pain is felt at the back of the neck, mid and lower back depending on the level of the disc bulge.
Radicular Pain- Radicular pain is sharp and piercing pain. Standing, bending, twisting, coughing and sneezing, provokes pain. Pain is felt worst at night. Pain radiates to upper and lower extremities when cervical or lumbar nerves are irritated or stimulated. Bulge of cervical or lumbar disc causes stimulation of cervical or lumbar nerve when nerve is pinched or irritated. Large disc bulge between L1 and L5 level of vertebral column causes sciatic nerve pain. Large disc bulge either irritates or pinches branches of sciatic nerve within spinal canal. The pain is felt over lateral side of the feet and back of the lower leg.
Tingling and Numbness- Continuous pressure on spinal segmental nerve eventually causes symptoms like tingling and numbness. Tingling precedes numbness. Symptom is reversible if cause is treated before permanent damage is observed within the nerve. The symptom of tingling and numbness over the back is spread over the dermatome the nerve is distributed. Tingling and numbness precedes initial symptoms of pain
Paravertebral Muscle Spasm- Paravertebral muscle spasm is observed in neck, mid and lower back depending on the level of disc bulge or herniation. Muscle spasm is often continuous and causes severe pain secondary to muscle fatigue and lactic acid accumulation in muscles.
Muscle Weakness In Lower Leg- Severe continuous pressure over the spinal nerve within intervertebral foramina in neck, mid or lower back causes ischemic (lack of blood supply) changes in motor nerve. Ischemic changes causes decrease blood flow to motor nerve, which results in degeneration of motor nerve. The motor nerve degeneration follows weakness of lower leg. The back muscle weakness is observed during movements of vertebral column. Patient observes progressive difficulties in back movements during change of body position like getting in and out of sitting or lying down position. Nerve lesion in neck and lower back causes muscle weakness in upper and lower extremities. The muscle weakness causes difficulties of flexion, extension, abduction and adduction of upper and lower extremities. Dermatomal distribution of weakness depends on the level of lesions of spinal nerve and spinal cord.
Absence of Knee and Ankle Joint Reflexes- Knee Reflex- Nerve lesion of L2 and L3 spinal nerve causes abnormal knee joint reflexes. Ankle reflex (tendo-achillis reflex)- The nerve lesions of level L4, 5 and S1 causes abnormal ankle joint reflex.
Muscle Atrophy- The spinal nerve supplies the motor nerve to the muscles belong to the same dermatome. The motor nerve lesion causes degenerative changes of motor nerve, which follows atrophy of the muscles of the same dermatome. Muscle atrophy or thinning is associated with weakness in leg.
Lab Studies To Diagnose Disc Diseases:
Abnormal Blood Examination-
- Blood examination in most cases is normal.
- WBC Count- Occasional white blood cell count is increased in patients suffering with discitis.
- ESR (Erythrocyte Sedimentation Rate)- ESR is increased in Osteoarthritis. Osteoarthritis causes degenerative changes of disc.
X-ray images show thinning and narrowing of disc caused by degenerative disc disease. X-Ray also shows foraminal stenosis or narrowing. Bulge or herniated disc is not observed in X-ray image.
Magnetic resonance imaging (MRI)
MRI images of disc are helpful in diagnosis of disc degeneration, bulge and herniated disc. Discitis is suspected when MRI of young or middle age patient shows thin and narrowed disc. Narrow or thin disc in elderly patient suggests degenerative disc disease caused by aging of disc or osteoarthritis.
Disc biopsy is indicated when discitis is suspected in young individuals. Disc biopsy shows inflammatory changes of disc but may not show bacterial presence.
Ultrasound study is often normal or non-conclusive.
Differential Diagnosis of Disc Diseases-
Discitis is diagnosed when thin or narrowed disc in young or middle age patient associated with increase WBC count.
Degenerative disc disease is diagnosed when X-Ray images shows thin and narrowed disc in elderly or middle age patient with sign of osteoarthritis.
MRI helps to differentiate degenerative disc disease, discitis, bulge disc and herniated disc.
Disc biopsy differentiates the cause of thin disc, which is either discitis or degenerative disc disease.
- Herniated Disc
- What is Herniated Disc?
- Intervertebral Disc Herniation: Types, Symptoms, Treatment, Diagnosis, Prevention
- Discitis or Diskitis: Types, Causes, Risk Factors, Signs, Symptoms, Treatment
- Lumbar Disc Herniation: Causes, Symptoms, Treatment-Manual Therapy, PT, Surgery
- Lumbar Disc Bulge: Causes, Symptoms, Treatment- Manual, Physical, Magnet Therapies
- Slipped Disc: Disc Anatomy, Symptoms, Signs, Investigations, Treatment, Medications, Biofeedback, Preventive Measures
- Lumbar Disc Pain: Symptoms, Treatment- Conservative, Lumbar Decompression Surgery