Herniated Discs: Definition, Progression & Diagnosis
What is a Herniated Disc?
Herniation of the nucleus pulposus (HNP) occurs when the nucleus pulposus (gel-like substance) breaks through the anulus fibrosus (tire-like structure) of an intervertebral disc (spinal shock absorber).
Progression of Herniated Disc
The extremities affected are dependent upon the vertebral level at which the HNP occurred. Consider the following examples:
Cervical – Pain in the neck, shoulders, and arms
Thoracic – Pain radiates into the chest
Lumbar – Pain extends into the buttocks, thighs, legs
Cauda Equina Syndrome occurs from a central disc herniation and is serious requiring immediate surgical intervention. The symptoms include bilateral leg pain, loss of perianal sensation (anus), paralysis of the bladder, and weakness of the anal sphincter.
Diagnosis of a Herniated Disc
The spine is examined with the patient laying down and standing. Due to muscle spasm, a loss of normal spinal curvature may be noted. Radicular pain (inflammation of a spinal nerve) may increase when pressure is applied to the affected spinal level.
A Lasegue test, also known as Straight-leg Raising Test, is performed. The patient lies down, the knee is extended, and the hip is flexed. If pain is aggravated or produced, it is an indication the lower lumbosacral nerve roots are inflamed.
Other neurological tests are performed to determine loss of sensation and/or motor function. Abnormal reflexes are noted as these changes may indicate the location of the herniation.
Radiographs are helpful, but Computed Axial Tomography (CAT) or Magnetic Resonance Imaging (MRI) provides more detail. The MRI is the best method enabling the physician to see the soft spinal tissues unseen in a conventional x-ray.
Radiographic Evidence of HNP
The findings from the examination and tests are compared to make a proper diagnosis. This includes determining the location of the herniation so treatment options can be reviewed with the patient.