Neurological Disorders: Herniated Disc

Herniated Disc is a common neurological condition that generally presents with severe neck or back pain with or without radiation to the arms or legs. This condition is also commonly called as disc herniation, prolapsed disc, HNP (herniated nucleus pulposus), slipped disc etc. A Neurologist is frequently involved in the care of these patients.

Disc; more specifically called as inter-vertebral disc is a soft material found in between the adjacent vertebrae in the spine and is enclosed within a fibrous sheath called as annulus fibrosus which prevents the leakage of this material. If annulus fibrosus develops a tear due to any reason the disc material will protrude out through this breach and such condition is called as herniated disc. A disc bulge is a milder form in which the disc material doesn’t leak out.

Structures called spinal nerve roots are connected to the spinal cord; there is a pair of motor roots on to the front and the side aspect and another pair of sensory roots on the rear and side aspect of the spinal cord. The motor roots carry the impulses from the spinal cord mainly to the muscles and the sensory roots carry sensory impulses from the body and limbs to the spinal cord. These nerve roots travel in a somewhat lateral direction away from the spinal cord and little later unite to form a spinal nerve. Normally human spine has 33 vertebrae and 31 pairs of spinal nerves.

The prolapsed disc may impinge upon these nerve roots and this condition is called as pinched nerve root and it is a relatively common problem. The clinical condition produced due to pinching is radiculopathy where back or neck pain radiates down to legs or arms respectively.

Herniated-disc condition is more common in adults than children. Although the disc problems are frequent in older people (example - degenerative disc disease) the actual disc herniation is infrequent in them. This is because the disc dries up as age advances and the tendency to herniate or prolapse diminishes.

Common predisposing and aggravating factors include;

• Injuries to the back
• Lifting heavy weights
• Coughing and/or sneezing
• Overweight/Obesity
• Unknown causes

Disc herniation is much more common in the lower back (lumbar) and the neck region as compared to the thoracic region (mid back area). This is ascribed to the mobility of these regions, and the repeated strain and the resulting wear and tear. Further it is more frequent in lumbar region as compared to the neck region, and in both these places the lower couple of discs are more prone to develop herniation than the upper discs.

Depending upon the location of herniated disc these symptoms are commonly seen;

• Back pain
• Neck pain
• Back pain radiating down the legs
• Neck pain radiating down to the arms
• Back and/or neck stiffness
• Urinary bladder retention or incontinence
• Tingling (pins & needle) sensation in the limbs
• Numbness feeling in the extremities
• Muscle weakness in the extremities etc

The skin & muscles of the limbs are supplied by particular nerve root or roots; accordingly each slipped disc presents with its own unique motor (muscle related) and sensory clinical picture and this helps in correctly identifying the disc and spinal roots damaged. For example if C5 spinal root (first cervical spinal nerve root) is pinched by the disc then muscles supplied by C5 root including biceps, the tendon reflex served by C5 root (biceps reflex), and skin over the leg supplied by C5 (shoulder area) all may get affected.

The following neurology tests may be required (decided on case to case basis);

• CT scan of spine
• MRI scan of spine
• X-ray of spine
• EMG/NCS (electromyography and nerve conduction studies) etc

Surgery is avoided for hearniated disc unless it is really necessary, for example for a large disc, cauda equina or conus medullaris syndrome, myelopathy or not responding to the conservative approach etc.

The conservative or non-surgical treatment generally includes;

• Short term bed rest (not long term)
• Pain killers
• Muscle relaxants
• Physical therapy as tolerated
• Epidural steroid shots etc

There are now-a-days varieties of surgical options for a herniated disc. For small discs generally minimally invasive endoscopic procedures are tried and for large or multiple level discs an open surgery (more extensive) is tried. Spinal instrumentation/spinal fusion surgeries are also done as necessary.