Vertebral column, disk and slipped disk
The vertebral column in our body is composed of 33 vertebrae. These are Cervical (7), Thoracic (12), Lumbar (5), Sacral (5) and Coccyx (4) bones. The names of vertebrae are given according to their location. The vertebrae of vertebral column are so arranged as to form a canal type structure, called Spinal canal.
The spinal canal is a complex network of nerves and blood vessels. It accommodates a long, thin and tubular bundle of different nerve tissues and support cells, called spinal cord and blood vessels. The spinal cord is originated from Medulla Oblongata (hind portion of brain), in brain stem upto the lumbar region of vertebral column. The brain and spinal cord together form the Central Nervous System (CNS).
*For details, please refer to my previous write up, in folder “know your body>major systems”.
The spinal cord starts from Occipital bone in brain and ends down where 1st and 2nd lumbar vertebrae meet each other. It does not run throughout the vertebral column. The spinal cord is generally found to be 43-45 cm long, with varying thickness at different locations like ranging from 13 mm in cervical & lumbar regions to 6.4 mm in thoracic area. The primary function of spinal cord is to transmit, control and coordinate various neural signals from Brain and rest of the body and vice versa through sensory nerves and Motors, having independent control of all reflexes.
If the anatomy of spinal cord is studied, it is observed that the cord starts tapering from 1st and 2nd lumbar bone in our body. The most distal swollen (bulbous) part of the spinal cord is called the ‘conus medullaris’ and the point where its tapering ends, is known as ‘filum terminale’. After that, at the end of the spinal cord, all nerve roots are collected in horse tail type appearance, called the ‘cauda equina’. It is a bundle of many spinal nerves and their roots, extending from 5th lumbar nerve pairs to the 5th sacral nerve and up to coccygeal nerve. Any injury in ‘cauda equina’ area may cause severe pain and weak sensation in lower back and legs by which the control on bowel or bladder may also be lost.
Disk and Causes of its slipping:
The series of vertebral bones are joined with each other from top to bottom. These bones are joined through a cushioning support, called Disks. The disks protect the vertebrae by providing shock absorbing effect.
The disk may be slipped due to shock and jerk, felt in body & lifting of heavy weight. Over-weight individuals also possess high risk of slipped disk disorder. The person while performing routine activities like walking (sudden falling), lifting heavy material (with jerk) and twisting the body (torsion effect) may develop the slipped disk problem.
The disk has 2 rings, named outer ring which is composed of hard tissues and inner ring which is soft and gelatinous. Any injury or weakness of disk, may cause its inner portion to somewhat protrude through the outer ring.
This condition of disk is known as a slipped, herniated, or, prolapsed disk. The slipped disk exerts an extra pressure on nerves and the muscles around it.
The tearing of disk mostly occurs in posterior-lateral (dorsal side of body) direction due to presence of posterior longitudinal ligament around spinal canal which results into release of such chemicals, causing inflammation, followed by severe pain even in the absence of nerve root compression.
Most of the times, it is observed that the minor herniated disk heals itself within few weeks. But, in case of severe herniation where the disk is not self healed, it may require surgery. This condition is widely known as slipped disk. However, this condition is not medically accurate because it is said that the disks are firmly attached between the vertebrae and cannot “slip” out of place.
Complications & Symptoms of slipped disk:
If the slipped disk compresses any one or, more spinal nerves, the patient may also experience numbness and pain along the affected nerve. In many cases, the patient may require surgery to remove or repair the slipped disk. The symptoms of slipped disk are mentioned below:
Pain and numbness is sensed on one side of the body.
Pain is extended to arms and legs.
Pain is normally more acute during night or in association with certain specific postures.
Pain is increased after standing or sitting and walking short distances.
Pain and burning sensation in the affected area with feeling of muscle weakness.
Another long-term complication, a condition known as saddle anesthesia may occur due to slipped disk problem in which, as the slipped disk compresses nerves, the sensation in inner thighs, at back and around rectum is weakened.
Diagnosis of slipped disk:
The diagnosis of slipped disk involves various clinical tests for nerve function, muscle strength, pain sensation while, walking and on touching the affected area.
The medical history, symptoms and many investigations like X-Ray, CT Scan, MRI Scan, Discograms (Radiographic examination) etc. help the Doctor to diagnose the problem and to decide the course of treatment. The slipped disk, if not taken care of, may cause permanent nerve damage and may, later on, cut off the nerve impulses also.
Treatment of slipped disk:
The treatment for slipped disk is totally subjective, depending upon case history and various factors including the patient’s age, gender, location and extent of bulging of slipped disk, severity of inflammation, presence or absence of pain (mild or severe) and last but not the least, the time since when problem has arisen.
The treatment may prolong for short time or long time and rarely, the dislocation may be found to be incurable. In certain cases, surgery is also advised if the disk is not possible to be placed at proper location by any other method and the pain is not reduced within 6 weeks, affecting muscle function.
The anti inflammatory drugs (NSAIDs), muscle relaxants are prescribed to relieve spasmic pain, narcotics are sometimes prescribed to relieve pain and other nerve pain related medicines like Gabapentin, Duloxetine etc. are prescribed, which subsidize the sensation of pain till their medicinal effect lasts. These medicines do not cure the slipped disk problem and they have their own primary and secondary side effects if taken for long periods of time. However, the physiotherapy under guidance of skilled physiotherapist is quite helpful for strengthening the muscles of back and reducing the pain or, one should opt for surgery at last.
There are different ways to treat slipped disk disorder through surgical procedures some of which are mentioned below:
Microdiskectomy: Removal of herniated or protruded part without removing the entire disk.
Laminectomy: Replacement of entire disk with an artificial disk and fusing it with vertebrae (spinal fusion). It adds the stability to spinal column.
Transcutaneous Electrical Nerve Stimulation (TENS): It is also a good non-invasive treatment option in which a small electrical current to critical points is allowed to pass through a device along the path of a nerve. It doesn’t hurt the patient in any way and works positively in some patients.
The disk degeneration may permanently affect the nerves which control muscle movement. Herniated disks generally heal themselves and surgery is rarely necessary.
If the disk is just temporarily distorted, the probability of complete recovery is excellent. But, if the outer membrane is actually broken or, ruptured and has lost some of its gelatinous centre, the damage to the disk may be permanent.
Similarly, the Acupuncture and Accupressure are other non-surgical therapies which provide significant relief to the patients sometimes.
Precautions to avoid slipped disk:
The slipping of disk can be avoided by taking the following precautions:
Lifting techniques – Always bend and lift the weight from knees only and never from waist.
Weight management – Always maintain weight within normal range according to height.
Seating techniques – Always sit in correct posture and don’t remain seated for long periods.
Fitness techniques – Regular exercise is very important for strengthening the muscles, especially in back, legs, and the abdominal areas.