Prolapsed Intervertebral Disk (PIVD)
The herniated disk also known as the prolapsed intervertebral disk is a condition affecting the spine frequently causing neck pain or back pain. The intervertebral disk is a disc-shaped circular tissue present between the adjacent vertebrae. The disk acts as a cushion between two vertebrae and provides stability.
Anatomy of the Intervertebral disk.
The intervertebral disks consist of a thick fibrous outer layer known as the annulus and a soft center known as the nucleus pulposus. The outer layer adjoining the vertebrae is known as the endplate. The endplate is formed by cartilage that contributes to the growth of the vertebra. The endplate is thick in childhood and gradually decreases in thickness.
The annulus fibrosis consists of concentric layers of thick fibers which imparts it the property of elasticity while being tough. The nucleus pulposus has a watery gel-like consistency giving it the ability to resist compression and allow cushioning action. The sinuvertebral nerve arises from the dorsal root ganglion and supplies the most superficial layer of the annulus fibrosis.
A disc herniation results from the protrusion/extrusion of the nucleus pulposus through the annulus fibrosis of the disk. The vertebral canal has only enough room for the spinal cord/spinal nerves and the spinal fluid. The herniated disk causes inflammation and impinges/compresses the nerves/spinal cord causing symptoms of pain.
Classification based on anatomy.
The herniated disc may either occur in the form of protrusion where the nucleus pulposus is still covered by a thin layer of the annulus fibrosis. In the case of disk extrusion, the nucleus pulposus herniates through the annulus fibrosis but is still contained within the disc space. In cases where the herniated nucleus pulposus loses contact with the original disk material, it is known as disk sequestration.
Classification based on location.
The disk may herniate centrally known as central disk herniation. The disk material commonly compresses the spinal cord and in severe cases may result in cauda equina syndrome. Most frequently, the disk material herniated to the sides known as posterolateral/paracentral disk herniation.
In paracentral disk herniation descending nerve roots are commonly compressed leading to symptoms of pain in the area supplied by the nerve. Less commonly, the disk may herniate at extreme sides known as foraminal (far lateral) herniation. In foraminal herniation, the nerve exiting the foramen is impinged leading to symptoms.
The herniated disk in the majority of the cases occur in the lower back (lumbar spine) and the rest of the cases involve the neck (cervical spine). The prolapsed intervertebral disk is more common in adults aged 30 and more as with age the nucleus pulposus starts losing the water content, making it more susceptible to injuries.
Repetitive activities such as bending, turning, twisting may cause tears in the annulus. Obesity, smoking, and improper posture while sitting or standing to make the disks more vulnerable to injuries resulting in PIVD. Lifting weights and traumatic injuries frequently result in PIVD.
The symptoms of a herniated disk depend on the location of the herniation and the amount of compression on the neural structures. In the lower back, a herniated disk commonly results in pain of the lower back. The patients may also experience shooting pains in the buttocks radiating to the back of the legs and feet. Some patients may complain of numbness and tingling of the feet or legs. Patients may also experience weakness of the legs or feet.
Cauda equina syndrome results from compression of the nerve roots from a large central disk herniation below the L1-L2 vertebrae. The compression of the sac below this level may result in loss of bowel bladder control, numbness of the saddle area. The condition is an emergency and requires immediate surgery.
The symptoms from disk herniation in the neck may result in pain in the region between the neck and the shoulders. The patients may experience radiating pain down the shoulders, arm, forearm, and hand. There may be numbness and tingling in the region supplied by the impinged nerve. The patients may complain of weakness of the muscles of the hand, forearm, arm, or shoulders depending upon the location of the impingement.
The diagnosis of a herniated disk is made by your examining physician. An extensive history is obtained regarding the onset of the symptoms and the activities leading to the symptoms. The physician will usually perform an extensive physical examination. The physical examination consists of different tests used to illicit the symptoms to localize the area of herniation. The physician will also assess the motor and sensory functions of the limbs.
The vast majority of the cases of prolapsed intervertebral disks respond to conservative/non-surgical treatment. The conservative management consists of rest and avoidance of activities precipitating the pain.
Nonsteroidal anti-inflammatory medication and muscle relaxants provide significant relief in the majority of the patients. Cold therapy provides symptom relief and heat therapy helps once the spasm has decreased.
The herniated disc material is slowly reabsorbed by the body which results in relief of the nerve impingement. Therefore most patients experience significant relief over a period of months. Once the pain subsides, the patients are advised to physical therapy to strengthen the muscles around the spine for providing better stability.
In cases, patients are unable to participate in physical therapy due to pain, epidural or foraminal steroid injection is given to provide relief from symptoms.
Rarely patients whose symptoms are not relieved with conservative therapy may require surgical intervention. Surgical management of lumbar disk herniations commonly consists of Microdiskectomy which is usually performed on an outpatient basis.
The surgery involves the use of a microscope to aid in performing the surgery through a very small incision in the back. The surgery involves the removal of the herniated disk and any part impinging upon the nerve root.
In the case of cervical disk herniation, surgical management usually consist of a fusion of the two adjoining vertebrae in addition to the removal of the disc material.
The instruments in the image above are used to remove the intervertebral disc material, create raw surface for the insertion of the bone cage and insert the pedicle screws.
The transforaminal lumbar interbody fusion (TLIF) utilizes a lateral incision from the back for fusion of the vertebrae. The image above shows distraction forceps used to create a space between the vertebra for insertion of the bone cage along with the bone graft material for aiding the fusion of the involved segment.