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Discal spinal hernia is a protrusion that takes place on the intervertebraldiscs due to strong, rude and/or repeated efforts. Those protrusions ordiscal hernias compress the nerve roots in the spine that lead to the armsand legs. When in the neck, cervical discal hernia may produce the so called"Cervical-Brachial Neuralgias" (neck, shoulders and hernia-sidearm pain) and if lumbar, hernias produce sciatica or lumbo-sciatica, thatis pain in the low-back that spreads to the leg on the hernia side.
Discal hernias can occur in Cervical or atLumbar discs.
Theintervertebral
discs are cartilaginous plates surrounded by a fibrous ringwhich lie between
the vertebral bodies and serve to cushion them. Throughdegeneration, wear and
tear, or trauma, the fibrous tissue (annulus fibrosus)constraining the soft
disc material (nucleus pulposus) may tear. This resultsin protrusion of the
disc or even extrusion of disc material into the spinalcanal or neural foramen.
This has been called herniated disc, ruptureddisc, herniated nucleus pulposus,
or prolapsed disc.
This disc herniation may become significant if a nerve root is compressed.Irritation of the nerve root produces pain in the distribution of thatnerve, typically down the back of the leg, side of the calf, and possiblyinto the side of the foot. For this reason, a herniated lumbar disc characteristicallyproduces sciatica but not back pain per se. If sensory function of theimpinged nerve root is impaired, numbness will result. The exact area ofnumbness is determined by the particular root, and may be in the innerankle, the great toe, the heel, the outer ankle, the outer leg, or a combinationof these. Impairment of motor function of the root will cause weaknesswhich again depends on the particular root, and may include weakness ofbringing the ankle upward or downward or raising the great toe.
| Manifestation | Level of Disc Herniation | ||
|---|---|---|---|
| L3-L4 | L4-L5 | L5-S1 | |
| Root Compressed | L4 | L5 | S1 |
| Weakness | quadriceps, tibialis anterior | extensor hallicus longus (extension of great toe) | gastrocnemius (ankle plantarflexion) |
| Reflex Involvement | knee jerk | none significant | Achilles |
| Sensory Loss | medial ankle | great toe | lateral foot & heel |
| Pain Distribution | anterior thigh | back of thigh | back of thigh, lateral calf |
Table. The most common clinical manifestationsof lumbar disc herniation.
Table summarizes the major lumbar disc herniation syndromes. Note thatthe L5-S1 disc is involved 45-50% of the time, L4-L5 40-45%, and L3-L4 about5%. Disc herniation at the other lumbar levels is rare. The root compressedis the one exiting the level below, in the vast majority of cases. However,if the herniation is lateral, into the foramen, then the root compressedwill be the one above. This is known as a far lateral disc herniation andoccurs in about 3-10% of cases. It is also important to note that whilethese signs are helpful in the diagnosis and decision regarding type oftreatment, not all of the signs and symptoms associated with a root maybe present in an individual, and multiple root signs may even be present.
The diagnosis should be suspected from the history and physical examination.Radiographic studies should be done to make the diagnosis and define itslocation and configuration. Generally, an MRI scan is preferred becauseit is noninvasive (no needle punctures or injections are required) whileproviding excellent detail. CT scan, while inferior to MRI in soft tissuedetail, are superior in bony detail, and are faster and less expensive.For this reason, a good quality CT scan is often sufficient in an uncomplicatedherniated lumbar disc. Myelography with CT has long been the gold standard,because of its excellent definition of the spaces around the nerve roots.Its disadvantage is that it requires injection of contrast dye througha lumbar puncture. It has to a large extent been supplanted by MRI, butit should be viewed as a complementary rather than an alternative test,and in many cases it is indispensable.
As
in the lumbar and thoracicspine, herniation ofthe contents of an intervertebral
disc may occur when a tear occurs inthe annulus fibrosus that surrounds the
disc. However, whereas in the lumbarspinal canal only nerve roots are present,
in the cervical canal the spinalcord may be compressed.
The symptoms and signs produced are the result of nerve root compression,spinal cord compression, or both.
The most common complaint is neck pain which limits motion and is aggravatedby neck extension. Pain also may radiate into one arm, in a pattern characteristicof the particular root involved (see below). Patients often hold the armelevated and behind the head, presumably because this maneuver reducesthe tension on the nerve root and thus lessens the pain. In most cases,the onset of pain is upon awakening, without identifiable trauma or otherprecipitating event.
| Manifestation | Level of Disc Herniation | |||
|---|---|---|---|---|
| C4-C5 | C5-C6 | C6-7 | C7-T1 | |
| Root Compressed | C5 | C6 | C7 | C8 |
| Weakness | deltoid | biceps | triceps, wrist extension | hand intrinsics, wrist flexion |
| Sensory Loss | lateral shoulder | lateral arm & forearm, thumb & lateral aspectof index finger | middle finger | ring & little fingers |
| Reflex Involvement | deltoid, pectoralis | biceps | triceps | finger flexion |
Table. The most common clinical manifestationsof cervical disc herniation.
The Table shows the usual cervical root syndromes (radiculopathy).Note that the C6-7 disc is the most frequently herniated, about 2/3 ofcervical herniations. The C5-C6 disc is involved about 20% of the time,the C7-T1 about 10%, and the C4-C5 about 2%.
If the disc herniation compresses the spinal cord, certain deficitsmay result (myelopathy). Weakness in the hands and arms may be moregeneralized or bilateral, rather than confined to a root distribution.In addition, there may be leg weakness, usually manifested initially bya feeling of heaviness in the legs and noticable difficulty in walkingusual distances or up stairs. Examination may show hyperactive reflexes,pathological reflexes, and a spastic gait. Finally, sphincter and sexualfunction may be compromised, usually later in the progression of myelopathy.
Lhermitte's sign refers to a sudden electrical sensation downthe neck and back triggered by neck flexion. This was originally describedin a patient with multiple sclerosis and dorsal column dysfunction. Theconditions which can produce a Lhermitt's sign are:
Other signs may help in aiding the physical diagnosis. These are verysuggestive of cervical disc herniation when present, but are frequentlyabsent in the presence of the disease (that is, they are specific but notsensitive). Spurling's sign refers to the reproduction or exacerbationof pain upon pushing down on the head and bending it toward the involvedside. The reduction of pain when axial traction is applied to the headis also suggestive of a disc. Finally, in the shoulder abduction test raisingthe affected arm above the head reduces the pain.
The
radiographic evaluation of a suspected spine disorder beginswith plain X-rays.
A herniated disc, being composed of soft tissuerather than bone, will not be
seen on X-ray, however other associated changesmay be seen, such as the characteristic
bony ridges of cervical spondylosis.In addition, the alignment can be accurately
assessed.
MRI has in most cases become the study of choice in cervicaldisc herniation. Its superior resolution of soft tissues gives good definitionof disc material, cord compression, and root compression. When bony detailis required, a myelogram/CT should be obtained.
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