MRI scan
During a MRI scan, pictures of almost all the tissue in the body are taken. The tissue that has the least hydrogen atoms, such as the bones turns out dark. The tissues that have many hydrogen atoms, such as fatty tissue looks much brighter. The timing of the radio wave pulses is constantly changed to gain information about the different types of tissues present. An MRI scan is normally used as an extremely accurate method of disease detection and structural abnormalities throughout the body.
Patient with any metallic materials within the body must notify their physician prior to the MRI scan. This is because, metallic chips, materials, metal implants, surgical clips or foreign materials (artificial joints, metallic bone plates or prosthetic devices, etc) can significantly distort the images obtained by an MRI scanner. Patients with pacemakers, metal chips or clips in and around the eyeballs cannot be scanned by an MRI because of the risk that the magnet may move the metal in these areas. Patients with artificial heart valves, metallic ear implants, bullet fragments and chemotherapy or insulin pumps should not undergo MRI scanning.
MRI scan can cause a small risk to the fetus in the first 12 weeks of pregnancy. Therefore scans are not performed on pregnant women. The MRI machine produces loud thumping and humming noise when the procedure is performed. Therefore ear plugs are usually given to the patients to reduce the noise. MRI scans are a useful aid in the assessment of certain back conditions. MRI is an aid to detail studies of nerve root injuries like lumbar disc herniation and lumbar spinal stenosis. It is also extensively used in spinal disc and lumbar disc diseases and isthmic spondylolisthesis. It is also useful to rule out tumors and spinal infections.
Anterior Cord Syndrome
Anterior Cord Syndrome refers to the Anterior Spinal Artery Syndrome. The anterior spinal artery originates from the vertebral arteries and basal artery at the base of the brain. It supplies the anterior two thirds of the spinal cord to the upper thoracic, that is chest, region. Anterior cord syndrome results from injury to the motor and sensory pathways in the anterior cord. Patients suffering from Anterior Cord Syndrome may feel some crude sensations, but their movement and more detailed sensation is lost. In Anterior cord syndrome there is damage primarily in the anterior 2/3 cord. This is related to vascular insufficiency, sparing the posterior columns. Anterior cord syndrome usually results from the compression of the artery that runs in front of the spinal cord. The compression may be from bone fragments or a large disc herniation.
- In Anterior Spinal cord syndrome, there is usually complete loss of strength below the level of the injury. Anterior spinal artery syndrome produces variable loss of motor function and of sensitivity to pinprick and temperature. Thus the patient undergoes complete sensory loss. But the sensitivity to vibration (vibratory sense) and position sense (proprioception) is preserved.
- In Anterior Cord syndrome, the anterior section of the spinal cord is injured. This results in loss of movement and sensory perception. In anterior cord syndrome, there is complete motor paralysis.
- In Anterior Cord Syndrome, there is sparing of the dorsal column. The patient therefore exhibits greater motor loss in the legs than arms.
- It is interesting to note 80% of spinal cord injuries occur in males. Children suffer spinal cord injuries due to sports activities. Adult suffer spinal cord injuries that are work related.
MRI is a most accurate imaging test for spinal disorders. This is because in MRI the spinal cord parenchyma, soft tissue lesions like hematomas, tumors and interverterbral disks, bony lesions like erosion, hypertrophic changes, collapse, fracture and subluxation are revealed. Myelography with a radiopaque agent is used less often. Physicians normally use CT scans to demonstrate bony fragments compressing the anterior spinal cord. X rays may help to detect bony lesions.
Anterior cord syndrome is said to have the worst prognosis of all cord syndromes. The prognosis is usually good if the recovery is evident and progressive in the patient during first 24 hours. However, if there are no signs of sacral sensibility to pinprick or temperature are present after 24 hours, then the prognosis for functional recovery can be said to be poor. There is no standard course of treatment or cure for anterior cord syndrome. Physicians adopt drug therapies and surgery as part of the treatment program. There have been some exceptional cases where sensations that travel along pathways are still intact after the injury. Normally, it is observed that only 10 to 15% of anterior cord syndrome sufferers demonstrate any improvement in functions over a period of time.
Sciatica
Sciatica is described as pain, numbness or tingling in the leg due to compression of the sciatic nerve. The sciatic nerve runs down the back of each leg from the lower spine. The pain associated with sciatica can range from dull ache to excruciating pain that makes movement difficult. The pain may be felt in the buttock, down the back of the leg, below the knee and in the foot.
Causes of sciatica
- Disc herniation
- Pelvic fracture
- Spinal tumors
- Pelvic injury
- Pain along one side of the body
- Worsening in cold weather
- Osteoarthritis causing pressure on the sciatic nerve
A physical examination along with checking of reflexes on bending, lifting the leg etc are done. X-ray and MRI might be done. Typically sciatica is indicative of another medical problem; which must be attended to. NSAIDs and ice packs provide relief from the pain. Lifting of heavy objects and strenuous back bending are to be avoided. Physical therapy, massage therapy and stretching exercises might help in tackling chronic sciatica.
Bibliography / Reference
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