HERNIATION OF A LUMBAR DISK
Most lumbar disk herniations occur at the L4-5 or the L5-S1 interspaces (Humphreys & Eck, 1999). A herniated lumbar disk produces low back pain accompanied by varying degrees of sen-sory and motor impairment.
The patient complains of low back pain with muscle spasms, followed by radiation of the pain into one hip and down into the leg (sciatica). Pain is aggravated by actions that increase intra-spinal fluid pressure (bending, lifting, straining, as in sneezing and coughing) and usually is relieved by bed rest. Usually there is some type of postural deformity, because pain causes an alteration of the normal spinal mechanics. If the patient lies on the back and attempts to raise a leg in a straight position, pain radiates into the leg because this maneuver, called the straight leg-raising test, stretches the sciatic nerve. Additional signs include muscle weak-ness, alterations in tendon reflexes, and sensory loss.
The diagnosis of lumbar disk disease is based on the history and physical findings and the use of imaging techniques such as MRI, CT, and myelography.
The objectives of treatment are to relieve pain, slow disease pro-gression, and increase the patient’s functional ability. Bed rest for 1 to 2 days on a firm mattress (to limit spinal flexion) is encour-aged to reduce the weight load and gravitational forces, thereby freeing the disk from stress (Humphrey & Eck, 1999). The pa-tient is allowed to assume a comfortable position; usually, a semi-Fowler’s position with moderate hip and knee flexion relaxes the back muscles. When the patient is in a side-lying position, a pil-low is placed between the legs. To get out of bed, the patient lies on one side while pushing up to a sitting position.
Because muscle spasm is prominent during the acute phase, muscle relaxants are used. NSAIDs and systemic corticosteroids may be administered to counter the inflammation that usually occurs in the supporting tissues and the affected nerve roots. Moist heat and massage help to relax spastic muscles and have a sedative effect. Antidepressant agents appear to help in low back pain that is neuropathic in origin (Fishbain, 2000).
In the lumbar region, surgical treatment includes lumbar disk ex-cision through a posterolateral laminotomy and the newer tech-niques of microdiscectomy and percutaneous discectomy. In microdiscectomy, an operating microscope is used to visualize the offending disk and compressed nerve roots; it permits a small in-cision (2.5 cm [1 inch]) and minimal blood loss and takes about 30 minutes of operating time. Generally, it involves a short hos-pital stay, and the patient makes a rapid recovery. Percutaneous discectomy is an alternative treatment for herniated intervertebral disks of the lumbar spine at the L4-5 level. One approach in cur-rent use is through a 2.5-cm (1-inch) incision just above the iliac crest. A tube, trocar, or cannula is inserted under x-ray guidance through the retroperitoneal space to the involved disk space. Spe-cial instruments are used to remove the disk. The operating time is about 15 minutes. Blood loss and postoperative pain are min-imal, and the patient is generally discharged within 2 days after surgery. The disadvantage of this procedure is the possibility of damage to structures in the surgical pathway.
Complications of Disk Surgery.A patient undergoing a disk pro-cedure at one level of the vertebral column may have a degenera-tive process at other levels. A herniation relapse may occur at the same level or elsewhere, so that the patient may become a candi-date for another disk procedure. Arachnoiditis (inflammation of the arachnoid membrane) may occur after surgery (and after myelography); it involves an insidious onset of diffuse, frequently burning pain in the lower back, radiating into the buttocks. Disk excision can leave adhesions and scarring around the spinal nerves and dura, which then produce inflammatory changes that create chronic neuritis and neurofibrosis. Disk surgery may relieve pres-sure on the spinal nerves, but it does not reverse the effects of neural injury and scarring and the pain that results. Failed disk syndrome (recurrence of sciatica after lumbar discectomy) re-mains a common cause of disability.
Most patients fear surgery on any part of the spine and therefore need explanations about the surgery and reassurance that surgery will not weaken the back. When data are being collected for the health history, any reports of pain, paresthesia, and muscle spasm are recorded to provide a baseline for comparison after surgery. Preoperative assessment also includes an evaluation of movement of the extremities as well as bladder and bowel function. To facil-itate the postoperative turning procedure, the patient is taught to turn as a unit (called logrolling) as part of the preoperative prepa-ration (Fig. 65-9). Before surgery, the patient is also encouraged to take deep breaths, cough, and perform muscle-setting exercises to maintain muscle tone.
After lumbar disk excision, vital signs are checked frequently and the wound is inspected for hemorrhage because vascular injury is a complication of disk surgery. Because postoperative neurologic deficits may occur from nerve root injury, the sensation and motor strength of the lower extremities are evaluated at specified inter-vals, along with the color and temperature of the legs and sensa-tion of the toes. It is important to assess for urinary retention, another sign of neurologic deterioration.
In discectomy with fusion, the patient has an additional sur-gical incision if bone fragments were taken from the iliac crest or fibula to serve as wedges in the spine. The recovery period is longer than for those patients who underwent discectomy with-out spinal fusion because bony union must take place.
To position the patient, a pillow is placed under the head and the knee rest is elevated slightly to relax the back muscles. When the patient is lying on one side, however, extreme knee flexion must be avoided. The patient is encouraged to move from side to side to relieve pressure and is reassured that no injury will result from moving. When the patient is ready to turn, the bed is placed in a flat position and a pillow is placed between the legs. The patient turns as a unit (logrolls), without twisting the back.
To get out of bed, the patient lies on one side while pushing up to a sitting position. At the same time, the nurse or family member eases the patient’s legs over the side of the bed. Coming to a sitting or standing posture is accomplished in one long, smooth motion. Most patients walk to the bathroom the same day as surgery. Sitting is discouraged except for defecation.
The patient is advised to graduallyincrease activity as tolerated because it takes up to 6 weeks for the ligaments to heal. Excessive activity may result in spasm of the paraspinal muscles.
Activities that produce flexion strain on the spine (eg, driving a car) should be avoided until healing has taken place. Heat may be applied to the back to relax muscle spasms. Scheduled rest pe-riods are important, and the patient is advised to avoid heavy work for 2 to 3 months after surgery. Exercises are prescribed to strengthen the abdominal and erector spinal muscles. A back brace or corset may be necessary if back pain persists.
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