MRI deomonstrating a large L4-L5 disc herniation (arrow) resulting in significant narrowing of the spinal canal and pressure on the L5 nerve.
Lumbar disc herniation is a common condition that frequently affects the spine in young and middle-aged patients. The lumbar intervertebral disc is a complex structure composed of collagen, proteoglycans, and sparse fibrochondrocytic cells that serve to dissipate forces exerted on the spine. The disc essentially functions as a shock absorber. As part of the normal aging process, the disc cells decrease their metabolic activity which results in diminished proteoglycan production. This in turn leads to a loss of water content and disc collapse, which increases strain on the fibers of the annulus fibrosus(outer fibers surrounding the disc). Tears and fissures in the annulus(outer covering of the disc) can result. This in turn can result in herniation of disc material, should sufficient forces be placed on the disc. Alternatively, a large force(eg. car accident, fall, lifting heavy object) placed on a healthy, normal disc may lead to extrusion of disc material in the setting of catastrophic failure of the annular fibers.
Regardless of the cause, disc herniations represent protrusions of disc material beyond the confines of the annular lining and into the spinal canal. Back pain may occur due to disc protrusions that do not enter the canal or compromise nerve roots. The more treatable condition of lumbar radiculopathy(pain traveling down the leg), arises when extruded disc material contacts, or exerts pressure, on neural structures. The pain associated with lumbar radiculopathy occurs due to a combination of nerve root ischemia(decreased oxygen delivery to nerve tissue secondary to decreased blood flow) and inflammation resulting from local pressure and neurochemical inflammatory factors present within the disc material.
There are many studies showing that lumbar herniations, protrusions, and annular tears are present in asymptomatic(pain free) individuals and, in certain instances, can represent normal aging of the intervertebral disc. A variety of studies have suggested that 90% of patients with lumbar disc herniations will improve within 8-12 weeks from onset of symptoms without significant medical intervention(no surgery!).
The constellation of symptoms associared with a disc herniation can include numbness and weakness, but most often consists solely of leg pain that radiates into the buttock, travels down the thigh and below the knee from nerves L5 and S1 (sciatica); or, less commonly, into the anterior thigh or groin from nerves L2, L3, and L4 (femoralgia). Sensory abnormalities in the genitals, anus, or perineum often coupled with loss of bladder control (cauda equina syndrome), as well as progressive loss of sensation or motor function in the legs, warrant urgent evaluation and treatment. In situations where leg pain is the primary symptom, treatment begins with conservative management including physical therapy, pain medication and epidural injections. Surgical indications include progressive weakness and failure of conservative management.
Most of the current literature demonstrates earlier relief of pain-related symptoms, and possibly earlier restoration of function, in patients who undergo surgery. Advantages of surgical intervention have been shown to persist for up to four years following surgery.
Additionally, if symptoms have already been present for an extended period of time, surgery is more likely to relieve symptoms than continued nonoperative management.
While both conservative and surgical options are shown to be effective, the ultimate decision regarding initial and definitive management should be made by the patient based on their desires and individualized requirements, following a frank discussion regarding risks and benefits of the various treatments with the surgeon.