The Role of Spinal Fusion and the Aging Spine: Stenosis with Deformity

Published on 11/04/2015 by admin

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51 The Role of Spinal Fusion and the Aging Spine

Stenosis with Deformity

Definition of Stenotic Degenerative Disease in Deformity

Lumbar spinal stenosis is defined as a narrowing of the spinal canal that produces compression of the neural elements before their exit from the neural foramen. The narrowing may be limited to a single motion segment (two adjacent vertebrae and the intervening intervertebral disc, facet joints, and supporting ligaments) or it may be more diffuse, spanning two motion segments or more.

Adult deformity of the spine with degenerative disease can be a major contributing factor in the narrowing of the spinal canal. Adult degenerative scoliosis occurs on the right and left sides with equal frequency. Adult degenerative scoliosis develops as a result of asymmetrical narrowing of the disc space and vertebral rotation secondary to the instability caused by degeneration of the disc.

Neural compression associated with adult lumbar scoliosis is commonly manifested as a radicular pain that may be related to physical activity. As the apex of a curve rotates, there is associated hypertrophy and subluxation of the facet joints in the concavity of the curve. Additionally, collapse in the concavity results in narrowing of a neural foramen between adjacent pedicles. As a result, symptoms occur in the anterior portion of the thigh and leg (resulting from compression of the cephalic and middle lumbar nerve roots). Radiating pain in the posterior portion of the lower extremity is more common on the side of the convexity of the lumbar curve; such pain is due to compression of the caudal lumbar nerve roots and the sacral nerve roots, well caudad to the apex, as the spine curves back to meet the pelvis. 2

Clinical Complex of Symptom Presentation

The degenerative aging spine with deformity creates the complex of four major categories of clinical symptom presentation:

Neurologic pain occurs with activity-related claudication caused by diminished blood flow to the nerves. It is incumbent upon the healthcare provider to rule out common causes of leg pain such as peripheral vascular disease, cardiac disease, arteriosclerotic vascular disease, and/or primary neurologic disease. Compressive radicular pain occurs on the concave collapsing side of a degenerative scoliosis, from direct compression of the nerve at the exiting foramen or subarticular space. Nerve stretch radicular pain occurs on the convex nerve roots that are exiting from the stenotic collapsing scoliotic spine. Therefore, a patient may present with either convex radicular pain or concave nerve root pain, or both.

Back pain may be caused by arthrosis and normal aging body changes of the discs, facets, or other structures. Another cause of back pain may occur from abnormal restricted segmental spine motion, as referred to by the term “mechanical pain.” Also, back pain may occur secondary to nerve root compressive pain, which is secondary to decreased circulation and/or nerve compression.

Activity-related complaints from the aging spine patient generally involve lifestyle changes. Often the patient will present to the healthcare provider with statements describing restriction of normal activities of living. The patient may state that she or he cannot participate in dance, golf, normal work, recreational activities of hunting and fishing, or normal walking and exercise.

Deformity-related issues include complaint of a cosmetic changing appearance to the body, with or without a rib producing pressure on the pelvis. The patient may be twisting and leaning more on one side relative to the other side of his or her body. Less often, the patient will describe a shortness of breath secondary to restrictive lung capacity from scoliotic collapse and degenerative changes around the chest. The final and probably the most daunting problem is when the patient presents with complaints of balance and instability that affect normal ambulation. The patient may have a spine deformity that is so significant that he or she is not able to maintain normal balance, and requires orthotic spine supports such as a cane or walker to ambulate through daily activities.

Adult Scoliosis Classification

Adult Scoliosis is classified by Aebi 3 using an AO system based on a pathoanatomic etiology and on a temporal onset of deformity. His classification defines adult scoliosis as spinal deformity in a skeletally mature patient with a Cobb angle of more than 10 degrees in the coronal plane. Aebi separates adult scoliosis into four types:

Schwab et al.4 proposed a three-tier classification system for adult scoliosis based on parameters of coronal and sagittal plane. These radiographic criteria include lumbar lordosis, location of coronal curve apex, olisthesis of vertebra segments relative to each other, and sagittal balance on x-ray (Figures 51-3 through 51-6). The classification system has accurately correlated radiographs with clinical significance, in an attempt at suggesting the most appropriate successful treatment in the adult patient. The rate of disease progression is influenced by the magnitude of the curve, the degree of lateral listhesis, the quality of the bone and the severity of associated spondylotic disease. Table 51-1 shows two classification schemes.