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This disorder is due to a defect in fibrillin-1, an extracellular protein found in elastic connective tissues. This has been found in periosteum, perichondrium, and cartilage matrix. The key themes in this disorder are excessive long bone growth and, to a lesser extent, ligamentous laxity. A diagnosis is confirmed when there is involvement of three systems with two major diagnostic manifestations. The major
manifestations include aortic root enlargement, aortic dissection, lens dislocation, dural ectasia, presence of four specific skeletal findings, an affected first-degree relative, or a molecular confirmation of a fibrillin mutation.
Spinal problems include scoliosis, kyphosis, spondylolisthesis, degenerative spondyloarthropathy, and dural ectasia. Cervical problems are much less common. Scoliosis is seen in about 60% of patients, but only about 10% of Marfan patients require treatment. Interestingly, even among affected members of the same family, spinal manifestations differ markedly. Curve patterns are not unlike those seen in idiopathic scoliosis. Differences include an increased percentage of triple curves and an increased prevalence of kyphosis. The kyphosis often extends across the thoracolumbar junction. A sagittal curve inversion with a thoracic lordosis and a lumbar kyphosis can be observed in some cases. The progression rate of curves in growing children is greater than that for idiopathic scoliosis. Curves greater than 30 to 40 degrees at maturity are likely to progress in adulthood.
Brace treatment is not often effective in Marfan¡¦s syndrome. There fore, it probably should be employed only in patients with smaller curves (15 to 20 degrees), and treatment should not persist if the curve progresses.
Fusion is indicated for most curves over 40 degrees. Special features of the syndrome should be noted. It is often helpful to have patients followed perioperatively by a cardiologist or geneticist. There is a tendency to increased blood loss. The levels to be corrected should be carefully selected based upon a review of both the coronal and the sagittal planes. The pedicles and laminae are thin, and the use of both hooks and screws should be planned carefully preoperatively. A computed tomography (CT) scan may be helpful in assessing the shape and width of the pedicles. There is an increased risk of spinal fluid leak when dissecting inside the spinal canal.
By exercising common sense about the patient's overall medical condition, avoiding techniques that have been proven ineffective, and careful analysis of the curves, satisfactory results can usually be obtained. |
