24 Perioperative Session: Neurologic Complications
The concept of early onset scoliosis was introduced by Robert Dickson to define scoliosis starting before the age of 5 years, regardless of the etiology. Over the last two decades, the management of these conditions has changed drastically. Physicians became rather disappointed with the outcomes of treatment with the very conservative approach of serial plaster casts, and they have now adopted a more aggressive attitude, using surgery to reduce the progression of severe deformities. Modern developments in surgical techniques and appliances have brought new hope that rapidly progressive scoliotic curves in these very unfortunate children can be controlled. However, with the introduction of a more sophisticated surgical armamentarium and the treatment of higher-risk patients with scoliosis of different pathogenetic mechanisms, the frequency of perioperative complications has increased.
The complexity and diversity of perioperative complications result from the different conditions diagnosed in association with early onset scoliosis—congenitally abnormal vertebrae, neuromuscular conditions, syndromic spinal deformities, connective tissue disorders, and idiopathic spinal deformities—each carrying its own potential problems. Not only are associated medical problems the cause of complications; in addition, pulmonary function and lung development can be compromised when spine and chest deformities start very early in life.
Procedures that allow the spine and the chest to develop and grow have become popular for the treatment of early onset scoliosis. However, the high rates of complications reported may result from both the need for repeated operations and issues related to the critical health conditions of these children. 2 , 3
24.1 The Context
The report of the Scoliosis Research Society on complications in the surgical treatment of pediatric scoliosis (patients younger than 18 years) included the following etiologic groups: idiopathic, congenital, neuromuscular, and others. 4 With an overall rate of 10.2%, the complications did differ significantly among the three main groups.
Regarding neurologic complications, an overall rate of 0.72% was reported in the Scoliosis Research Society series, 4 but the rates of neurologic deficit differed among the three groups; the highest rate was reported in the treatment of congenital scoliosis (2%), followed by neuromuscular (1.1%) and idiopathic (0.8%) scoliosis. An association between the type of instrumentation used and type of procedure performed and the occurrence of new neurologic deficit was also established, with revision surgery having the highest risk.
However, these are overall figures for neurologic complications in the population of patients younger than 18 years of age, and they do not address specifically the group of patients with early onset scoliosis. In order to focus on this particular problem, we must review the principles of treatment and the types of procedures used, assuming that they do include scoliosis with a variety of etiologies.
24.2 The Principles
Because the development of rapidly progressive spinal deformities early in life leads to significant pulmonary compromise in adulthood, more recent treatment options have addressed not only spinal deformity but also chest development to improve the patient’s quality of life. A new nomenclature (growth-sparing surgery, also known as fusionless surgical technique) has been created to include a group of different procedures with the same therapeutic objectives of preserving growth of the spine, thorax, and lungs while controlling the deformity. The surgical options are complex, and complications are understandably common if we consider that children with early onset scoliosis are high-risk patients because of their numerous associated comorbidities.
If we focus on the mechanism of treatment of severe spinal deformities in these very young patients, growth-sparing surgical procedures can be divided in three main groups: distraction-based, guided-growth, and tension-based procedures. The first group, distraction-based, includes growing rods and vertical expandable prosthetic titanium rib (VEPTR) techniques; the second group, guided-growth, includes procedures like the Shilla and the Luque trolley; and the third group, tension-based, includes spinal stapling and spinal tether (still experimental). The theoretical benefit of a guided-growth procedure is that it may not require the patient to undergo serial lengthening procedures (but occasionally rod exchange) and therefore may be definitive, although the original operation is more demanding and aggressive.
Because these procedures have been developed to help the young deformed spine to grow, they are not definitive operations per se; rather, they are done in stages: original insertion of the rods or implant, then several interval procedures for rod lengthening and implant exchange (often repeated several times) until the definitive procedure during adolescence.
When we talk about neurologic deficit, we must realize that the type of injury that can arise after one of these procedures is not always the same. On the one hand, types of deficit differ; they may be a cord lesion (total or partial), brachial plexopathy, or radiculopathy; on the other hand, however, it is important to mention that the mechanisms of neurologic injury can also differ; the injury can result from direct trauma, ischemia, or compression of any of the neural structures.
In order to assess the rate of neurologic complications associated with these procedures, we will look into the occurrence of new neurologic deficit in the first two groups of procedures.
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