Patient selection: A key factor in surgery for degenerative spinal deformity
"While some of my most satisfied patients are adults who have had surgical correction for thoracolumbar spinal deformities, careful patient selection is critical to successful outcome," explains Mark A. Pichelmann, M.D., a neurosurgeon at Mayo Clinic in Rochester, Minn.
The past decade has seen advances in surgical techniques and instrumentation for the correction of adult spinal deformity, but it remains a complex and lengthy procedure. The risks associated with it are relatively high, so careful consideration and evaluation must be given to:
- Medical comorbidities
- Nature and severity of the deformity
- Level of support during the lengthy recovery period
At Mayo, candidacy for the surgery typically includes evaluation by specialists in general and internal medicine and in physical medicine and rehabilitation (PM&R), as well as neurology and neurosurgery.
Many people have some degree of curvature of the spine, or scoliosis, yet are asymptomatic. Symptoms include back pain, physical deformity and nerve compression, which can generate numbness, weakness and leg pain, especially upon standing or walking. In some cases, and particularly as people age, the symptoms can be severe enough that they seek surgery.
Curvature of the spine in adults has been classified into two main types:
- Progressive scoliosis in people who had adolescent idiopathic scoliosis (AIS) that was either asymptomatic or minimally symptomatic until later in life is called type I adult scoliosis. Symptoms may develop in response to accelerated curve progression due to subsequent degenerative changes or as a result of previous spine surgeries.
- People with the second type of scoliosis, called type II adult scoliosis, have curvature of the spine as adults, most commonly in response to degenerative disease of the spinal column or, less frequently, in response to abnormalities that are not spine specific, such as osteoporosis, leg-length discrepancy or previous spine surgeries.
Osteoporosis, for example, may weaken the bones of the spine enough to create small fractures that can result in asymmetrical spinal strength and cause the spine to bend toward the weaker side.
In a majority of patients with AIS, some progression of spinal curvature develops after they reach 40 years of age. The curvature progression in type II adult scoliosis with degenerative characteristics can occur at a much more rapid pace than in type I adult scoliosis.
Surgical candidate evaluation at Mayo Clinic
Abnormal preoperative adult degenerative scoliosis with curve progression and neurologic symptoms
Abnormal postoperative thoracolumbar fusion with curve correction and resolution of neurologic symptoms
The degree of curvature is just one factor in the decision to proceed to surgery. Other factors include the risk of curvature progression, physical and cosmetic effects of the deformity, and spinal balance.
For example, healthy adults with curvatures of greater than 50 degrees who are younger than 40 years of age may have relatively mild symptoms but may be good surgical candidates because of the propensity for the curvature to progress. Older patients more often seek surgical advice as a result of neurologic symptoms (for example, leg pain or weakness) than for the deformity itself.
Pre-existing conditions such as diabetes mellitus, heart disease, osteoporosis, a history of smoking, and respiratory conditions are comorbidities that can increase the risk of postsurgical complications. Age is another major factor.
"I usually tell my patients who are in their late 60s that risks are higher of having a minor or major complication as a result of having surgery. In some groups, there is approximately a 70 percent chance of a minor complication, such as a urinary tract infection or minor case of pneumonia, following surgery, but there is also an approximately 20 to 30 percent chance that they will have a major complication, such as wound infection, instrumentation failure or fracture, or some other medical complication that prolongs their recovery."
Surgical correction involves fusion to prevent progression and to alleviate nerve compression. Fusion may include an area from the low thoracic spine to the sacrum or, in some cases, a portion of the lumbar spine.
For this reason, Dr. Pichelmann often has his patients seen by an occupational and physical therapist in PM&R before surgery so that the patients can understand the physical limitations surgery will impose. He believes that patients receive great benefit from being thoroughly informed about the ways in which a rigid spine will affect common activities of daily living.
Dr. Pichelmann finds it also is critical to ask patients about their support at home for the recovery period, which can last from many months to even a year or more after surgery. In carefully selected patients, surgery can be a satisfying and effective management strategy.
At Mayo, if surgery is not a viable option, patients receive a multidisciplinary treatment approach to their symptomatic scoliosis that may include specialists in anesthesiology, psychology and the Pain Rehabilitation Center.