Extract
Spinal deformity occurs in children who have problems with motor control
involving the trunk muscles. This lack of control allows the growing spine to
collapse. Most commonly, this collapse is due to spasticity in children with
the quadriplegic pattern of cerebral palsy. The most typical collapse pattern
is scoliosis, although kyphosis or lordosis may also develop. Children who
have severe hypotonia may also have development of spinal deformities, often
with substantial kyphosis. Individuals with severe extensor posturing may have
development of total spinal lordosis. A severe lack of motor control,
expressed as a movement disorder such as athetosis or dystonia, is associated
with a lower incidence of scoliosis than spasticity is. The incidence of
scoliosis in institutionalized individuals, most of whom have a spastic
quadriplegic pattern, has been reported to be 64%, with a strong inverse
relationship to ambulatory
ability1. This means
that individuals who are dependent sitters with no head control may have a
rate of scoliosis as high as 90%. We are not aware of published data on the
incidence of spinal deformity with other movement disorders.
Spinal deformity occurs in children who have problems with motor control
involving the trunk muscles. This lack of control allows the growing spine to
collapse. Most commonly, this collapse is due to spasticity in children with
the quadriplegic pattern of cerebral palsy. The most typical collapse pattern
is scoliosis, although kyphosis or lordosis may also develop. Children who
have severe hypotonia may also have development of spinal deformities, often
with substantial kyphosis. Individuals with severe extensor posturing may have
development of total spinal lordosis. A severe lack of motor control,
expressed as a movement disorder such as athetosis or dystonia, is associated
with a lower incidence of scoliosis than spasticity is. The incidence of
scoliosis in institutionalized individuals, most of whom have a spastic
quadriplegic pattern, has been reported to be 64%, with a strong inverse
relationship to ambulatory
ability1. This means
that individuals who are dependent sitters with no head control may have a
rate of scoliosis as high as 90%. We are not aware of published data on the
incidence of spinal deformity with other movement disorders.
Friedreich ataxia is a condition in which the primary neurologic
manifestation is also a lack of motor control and in which the development of
spinal deformities, primarily scoliosis, is common. Progressive scoliosis
requiring surgical stabilization develops in approximately 50% of these
individuals2.
Individuals with motor-control problems tend to have development of spinal
deformity in late childhood. Initially, the child often has very flexible
postural curves and tends to lean toward one side. Typically, as the child
enters early adolescent growth, the spine develops a structural torsional
deformity with increasing stiffness. This structural curve may become so stiff
that physical correction, even when the child is in a lying position, is
impossible. The stiffness typically increases as the child approaches hormonal
maturity and as the curve magnitude increases toward the end of growth. The
material in this manuscript is based on a literature review and on personal
experience in managing a large population of children with cerebral palsy.
Nonoperative management of the neurologic spinal deformity in individuals
with spasticity or other motor-control issues is directed at providing the
child with improved sitting or postural stability to maximize motor and
cognitive
function3,4.
However, when spastic quadriplegic patients who received orthotic management
were compared with similar patients who did not receive orthotic management,
the results indicated that the orthotic devices had no impact on the rate of
progression or on the eventual magnitude of the scoliotic
curve5. Because the
goal of orthotic management should be to provide comfortable postural support,
the orthosis should be made of a soft material and used in the manner of a
corset3. Since
postural support is used for the benefit of sitting, there is no indication
for the use of an orthosis during the night or at other times when the child
is in a lying position. Since many of these children also have respiratory
restrictions or gastrointestinal motility problems, care must be taken that
use of the orthosis does not cause further impairment of respiratory or
gastrointestinal function.
Another excellent option for the conservative management of scoliosis when
the spine is in its flexible stage of growth is the use of offset lateral
chest supports with modular seating adjustments to help prop up the child in
the wheelchair. This approach is relatively simple for the family to use;
however, a disadvantage is that the adjustments for seasonal clothing wear are
more difficult to make. Other modalities of treatment, such as therapeutic
stretching or positioning, electrical stimulation, or botulinum toxin
injection, have not been documented to have any impact on the natural history
of the deformity.
The spinal deformity should be monitored clinically by physical examination
for both the magnitude and flexibility of the curve. As soon as a definite
structural curve is identified, routine radiographs, usually every six months,
should be made with the patient in a standardized sitting frame. As the spinal
deformity increases toward 60° to 90° in magnitude, the stiffness of
the deformity demonstrated by physical examination will also increase. This
combination of increasing curve magnitude to approximately 60° with
increasing stiffness is an indication to proceed to spinal instrumentation,
even if substantial growth potential remains. As long as the scoliosis
maintains substantial flexibility on the physical examination, a posterior
spine fusion alone can be performed for deformities of up to approximately
90°.
For curves of =90° or with severe stiffness, anterior release of the
apex of the curve is indicated. Anterior release will increase the
complication rate associated with the
procedure6,7;
however, it is necessary to gain flexibility to be able to achieve correction.
It is not clear at this time whether it is safer to perform the release on the
same day or if the two steps should be staged, approximately a week apart. In
one study, approximately the same rate of complications occurred with either
approach8. In
another study, however, slightly fewer complications occurred when the
procedure was
staged9. Our current
practice is to stage surgery for patients who have very severe cerebral palsy
and multiple medical complications and problems. However, we tend to use
one-stage management for patients who are relatively healthy. An anterior
fusion to prevent the occurrence of a so-called crankshaft deformity in
children with open triradiate cartilages is not indicated when unit rod
instrumentation is used for the fusion.
Scoliosis of >40° or 50° is an indication for posterior spinal
fusion in patients who have problems with neurologic control and who have
completed their growth. It is believed that a spinal deformity of this
magnitude is very likely to progress. However, minor curves, especially those
that are <30°, have less likelihood of progression, although published
evidence based on long-term follow-up of these patients is not available.
Individuals with motor-control problems may also have the development of a
pathologic kyphosis or lordosis. The indications for surgical treatment of
these deformities, however, are much less clear. In very young children, the
kyphosis is often due to severe truncal hypotonia and the continued use of
appropriately modified wheelchairs with shoulder harnesses allows easy control
of the deformity. In some patients, the kyphosis may be due to very tight
hamstrings and can be improved by lengthening of the hamstrings, which will
prevent the pelvis from tilting posteriorly and forcing the child into a
kyphotic sitting posture. However, as children get older and larger, these
same adaptations no longer work as well. As the adolescent becomes heavier, it
becomes more difficult for him or her to lift up the head to look forward.
This is an especially common pattern in children with hypotonia and blindness,
who have never had the drive to raise the head for visual stimulation. In
patients with functional vision, it is reasonable to consider segmental spinal
instrumentation to treat progressive collapsing kyphosis because the procedure
can improve sitting posture and allow more interaction with the
environment10.
Some individuals also have the development of rather severe lumbar
lordosis, which is often, but not always, associated with scoliosis. This
lordosis may be totally asymptomatic and may cause few problems until it
suddenly causes pain. When the lordosis becomes painful, it is often
impossible to provide any seating adaptations or make any other changes to
alleviate the pain. In these individuals, segmental spinal instrumentation is
indicated because it is the only treatment that alleviates the pain associated
with sitting10.
More than half of the individuals who have had development of a painful
lordosis have had a posterior dorsal rhizotomy as a younger child.
There are a number of children with very severe neurologic disability, no
head control, and severe mental retardation for whom the benefits and risks of
the surgical procedure may sometimes be difficult to weigh. If family members
have decided to provide only comfort care and not aggressive medical care for
these individuals, they may elect not to treat the spinal deformity. However,
if a family is intent on providing maximal medical treatment to the child,
with the goal of keeping the child in the home as well as taking him or her
out into the community, then spinal instrumentation is the procedure that will
allow the performance of such activities with ease and comfort. The risks and
complications associated with this large operation are directly related to the
severity of the neurologic impairment. Specifically, a child who is unable to
feed orally, who is severely mentally retarded, who cannot speak, and who
cannot sit independently has, by far, the highest rate of
complications11.
Before any surgery is performed, the child should be receiving the maximum
amount of medical management possible for the purpose of controlling seizures
and gastroesophageal reflux and enhancing gastric motility. It may be
difficult to assess the nutritional level of such a child or to track specific
preoperative nutritional values. Laboratory values, such as the serum albumin
and pre-albumin levels, are not very reliable indicators of the nutritional
status of this type of child. We find that a child who is overweight as a
result of gastrostomy tube feeding is at a higher risk for having
complications than an underweight child is. Except for children who are in an
extremely severe stage of malnutrition, we have found no nutritional markers
to be related to the type or rate of surgical
complications11.
The surgical procedure requires intra-arterial monitoring of blood pressure
and good vascular access, usually through the use of a large central venous
catheter plus several peripheral lines. Blood loss in children with cerebral
palsy is unpredictable, but there is a tendency for increased bleeding even
when the prothrombin time or the partial thromboplastin time is completely
normal12. The
anticipation of excessive blood loss is important to prevent one of the most
severe complications of this procedure—having to alter or abort the
operation prior to its completion because of blood loss. Our preferred
instrumentation is the unit rod, which was specifically developed to treat
neuromuscular
scoliosis6
(Figs. 1-A through 1-D). This
rod comes precontoured for the purpose of achieving instrumentation from the
pelvis to T1. It includes both a normal lumbar lordosis and a thoracic
kyphosis. After implanting the rod into the ilium with use of the Galveston
technique, a long lever arm is created, which can be used to correct pelvic
obliquity, scoliosis, and kyphosis.
Intraoperative spinal cord monitoring of somatosensory-evoked potentials
(SSEPs) or motor-evoked potentials (MEPs) should be utilized in children with
neuromuscular disorders if the child has substantial motor function
preoperatively. Specifically, monitoring is indicated for individuals who can
perform standing transfers or who can walk. When a child has no ability to
stand or walk, the ability to adequately monitor SSEPs and MEPs is greatly
reduced13.
Furthermore, in this group of individuals with severe motor impairment, all
attempts should be made intraoperatively to provide safety with the
instrumentation and prevent neurologic injury. In the event of neurologic
insult, however, it is very difficult to justify not proceeding with the
surgical procedure, correction of deformity, and implantation of the
instrumentation. Children who have the ability to walk or bear weight have a
technically greater capacity for SSEP and MEP monitoring and thus have a more
favorable functional risk-to-benefit
ratio13. For these
patients, one might consider removing instrumentation or not applying
instrumentation to a curve on the basis of neurologic changes obtained during
monitoring. However, the risk-to-benefit ratio of leaving the operating room
after performing the planned procedure must always be considered for each
individual child. It is important to realize that the child has undergone a
high-risk major operative procedure but will receive no benefit from the
operation if the instrumentation is not completed, and it is also important to
understand that the appropriate treatment for a paralyzed child who has a
severe spinal deformity is spinal instrumentation and fusion. Therefore, when
considering whether or not to abort a surgical procedure before the original
goal has been accomplished, a surgeon should always carefully weigh the
risk-to-benefit ratio with regard to the child.
Because many of these children have multiple-system involvement, they
should be managed in an intensive care unit where specialized intensive care
is available. The intensive care management should continue, including careful
monitoring of the blood pressure and maintenance of urinary output at a level
of 0.5 to 1.0 mL/kg/hr. The hemoglobin level should be maintained above 90 g/L
for the first forty-eight hours because rapid fluid shifts may cause it to
drop, thereby exposing the child to the risk of becoming hypotensive.
Prophylactic antibiotics are typically administered over the course of
twenty-four hours. Careful respiratory management is extremely important, with
the child often needing to be intubated overnight or for several days if
respiratory function is very poor. Aggressive postoperative nutrition is
important, especially for patients with very poor nutritional reserve. Seldom
should more than three or four days pass without the child being fed. This
often requires intravenous central hyperalimentation, which is typically
started on postoperative day two or three.
After the acute recovery period, the child needs to be quickly mobilized
out of bed and into a wheelchair. There is no need to use any external support
such as an orthosis. Range-of-motion exercises of the upper and lower
extremities should be started early. The personal wheelchair of the child
should be carefully readjusted because of the very high likelihood of the
child developing pressure sores if he or she is forced back into the same
wheelchair that was used preoperatively. Typically, children can return to
school three to four weeks after the operation. We give the children no
activity restrictions at the time of discharge and allow them to go back to
their normal activities as soon as they are comfortable doing so.
Because spine surgery is such an extensive procedure, patients with
multisystem compromise may experience complications affecting other systems.
The most commonly seen complications occur in the pulmonary system and range
from mild problems, such as atelectasis, to severe problems that require
prolonged ventilatory support. Children who require long-term intensive care
for respiratory problems have the poorest long-term
survival14.
The next most commonly seen complications are related to the
gastrointestinal system: pancreatitis, prolonged ileus, superior mesenteric
artery syndrome, gall bladder disease, and poor gastric motility are all
relatively common. There is clearly an increased rate of pancreatitis in these
children as compared with the rate in children with idiopathic scoliosis who
are treated surgically. This complication may be related to an ischemic
reperfusion
syndrome15.
Seizures can also be a problem but usually can be managed with adequate
medication.
The most potentially severe surgical complication is a wound infection.
Deep wound infection occurs in approximately 3% to 5% of children who have
undergone spinal fusion and who have cerebral
palsy16,17.
Most patients with deep infections can be managed with wound
débridement, allowing the wound to heal by secondary
intention17. Some
individuals with deep wound infections will require hardware removal, but this
course of action is more common in patients with myelomeningocele than in
those with cerebral
palsy16.
Correction of the spinal deformity with the unit rod allows correction of
approximately 75% to 80% of the scoliosis and pelvic obliquity, with excellent
alignment in the sagittal
plane6. For children
with a substantial amount of growth remaining, recurrent crankshaft
deformities are a major concern; however, when the operative procedure
includes unit rod instrumentation with only posterior spinal fusion,
sufficient stability is obtained to prevent recurrent spinal deformity or the
crankshaft
phenomenon18,19.
When a neurologic type of scoliosis extends into the lumbar spine in
children who are able to walk, the correction may require a fusion to the
pelvis. Fusion to the pelvis does not alter the walking ability of children
with cerebral palsy if the sagittal plane alignment, lordosis, and kyphosis
are maintained in a similar way to that with unit rod
instrumentation20.
The sagittal plane balance can be well maintained with use of unit rod
instrumentation; however, lordotic deformities have higher mechanical
complication rates because of the difficulty encountered in implanting the
unit rod in patients with this deformity. There are also substantial problems
with sagittal plane deformity when individual rods are used and then
cross-connected, especially with regard to backing out at the pelvis. If the
instrumentation does not extend at least to T1 or T2, proximal junctional
kyphosis deformity often occurs.
The outcome of spinal fusion and segmental instrumentation for individuals
with motor-control problems demonstrates a consistently high satisfaction rate
among parents and
caretakers21,22.
It is somewhat more difficult to determine functional benefits in the
individual patients. In a group of children that included those with the most
severe neurologic involvement with spinal deformity, there was a predicted 70%
survival rate at eleven years following
surgery14. Except
for very severe scoliosis and prolonged postoperative intensive-care-unit
requirements for pulmonary problems, there were no other correlations with
poor survival.
In summary, spinal deformity is common in children with motor-control
problems, particularly children with spastic cerebral palsy. Individuals with
other motor-control problems have a lower incidence of deformity. The vast
majority of the children with spinal deformities require surgical
stabilization if the goal is good long-term sitting ability. This
instrumentation can be performed with an acceptable rate of complications,
with unit rod instrumentation being the current preferred method for this
group of children. Caretaker satisfaction can be expected to be very high
following this procedure. ?
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