2. Review of current treatments of spasticity
In the last decade, treatment of spasticity has been proposed in the
fields of neurosurgery and physical medicine with the use of dorsal
rhizotomy, intrathecal medication, intramuscular injection and oral
medication and availability of these treatments has been mentioned.1-6
Goals for the use of these treatments are to improve functions for
easier nursing of these children and to prevent contractures,
dislocations and pain.
Oral medication of Baclofen, Diazepam and Dantrolene has
been commonly used for reduction of spasticity. Oral medications act
on the whole body and can cause short-term relaxation of the muscles
on children and patients with spasticity. It is said that these
medications may enhance an individual's ability to sit, stand or walk
as well as maintain appropriate posture. Such enhanced capabilities
may improve communication skills, by decreasing spasticity of throat
and tongue muscles. This would be true as far as this aspect is
concerned. However, it is also true that medications of baclofen,
diazepam and dantrolene sodium can cause crucial side effects such
as drowsiness, unsteadiness or short-term memory deficit depending
upon the dosage of medication.2 This drowsiness may mean that
mental activity is disturbed with medication of these drugs.
Motivation for active life and vividness may be decreased according
to the dose of the drugs. Attention of physicians and surgeons should
be focused on how to minimize the use of these drugs that cause such
symptoms as drowsiness, unsteadiness and memory deficit.
Another serious problem of this antispasticity medication is
reduction of muscle tone in the whole body without being selective.
The most fatal aspect is to weaken respiratory muscles and to
decrease volume of breathing. In addition, it would weaken
body-supporting muscles with the loss of stability causing fatigue.
Although severely involved patients cannot complain of this fatal
disadvantage, loss of breathing capacity will affect comfortable living,
and will damage these patients both mentally and physically.
Recently, Intrathecal Baclofen Therapy (ITB) has been advocated
in the US, released by the Food and Drug Administration.1,4,5 In
this therapy, Baclofen is administered continuously into the spinal
fluid by means of a pump that is implanted under the skin of the
abdomen. Dosage is precisely controlled by adjusting the pump with a
computer. It is mentioned that with use of ITB, spasticity in the arm
and leg muscles have been reduced. It is also reported that day-to-day
functions such as speech, swallowing, and use of communication
devices are facilitated. Certainly, it will help patients to sit in a
wheel chair by relaxing the hips if they are suffering from extended
trunk and hips. Wearing of AFO (Ankle and foot orthosis) might
become easier. Nursing may also become easier.
However, there could still be some serious disadvantages. The
most serious problem would be whether the spinal cord and spinal
mechanism can tolerate placement of such an inserted tube for a
long time. There will be dangers of infection and fibrosis or
microtraumatic changes around the tube. Meningitis can be another
disadvantage. Replacement of the tube and refilling of the pump will
force these children to undergo a series of operations which may be
hazardous and entail many visits to the neurosurgeon.
There is also a potential for causing respiratory problems or
temporary unconsciousness due to overdose. The possibility of causing
loss of life is also mentioned.4 The flow of baclofen into the spinal
fluid at the thoracic level will decrease the movement of external and
internal intercostal muscles and reduce respiratory volume. This
constant decrease in respiratory volume will affect vividness, and
lessen comfortable livelihood of the patients. All involved in the
treatment should be sensitive to such disadvantages in these patients
and must make efforts to develop safer substitute methods without
these problems.
Intramuscular injection of Botulinum toxin (BtA) is another
possible method of the treatment of spasticity in cerebral palsy.3 In this
therapy, a specified dosage of purified Botulinum toxin is injected
into the spastic muscles according to the size of the muscles and the
severity of spasticity. Various reports on BtA treatment for patients
with cerebral palsy have been published. Koman and associates
documented that Botulinum injection is a potentially valuable adjuvant
technique in the management of dynamic deformity in the lower
extremities and spine in patients with cerebral palsy by diminishing
spasticity.7,8 Corry and associates presented a double-blinded trial of
Botulinum toxin A for the hemiplegic hand and stated that BtA
injection significantly increased maximum active elbow and thumb
extension and significantly reduced tone at wrist and elbow.9
However, they also mentioned that fine motor functions did not improve
and actually deteriorated in some cases. Cosgrove and associates also
reported Botulinum toxin injection in management of the lower limbs in
cerebral palsy and concluded that botulinum toxin can objectively
reduce spasticity and yield improvements in range of motion at the
knee and ankle.10
It is understandable that spasticity at the injected muscles can be
temporarily reduced with the injection and range of motion can be
increased. Intolerable pain due to spasticity can be relieved and this
therapy may have the long-term benefit of improving longitudinal
growth of muscle fibers by reducing spasticity.
However, the limitation of BtA is that its effect is temporary.
Even if activities of the antagonistic muscles are restored, when BtA
therapy is discontinued, spasticity at the injected muscles will again
easily become predominant against the activity of these antagonists.
In children, general anesthesia is necessary to avoid pain during
injection. Children cannot tolerate repeated BtA injections throughout
their lives. Regarding this point, Bleck mentioned that "One wonders
how long children can be cajoled to accept repeated injections over a
period of a year or more. It remains a clinical experiment for a few
centers, if it is proposed as a treatment rather than a temporary
measure just as in cases in which we used alcohol in the past."11
Bleck also mentioned that it is unlikely that the abnormal motor
pattern of the muscles will reverse permanently with temporary and
limited induced partial flaccid paralysis.11
Although there has been no definite report of systemic toxic
symptoms following BtA administration, decrease in respiratory and
swallowing functions can also be considerable. Originally, Botulinum
toxin was designated as a respiratory inhibiting toxin. It is common
sense to consider that some of the injected BtA will act on the
neuromuscular junctions and cause flaccid paralysis of the injected
side. However, scientifically, some of the BtA injected at the
neuromuscular junction will flow into the blood stream. This
over-flowed BtA will reach the neuromuscular junctions of the
thorax, diaphragm and laryngeal and pharyngeal muscles and will
inhibit movement of these muscles causing unrecognized weakness of
respiratory and swallowing activities proportional to the injected
dosage. These problems seem to be very dangerous and may decrease
vividness in children. In Japan and the US, use of BtA is not allowed.
We understand that the Botulinum therapy is useful only
temporarily. However, we also understand that this therapy cannot be
a decisive treatment for spasticity-control, since this treatment could
cause paralysis of breathing and swallowing muscles. We should
develop another long lasting and more reliable spasticity-reducing
approach, without such adverse side effects.
Selective dorsal rhizotomy (SDR) is a neuro-surgical procedure
that is designed to reduce spasticity in cerebral palsy, and currently
has been performed in many centers all over the world.6,12
Oppenheim mentioned that appropriate division of dorsal roots could
theoretically reduce muscle tone because of the loss of inhibition from
higher centers implicit in cerebral palsy lesion. This reduced muscle
tone will increase range of motion in the affected joints. Almost all
papers reporting results of gait analysis mentioned
increased range of motion in dynamic gait.
However, there are many reports that suggest that SDR not only
reduces spasticity, but also weakens all the muscles unselectively.
Though many reports have mentioned of a change in ambulatory status
such as an increase in dynamic range of motion after SDR, few showed
improvement in walking stability such as an increase in absolute velocity
or increase in single stance phase.
Boscarino and associates conducted gait analysis to study effect of
selective dorsal rhizotomy and presented us with very interesting facts.
13 In their report, the parameters that showed an increase or decrease in
the range of motion are improved while parameters showing antigravity
stability such as the pelvic tilt are not improved.
Thomas and associates in 1996 also documented an increase in ROM,
stride length and velocity.14 However, an exaggerated anterior
pelvic tilt during gait cycle is also documented. Anterior pelvic tilt is
an unpleasant and undesirable deformity in the hip region that disturbs
stable weight bearing and worsens cosmesis. Increase in anterior pelvic
tilt suggests definite weakening of antigravity extensors such as gluteus
maximus and medius. In their latest study in 1997, they presented
many signs of improvement in ROM of hip extension, knee extension
and ankle dorsiflexion in both independent and dependent gait groups
in joint kinematics. They also showed significant increase in absolute
stride and step length. However, they also described the negative effect
of an increase in ROM. As they mentioned, extreme anterior tilt of the
pelvis is observed. This excessive anterior pelvic tilt is a major
drawback of SDR. All the parameters, which are closely related to
body-supporting stability, remain unchanged as well.
Absolute walking velocity did not show a significant change in both
independent and dependent groups. Walking velocity could mean the
possibility of walking without falling in various directions with use of
antigravity stability mechanism. No change in walking velocity in their
work indicates that SDR is not effective for gaining antigravity
stability.They also reported increased stance phase in both groups,
which also indicate some loss of stability as well as showing difficulty
in keeping single stance during gait.
On the other hand, Cahan and associates documented an
increased velocity after SDR. However, it is not clear whether velocity
was taken at maximum speed or not. No sign of increased stability
such as an increase in time of single-limb support or comparative
decrease of stance time is described in their paper.16
Length of stance phase will be another indicator for antigravity
stability. Prolonged double limb stance phase means a decrease in
antigravity stability. Boscarino and associates documented that both
independent and dependent groups showed a slight increase in the
stance phase in the gait cycle. The independent group was within
normal limits in stance phase, both pre-and postoperatively, whereas
the dependent ambulator showed a longer than normal stance phase
postoperatively. This increase in stance phase seems to show some
postoperative worsening of antigravity stability and loss of function.
They mentioned also that the anterior pelvic tilt increased significantly
after SDR in both groups. This increase in anterior pelvic tilt means a
negative effect for ambulatory status while indicating weakness of the
abdominal muscles and that of the hip extensors. Boscarino and
associates also mentioned that hip extension did not change. For
treating hip deformity, an increase in hip-extension is most important.
This unchanged hip extension strongly suggests antigravity extensors
such as gluteus maximus and adductor magnus are simultaneously
damaged. They clearly documented in their discussion that the
independent group showed an increase in anterior pelvic tilt, possibly
owing to an imbalance of the hip musculature because the SDR
addressed the whole hip extensors and not the whole flexors. They
also described that the femur was in a more vertical position
postoperatively in this study. This vertical position of the femur
combined with increased anterior pelvic tilt and increased dorsiflexion
of the foot and ankle may indicate that another type of crouched
posture is caused by weakness of the hip extensors and weakness of
the ankle plantar flexors.
After studying motion of the pelvis in sagittal plane, Thomas and
associates also presented postoperative increase of anterior tilt of the
pelvis showing the negative aspect of SDR. They also mentioned that
in EMG study, SDR could not even present consistent phasic change
in the pre and postoperative activity in the muscle tested, and most
muscles showed premature, prolonged and out of phase activity
postoperatively. This means that SDR did not bring well-separated
movements of affected joints. 15
Cahan and associates presented a paper, in which results of SDR
are assessed with the use of gait analysis, stride characteristics and
EMG. In their report, improvement in range of motion, a decrease in
spasticity, an increase in stride length and increased velocity are mentioned.
Increase in velocity seems to suggest an increase in body-supporting
stability. They seemed to conclude that SDR could work to improve
body-supporting stability, as ambulatory status remained at the same
level in 13 of 14 patients for whom SDR was conducted. They also
described that the signs showing an increase in body-supporting stability
such as gait cycle duration and single and double-limb support time
showed no statistically significant changes. They also pointed out that
persistent knee flexion, planovalgus and excessive ankle dorsiflexion
were frequently observed. They described that this flexion deformity
of the knee can be related to weakened plantar flexors of the foot and
ankle.16
Carroll and associates reported some aspects of SDR. They
noticed decreased tone in all 112 patients after rhizotomy by
measuring with the Ashworth scale. However, they also mentioned
that no statistically significant change in ambulatory status was
found.17 In this study, they pointed out that progression of hip
subluxation and occurrence of planovalgus are the most common
disasters and decreased tone after SDR may be the cause of these
deformities. They described in detail many hypotonic conditions of
the foot induced after SDR. This study clearly suggests that SDR
weakens body-supporting activities of the antigravity muscles around
the foot and ankle, to a level of hypotonia, causing the typical
planovalgus. Weakening of the antigravity muscle around foot and
ankle can totally damage antigravity stability of the patients. They
were uncertain about whether these children in whom SDR were
conducted would have walked with continued growth, development
and physiotherapy without SDR.
Thus, there are many reports suggesting weakness of antigravity
stability in the lower extremities after SDR. Hence, SDR needs to be
reassessed regarding weakening of antigravity stability.
Rapid-progression of hip subluxation is a crucial problem after
SDR. Carroll and associates commented that progressive hip dysplasia
and subluxation were common in their series. Twenty-eight of 112
patients required either femoral or pelvic osteotomies or both for this
subluxation.17 Greene and associates in 1991 reported rapid
progression of hip subluxation in 7 hips of cerebral palsy after SDR.18
They mentioned that rapid progression with increased lateral extrusion
of the femoral head occurred in 25-50% of the cases in an average
time of 1.1 years which is much higher compared to the 5.5 %
occurring within a year in children with cerebral palsy who did not
have the surgery. They mentioned that the SDR performed did not
section L1 nerve rootlets, hence, spasticity in the hip flexors may not
be decreased as much as that of the antagonistic extensors. Therefore,
they stated that children still have residual muscle imbalance and
greater asymmetry of the hip flexors as compared to hip extensors
and abductors. Thus, weakening of the hip extensors and abductors is
considered to cause progression of the hip subluxation. In general,
rapid progression of subluxation is not induced after orthopaedic
release surgery; instead, subluxation can be reduced gradually in most
of the patients. This paper may suggest that SDR can damage
antigravity supporting muscles around the hip and damage antigravity
stability of the hip as well.
Thus, one of the most serious concerns about SDR is that the
dorsal rootlets contributing to spasticity cannot be technically
separated from the nerve fibers to the muscle contributing to
antigravity stability. The antigravity muscles seem to be
indiscriminately damaged. Regarding this point, Cohen and associates
in 1991 documented as follows: The procedure is based upon an
assumption that intraoperative neurophysiologic stimulation and
monitoring can accurately identify two populations of dorsal rootlets:
those involved in abnormal circuits contributing to spasticity and
those that are "normal". However, the definition of normal and
abnormal responses varies among investigators and the normal
response to this stimulation has not been critically evaluated in human
subjects. Therefore, it is not clear what is being selected in the SDR
procedure or even whether SDR is superior to non-selective random
sectioning of dorsal rootlets.19
Severe spinal deformity is another disastrous result after dorsal
rhizotomy, suggesting that unselective section in SDR causes
weakness and imbalance of the antigravity abdominal and truncal
muscles. Crawford and associates in 1996 reported severe lumbar
lordosis in two patients after SDR who complained of back pain,
deformity and difficulty in sitting.20 One of them could not even
maintain a hand-free upright posture in his wheel chair. Functionally,
one remained nonambulatory while the other had his activity reduced
to the level of an exercise ambulator. They pointed out that
preservation of "hip-flexor" spasticity due to proximal innervation of
the iliopsoas in face of weakened hamstrings and gluteus muscles led
to the development of hip-flexion contractures. As the pelvis is flexed
forward on the femora by hip flexion contractures, the lumbar spine
may respond by becoming hyperlordotic to maintain an upright
posture. They also postulate that the dorsal defect caused by the
multilevel laminectomy leads to instability of the spine. Structural
weakness by removing posterior bony structures can be enormous. By
stripping all short body-supporting muscles from the spinous
processes and cutting off all the acting point of these muscles, ability
to raise the trunk to the upright will be severely damaged (Fig.42, 43,
44, 45). Repositioning of the resected laminae do not work so
effectively since all the stripped muscles will not be able to be
reattached as firmly as in the preoperative condition. These muscles
are fairly weakened and will no more be able to support the body so
effectively. Paralysis of the abdominal antigravity muscles as
suggested by Boscarino and associates would be a serious drawback.
As mentioned later, it is estimated that many antigravity muscles
contributing to the stability of the trunk exist in the abdominal wall
and the back (Fig. 45, 46). There is no detailed description how SDR
can preserve all these antigravity muscles selectively, and how can it
prevent total weakening of antigravity stability of the trunk. Thus, it
is most obvious that SDR could cause paralysis of antigravity muscles
in the lower trunk, hips and feet by sectioning all nerves to these
muscles unselectively. For this reason, it can be concluded
that SDR will not be able to control spasticity selectively without
sacrificing antigravity muscles related to stability of the body.
There is also a possibility of persistent and diffuse loss of
sensation after SDR. Although total loss is prevented by partial
sectioning of the rootlets and overlapping of dermatomes, the question
still arises whether or not the decreased sensation is caused by the
sectioning of 50% of sensory nerves and again whether this decreased
sensation will cause any serious disadvantage for the patients even if
no disadvantage could be identified and described by examiners. It is
still not clear what is being selected in the SDR procedure.
Anatomically, each rootlet has its own sensory nerve fibers and Ia
fibers as well. It seems impossible to identify sensory nerves from Ia
fibers in each small rootlet. Anatomically in the dorsal rootlets,
various kinds of fibers coexist in a mixed condition and no separated
localization of each fiber such as 1a fiber, myostatic fiber and C fiber
is seen. Thus after SDR, occurrence of diffuse sensory loss could be
inevitable. Hence, with sectioning of the rootlets, sensory nerve will
be sectioned. Abbott mentioned that 4 of 250 patients have experienced
focus area of sensory loss in one of their ten toes and loss of
temperature sensation in the dermatome, at their 6th month
postoperative reevaluation.6 However, one wonders why is this
diffuse sensory loss not taken into account? Dysesthesias or loss of
needle pin sensation in the legs is also mentioned by Abbott. Urinary
retention and bowel dysfunction are also reported as temporary
symptoms. However, there is no guarantee that this will be temporary.
Infants, both boys and girls will not be able to complain of any
unpleasantness of this
diffuse loss of sensation. I wonder if somatosensory evoked potential
(SEP) will be able to detect sensory loss precisely after partial section
of neural fibers? Theoretically on the basis of scientific consideration, if
50% of the rootlet of the posterior root in S1, S2 and S3 are sectioned,
50% of diffuse loss of sensation, urinary and bowel dysfunction and
dysfunction even in ejaculation due to injuries of autonomic nerve
fibers can be caused. Carroll and associates described that the sacral
roots are often spared for fear of compromising bladder functions.16
This can be a sign that neurosurgeons possess a fear of inducing
bladder and bowel dysfunction with the use of SDR.
As Mclaughlin and associates mentioned, there are growing
skepticism regarding the electrophysiological monitoring technique
and the undercurrent of concern about long-term complications.21
This can include loss of antigravity stability, sensory loss, sympathetic
nerve injury, and occurrence of iatrogenic deformities such as
excessive anterior pelvic tilt, extreme lordosis of the spine,
dislocation and subluxation of the hip, extreme planovalgus deformity
and heterotopic ossification. Wright and associates clearly
documented that it cannot be assumed that proportion of spinal
rootlets that respond abnormally to the most commonly used method
of intraoperative stimulation at SDR always represent the degree of
spasticity at a given spinal segment, nor can it be assumed that
proportion of rootlets identified by this method and then ablated
consistently correlate with the degree of change in spasticity and
motor function after SDR.22 The serious problems of selecting
nerve fibers to spastic muscle and to (normal) muscle fibers with
antigravity muscles is also described in their paper. Thus, it can be
considered a scientific opinion that SDR is not reducing spasticity
selectively, but is weakening the muscle power unselectively
according to the amount of section.
Witherow in 1996 documented in his editorial that the place of
selective posterior rhizotomy in cerebral palsy is not yet fully
defined.23 Short-term results seem to be encouraging, although results
have been limited to patients with relatively good functions. There
have been some anxieties about inducing persistent sensory change,
an increased risk of hip subluxation, back pain, and later development
of bladder and bowel dysfunction in many of patients after SDR. SDR
seems to be an invasive procedure which can cause irreversible
sensory loss and bladder dysfunction, making life more miserable and
uncomfortable. No surgeon will be able to compensate this miserable
sensory loss. We should not inflict any further sensory disorders
even in these children with cerebral disorder. Review of most of the
literatures raises pertinent questions: Is this really the time to introduce
SDR as a promising treatment for spasticity in children with cerebral
palsy? Why is the scientific tradition of evaluations, interpretations
and documentation so poor and not so careful, regarding induced
muscle weakness, loss of stability and possibility of inducing serious
complications due to sectioning of sensory nerve? We should consider
again; how selective the SDR is ? Can sensory nerve be really selected
from the Ia fibers in the small rootlets?
Recently, DREZ-tomy (Dorsal root entry zone tomy) or
microDREZ-tomy was introduced by Sindou 24 and developed by
Nashold 25 to relieve pain and applied to relieve spasticity in cerebral
palsy and cerebro-vascular accident. However, it is also not well
mentioned that C fibers, which transmit pain, can be clearly
differentiated from myostatic fibers. Difficulty in differentiation
between the nerve fibers to spasticity-related muscles and the ones to
normal or antigravity-related muscles also still exists in this technique.
There is the possibility that these problems can cause serious
damage to antigravity (body-supporting) stability in patients with
cerebral palsy. If this technique is going to be used for controlling
spasticity, detailed and careful analysis and long-term follow-up study
of this procedure would be needed to avoid inducing further
complications in these patients.
Thus, control of spasticity is not easy and seems to be
impossible, especially when it is attempted without sacrificing
sensation and antigravity (body-supporting) stability.
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