Cerebral palsy, or CP, refers to a group of developmental conditions
that have several features in common (Rosenbaum, Paneth, Leviton,
Goldstein, & Bax, 2007). All are associated with (caused by) some
kind of injury to the developing brain. The injury can occur in the
womb, during the birth of the baby, or in the first couple of years
after birth (usually because of infection or trauma to the brain).
In Canada, CP affects 1 in every 400 individuals and is the most
common physical disability in children.
Conventional treatment and ‘management’ of CP include the advice,
ideas and experience of occupational, physical and speech therapists
and doctors with experience with development, as well as mechanical
devices, drugs and surgery (Lacey, Stolfi, & Pilati, 2012)
There are many treatments in medicine that are referred to as
‘alternative’ or ‘complementary’ therapies. Some are simply too new
to have been studied and evaluated carefully. Others are based on
ideas about CP and development and human biology that are very
different from how most scientists understand these issues. HBOT
fits into this group of ‘therapies’, but is different because it has
been very carefully studied.
What is Hyperbaric Oxygen Therapy?
Hyperbaric Oxygen Therapy (HBOT) is a technique that allows 100%
oxygen to be delivered to the body's tissues under increased
atmospheric pressure. To achieve this, the patient enters a
"pressure chamber" that makes it possible to increase the
atmospheric pressure to "hyperbaric" levels, i.e., above the earth's
atmospheric pressure at sea level (Rosenbaum, Fehlings, & Iliffe,
2001).
HBOT has been approved by the US Food and Drug Administration (FDA)
as an effective approach for the treatment of certain wounds, carbon
monoxide poisoning and decompression illnesses in deep sea divers
(e.g., the ‘bends’); however using HBOT to treat CP remains
controversial and unproven (McDonagh et al., 2007).
Short Summary of the Evidence: HBOT is being used in many places
around the world to treat children with CP, even though there is
sound scientific evidence to show that this treatment does not work.
Studies also provide information on the side effects that are
associated with its use (Collet et al., 2001). In two very
well-executed clinical trials comparing HBOT and ‘placebo’
treatment, HBOT has been shown to have no effectiveness for CP. Most
of the other ‘evidence’ for HBOT (and often for other alternative
therapies) comes from stories, or from testimonials from people who
sell these treatments. The individual stories may be true but they
do not constitute scientific ‘evidence’
How does HBOT work in the human body?
The air in a room usually contains 21% oxygen. In hospitals, oxygen
may be given from 21% to 100% (for medical emergencies). A
hyperbaric chamber can increase oxygen to a higher pressure than
normal, so that more oxygen is dissolved in the blood (Rosenbaum,
Fehlings, & Iliffe, 2001).
Within the body, oxygen is attached to hemoglobin (in red blood
cells) and is transported by the blood. A small amount of oxygen
remains “free” in the bloodstream. This “free” oxygen is used by the
body’s tissues and can travel 10 to 15 times further into the
tissues. HBOT increases the amount of “free” oxygen circulating in
the blood. Therefore, hyperbaric oxygen (HBO) can be used to
increase the delivery of oxygen to areas of the body that have been
subjected to hypoxia, that is, low oxygen (Rosenbaum, Fehlings, &
Iliffe, 2001).
Why is HBOT believed to be useful to treat CP?
HBOT is being used to treat CP based on the (unproven) theory that,
along with damaged brain cells, people with CP have some inactive
(‘dormant’) brain cells that possess the potential to recover. This
recovery is thought to take place if these dormant cells are
stimulated by improving oxygen availability, thereby allowing the
cells to function normally and reactivating them metabolically or
electrically (McDonagh et al., 2007). Current understanding of brain
science does not support this seemingly appealing theory.
Improvements in spasticity, cognition, memory and attention have
been reported anecdotally, but have been poorly documented. Very few
evidence-based studies on the supposed benefits of HBOT have been
published in peer-reviewed journals and those that are available
have consistently showed no benefits (see below) (Lacey, Stolfi, &
Pilati, 2012).
Why is the topic important?
Parents of children with CP may feel obligated to try every possible
intervention, with the hope of ‘fixing’ their child. This means that
parents can be vulnerable to claims about the effectiveness of new
interventions. Some parents decide to try treatments such as HBO
because they believe that they have nothing to lose, and because
they are dissatisfied with the outcomes of existing interventions
(Novak & Badawi, 2012). Our belief is that, in general, if something
sounds too good to be true it probably is!
We believe that parents are entitled to be able to consider the
latest evidence about the efficacy and effectiveness of HBOT when
making decisions that involve their child’s health (Novak & Badawi,
2012). The approach taken by the writers of this review is based on
principles of sound clinical science, and whatever advice is offered
is presented in light of these perspectives. Professionals working
to improve the health and well-being of children with CP need to
have access to and evaluate evidence-based information on the
potential benefits of new therapies. In doing so, they will be able
to assist parents with making an informed decision regarding new
treatments (Rosenbaum, Fehlings, & Iliffe, 2001).
In-Depth Summary of the Evidence
Methods
The findings included in this update are based on a recent
systematic review and a meta-analysis conducted by Novak and Badawi
(2012 and 2013). This review looked at the available scientific
literature – both published and unpublished – in order to find and
assess credible scientific evidence about the effectiveness of HBO
to treat CP. Three randomized control trials were identified, which
compared 40 HBOT treatments to hyperbaric air (HBA).
HBO treatment involves administration of 100% oxygen, whereas HBA
involves a mixture of gases (14% oxygen) in order to provide some
pressure and to simulate 21% oxygen that is present in room air
(Lacey et al., 2012).
The objective of the Novak and Badawi (2012) review was to determine
whether hyperbaric oxygen treatment could improve the self-care and
gross motor skills of children with CP, as is claimed by the people
who provide it.
Results
Collet et al (2001) conducted a large randomized controlled trial,
and found no beneficial effects for HBOT in CP. The study involved
111 children with CP who, on a randomized basis, received either 40
daily ‘treatments’ of HBO at 1.75 atmospheres of pressure with 100%
oxygen, or 40 daily ‘dives’ using room air (the usual air we
breathe) at 1.3 atmospheres (slightly above ordinary pressure). None
of the children, the families or the researchers knew which children
were receiving HBO and which received the ‘pretend’ treatment until
after the study was completed and analyzed.
Cerebral Palsy Testimonials
Trained ‘masked’ observers assessed several aspects of function.
These included gross and fine motor function, language skills and
learning abilities. The assessments were carried out before the
treatment started, after 20 treatments, after 40 treatments and
again three months after the last treatment ended. The study found
that both groups of children showed virtually identical amounts of
change on all the functional outcomes measured. There was absolutely
no extra benefit of exposure to HBO compared with the 'pretend'
treatment. It was found, however, that more children in the HBO
(higher pressure) group had episodes of ear pain, and that these
occurred more often, than the children in the ‘control' group who
had been exposed to a lower amount of increased pressure.
These findings show clearly that the apparent benefits being
observed and reported from HBO cannot reasonably be attributed to
pressurized oxygen, since both groups changed equally. There is no
credible evidence that small amounts of increased oxygen or
pressure, as experienced by the comparison (control) group, are
therapeutic. Rather, the results (i.e., the observed changes in both
groups) appear to reflect the effect of the hopes, expectations and
extra involvement of the families with their children over the two
months of ‘treatment’. Thus while one can celebrate the observed
improvements seen in all the children, it is not possible to accept
that these changes occurred as a result of exposure to HBO (Collet
et al., 2001; Rosenbaum, Fehlings, & Iliffe, 2001).
Most recently, the Lacey et al. study (2012) consisted of a
randomized double-blind controlled trial over a period of 4 years.
The trial found that HBO was not associated with any significant
improvement in self-care and gross motor function. The study
included 49 children with CP who were randomized to receive either
40 treatments of HBO with 100% oxygen at 1.5 atmospheres of pressure
or 40 treatments of HBA with 14% oxygen (similar to the air we
breathe) at 1.5 atmospheres of pressure, for 8 weeks. None of the
participating children, or their families, or the researchers knew
which treatment each child was receiving until after the study was
completed and the data were analyzed.
The primary outcome used in this study included the Gross Motor
Function Measure (GMFM) global score. Other measures of outcome used
included the Pediatric Evaluation of Disability (PEDI) and the Test
of Variable Attention (TOVA). Assessments were conducted before the
study began (to measure baseline levels of function) and after 40
treatments, as well as 3 and 6 months after the treatments ended.
Results of the study demonstrated that HBO did not improve GMFM
scores. In addition, both HBO and HBA were equally effective in
improving PEDI scores, although the improvements observed were
minimal.
It is important to note that both the Lacey and Collet studies used
gold standard methods and measures, i.e. the GMFM and PEDI, to
assess outcomes on data that were collected immediately after HBOT.
This gave HBO the best chance of demonstrating efficacy and showing
positive outcomes (Novak & Badawi, 2012).
Conversely, Packard (2000) conducted a randomized controlled trial,
which demonstrated positive effects of HBOT in children with
moderate to severe CP. The study was a randomized, delayed entry
trial. In other words, 26 children with CP were randomized to
receive 40 one-hour sessions of HBOT at 1.5 atmospheres of pressure
(immediate group) or HBOT treatment only after 6 months (delayed
group). In order to measure outcomes for each group, a neuro-developmental
assessment, the Bayley II (a cognitive assessment), Preschool
Language Scale (a language assessment), the Peabody Motor Scales
(for gross and fine motors skills) and PEDI (in which parents report
on mobility, self-care and social interactions) were administered.
These assessments were carried out four times: at enrollment, after
the ‘immediate group’ received HBOT, before the ‘delayed group’
received HBOT (5 months after enrollment), and after the ‘delayed
group’ received HBOT.
While parental reports and observations during therapy reported
benefits of HBOT, the blinded assessments (not knowing which group
each child was in) did not show any significant benefits that could
be attributed to HBOT.
Interestingly, the Packard study was not published, did not undergo
any peer-review process, did not report enough statistical data, had
a very small sample size and was subject to bias. Therefore, the
results of this study are not considered, from a scientific
perspective, to be applicable to the general population.
The meta-analysis (including all the findings from available
studies) confirmed that there is no favourable benefit of HBO over
HBA for improving gross motor function. In summary, although HBOT is
effective in specific patient populations for specific medical
conditions, it has not been proven beneficial for the treatment of
CP. In fact the small number of high quality CP studies conducted
conclude the opposite.
High-quality Grading of Recommendations Assessment, Development and
Evaluation evidence concludes that HBOT does not have a clinically
important effect on gross motor and self-care skills in children
with CP (Novak & Badawi, 2012).
Risks of HBOT
Side effects (unintended consequences) of HBOT are often related to
high pressure and oxygen toxicity (Muller-Bolla et al., 2006).
* Rupturing of the eardrum has been associated with hyperbaric
pressure oxygen treatment (Muller-Bolla et al., 2006).
* Pneumothorax (collapsed lung) is another potential risk of HBOT.
This can happen because children with CP may sometimes have a
history of lung problems and experience difficulty clearing
respiratory secretions (Rosenbaum, Fehlings, & Iliffe, 2001).
* Nearsightedness is a temporary side effect of HBOT that has been
observed in 40% of adult patients. It usually subsides, but studies
have shown that it may persist in some cases (Rosenbaum, Fehlings, &
Iliffe, 2001).
* Seizures have been reported after HBOT, and could be due to oxygen
toxicity. However, this does not pose a risk for children, because
the recommended pressure levels used in the hyperbaric chamber are
too low to produce oxygen ‘poisoning’ (Rosenbaum, Fehlings, & Iliffe,
2001).
Conclusion
Based on solid clinic research evidence it can be concluded that HBO
is not an effective intervention for children with CP. HBOT may,
however, negatively affect respiratory functioning and hearing, as
well as cause nearsightedness, ear pain and seizures. Children with
CP have a short period of developmental opportunity before their
motor skills plateau (Novak & Badawi, 2012). Therefore, it could be
argued that providing ineffective treatment to these children is not
in their best interest. Based on current research, it cannot be
considered ethical to sell or recommend HBOT to children with CP
(Novak & Badawi, 2012). Health care professionals and parents should
focus their efforts on interventions that have been proven
successful.
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