Hyperbaric oxygen in chronic progressive multiple sclerosis: visual evoked potentials and clinical effects

Hypoxia in multiple sclerosis; is it the chicken or the egg?

Over the past 50 years, intense research effort has taught us a great deal about multiple sclerosis. We know that it is the most common neurological disease affecting the young-middle aged, that it affects two to three times more females than males, and that it is characterized as an autoimmune disease, in which autoreactive T lymphocytes cross the blood-brain barrier, resulting in demyelinating lesions. But despite all the knowledge gained, a key question still remains; what is the initial event that triggers the inflammatory demyelinating process? While most research effort to date has focused on the immune system, more recently, another potential candidate has emerged: hypoxia. Specifically, a growing number of studies have described the presence of hypoxia (both 'virtual' and real) at an early stage of demyelinating lesions, and several groups, including our own, have begun to investigate how manipulation of inspired oxygen levels impacts disease progression. In this review we summarize the findings of these hypoxia studies, and in particular, address three main questions: (i) is the hypoxia found in demyelinating lesions 'virtual' or real; (ii) what causes this hypoxia; and (iii) how does manipulation of inspired oxygen impact disease progression?

A review on the neuroprotective effects of hyperbaric oxygen therapy

Hyperbaric oxygen therapy, intermittent breathing of 100% oxygen at a pressure upper than sea level, has been shown to be some of the neuroprotective effects and used therapeutically in a wide range of neurological disorders. This review summarizes current knowledge about the neuroprotective effects of hyperbaric oxygen therapy with their molecular mechanisms in different models of neurological disorders.

Double-blind trials in hyperbaric medicine: A narrative review on past experiences and considerations in designing sham hyperbaric treatment

Background

Hyperbaric oxygen therapy, which consists of breathing 100% oxygen under a higher atmospheric pressure than normal, is utilized worldwide in the treatment of several diseases. With the growing demand for evidence-based research, hyperbaric oxygen therapy has been criticized for delivering too little high-quality research, mainly in the form of randomized controlled trials. While not always indispensable, the addition of a sham-controlled group to such a trial can contribute to the quality of the research. However, the design of a sham (hyperbaric) treatment is associated with several considerations regarding adequate blinding and the use of pressure and oxygen. This narrative review discusses information on the sham profile and the blinding and safety of double-blind trials in hyperbaric medicine, irrespective of the indication for treatment.

Methods

MEDLINE, Embase and CENTRAL were searched for sham-controlled trials on hyperbaric oxygen therapy. The control treatment was considered sham if patients were blinded to their allocation and treatment took place in a hyperbaric chamber, with no restrictions regarding pressurization, oxygen levels or indication. Studies involving children or only one session of hyperbaric oxygen were excluded. Information on (the choice of) treatment profile, blinding measures, patient’s perception regarding allocation and safety issues was extracted from eligible studies.

Results

A total of 42 eligible trials were included. The main strategies for sham treatment were (1) use of a lower pressure than that of the hyperbaric oxygen group, while breathing 21% oxygen; (2) use of the same pressure as the hyperbaric oxygen group, while breathing an adjusted percentage of oxygen; and (3) use of the same pressure as the hyperbaric oxygen group, while breathing 21% oxygen. The advantages and disadvantages of each strategy are discussed using the information provided by the trials.

Conclusion

Based on this review, using a lower pressure than the hyperbaric oxygen group while breathing 21% oxygen best matches the inertness of the placebo. Although studies show that use of a lower pressure does allow adequate blinding, this is associated with more practical issues than with the other strategies. The choice of which sham profile to use requires careful consideration; moreover, to ensure proper performance, a clear and detailed protocol is also required.

Hyperbaric oxygen therapy for multiple sclerosis

Multiple sclerosis (MS) is a chronic, inflammatory, and degenerative neurological illness with no cure. It has been suggested that Hyperbaric Oxygen Therapy (HBO(2)T) may slow or reverse the progress of the disease. This article summarizes the clinical evidence for the use of HBO(2)T in the treatment of MS. We conducted a literature review focused on the interaction of hyperbaric oxygenation and MS. In particular, we appraised the clinical data regarding treatment and performed a meta-analysis of the randomized evidence using the methodology of the Cochrane Collaboration. We found 12 randomized studies in the area, all of which were performed between 1983 and 1987. A meta-analysis of this evidence suggests there is no clinically significant benefit from the administration of HBO(2)T. The great majority of randomized trials investigated a course of 20 treatments at pressures between 1.75ATA and 2.5ATA daily for 60-120 min over 4 weeks against a placebo regimen. None have tested the efficacy of HBO(2)T against alternative current best practice. No plausible benefit of HBO(2)T on the clinical course of MS was identified in this review. It remains possible that HBO(2)T is effective in a subgroup of individuals not clearly identified in the trials to date, but any benefit is unlikely to be of great clinical significance. There is some case for further human trials in selected subgroups and for prolonged courses of HBO(2)T at modest pressures, but the case is not strong. At this time, the routine treatment of MS with HBO(2)T is not recommended.

Hyperbaric oxygen therapy for multiple sclerosis

BACKGROUND

Multiple Sclerosis (MS) is a chronic, recurrent and progressive illness with no cure. On the basis of speculative pathophysiology, it has been suggested that Hyperbaric Oxygen Therapy (HBOT) may slow or reverse the progress of the disease.

OBJECTIVES

The object of this review was to evaluate the efficacy and safety of HBOT in the treatment of MS.

SEARCH STRATEGY

We searched the Cochrane MS Group trials register (July 2002), the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 2, 2002), MEDLINE (January 1966 to October 2002) and the National Library of Medicine (NLM) database (July 2002), along with specialised hyperbaric resources and handsearching of relevant journals and proceedings.

SELECTION CRITERIA

All randomised, controlled trials involving a comparison between HBOT and a sham therapy in MS were evaluated.

DATA COLLECTION AND ANALYSIS

Two reviewers independently appraised all comparative trials identified, extracted data and scored them for methodological quality.

MAIN RESULTS

We identified ten reports of nine trials that satisfied selection criteria (504 participants in total). Two trials produced generally positive results, while the remaining seven reported generally no evidence of a treatment effect. None of our three a priori subgroup analyses placed these two trials in the same group and were therefore unable to account for this difference. Three analyses (of 21) did indicate some benefit. For example, the mean Expanded Disability Status Scale (EDSS) at 12 months was improved in the HBOT group (group mean reduction in EDSS compared to sham -0.85 of a point, 95% confidence interval -1.28 to -0.42, P = 0.0001). Only the two generally positive trials reported on this outcome at this time (16% of the total participants in this review).

REVIEWER'S CONCLUSIONS

We found no consistent evidence to confirm a beneficial effect of hyperbaric oxygen therapy for the treatment of multiple sclerosis and do not believe routine use is justified. The small number of analyses suggestive of benefit are isolated, difficult to ascribe with biological plausibility and would need to be confirmed in future well-designed trials. Such trials are not, in our view, justified by this review.

Neural therapy in the treatment of multiple sclerosis

OBJECTIVE

To assess the therapeutic potential of neural therapy, a modified form of acupuncture, in multiple sclerosis.

DESIGN

A pilot study followed by a double-blind, placebo-controlled randomized study.

SETTING

The Glasgow Homoeopathic Hospital, Glasgow, Scotland.

PATIENTS

An unselected group of 61 new patients referred to the Glasgow Homoeopathic Hospital, suffering from any type of multiple sclerosis, who fulfilled the criteria of Schumacher and had a Disability Status Score (DSS) or Expanded Disability Status Score (EDSS) grade of 1-7.

INTERVENTION

Neural therapy, which is the injection of small amounts of local anesthetic without adrenaline, into specific trigger points in the ankles and around the greatest circumference of the skull.

MAIN OUTCOME MEASURES

Improvements in the Kurtzke scales and the DSS or EDSS assessments.

RESULTS

Sixty-five percent (65%) of the patients in the pilot study (n = 40) and seventy-six percent (76%) of the patients in the double-blind trial (n = 21) benefitted from this treatment as assessed by Kurtzke scale improvements. On long-term follow-up of 2.0 to 3.5 years, more than 50% of the patients continued to show improved Kurtzke scale ratings. Improvements could be rapid. No toxic side effects were noted when injections were administered at a frequency of once or twice weekly or less.

CONCLUSIONS

Neural therapy is an effective, nontoxic and inexpensive treatment for multiple sclerosis that can confer both immediate and long-term benefits.

Evoked potentials in clinical trials for multiple sclerosis

Multiple sclerosis produces disruption of conduction in the central nervous system by a variety of mechanisms, relating, in part, to loss of the myelin sheath. Although often not well correlated with the clinical course of the disease in individual patients, the resulting evoked potential (EP) disturbances can serve as measures of an accumulating disease burden, particularly in longitudinal population studies. Accordingly, EPs can serve as useful instruments for assessing the effectiveness of therapeutic agents which may alter the course of the multiple sclerosis. Furthermore, since EPs measure conduction within the central nervous system, they provide a means of directly assessing symptomatic treatments designed to improve central conduction.

Hyperbaric oxygen for multiple sclerosis. Review of controlled trials

This review assesses the evidence of the efficacy of hyperbaric oxygen in multiple sclerosis. Material & methods - We used a list of predefined criteria for good methodology and interpreted the results of 14 identified controlled trials with emphasis on the quality. Results - At least eight trials can be considered to have a reasonable to high quality. In one of these 8 trials the results were in favour of hyperbaric oxygen treatment; the others found no clear positive effects. The patients had chronic progressive or chronic stable multiple sclerosis. In most trials, hyperbaric oxygen was supplied at pressures of 1.75-2 ATA, during 20 sessions of 90 min in 4 weeks. The principle endpoint was the (Expanded) Disability Status Score [(E)DSS] and the Functional Status Score as described by Kurtzke. Also specific outcomes such as evoked potentials were frequently used, but no consistent positive effects were demonstrated. Side effects were generally minor, ear and visual problems predominated. Conclusions - The majority of controlled trials could not show positive effects. Further evidence might consist of trials in patients with disease of recent onset or with other dosing regimens but the case for such further trials is not strong. Considering the state of affairs we cannot recommend the use of hyperbaric oxygen in the treatment of multiple sclerosis.

Effect of hyperbaric oxygen treatment on immunological parameters in multiple sclerosis

Hyperbaric oxygen (HBO) treatment has been reported to cause amelioration of clinical symptoms in patients with multiple sclerosis (MS). We have treated 10 MS patients with hyperbaric oxygen (100% O2 at 2 atmospheres absolute for 90 min daily for a total of 20 exposures), and performed immunological studies on peripheral blood and cerebrospinal fluid (CSF). After treatment there was a significant increase in total and helper T lymphocyte counts in peripheral blood, as well as an increase in both E, Fc gamma and C3b receptor-bearing lymphocytes. The responses to the mitogens PHA, con A and PWM were unchanged. Granulocytes showed an increased proportion of Fc gamma receptor and C3b receptor positive cells after treatment. The O2 consumption of granulocytes also increased, but phagocytosis, as measured by chemiluminescence, was unchanged. Serum IgA levels were slightly increased, while IgG and IgM concentrations remained unchanged after treatment. Cerebrospinal fluid cell counts, protein and IgG concentrations, as well as IgG indexes remained unchanged.

Hyperbaric oxygen. A therapy in search of diseases

The application of HBO to the therapy of various human diseases developed over a 300 year period. Like most of medicine, the basis of these applications was and continues to be pragmatic in nature, and involves uncritical and untested judgments. The possibility of risks has been understated and possible benefits have been overstated. Individual physicians offering HBO and organized groups, such as the Undersea Medical Society, advocating its use may well be highly motivated, well meaning, and sincerely convinced that HBO is an important therapeutic approach. It may be that, buried among the host of indications, will be some disorders for which HBO is uniquely and highly effective. If so, the present nonsystem for evaluating responses to HBO will require modification, so that these potentially valuable additions to therapeutics are not lost. Because of its almost global application to a wide variety of diseases, HBO therapy lends itself easily to medical adventurism (therapy in search of a disease) and economic exploitation. If there is some patient benefit to come from the experience of the last 300 years, changes in approach, initiated by baromedical devotees or by medicine generally, or resulting from pressures outside of medicine, will be required.

Hyperbaric oxygen and multiple sclerosis: final results of a placebo-controlled, double-blind trial

The long term results are reported of a trial involving 120 patients with chronic multiple sclerosis who were randomised to receive either 100% oxygen at 2 atmospheres absolute (ATA) for 90 minutes daily for 20 sessions or placebo therapy with air using a simulated compression procedure. The previous finding of subjective improvement in bowel/bladder function at the end of treatment was not confirmed by objective urodynamic assessment. The treatment did not alter disease progression as measured by the Kurtzke disability status scale nor did it alter the rate of acute relapse. There was less deterioration in cerebellar function at one year in the treated patients as measured by the Kurtzke functional systems scale. No other differences were found between the two groups. Psychometric tests and measurements of lymphocyte sub-populations showed no treatment related effects. Evoked potential studies showed no improvements but there was a significant reduction in amplitude of the visual evoked potential in the treated patients at the end of therapy. This might indicate a reversible degree of retinal damage induced by oxygen toxicity.