TL;DR: Hyperbaric oxygen therapy (HBOT) for stroke recovery is an active area of research with important distinctions between acute and chronic stroke. A landmark Israeli RCT demonstrated that HBOT can induce neuroplasticity and produce meaningful neurological improvements in chronic stroke patients even years after the event. A 2024 meta-analysis of acute ischaemic stroke found no clear benefit during the emergency phase. This research summary examines what the current evidence supports, where the gaps remain, and what it means for Canadian clinicians considering HBOT referrals for stroke patients.
Estimated reading time: 9 minutes
What Is the Current Evidence for HBOT in Stroke Recovery?
Stroke recovery is one of the most actively investigated emerging applications of hyperbaric oxygen therapy. Stroke is the third leading cause of death in Canada and a major driver of long-term disability, with approximately 62,000 Canadians experiencing a stroke each year. While HBOT is not currently among the 14 conditions recognised under Health Canada’s device licensing framework for hyperbaric chambers, a growing body of clinical research – particularly from Israel – suggests it may have a role in chronic post-stroke rehabilitation.
The evidence falls into two distinct categories that must not be conflated: HBOT during the acute stroke phase (within hours to days of onset), and HBOT for chronic post-stroke neurological deficits (months to years after the event). The evidence base is substantially different for each.
What Does the Research Show for Acute Ischaemic Stroke?
The evidence for HBOT in acute ischaemic stroke is currently weak and inconclusive. A 2024 systematic review and meta-analysis published in BMC Neurology examined 8 randomised controlled trials involving 493 patients. The analysis found no statistically significant differences between HBOT and control groups in NIHSS scores (a standard measure of stroke severity), Barthel index scores (a measure of functional independence), or inflammatory markers (Wang et al., BMC Neurology, 2024).
An earlier Cochrane systematic review reached a similar conclusion: the available RCTs were insufficient to demonstrate clear clinical benefit during the acute stroke window. The reviewers noted that while clinical benefit had not been excluded, the existing evidence did not support routine use.
Clinicians should distinguish between acute and chronic stroke when evaluating HBOT evidence. The two contexts have fundamentally different evidence profiles and biological rationales.
What About HBOT for Chronic Post-Stroke Recovery?
This is where the evidence becomes more compelling. The most significant research programme in this area comes from Professor Shai Efrati and colleagues at the Sagol Centre for Hyperbaric Medicine and Research at Assaf Harofeh Medical Centre in Israel.
The Efrati RCT: Neuroplasticity in Chronic Stroke
In a prospective, randomised controlled trial published in PLoS ONE (Efrati et al., 2013), 74 patients who had experienced a stroke 6 to 36 months earlier were randomly assigned to receive HBOT or serve as a crossover control group. The treatment protocol was 40 sessions of 90 minutes each at 2.0 ATA, delivered 5 days per week.
The results demonstrated that HBOT produced statistically significant neurological improvements even in this chronic, late-stage population where spontaneous recovery would not be expected. Brain imaging (SPECT scans) showed increased metabolic activity in previously dormant brain regions. The control group showed no significant improvement during the waiting period but demonstrated similar gains after crossing over to receive HBOT.
Neurocognitive Follow-Up (2020)
A retrospective analysis of 162 post-stroke patients treated with HBOT at the Sagol Centre (Hadanny et al., Restorative Neurology and Neuroscience, 2020) found that 86% of patients achieved clinically significant cognitive improvements. The study reported gains across all cognitive domains, including memory, attention, processing speed, and executive function. These improvements were observed even in patients treated years after their stroke.
The Neuroplasticity Mechanism
The biological rationale for HBOT in chronic stroke differs from the acute-phase oxygen-delivery hypothesis. In chronic stroke, the proposed mechanism involves:
- Reactivation of dormant neural pathways: HBOT may stimulate metabolic activity in brain tissue that is alive but functionally inactive in the ischaemic penumbra zone surrounding the stroke core
- Angiogenesis: Growth of new blood vessels in oxygen-deprived brain regions, restoring perfusion to tissue that has been chronically hypoxic
- Stem cell mobilisation: HBOT has been shown to mobilise endogenous stem cells, which may support neural repair
- Neuroplasticity signalling: The intermittent hyperoxia-hypoxia cycle created by repeated HBOT sessions appears to trigger gene expression changes associated with neuroplasticity
How Do These Results Compare to Standard Stroke Rehabilitation?
| Approach | Timing | Evidence Level | Key Outcomes |
|---|---|---|---|
| Standard rehabilitation (PT/OT/SLP) | Acute and chronic | Strong (standard of care) | Functional improvement, task-specific recovery |
| HBOT – acute ischaemic stroke | Within hours/days | Weak (meta-analysis negative) | No clear benefit in RCTs |
| HBOT – chronic stroke (6+ months) | Months to years post | Moderate (RCT + retrospective) | Neurological and cognitive gains in 86% of patients |
| tDCS / rTMS neuromodulation | Subacute and chronic | Moderate (growing RCTs) | Motor and language improvements |
HBOT is not proposed as a replacement for conventional stroke rehabilitation. The Israeli research positions it as a potential adjunctive therapy that could enhance neuroplasticity alongside physiotherapy, occupational therapy, and speech-language pathology.
What Are the Limitations of the Current Evidence?
Researchers and clinicians reviewing this evidence should note several important limitations:
- Sample sizes are small: The landmark RCT included 74 patients. Larger, multi-centre trials are needed to confirm the findings
- Most research comes from a single centre: The majority of positive chronic stroke data originates from the Sagol Centre in Israel. Independent replication in other countries and settings is essential
- No standardised protocol exists: Treatment parameters (pressure, duration, number of sessions) vary across studies, making direct comparison difficult
- Long-term follow-up data is limited: It remains unclear how long cognitive and neurological improvements persist after completing HBOT
- Patient selection criteria are not well defined: Which chronic stroke patients are most likely to benefit has not been established through predictive biomarker studies
- Cost-effectiveness is unknown: A course of 40 to 60 sessions represents a significant treatment commitment with uncertain cost-benefit in the Canadian healthcare context
Is HBOT for Stroke Covered in Canada?
Stroke is not currently among the 14 conditions recognised under Health Canada’s device licensing framework for hyperbaric chambers. It is not covered by OHIP, MSP, AHCIP, or other provincial health insurance plans for this indication.
Patients seeking HBOT for post-stroke recovery in Canada would need to access treatment at a private facility at their own expense. Out-of-pocket costs for a 40-session course at a private clinic typically range from $6,000 to $16,000 CAD depending on the facility and province.
For information on the 14 conditions that are covered, visit the Canada Hyperbarics coverage guide. To locate hospitals and regulated facilities across Canada, use the facility directory.
What Should Referring Clinicians Consider?
For physicians evaluating whether to discuss HBOT with chronic stroke patients:
- Distinguish acute from chronic: The evidence does not support HBOT during the acute ischaemic stroke window based on current RCT data
- Consider the chronic window: Patients with persistent neurological deficits 6+ months post-stroke who have plateaued in conventional rehabilitation may be candidates based on the Israeli research
- Manage expectations: While 86% of patients in the Sagol cohort showed improvement, the evidence base is limited and comes primarily from a single research programme
- Address regulatory context: Patients should understand that stroke is an investigational indication for HBOT in Canada and is not provincially funded
- Review contraindications: Standard HBOT contraindications apply. Patients with untreated pneumothorax, certain ear conditions, or unstable cardiac status require careful screening
For a comprehensive overview of all recognised and emerging indications, visit the conditions and clinical evidence page on Canada Hyperbarics.
Frequently Asked Questions
Is HBOT a proven treatment for stroke?
HBOT is not a proven standard treatment for stroke. For acute ischaemic stroke, a 2024 meta-analysis found no clear benefit. For chronic post-stroke recovery, an Israeli RCT showed significant neurological improvements, but the evidence base is still limited and requires independent replication in larger, multi-centre trials.
How many HBOT sessions are used in stroke recovery research?
The main chronic stroke RCT used 40 sessions at 2.0 ATA, 90 minutes each, delivered 5 days per week over 8 weeks. Some protocols extend to 60 sessions. The retrospective analysis of 162 patients used similar parameters.
Can HBOT help years after a stroke?
The Israeli research specifically studied patients 6 to 36 months post-stroke and found improvements even at these late stages. The retrospective analysis included patients treated years after their stroke with positive cognitive outcomes. However, this evidence comes primarily from a single research centre.
Is stroke recovery with HBOT covered by OHIP or other Canadian provincial health plans?
No. Stroke is not among the 14 conditions recognised under Health Canada’s device licensing framework. HBOT for stroke recovery is considered investigational in Canada and is not covered by provincial health insurance. Patients would need to access treatment privately at their own cost.
What is the difference between acute and chronic stroke treatment with HBOT?
In acute stroke (within hours or days), HBOT was tested as an emergency oxygen-delivery intervention, but RCTs have not shown clear benefit. In chronic stroke (months to years later), HBOT is investigated as a neuroplasticity-inducing therapy to reactivate dormant brain tissue, with more promising results from controlled studies.
Where can I find a hyperbaric facility in Canada?
Canada Hyperbarics maintains a directory of 31 hospitals and regulated facilities across 10 provinces. Visit the facility directory to search by province or postal code. Note that for investigational indications like stroke recovery, treatment would typically be available only at private facilities on an out-of-pocket basis.
References
- Wang J, et al. Efficacy and safety of hyperbaric oxygen therapy in acute ischaemic stroke: a systematic review and meta-analysis. BMC Neurology. 2024;24:51. View in Canada Hyperbarics Research Database.
- Efrati S, et al. Hyperbaric oxygen induces late neuroplasticity in post stroke patients – randomized, prospective trial. PLoS ONE. 2013;8(1):e53716. DOI.
- Hadanny A, et al. Hyperbaric oxygen therapy improves neurocognitive functions of post-stroke patients – a retrospective analysis. Restorative Neurology and Neuroscience. 2020;38(1):93-107. DOI.
- Bennett MH, et al. Hyperbaric oxygen therapy for acute ischaemic stroke. Cochrane Database of Systematic Reviews. 2014. PubMed.
This content is for informational purposes only and does not constitute medical advice. HBOT for stroke recovery is an investigational use that is not currently recognised under Health Canada’s device licensing framework. Consult your physician or a certified hyperbaric medicine specialist for treatment decisions. Canada Hyperbarics is an independent educational resource and is not affiliated with any specific clinic or manufacturer.