Introduction
Stroke is a major cause of mortality and long-term disability. The lifetime risk of stroke is approximately 25% [1]. Over half of stroke victims have some disability at one year [2]. Furthermore, stroke accounts for over 4% of all direct healthcare costs in high-income countries [3].
The estimated annual stroke-related cost of healthcare, lost wages, and
decreased productivity in Canada is approximately $3.6 billion [4].
Most of the neurological improvement among stroke survivors occurs in the first 30 to 90 days [5].
Further modest functional improvements are possible after this period
with interventions from an interdisciplinary rehabilitation team, but
major disability often persists [2].
Hyperbaric oxygen therapy (HBOT) has been advocated and used by some
healthcare providers as a therapy to improve disability post-stroke.
HBOT involves the administration of inhaled 100% oxygen at increased
ambient pressure inside a closed vessel, producing greatly elevated
arterial and tissue oxygen tensions, and a wide variety of physiological
effects at the cellular and sub-cellular levels [6,7].
HBOT has been studied as a treatment in the acute/subacute phase and
chronic (3-6 months post-stroke) phase of stroke. A 2014 Cochrane
systematic review of HBOT for acute ischemic stroke found that “there
was no good evidence to show that HBOT improves clinical outcomes when
applied during acute presentation of ischemic stroke”, although the
possibility of clinical benefit had not been excluded [8].
The use of HBOT in chronic stroke has been less studied. A PubMed
search for randomized controlled trials of HBOT in chronic stroke
(Hyperbaric Oxygenation/ AND (Stroke Rehabilitation/ OR Stroke/) AND
randomized controlled trial.pt.) published between 1960 and
2024 identified one publication. There were significant limitations with
the trial: it used a waitlist control, which can lead to overestimates
of treatment effects [9,10], and the validity of the primary outcome, NIHSS, is uncertain in chronic stroke [11].
In an attempt to more definitively evaluate the use of HBOT as a
treatment in the chronic phase of ischemic stroke, we designed a
randomized clinical trial comparing the effect of sham HBOT and true
HBOT on the neurological status of participants who were between six
months and three years post-stroke. We hypothesized that a course of 40
treatments of HBOT would improve neurological function, as reflected in
Stroke Impact Scale-16 (SIS-16) scores.
