The purpose of this study is to examine the role of Hyperbaric Oxygen Therapy (HBOT) in improving neurological function in patients who are 6 to 36 months post ischemic stroke.

The purpose of this study is to examine the role of Hyperbaric Oxygen Therapy (HBOT) in improving neurological function in patients who are 6 to 36 months post ischemic stroke.

Hyperbaric oxygen therapy (HBOT) involves the administration of inhaled 100% oxygen at increased ambient pressure inside a closed vessel. HBOT produces greatly elevated arterial and tissue oxygen tensions, producing a wide variety of physiological effects at the cellular and sub cellular level. Some of these effects have been postulated to be beneficial in the context of ischemic stroke.

Most of the recovery after stroke occurs in the first 30 to 90 days after the acute event. Recovery is largely based on recovery of brain that is injured, but viable. Physiological imaging studies (PET, EEG) have demonstrated that brain tissue may remain alive but not functional for months or years after ischemic insult.

Subjects will be selected from the stroke population based on an expectation that they would experience a clinically significant improvement. Eligible subjects will have suffered an ischemic stroke involving the cerebral cortex within the last 6 to 36 months. The study will be enrolling 140 subjects and will be randomized to two different treatment arms: experimental group and a waitlist group.

Each subject will receive a series of forty 2 hour treatments, delivered once a day, 5 days a week, within the hyperbaric oxygen chamber.There will be assessments completed before treatment series begins, 3 weeks and 6 weeks into treatment and then again at the end of treatment. After treatment ends, the investigators will conduct these assessments again at 3 months, 6 months, 9 months and 1 year from the date of the participants last treatment.

Inclusion Criteria:

1. Age between 19 and 85.
2. Able to speak English and give informed consent or have a substitute decision maker and able to assent.
3. One or more ischemic stroke(s) involving the cerebral cortex or cerebellum within the last 6 to 36 months
4. Able to sit in the chamber with the assistance of a waist and chest strap for 120 minutes.

Exclusion Criteria:

1. Contraindication to HBOT (Appendix C) including:

   1. Untreated collapsed lung (pneumothorax)
   2. Have taken the chemotherapy drug Doxorubicin within 72 hours
   3. Have taken the chemotherapy drug Bleomycin within 4 months
   4. Bowel obstruction
   5. Heart pacemaker of unknown make and model
   6. Pregnancy
   7. Cigarette Smoking
   8. Chronic Obstructive Pulmonary Disease (COPD)

2. Participation in other stroke related studies.

3. Previous history stroke > 36 months prior to study baseline