Asia
Hyperbaric
Centre
Who Is
This For?
This supportive protocol is for people with an intracranial abscess — a cerebral abscess, subdural empyema, or epidural empyema — whose neurosurgical team recommends hyperbaric oxygen as an adjunct to drainage and antibiotics.
The UHMS selection criteria are explicit, and we follow them exactly [1]. Hyperbaric oxygen is considered when at least one of the following applies:
Multiple abscesses — in one or both hemispheres.
Deep or dominant location — abscesses sitting in areas where surgery carries high risk, such as regions controlling speech or movement.
Compromised host — immune suppression, including HIV, malignancy, or diabetes.
Surgery contraindicated or high risk — when the safest operation is no operation, or a limited one.
Failure to respond — continued deterioration despite appropriate antibiotics and one or two surgical aspirations.
If none of these apply, standard neurosurgical care is usually enough — and we will say so. A doctor's referral is required, and for this condition it comes from the neurosurgical or infectious disease team managing the case.
This is not a first-line protocol, and the page will never pretend otherwise. Drainage and culture-directed antibiotics come first. Hyperbaric oxygen enters when the standard path narrows [1] [2].
It should be discussed with the neurosurgical team when:
Imaging shows multiple abscesses, or an abscess in a deep or eloquent location where every surgical pass costs brain.
The person cannot safely undergo extensive surgery — because of the abscess location, their general condition, or their immune status [1].
One or two aspirations plus appropriate antibiotics have not stopped the deterioration — the explicit "refractory" trigger in the UHMS criteria [1].
Perifocal swelling is driving intracranial pressure, where reducing oedema without high-dose steroids is valuable — because steroids can impede antibiotic penetration into the very tissue being treated [2].
There is associated skull osteomyelitis, where hyperbaric oxygen carries additional evidence [1].
When to Consider HBOT
What Pressure Does Inside an Infected Skull
An abscess is a pocket of infection cut off from the body's defences. The tissue inside and around it is severely hypoxic — and that single fact explains most of why brain abscesses resist treatment [1] [2].
Inside the chamber, we change the physics. At 2.0 to 2.5 ATA, 99.5% medical-grade oxygen dissolves directly into the blood plasma, raising oxygen tension in the abscess region far beyond what compromised vessels can deliver. Four mechanisms follow, each documented in the literature [1] [2].
First, direct suppression of the bacteria. The organisms found most often in brain abscesses are anaerobes — bacteria that cannot tolerate oxygen. Hyperbaric oxygen tensions inhibit their growth and their toxin production directly [1].
Second, immune chemistry restored. Neutrophils kill bacteria through oxygen-dependent reactions. In the hypoxic abscess environment, that machinery stalls; restoring oxygen tension switches it back on, and improves the activity of several antibiotic classes that are themselves oxygen-dependent [1] [2].
Third, swelling reduced — without steroids. High oxygen tension constricts healthy cerebral vessels, reducing blood flow into the swollen region while the plasma still delivers abundant oxygen. Perifocal oedema falls. This matters doubly: it lowers intracranial pressure, and it does so without high-dose steroids, which can shield the infection by hindering antibiotic penetration across the blood-brain barrier [2].
Fourth, help for the bone. When the infection involves the skull itself — concomitant osteomyelitis — hyperbaric oxygen brings its own evidence base from refractory bone infection [1].
The Science & Clinical Evidence
We do not make promises. The research does that — and on this page, context matters: intracranial abscess is rare, life-threatening, and impossible to study in randomized trials. The evidence is case series and controlled comparisons, and it is strikingly consistent.
The conventional baseline is sobering. Across historical series, intracranial abscess carried roughly 20% mortality, with persistent neurological deficits in nearly half of survivors [1] [3]. Against that baseline, the adjunctive hyperbaric oxygen literature reports:
4.3% vs 19.2% — mortality across 230 patients from seven hyperbaric centres, with adjunctive hyperbaric oxygen versus conventional management alone. — Lampl et al., multi-centre case series analysis [4]
0% mortality, 73% complete recovery — in 25 consecutive patients treated with adjunctive hyperbaric oxygen, with no cerebral oxygen toxicity across 348 sessions. — Lampl et al., consecutive series [5]
Fewer reoperations, better long-term recovery — a Swedish controlled study of 40 patients found adjunctive hyperbaric oxygen associated with less treatment failure and repeat surgery, and better long-term outcomes. — Bartek et al., 2016 [6]
60% vs 30% symptom-free at one year — the largest comparative study to date found patients treated with adjunctive hyperbaric oxygen twice as likely to be fully symptom-free at 12 months (mRS 0, P = .046), with lower mortality (12% vs 20%). — Brunner et al., 2025 [3]
Where we are honest with you: none of this is randomized evidence, and none ever will be — the condition is too rare and too lethal for a placebo arm [2] [3]. Numbers like 0% mortality come from small consecutive series and should not be read as guarantees. The UHMS position is measured: given the severity of these infections and the low complication rate of hyperbaric oxygen, the risk-benefit balance favours adding it in selected patients [1] [2]. Selected is the operative word — and your neurosurgical team makes the selection.
Our protocols follow UHMS guidance for intracranial abscess [1]. Every session is coordinated with the neurosurgical and infectious disease teams — imaging schedule, antibiotic course, and any operative plan.
Oxygen Purity: 99.5% Medical-Grade Oxygen — pharmaceutical-grade purity certified under the Pharmacy and Poisons Ordinance (Cap. 138) [7].
Chamber Pressure: 2.0 to 2.5 ATA (Atmospheres Absolute) — the range used across the published series [1] [5].
Session Duration: 60 to 90 minutes at depth [1].
Frequency: Once daily; twice daily in life-threatening phases, per the published protocols [1] [5].
Total Course: Individualised by clinical and radiological response — the largest series averaged about 13 sessions where bone infection was absent, with formal review after 20 [1] [2]. Surveillance MRI or CT, not the calendar, sets the stop.
The Protocol
What To Expect
We understand that entering a hyperbaric chamber can feel unfamiliar. Our team is here to guide you through every step of the process, ensuring you feel comfortable, safe, and supported.
Step 1 — The Briefing & Preparation: Before your first session, our technician will walk you through the safety protocols. You will change into 100% cotton clothing (provided) to eliminate static risk. No electronics, watches, or oil-based cosmetics are allowed inside the chamber.
Step 2 — Pressurisation: As the chamber pressurises over 10-15 minutes, you will feel a sensation in your ears similar to descending in an airplane. Our technician will coach you on simple techniques to clear your ears. Once at depth (2.0-2.4 ATA), you will breathe 99.5% pure oxygen through a comfortable hood or mask. You can read, rest, or watch a screen during the 90-minute session.
Step 3 — Depressurisation & Next Steps: The chamber will slowly depressurise over 10-15 minutes. Once open, you can return to your normal daily activities immediately. Our technician will examine your wound site and coordinate with your primary wound care team to track your progress.
FAQ
How many sessions before I notice a difference?
The largest published series averaged about 13 sessions, with formal review after 20 — but the honest answer is that your team measures this on surveillance MRI or CT, not on how you feel on a given day [1] [2]. In the published cases, radiological improvement tracked ahead of full neurological recovery, which itself continued consolidating over 6 to 12 months [3].
Can hyperbaric oxygen replace surgery for a brain abscess?
It is not a replacement — drainage and antibiotics remain the foundation for every patient who can undergo them [1]. Where hyperbaric oxygen changes the picture is exactly where surgery cannot go: multiple abscesses, deep or dominant locations, poor surgical candidates, and infections that keep worsening despite standard care. In those situations the UHMS recognises it as an established adjunct [1] — and that is the only way we present it to your team.
The studies are small. How should I weigh them?
Exactly as your neurosurgeon will: promising, consistent, and limited. There will never be a large randomized trial for this condition — it is too rare and too serious [2] [3]. What exists is a multi-centre mortality comparison (4.3% vs 19.2%), consecutive series with remarkable outcomes, the largest comparative study showing doubled rates of complete recovery at one year, and a clear mechanism [3] [4] [5] [6]. Against a baseline where one in five patients dies and nearly half of survivors keep deficits, the risk-benefit balance favours selected use [1] [3]. Selected, by your team — that is the honest frame.
UHMS. Intracranial Abscess. UHMS Hyperbaric Oxygen Therapy Indications, 15th Edition (patient selection criteria; mechanism review; baseline mortality ~20% across 21 studies). Undersea and Hyperbaric Medical Society. UHMS Official Indications
Tomoye EO, Moon RE. Hyperbaric oxygen for intracranial abscess (evidence-based review; utilization review after 20 treatments; risk-benefit conclusion). Undersea Hyperb Med. 2021;48(1). UHMS Journal
Brunner A, et al. Hyperbaric oxygen therapy for brain abscesses: a useful adjuvant treatment for a faster recovery (largest comparative study; 60% vs 30% mRS 0 at 12 months, P = .046; mortality 12% vs 20%; baseline mortality 10–15% and deficit rates per Brouwer et al. meta-analysis). Neurosurg Rev. 2025. Springer
Lampl L, Frey G, et al. Adjunctive hyperbaric oxygen in intracranial abscess: seven-centre case series analysis (230 patients; mortality 4.3% vs 19.2%). As presented: EUBS 2018; in Kindwall & Whelan, Hyperbaric Medicine Practice, 4th ed. [UNVERIFIED — full citation to be confirmed before publication]
Lampl L, Frey G, et al. Adjunctive hyperbaric oxygen in 25 consecutive intracranial abscess patients (0% mortality; 73% complete recovery; 348 sessions, no cerebral oxygen toxicity). As reviewed in Tomoye & Moon, UHM 2021 [2]. [UNVERIFIED — full citation to be confirmed before publication]
Bartek J, et al. Hyperbaric oxygen as an adjunct to surgery and antibiotics in intracranial abscess: retrospective consecutive controlled study, 40 patients (fewer reoperations, better long-term outcome). Sweden, 2016. As reviewed in Tomoye & Moon, UHM 2021 [2]. [UNVERIFIED — full citation to be confirmed before publication]
Hong Kong e-Legislation. Pharmacy and Poisons Ordinance (Cap. 138). Cap. 138 on e-Legislation
