Hyperbaric Oxygen Therapy for Intracranial Abscess

The first hyperbaric chamber was constructed in 1662 by Nathaniel Henshaw, a British clergyman. Over the years, various hyperbaric devices were used to treat different ailments, with varying degrees of success until 1955. Until then, the use of hyperbaric methods had minimal scientific support. The clinical application of hyperbaric oxygen therapy (HBOT) began in 1955 when Churchill-Davidson and colleagues explored its potential to enhance the effects of radiation therapy in cancer patients. HBOT is a therapeutic modality that delivers 100% oxygen in a chamber or environment pressurized to more than 1.4 atmospheres absolute (ATA). The antimicrobial effects of HBOT are partly attributed to generating reactive oxygen species. HBOT is being explored as an adjunctive treatment for various conditions, including intracranial abscesses, with common examples being cerebral abscesses and subdural and epidural empyema. Please see StatPearls' companion resources, "Brain Abscess," "Subdural Empyema," and "Epidural Abscess," for more information about these clinical conditions. An intracranial abscess is a localized, encapsulated collection of pus within the cranial cavity. While brain abscesses are relatively rare, occurring in only 0.3 to 1.3 per 100,000 individuals, their incidence is significantly higher among high-risk patients, particularly those with HIV infection or AIDS. The development of an intracranial abscess involves several mechanisms, as mentioned below. Direct spread: This occurs when an initial infection spreads contiguously into adjacent tissues, such as the sinuses, ears, mastoid air cells, or teeth, affecting up to 60% of patients. Hematogenous seeding: Infectious agents can reach the brain via the bloodstream, often leading to multiple abscesses. Cranial trauma: Penetrating head injuries can provide a direct route for microorganisms to enter the skull. and species are the most common bacterial causes of brain abscesses, with viridans group streptococci (VGS) and  being the most prevalent. Anaerobes are also commonly found in brain abscesses, originating from the normal oral flora. When determining the cause of an infection, it is essential to consider the patient's immune status. Bacterial abscesses are typically observed in immunocompetent individuals, whereas immunocompromised patients may be infected by various organisms, including fungi. Although brain abscesses are a rare condition, mortality rates remain high among affected patients. However, the prognosis for these individuals has significantly improved compared to historical data. A systematic review and meta-analysis revealed that over the past 6 decades, the case fatality rate has decreased from 40% to 10%, while the proportion of patients achieving full recovery has increased from 33% to 70%. Additionally, a study of 289 patients with pyogenic brain abscesses treated between 1999 and 2006 reported a mortality rate as low as 2.7%. Several factors, as mentioned below, have contributed to this positive trend. Computed tomography: The advent of computed tomography (CT) imaging has significantly improved outcomes by enabling faster diagnoses and facilitating less invasive, more precise neurosurgical interventions, such as stereotactic aspiration. One retrospective study showed a reduction in mortality from 40% to 20% within the first decade following the introduction of CT. Neurosurgical techniques: Advancements in neurosurgical procedures and the precision offered by CT-guided interventions have improved abscess drainage and reduced complications. Antimicrobial therapy: The development of more effective antibiotics has been crucial for controlling infections.