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Pyogenic and Invasive Fungal Intracranial Abscesses

Pyogenic and Invasive Fungal Intracranial Abscesses


Pyogenic and Invasive Fungal Intracranial Abscesses


Treatment Protocol Guidelines

The following hyperbaric medicine treatment protocol is based upon the recommendations of the Hyperbaric Oxygen Committee of the Undersea and Hyperbaric Medical Society.  Clinical protocols and/or practice guidelines are systematically developed statements that help physicians, other practitioners, case managers and clients make decisions about appropriate health care for specific clinical circumstances.  

Protocols allow health providers to offer evidence-based, appropriate, standardized diagnostic treatment and care services to patients undergoing hyperbaric oxygen therapy (HBOT).  Evidenced-based medicine offers clinicians a way to achieve improved quality, improved patient satisfaction, and reduced costs.  This discussion includes adjunctive HBOT for pyogenic and invasive fungal intracranial abscesses. Utilization Review should be initiated when clinical decisions result in deviation from or modification of treatment protocols.  This includes any course of treatment at or above the recognized threshold limits. 

Medical Necessity

Medicare.gov defines “medically necessary” as “health-care services or supplies needed to prevent, diagnose, or treat an illness, injury, condition, disease, or its symptoms and that meet accepted standards of medicine.” 

The following condition is NOT a covered indication per the National Coverage Determination (NCD) 20.29. [1] This medical condition shall not be treated adjunctively or primarily by HBOT for reimbursement by the Medicare program as data supporting its use has not been established as medically beneficial. Services deemed treatment for these primary conditions will be denied as Not Reasonable and Necessary. Some third-party private insurers and state Medicaid, do cover this diagnosis. Be sure to carefully read the insurer local coverage determination (LCD).


 Sample Physician Order   | $ ICD-10 Crosswalk  |  Treatment Table

Background The term intracranial abscess (ICA) includes cerebral abscess, subdural empyema and epidural empyema. Infection may occur and spread from a contiguous infection (such as sinusitis, otitis, mastoiditis, or dental infection), hematogenous seeding or cranial trauma. The length of time on antibiotics can be shortened with the use of HBO as an adjunctive treatment [2]

Invasive fungal infections (IFI) are difficult to treat and often fatal in immunocompromised patients, diabetics, and trauma patients. Hyperbaric oxygen therapy (HBOT) has been advocated as an adjunctive treatment for IFIs- mainly mucormycosis, actinomycosis and aspergillosis. Mucormycosis is the second most common mold infection and the third most common invasive fungal infection in patients with hematologic malignant tumors and organ transplantations. [3]

These are often critically ill patients and require intubation, ventilation, and infusion of catecholamines in order to supplement blood pressure. Surgical excision of these abscesses in the orbit, nose, brain, head, or neck are often referred to as "commando procedures."  

Goals of HBOT

  • Correct tissue hypoxia, inhibit growth of anaerobic and micro-aerophilic organisms
  • Strengthen host defense through enhanced neutrophil-mediated phagocytosis of infecting organisms
  • Reduce intracranial pressure and symptoms through reduction of cerebral edema, without steroid use (steroid may decrease penetration of antibiotics across the blood-brain barrier)
  • Enhance effects of antibiotic agents by improving metabolic environment of acidosis 
  • Concomitantly treat associated skull osteomyelitis, if present
  • Reducing fungal growth
  • Augment amphotericin B activity


    • The term intracranial abscess (ICA) includes cerebral abscess, subdural empyema and epidural empyema.
    • The classic triad of symptoms, present in less than 50% of cases, includes: fever in 50% of patients, headache >75% and focal neurologic deficit 60%
    • Other signs include: stiff neck, hemiparesis with frontal lobe abscess, and signs of raised intracranial pressure
    • Clinical presentation supported by computerized tomography (CT) or magnetic resonance imaging (MRI)
    • Diagnoses vary according to the type of fungal infection. These invasive fungal infections are typically opportunistic and affect host-compromised patients. Histopathology with culture are often relied upon, however, culture may demonstrate no growth, and histopathology may be non-specific. These tests need to be interpreted in light of history, signs/symptoms and underlying disease. 
    HBO Criteria

    Adjunctive HBO should be considered under the following conditions:

    • Multiple abscesses in deep or dominant location(s)
    • Patient is immunosuppressed, particularly if abscess caused by fungus
    • In situations where surgery is contraindicated or where the patient is a poor surgical candidate, with no response or presenting with further deterioration in spite of standard surgical treatment with needle aspirates and antibiotic therapy.   
    • Surgical referral with diagnosis of an invasive fungal infection
    • Inability to tolerate or contraindication to use of amphotericin B 


    • Past medical history should include:
      • Any past incidence of sinusitis, otitis media, recent dental procedure, or infection and treatment (antibiotics). 
      • A known history or potential risk of HIV or other immunocompromised states which includes out of control diabetes mellitus.
    • Physical examination focusing on source of infection (ears, sinus and oral cavity). Neurologic exam to establish initial clinical status.
    • Labs to order: 
      • Complete Blood Count (CBC)
      • Erythrocyte Sedimentation Rate (ESR)
      • C-reactive protein (CRP)
      • Coagulation profile
      • Comprehensive Metabolic Panel (CMP)
      • Blood cultures
      • Culture and Sensitivity (C&S) and tissue culture
      • Arterial Blood Gas (ABG)
    • Radiologic testing to include:
      • X-Ray
      • CT or MRI, ultrasound in infants with open fontanelles.
    • Intracranial Pressure (ICP) monitoring for patients with increased intracranial pressure.
    • Evaluation of tympanic membranes before HBOT and as needed. Consider emergent myringotomies.


    • 2.0-2.5 ATA for 90 minutes of oxygen breathing, with two 5-10 minute air breaks if treated at 2.5 ATA (Table 1 or 3)
    • Twice daily depending on the condition of the individual patient. May reduce to daily based on patient's clinical response and radiological findings.
    • The optimal number of HBO treatments for ICA is unknown. The duration of therapy must be based on clinical judgment. In the largest number of ICA patients treated with HBO, the average number of HBO sessions was 14 in the absence of osteomyelitis.
    • Concurrent treatment with antiepileptic medication is recommended for all patients unless contraindicated. With increased seizure risk during HBO, administration of air break is recommended. (Table 2)


    • Serial neurological assessments
    • Repeat radiologic testing
    • Bone scan for accompanying cranial osteomyelitis

    Treatment Period

    5 – 20 treatments (concurrent Utilization review is recommended after 20 treatments)


    Refer to the ICD-10 Guideline for the appropriate ICD-10 code


    • If diabetes mellitus is present, blood glucose should be checked within an hour prior to treatment and immediately post-HBO.
    • Seizure activity may be a manifestation of the underlying disease process or the effects of CNS oxygen toxicity. Clinical correlation must be utilized to discriminate between these two etiologies. If oxygen toxicity is suspected, administer more frequent air break(s) as tolerated. 
    • This indication is not covered by Medicare but may be covered by commercial carriers. If treating a Medicare patient, an advance beneficiary notice (ABN) must be completed and signed by the patient prior to treatment. 
    Primary Sources: Whelan and Kindwall [4]Weaver [5]
    Periorbital fungal infection

    Figure 1. Periorbital fungal infection (mucormycosis)



    Sample history for Invasive Intracranial Abscess is shown below: 

    "Cherie P. is a 36 y/o woman with a brief history of left-sided maxillary sinus pain and pressure in her left orbital region. She had mild sinus pain this morning. The pain persisted and grew as the day went on. By 6PM this evening, the pain was excruciating and she started losing visual acuity in the left eye. She called 911 and was transported to the emergency room. On arrival, she was noted to have severe orbital swelling and left eye protrusion. Her level of consciousness began to be unstable. An emergent CT scan showed a mass effect in the left orbit that extended into the maxillary sinus and posteriorly into the brain. The ENT surgeon was called for debridement and radical debulking of the mass. Initial diagnosis is a mucor type intracranial abscess. The most likely organism is fungal. 

    Pertinent past history is that Cherie has been an insulin-dependent Type 1 diabetes mellitus patient since she was 14 years-old. She has lost her health coverage and could not afford insulin for the past 3 or 4 months. Her hemoglobin A1c is 14%. Blood glucose in the emergency department was over 400.

    We have been asked to provide hyperbaric oxygen therapy in the presence of a fungal intracranial abscess. We are assembling our critical care team and will take Cherie from recovery room directly to the hyperbaric chamber. This infection has a significant mortality, so we are proceeding while cultures will lag for days to a week. She has been placed on broad spectrum antibiotics as well as Amphotericin B infusion."

    Physical Exam

    • The term intracranial abscess (ICA) includes cerebral abscess, subdural empyema and epidural empyema.
    • The classic triad of symptoms, present in less than 50% of cases, includes: fever in 50% of patients, headache >75% and focal neurologic deficit 60%
    • Other signs include: stiff neck, hemiparesis with frontal lobe abscess, and signs of raised intracranial pressure
    • Focusing on source of infection (ears, sinus and oral cavity). Neurologic exam to establish initial clinical status.


    • Pyogenic and Invasive Fungal Intracranial Abscesses Refer to ICD-10 Crosswalk

    Hyperbaric Plan

    Patients may be treated at 2.0 - 2.5 ATA for 90 minutes of oxygen breathing, interspersed with appropriate air breaks. In the early phase of therapy, twice daily hyperbaric treatments are preferred. However, almost all of these patients are critically ill and require extreme effort on the part of the surgical, medical, and hyperbaric team. These patients will be in the operating room daily to every other day for repeated debridements until stable. The optimal number of HBOT treatments is unknown with no randomized controlled trials. By review of case series and retrospective analyses, we estimate 14 - 20 treatments. 

    Risk and Benefit of Hyperbaric Oxygen Therapy 

    • Please refer to topic "Documentation HBO: Risks and Benefits"

    Indication for Hyperbaric Oxygen Therapy (HBOT)

    Intracranial abscess is a rarely diagnosed complication in patients with some underlying immune weakness. It is not uncommon in patients with diabetes, whose diabetes control is chronically absent. While bacterial infection can be the source from an underlying sinusitis, the more frequent organisms are anaerobic bacteria and fungal in nature. 

    Mortality of intracranial abscesses is high and approaches 20-25% in some studies. The surgical approach to the abscess is radical debulking in a combined approach with ENT surgeons and neurosurgeons. 

    Adjunctive HBOT is thought to benefit by inhibiting anaerobic growth, which is frequently seen. HBOT is effective at reducing swelling of brain tissue.  HBOT may affect antibiotic and antifungal medication crossing the blood-brain barrier. Finally, in cases of mucormycosis, HBOT is thought to slow germination of fungal spores and retard mycelial growth, thus slowing the advance of tissue destruction. 

    Sample Order

    •  See sample physician order


    • 2CFor patients with pyogenic and/or fungal zygomatoses and intracranial abscesses, we suggest the use of adjunct HBOT to increase chances of survival (Grade 2C). 
      • Rationale: causes of severe pyogenic and fungal infections (primarily of the brain, head, neck, and chest) are due to microaerophilic, anaerobic, and several invasive fungal species. These microorganisms are mainly found in immunocompromised individuals, especially patients with diabetic acidosis and rhinocerebral mucormycosis.[6] Because of the rarity of this event, a formal randomized controlled study has not been performed. However, there have been multiple case reports and small series reported in the literature since the 1970s. Clinical reports of case presentations and small case series demonstrate the adjunctive use of HBOT with surgical debridement, amphotericin B, and other therapeutic interventions.[7][8] With this rationale, and in moribund patients, HBOT has been included in critical care management of these critically ill patients. The mortality rate varies based on the organism cultured and state of health when discovered. However, the several analyses listed above demonstrate lower mortality when using adjunctive HBOT rather than clinical care alone.
      • When to start and end therapy: before starting adjunctive HBOT, your facility must have the ability to treat critically ill patients in the hyperbaric chamber. The sooner the patient begins hyperbaric therapy, the better response. The endpoint of HBOT is when there is hemodynamic stability and no evidence of end-organ (primarily brain, heart, intestines, and kidneys) failure due to the infection.
      • Coverage: this indication is not typically covered by Medicare.[1] It may be covered by some private insurers. Due to the mortality associated with this disease, we suggest no delay in treating these patients. However, the facility and provider may not be reimbursed. 


    7/3/2019Added section on Clinical Evidence and Recommendations
    5/12/2019Added section on Documentation
    Official reprint from WoundReference® woundreference.com ©2018 Wound Reference, Inc. All Rights Reserved
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    NOTE: This is a controlled document. This document is not a substitute for proper training, experience, and exercising of professional judgment. While every effort has been made to ensure the accuracy of the contents, neither the authors nor the Wound Reference, Inc. give any guarantee as to the accuracy of the information contained in them nor accept any liability, with respect to loss, damage, injury or expense arising from any such errors or omissions in the contents of the work.


    1. CMS. National Coverage Determination (NCD) for Hyperbaric Oxygen Therapy (20.29) . 2017;.
    2. Kutlay M, Colak A, Yildiz S, Demircan N, Akin ON et al. Stereotactic aspiration and antibiotic treatment combined with hyperbaric oxygen therapy in the management of bacterial brain abscesses. Neurosurgery. 2008;volume 62 Suppl 2():540-6.
    3. Petrikkos G, Tsioutis C et al. Recent Advances in the Pathogenesis of Mucormycoses. Clinical therapeutics. 2018;volume 40(6):894-902.
    4. Harry T. Whelan, Eric Kindwall et al. Hyperbaric Medicine Practice 4th Edition Best Publishing Company. 2017;.
    5. Richard C. Barnes, MD et al. Undersea and Hyperbaric Medical Society, Hyperbaric Oxygen Indications, 13th edition: Intracranial Abscess . 2014;.
    6. Barnes RC. Intracranial abscess. Undersea & hyperbaric medicine : journal of the Undersea and Hyperbaric Medical Society, In.... 2012;volume 39(3):727-30.
    7. Ferguson BJ, Mitchell TG, Moon R, Camporesi EM, Farmer J et al. Adjunctive hyperbaric oxygen for treatment of rhinocerebral mucormycosis. Reviews of infectious diseases. 1988;volume 10(3):551-9.
    8. John BV, Chamilos G, Kontoyiannis DP et al. Hyperbaric oxygen as an adjunctive treatment for zygomycosis. Clinical microbiology and infection : the official publication of the European Society of Clini.... 2005;volume 11(7):515-7.
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