Brain AbscessNCT04938362
Cognitive Function and Fatigue After Brain Abscess
An observational study of Brain Abscess and Fatigue, run by University of Oslo at 1 site in Norway.
Trial summary
Brain abscess is a focal bacterial or fungal infection of the brain. Treatment is neurosurgical drainage of pus followed by long-term antibiotic treatment. In spite of successful treatment of the infection, long-term cognitive problems or mental fatigue may ensue. Read more about this study
- Who is it for?
- Ages 16 years and older
- Conditions the study is for
- Brain Abscess, Fatigue, Cognitive Dysfunction
- What is being tested?
- FDG-PET and EEG
- How many people
- 50 participants
- Where
- 1 siteNorway
- Study dates
- 1 Jan 2020to 31 Dec 2030
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 16 years and older
- All sexes
- No healthy volunteers
- Child, Adult, Older adult
Study population: Patients older than 16 years, who have completed treatment for brain abscess and who agree to participate.
Who may be able to join
- Patients who have completed treatment for brain abscess and who agree to participate.
Who cannot join
- Patients who cannot undergo neuropsychological investigation due to unconsciousness
- Patients who cannot undergo neuropsychological investigation, being mentally too ill
- Patients who suffer from dementia
- Patients who cannot undergo FDG-PET due to claustrophobia
- Patients who cannot undergo EEG due to panic attacks
- Age under 16.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Norway1 site, 1 recruiting
- Recruiting
Oslo University Hospital
Oslo, 0450
Bjørnar Hassel, MD, PhD, +4722118080, bjornar.hassel@medisin.uio.no
Daniel Dahlberg, MD, PhD, +4723070000, danieldahlberg@gmail.com
About this study
Brain abscess is a focal bacterial or fungal infection of the brain. Treatment is neurosurgical drainage of pus followed by long-term antibiotic treatment. In spite of successful treatment of the infection, long-term cognitive problems or mental fatigue may ensue. The reason for this dysfunction may be a continuing inflammatory state or damage to brain tissue caused by the abscess. The investigators will evaluate these possibilities with the use of [18F]deoxyglucose-positron emission tomography (FDG-PET) and electroencephalography (EEG) in patients who have been treated for brain abscess and who experience cognitive problems and/or fatigue. FDG-PET may identify both inflammation and altered neuronal activity (the latter indicating damage to brain tissue), and EEG may identify altered neuronal activity, including changes in neuronal network activity.
Read the detailed description
Brain abscess is a focal bacterial or fungal infection of the brain, which results in a pus-filled cavity within the brain parenchyma. The incidence is approximately 1/100 000 per year, and all age groups are affected. Treatment is neurosurgical drainage of pus followed by long-term antibiotic treatment. Previously, the capsule that surrounds the pus was removed surgically; this is not usually done anymore. In spite of successful treatment of the infection, patients may experience long-lasting cognitive problems or mental fatigue. The reason for this brain dysfunction is not known.
The investigators formulated two hypotheses to explain why some patients experience long-lasting cognitive problems and/or fatigue: 1) The brain abscess caused damage to brain tissue, interrupting neuronal networks underlying cognition or 2) The abscess or the remaining capsule causes a long-lasting inflammatory state of the brain, affecting neurotransmission and cerebral function.
In this prospective study, the investigators evaluate brain abscess patients by cognitive examination by a neuropsychologist at 2 and 12 months after treatment. Participants then undergo [18F]deoxyglucose-positron emission tomography (FDG-PET). An inflammatory state in the abscess area would be identified by the FDG-PET signal. Likewise, a change in neuronal (neocortical) function would be detectable from a change in the FDG-PET signal. Participants also undergo EEG investigation to establish whether fatigue is related to alterations in EEG parameters: alpha, theta, and delta activity.
Importantly, brain damage caused by the abscess may be irreversible and functional improvement of the patient would probably have to rely on compensatory strategies, whereas an inflammatory state could probably be modified by anti-inflammatory treatment.
Further, the prognosis for the patients' cognitive problems and fatigue is probably different if the underlying cause is inflammation rather than tissue damage.
- Conditions
- Brain Abscess, Fatigue, Cognitive Dysfunction
- Being tested
- FDG-PET, EEG
- Medical subject headings
- Brain Abscess, Fatigue, Cognitive Dysfunction
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
FDG-PETOther
[18F]Deoxyglucose-positron emission tomography at 0-10 years after brain abscess
EEGOther
Electroencephalography (EEG) at 0-10 years after brain abscess
| Study group | Role | What they receive |
|---|---|---|
| Brain abscess patients with cognitive dysfunction and/or fatigue | This group of patients experience cognitive dysfunction and/or fatigue after brain abscess. Receives: Other: FDG-PET; Other: EEG | |
| Brain abscess patients without cognitive dysfunction and/or fatigue | This group of patients does not experience cognitive dysfunction and/or fatigue after brain abscess. Receives: Other: FDG-PET; Other: EEG |
What is being measured
The primary outcome is the main question the study is designed to answer.
A change in FDG-PET signal indicating inflammation
The FDG-PET signal indicates inflammation of brain tissue or the brain abscess capsule.
Measured: When all patients have been followed up for at least 1 year.
A change in FDG-PET signal indicating a change in neuronal activity
A change neocortical FDG-PET signal indicates a change in neuronal activity caused by brain tissue damage by the brain abscess.
Measured: When all patients have been followed up for at least 1 year.
A change in EEG activity indicating a change in neuronal activity based on EEG power in alpha, theta, and delta frequencies.
A change neocortical EEG activity indicates a change in neuronal activity caused by brain tissue damage by the brain abscess evident as changes in EEG power in alpha, theta, and delta frequencies..
Measured: When all patients have been followed up for at least 1 year.
Secondary outcomes (2)
Fatigue after brain abscess
Neuropsychological investigation with the use of Chalder's fatigue questionnaire. Degree of fatigue is determined from the answers to 11 questions. The answer "Better than before" gives a score of 0, "Same as before" gives a score of 1, "Worse than before" gives a score of 2, and "Much worse than before" gives a score of 3. Thus, a maximum fatigue score is 33, meaning a very high degree of fatigue.
Measured: When all patients have been followed up for at least 1 year.
No fatigue after brain abscess
Neuropsychological investigation with the use of Chalder's fatigue questionnaire. Degree of fatigue is determined from the answers to 11 questions. The answer "Better than before" gives a score of 0, "Same as before" gives a score of 1, "Worse than before" gives a score of 2, and "Much worse than before" gives a score of 3. Thus, a maximum fatigue score is 33, meaning a very high degree of fatigue.
Measured: When all patients have been followed up for at least 1 year.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted24 Jun 2021
- Study start1 Jan 2020
- Primary completion31 Dec 2030 (estimated)
- Study completion31 Dec 2030 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (4)Papers the sponsor has linked to this study.
- Other trials for Brain AbscessStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case only
- Time perspective
- Prospective
- Enrolment
- 50 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Oslo
- Sponsor type
- University, hospital or other
- Collaborators
- Oslo University Hospital, Sunnaas Rehabilitation Hospital
- Responsible party
- Principal investigator, Bjørnar Hassel, University of Oslo
- Investigators
- Bjørnar Hassel, MD, PhD, Principal investigator, University of OsloDaniel Dahlberg, MD, PhD, Principal investigator, Oslo University Hospital
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04938362
- Sponsor's protocol ID
- Cognition/fatigue/brainabscess
- Status last verified
- Jul 2025
- First submitted
- 13 Jun 2021
- Last updated
- 4 Jul 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Patient data will be published on a group basis without identifiable characteristics. Publication will be in an international, peer-reviewed medical journal.
Publications
Rogne AG, Muller EG, Udnaes E, Sigurdardottir S, Raudeberg R, Connelly JP, Revheim ME, Hassel B, Dahlberg D. beta-Amyloid may accumulate in the human brain after focal bacterial infection: An 18 F-flutemetamol positron emission tomography study. Eur J Neurol. 2021 Mar;28(3):877-883. doi: 10.1111/ene.14622. Epub 2020 Nov 27.
PubMed 33131195Dahlberg D, Holm S, Sagen EML, Michelsen AE, Stensland M, de Souza GA, Muller EG, Connelly JP, Revheim ME, Halvorsen B, Hassel B. Bacterial Brain Abscesses Expand Despite Effective Antibiotic Treatment: A Process Powered by Osmosis Due to Neutrophil Cell Death. Neurosurgery. 2024 May 1;94(5):1079-1087. doi: 10.1227/neu.0000000000002792. Epub 2023 Dec 12.
PubMed 38084989Hassel B, Niehusmann P, Halvorsen B, Dahlberg D. Pro-inflammatory cytokines in cystic glioblastoma: A quantitative study with a comparison with bacterial brain abscesses. With an MRI investigation of displacement and destruction of the brain tissue surrounding a glioblastoma. Front Oncol. 2022 Jul 29;12:846674. doi: 10.3389/fonc.2022.846674. eCollection 2022.
PubMed 35965529Muller EG, Dahlberg D, Hassel B, Revheim ME, Connelly JP. Brain Abscess Causes Brain Damage With Long-Lasting Focal Cerebral Hypoactivity that Correlates With Abscess Size: A Cross-Sectional 18 F-Fluoro-Deoxyglucose Positron Emission Tomography Study. Neurosurgery. 2024 Nov 11;97(1):138-147. doi: 10.1227/neu.0000000000003268.
PubMed 39526777
Study at a glance
From the registry record, last updated by the sponsor on 4 Jul 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Cognitive Function and Fatigue After Brain Abscess
- ClinicalTrials.gov ID
- NCT04938362
- Acronym / sponsor ID
- Cognition/fatigue/brainabscess
- Conditions
- Brain Abscess, Fatigue, Cognitive Dysfunction
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 50 participants (estimated)
- Lead sponsor
- University of OsloUniversity, hospital or other
- Collaborators
- Oslo University Hospital, Sunnaas Rehabilitation Hospital
- Study start
- 1 Jan 2020 (actual)
- Primary completion
- 31 Dec 2030 (estimated)
- Study completion
- 31 Dec 2030 (estimated)
- First posted
- 24 Jun 2021 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Brain abscess is a focal bacterial or fungal infection of the brain. Treatment is neurosurgical drainage of pus followed by long-term antibiotic treatment. In spite of successful treatment of the infection, long-term cognitive problems or mental fatigue may ensue. The reason for this dysfunction may be a continuing inflammatory state or damage to brain tissue caused by the abscess. The investigators will evaluate these possibilities with the use of [18F]deoxyglucose-positron emission tomography (FDG-PET) and electroencephalography (EEG) in patients who have been treated for brain abscess and who experience cognitive problems and/or fatigue. FDG-PET may identify both inflammation and altered neuronal activity (the latter indicating damage to brain tissue), and EEG may identify altered neuronal activity, including changes in neuronal network activity.
Detailed description
Brain abscess is a focal bacterial or fungal infection of the brain, which results in a pus-filled cavity within the brain parenchyma. The incidence is approximately 1/100 000 per year, and all age groups are affected. Treatment is neurosurgical drainage of pus followed by long-term antibiotic treatment. Previously, the capsule that surrounds the pus was removed surgically; this is not usually done anymore. In spite of successful treatment of the infection, patients may experience long-lasting cognitive problems or mental fatigue. The reason for this brain dysfunction is not known.
The investigators formulated two hypotheses to explain why some patients experience long-lasting cognitive problems and/or fatigue: 1) The brain abscess caused damage to brain tissue, interrupting neuronal networks underlying cognition or 2) The abscess or the remaining capsule causes a long-lasting inflammatory state of the brain, affecting neurotransmission and cerebral function.
In this prospective study, the investigators evaluate brain abscess patients by cognitive examination by a neuropsychologist at 2 and 12 months after treatment. Participants then undergo [18F]deoxyglucose-positron emission tomography (FDG-PET). An inflammatory state in the abscess area would be identified by the FDG-PET signal. Likewise, a change in neuronal (neocortical) function would be detectable from a change in the FDG-PET signal. Participants also undergo EEG investigation to establish whether fatigue is related to alterations in EEG parameters: alpha, theta, and delta activity.
Importantly, brain damage caused by the abscess may be irreversible and functional improvement of the patient would probably have to rely on compensatory strategies, whereas an inflammatory state could probably be modified by anti-inflammatory treatment.
Further, the prognosis for the patients' cognitive problems and fatigue is probably different if the underlying cause is inflammation rather than tissue damage.
Study design
- Observational model
- Case only
- Time perspective
- Prospective
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Brain abscess patients with cognitive dysfunction and/or fatigue | – | Other: FDG-PET, Other: EEGThis group of patients experience cognitive dysfunction and/or fatigue after brain abscess. |
| Brain abscess patients without cognitive dysfunction and/or fatigue | – | Other: FDG-PET, Other: EEGThis group of patients does not experience cognitive dysfunction and/or fatigue after brain abscess. |
Who may qualify
- Ages
- 16 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Child, Adult, Older adult
- Study population
- Patients older than 16 years, who have completed treatment for brain abscess and who agree to participate.
Key inclusion criteria (1 listed)
- Patients who have completed treatment for brain abscess and who agree to participate.
Key exclusion criteria (6 listed)
- Patients who cannot undergo neuropsychological investigation due to unconsciousness
- Patients who cannot undergo neuropsychological investigation, being mentally too ill
- Patients who suffer from dementia
- Patients who cannot undergo FDG-PET due to claustrophobia
- Patients who cannot undergo EEG due to panic attacks
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| FDG-PET[18F]Deoxyglucose-positron emission tomography at 0-10 years after brain abscess | Other | Brain abscess patients with cognitive dysfunction and/or fatigue, Brain abscess patients without cognitive dysfunction and/or fatigue |
| EEGElectroencephalography (EEG) at 0-10 years after brain abscess | Other | Brain abscess patients with cognitive dysfunction and/or fatigue, Brain abscess patients without cognitive dysfunction and/or fatigue |
Primary outcome
A change in FDG-PET signal indicating inflammation
Time frame: When all patients have been followed up for at least 1 year.
The FDG-PET signal indicates inflammation of brain tissue or the brain abscess capsule.
A change in FDG-PET signal indicating a change in neuronal activity
Time frame: When all patients have been followed up for at least 1 year.
A change neocortical FDG-PET signal indicates a change in neuronal activity caused by brain tissue damage by the brain abscess.
A change in EEG activity indicating a change in neuronal activity based on EEG power in alpha, theta, and delta frequencies.
Time frame: When all patients have been followed up for at least 1 year.
A change neocortical EEG activity indicates a change in neuronal activity caused by brain tissue damage by the brain abscess evident as changes in EEG power in alpha, theta, and delta frequencies..
2 secondary outcomes
Fatigue after brain abscess
Time frame: When all patients have been followed up for at least 1 year.
No fatigue after brain abscess
Time frame: When all patients have been followed up for at least 1 year.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 4 Jul 2025.
- Background: PubMed 33131195Rogne AG, Muller EG, Udnaes E, Sigurdardottir S, Raudeberg R, Connelly JP, Revheim ME, Hassel B, Dahlberg D. beta-Amyloid may accumulate in the human brain after focal bacterial infection: An 18 F-flutemetamol positron emission tomography study. Eur J Neurol. 2021 Mar;28(3):877-883. doi: 10.1111/ene.14622. Epub 2020 Nov 27.
- Background: PubMed 38084989Dahlberg D, Holm S, Sagen EML, Michelsen AE, Stensland M, de Souza GA, Muller EG, Connelly JP, Revheim ME, Halvorsen B, Hassel B. Bacterial Brain Abscesses Expand Despite Effective Antibiotic Treatment: A Process Powered by Osmosis Due to Neutrophil Cell Death. Neurosurgery. 2024 May 1;94(5):1079-1087. doi: 10.1227/neu.0000000000002792. Epub 2023 Dec 12.
- Background: PubMed 35965529Hassel B, Niehusmann P, Halvorsen B, Dahlberg D. Pro-inflammatory cytokines in cystic glioblastoma: A quantitative study with a comparison with bacterial brain abscesses. With an MRI investigation of displacement and destruction of the brain tissue surrounding a glioblastoma. Front Oncol. 2022 Jul 29;12:846674. doi: 10.3389/fonc.2022.846674. eCollection 2022.
- Derived from this study: PubMed 39526777Muller EG, Dahlberg D, Hassel B, Revheim ME, Connelly JP. Brain Abscess Causes Brain Damage With Long-Lasting Focal Cerebral Hypoactivity that Correlates With Abscess Size: A Cross-Sectional 18 F-Fluoro-Deoxyglucose Positron Emission Tomography Study. Neurosurgery. 2024 Nov 11;97(1):138-147. doi: 10.1227/neu.0000000000003268.
- Individual participant dataSharing planned: No. Patient data will be published on a group basis without identifiable characteristics. Publication will be in an international, peer-reviewed medical journal.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Bjørnar Hassel, MD, PhD principal investigator
University of Oslo
Daniel Dahlberg, MD, PhD principal investigator
Oslo University Hospital
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Brain Abscess and Fatigue, run by University of Oslo at 1 site in Norway.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 4 Jul 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Norway. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Peder H Utne (+4723066023, pedutn@ous-hf.no), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
A change in FDG-PET signal indicating inflammation (time frame: When all patients have been followed up for at least 1 year.). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT04938362, which also lists 4 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 4 Jul 2025; AzTrials last refreshed its copy on 28 Oct 2026.