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Subdural Empyema Workup

  • Author: Segun Toyin Dawodu, JD, MD, MS, MBA, LLM, FAAPMR, FAANEM; Chief Editor: Niranjan N Singh, MD, DM  more...
 
Updated: Dec 08, 2015
 

Laboratory Studies

See the list below:

  • CBC count may show a toxic leukocytosis.
  • Erythrocyte sedimentation rate (ESR) may be elevated.
  • Blood should be cultured for aerobic and anaerobic organisms.
  • Preoperative tests should include electrolytes, BUN, liver function tests, and CBC count if surgical intervention is being considered.
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Imaging Studies

Cranial MRI is now the imaging study of choice, being superior to cranial CT scan in outlining the extent of subdural empyema and demonstrating the convexity and interhemispheric collections.

MRI also shows greater morphological detail than CT scan.

The sensitivity of MRI is improved by using gadolinium contrast medium. See the image below.

MRI scan of a subdural empyema in the left parieta MRI scan of a subdural empyema in the left parietal area.

Cranial CT[1] scan was the standard technique for quick diagnosis before the advent of MRI. The use of high-resolution, contrast-enhanced CT scan increases diagnostic yield, although it sometimes gives equivocal or normal results.

On CT scan, subdural empyema shows as a hypodense area over the hemisphere or along the falx; the margins are better delineated with the infusion of contrast material. Cerebral involvement also is visible.

Cranial osteomyelitis may be seen.

CT scan is the modality of choice if the patient is comatose or critically ill and MRI is not possible or is contraindicated. See the image below.

CT scan of a subdural empyema in the left temporal CT scan of a subdural empyema in the left temporal/parietal area.

Cranial ultrasound[2] has been helpful in differentiating subdural empyema from anechoic reactive subdural effusion in infants with meningitis accompanied by complex features (eg, increased echogenicity in the convexity collections, presence of hyperechoic fibrinous strands or thick hyperechoic inner membrane, and increases in echogenicity of the pia-arachnoid).

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Other Tests

See the list below:

  • Preoperative - ECG, chest radiograph
  • Studies to define causes - Chest radiograph for pulmonary source, CT scan of paranasal sinuses and mastoid cells, sputum culture, nasal drip culture
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Procedures

Lumbar puncture is currently contraindicated because of possible cerebral herniation from increased intracranial pressure.

Lumbar puncture may be performed in the course of a workup to rule out meningeal infection when increased intracranial pressure has been excluded.

CSF examination[3] is an adjunctive test in the diagnosis of subdural empyema and may be obtained in addition to the other diagnostic tests previously outlined. CSF findings include the following:

  • WBC count (predominantly polymorphonuclear neutrophils) is increased. A significant increase (>50/µL) may be seen, although a slightly elevated cell count of 5-20/µL (reference range, 0-5/µL) does not rule out the possibility of subdural empyema.
  • Increased protein level greater than 100 mg/dL may be seen (reference range, 20-40 mg/dL), although less substantial elevations (50-90 mg/dL) do not rule out the possibility of subdural empyema.
  • Decreased glucose levels of 40 mg/dL or less usually are seen (reference range, 50-80 mg/dL). CSF glucose levels should be normalized with a blood glucose level obtained concurrently.
  • Occasionally, the CSF is normal and sterile in these cases.
  • The specific CSF findings should be compared with the accepted normal values of the treating physician's laboratory.
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Contributor Information and Disclosures
Author

Segun Toyin Dawodu, JD, MD, MS, MBA, LLM, FAAPMR, FAANEM Attending Interventional Physiatrist, Wellspan Health

Segun Toyin Dawodu, JD, MD, MS, MBA, LLM, FAAPMR, FAANEM is a member of the following medical societies: American College of Sports Medicine, American Academy of Physical Medicine and Rehabilitation, Royal College of Surgeons of England, American Association of Neuromuscular and Electrodiagnostic Medicine, American Medical Association, American Medical Informatics Association, Association of Academic Physiatrists, International Society of Physical and Rehabilitation Medicine

Disclosure: Nothing to disclose.

Coauthor(s)

Nicholas Lorenzo, MD, MHA, CPE Founding Editor-in-Chief, eMedicine Neurology; Founder and CEO/CMO, PHLT Consultants; Chief Medical Officer, MeMD Inc

Nicholas Lorenzo, MD, MHA, CPE is a member of the following medical societies: Alpha Omega Alpha, American Association for Physician Leadership, American Academy of Neurology

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Florian P Thomas, MD, PhD, Drmed, MA, MS Director, National MS Society Multiple Sclerosis Center; Professor and Director, Clinical Research Unit, Department of Neurology, Adjunct Professor of Physical Therapy, Associate Professor, Institute for Molecular Virology, St Louis University School of Medicine; Editor-in-Chief, Journal of Spinal Cord Medicine

Florian P Thomas, MD, PhD, Drmed, MA, MS is a member of the following medical societies: Academy of Spinal Cord Injury Professionals, American Academy of Neurology, American Neurological Association, Consortium of Multiple Sclerosis Centers, National Multiple Sclerosis Society, Sigma Xi

Disclosure: Nothing to disclose.

Chief Editor

Niranjan N Singh, MD, DM Associate Professor of Neurology, University of Missouri-Columbia School of Medicine

Niranjan N Singh, MD, DM is a member of the following medical societies: American Academy of Neurology, American Association of Neuromuscular and Electrodiagnostic Medicine, American Headache Society

Disclosure: Nothing to disclose.

Additional Contributors

Edward L Hogan, MD Professor, Department of Neurology, Medical College of Georgia; Emeritus Professor and Chair, Department of Neurology, Medical University of South Carolina

Edward L Hogan, MD is a member of the following medical societies: Alpha Omega Alpha, Society for Neuroscience, American Society for Biochemistry and Molecular Biology, American Academy of Neurology, American Neurological Association, Phi Beta Kappa, Sigma Xi, Southern Clinical Neurological Society

Disclosure: Nothing to disclose.

References
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  7. Sanford JP. Guide to antimicrobial therapy. Bethseda MD: Uniformed Services University Health Sciences. 1993. 3:

  8. Delgado Tapia JA, Galera Lopez J, Santiago Martin J, et al. Subdural empyema due to Mycoplasma hominis after a cesarean section under spinal anesthesia. Rev Esp Anestesiol Reanim. 2005. 52(4):239-242. [Medline].

  9. Dwarakanath S, Suri A, Mahapatra AK. Spontaneous subdural empyema in falciparum malaria: a case study. J Vector Borne Dis. 2004 Sep-Dec. 41(3-4):80-2. [Medline].

  10. Foerster BR, Thurnher MM, Malani PN, Petrou M, Carets-Zumelzu F, Sundgren PC. Intracranial infections: clinical and imaging characteristics. Acta Radiologica. October 2007. 48(8):875-93. [Medline].

  11. Hall WA, Truwit CL. The surgical management of infections involving the cerebrum. Neurosurgery. February 2008. 62 Supplement 2:519-30. [Medline].

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  13. Mauser HW, Van Houwelingen HC, Tulleken CA. Factors affecting the outcome in subdural empyema. J Neurol Neurosurg Psychiatry. 1987 Sep. 50(9):1136-41. [Medline].

  14. Migirov L, Eyal A, Kronenberg J. Intracranial complications following mastoidectomy. Pediatr Neurosurg. 2004 Sep-Oct. 40(5):226-9. [Medline].

  15. Placeholder.

  16. Moorthy RK, Rajshekhar V. Intracranial Abscess. Neurosurg Focus. 2008. 24 (6):E3.

 
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MRI scan of a subdural empyema in the left parietal area.
CT scan of a subdural empyema in the left temporal/parietal area.
 
 
 
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