Epidural Infections (Spinal Epidural Abscess) and Subdural Infections (Subdural Empyema) Workup

Updated: Jul 19, 2019
  • Author: Hina Z Ghory, MD; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
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Laboratory Studies

Sedimentation rate is often elevated and, in cases with low pretest probability for spinal epidural abscess, may be useful as a screening laboratory test. [14]

Liberal use of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) evaluation following historical risk factor assessment for spinal epidural abscess have been incorporated into a clinical decision guideline based on experience at one institution. [15]

CBC may reveal a high WBC count (but normal WBC counts reported as well).

Other tests may include blood cultures, electrolyte levels, and preoperative laboratory studies (as needed by neurosurgery, eg, prothrombin time [PT], activated partial thromboplastin time [aPTT], ECG, chest radiograph [CXR]).

Postsurgical tissue/fluid cultures of infected space may be indicated.


Imaging Studies

Spinal epidural abscess

Immediate imaging of the spinal cord is needed upon suspicion for spinal epidural abscess. Techniques that are immediately available vary at different institutions.

MRI with gadolinium contrast is the procedure of choice because of the noninvasive nature of the test. It also delineates the extent of the abscess, which frequently extends over several levels.

For patients with signs or symptoms suggestive of spinal cord compression, it is prudent to image the lumbar and thoracic spine because of the bony spine and spinal cord anatomy. Thoracic spine lesions may cause lower extremity neurologic symptoms, and imaging confined to the lumbar vertebrae may not demonstrate the level of spinal cord compression.

"Skip lesions," which are concurrent noncontiguous spinal epidural abscess lesions, may be present, and imaging should be considered to detect these, especially in patients with delayed presentations, concurrent infection outside the spine, or a very high sedimentation rate. [16]

CT scan myelography or conventional myelography may be used if MRI is unavailable.

Subdural empyema

Cranial CT scan is the modality of choice.



Lumbar puncture

Lumbar puncture (LP) is relatively contraindicated in both conditions because of the risk of precipitating shifts of CNS content in the presence of a mass lesion. However, LP often is performed in the course of patient evaluation, particularly since meningitis is in the differential diagnosis. A typical cerebrospinal fluid (CSF) profile for these parameningeal infections would reveal only a few inflammatory cells with elevated protein level and decreased glucose level.