Medication Summary
Antibiotic therapy
In clinically stable patients without significant neurological deficits, antibiotics should be held until after blood cultures and cultures from the operating room are drawn. Until the culture and sensitivity report of the infectious agent becomes available, the choice of empiric antibiotic therapy should be based on the underlying etiology. For example, when an intracranial abscess is thought to be due to extension of infection from paranasal sinuses involving staphylococcal, aerobic, and anaerobic bacteria, more than one antibiotic is necessary. Likewise, an antistaphylococcal agent would be an appropriate choice for infection occurring after a neurosurgical procedure. A reasonable broad-spectrum regimen is vancomycin, ceftazidime, and metronidazole. Depending on local antibiotic resistance patterns, other combinations including meropenem, ertapenem, or linezolid may be considered.
Once cultures have been finalized, the antibiotic regimen can then be narrowed to treat the cultprit organism. The length of therapy is determined by the patient's clinical response to treatment and by radiological resolution of the epidural abscess on follow-up imaging. Generally, antibiotic therapy should be continued for a minimum of 8 weeks if surgery is not undertaken, and for at least 4 weeks if the abscess is drained. In general, follow-up CT scanning or MRI should be obtained 2 weeks after antibiotic therapy has been discontinued.
Seizure therapy
Prophylactic seizure therapy is not generally recommended, but the provider should have a low threshold to administer AEDs if there is any clinical suspicion. If the IEA is not associated with a subdural empyema, seizures are unlikely to ensue. Patients who present with seizures should be given AEDs and then placed on video EEG postoperatively. Neurology consultation should be obtained to determine an appropriate weaning or taper of the AED, which generally would occur over months. Patients with a prior history of seizures who currently take AEDs should continue taking them.
Steroid Therapy
Steroids (eg, dexamethasone) may be considered in certain patients, particularly those with meningitic signs and symptoms.
Antibiotics
Class Summary
For patients presenting in the ED with intracranial epidural abscess, empiric antibiotics are the first-line pharmacologic therapy. These antibiotics must cover a broad spectrum of both aerobic and anaerobic bacterial organisms.
Penicillin G (Pfizerpen)
Along with chloramphenicol, constitutes first-line regimen for empiric treatment of intracranial epidural abscess in the ED. Provides coverage for anaerobes and streptococci.
Chloramphenicol
Constitutes the other half of classic first-line empiric regimen. Enhances anaerobic coverage to include Bacteroides fragilis, Enterobacteriaceae, and Haemophilus species infections.
Cefotaxime
In combination with metronidazole, can replace penicillin G and chloramphenicol. In this regimen, cefotaxime covers streptococci, staphylococci, Haemophilus species, and Enterobacteriaceae. Third-generation cephalosporin with broad gram-negative spectrum, lower efficacy against gram-positive organisms, and higher efficacy against resistant organisms. Arrests bacterial cell wall synthesis and inhibits bacterial growth by binding to one or more of the penicillin-binding proteins.
Metronidazole (Flagyl)
Second half of alternative regimen to penicillin/chloramphenicol. Imidazole ring-based antibiotic active against various anaerobic bacteria and protozoa. Has proved especially effective in otogenic intracranial epidural abscesses.
Nafcillin
Should be added to either regimen mentioned above if S aureus is strongly suspected. Treats infections caused by penicillinase-producing staphylococci. Used to initiate therapy when patients are suspected of having penicillin G resistant staphylococcal infection. Do not use for treatment of penicillin G susceptible staphylococci. Use parenteral therapy initially in severe infections. Very severe infections may require very high doses. Change to PO therapy as condition improves. Because of occasional occurrence of thrombophlebitis associated with parenteral route (particularly in elderly individuals), administer parenterally only for a short period (24-48 h) and change to PO route if clinically possible.
Vancomycin
Replaces nafcillin in patients who are allergic to penicillin and in patients who are suspected to have MRSA as an etiologic agent. Potent antibiotic directed against gram-positive organisms and active against enterococci species. Also useful in treating septicemia and skin structure infections.
Ceftazidime (Fortaz, Tazicef)
Should be added to empiric regimens if pseudomonads are suspected. Third-generation cephalosporin that has broad gram-negative spectrum, lower efficacy against gram-positive organisms, and higher efficacy against resistant organisms. Arrests bacterial cell wall synthesis and inhibits bacterial growth by binding to one or more of the penicillin-binding proteins.
Meropenem
A broad-spectrum carbapenem antibiotic, meropenem inhibits cell wall synthesis and has bactericidal activity. It is effective against most gram-positive and gram-negative bacteria. Meropenem has slightly increased activity against gram-negative organisms and slightly decreased activity against staphylococci and streptococci compared with imipenem.
Corticosteroids
Class Summary
Anti-inflammatory effects of steroid therapy can decrease associated cerebral edema, reducing ICP. These benefits are offset somewhat by the fact that steroid use decreases antibiotic penetration into the abscess and may slow encapsulation of the abscess site.
Dexamethasone (Decadron, Hemady)
Corticosteroid of choice for reducing ICP. Used in treatment of inflammatory diseases. May decrease inflammation by suppressing migration of polymorphonuclear leukocytes and reversing increased capillary permeability.
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CT scan showing lenticular-shaped intracranial epidural abscess.
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Intracranial epidural abscess. Enhanced MRI of the brain, axial section, revealing a left temporal epidural abscess with an abscess cavity and a thickened enhancing capsule. Adjacent thickened dura enhances as well. In addition, mass effect is evident.
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Intracranial epidural abscess. A coronal section of the MRI revealing a left temporal epidural abscess with an abscess cavity and a thickened enhancing capsule. Adjacent thickened dura enhances as well. In addition, mass effect is evident.
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Intracranial epidural abscess. MRI of the brain, unenhanced. A T1-weighted image (axial view) showing a left temporal epidural abscess with an abscess cavity, surrounding capsule, and the thickened dura underneath. Mass effect is evident.
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Epidural abscess in the posterior fossa following a suboccipital craniectomy.
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Epidural abscess photo, taken intraoperatively.
