Wednesday, May 02, 2007

Cerebral Abscess-- Quick Hits from AAN (Bartt lecture) 2007

1.  Mortality has declined in recent years.  In a recent review of 94 patients admitted to intensive care, 26 % died and 36 % had long term morbidity.  Recent rates of death are 13-14 % in both children and adults.  Factors that predicted mortality (independently) were sepsis and GCS < 9 , not location, deficits, organism or need for surgery. (Tattevin et al., 2003, AM J MED).
2.  Resolution of ring enhancing MRI is longer than the six weeks needed to treat the abscess with intravenous antibiotics.
3.  The purpose of surgery is to treat mass effect.
4.  Do not treat mycotic aneurysms (or worry excessively about them) until 4-6 weeks of treatment has already occurred. 
5. Steroids can reduce antibiotic penetration through the blood brain barrier and are not proven in abscess.
6.  Risk factors for abscess 1.7 % for acute or chronic sinusitis (esp ethmoid or sphenoid), 1-2 % for HIV, 4 % for stem cell or bone marrow transplant,  2.1 % of cyanotic heart disease, and 3.1-37.5 for pulmonary AVM's (worse with multiple AVMS's). 
7.  Otitis is more common in young males as a cause.
8.  The most common cause is headache in 70-80 % and less than half have HA, fever and focal deficit.  Less than half have pappilledema.  Nausea, vomiting, pappilledema are more common in otogenic with symptoms in posterior fossa and of increased intracranial pressure.
9.  Sed rate and blood cultures may be positive in less than 20 % and especially if bacterial endocarditis is present.
10. Factors on imaging favoring abscess over tumor (metastasis) include a more regular rim, homogenous enhancement, a thinner wall towards the ventricular surface, daughter satellite lesions and RESTRICTED DIFFUSION ON DIFFUSION WEIGHTED SEQUENCES  all favor abscess. 
11.  Do a TEE to look for paradoxical abscess and PFO in patients with a cryptogenic abscess. 
12.  Therapy suggestions:
Immunocompromised with lobar pneumonia, TMP-SMX; antifungals if bug not identified.
Frontal  (sinus, odontogenic)-- aer/anaer-- PCN + Flagyl or 3rd gen ceph + Flagyl
Temporal (Otogenic) - Str, Entero, Bacter.-- PCN + Flagyl + 3rd gen ceph.
Metastatic/ hematogenous-- nafcillin, Flagyl, cefotaxime
Penetrating trauma/ postop--Steph, enterob, pse.-- vancomycin + ceftazadime

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