Headache Answers 367337.The answer is b.(Tintinalli et al, pp 1389-1390.)The CT depicts sub-
arachnoid arachnoid blood. This patient may have had a sentinel bleed, a
small SAH, the previous week. Noncontrast CT misses a small percentage
of SAH and therefore, in cases of high suspicion, an LP must be obtained to
exclude the diagnosis.
Irritation of the meninges or inflammation of the brain (a)may not
appear at all on noncontrast CT of the brain. If contrast is used, meningeal or
cerebral enhancement may be apparent, but diagnosis of these conditions is
not based on imaging. High clinical suspicion must be present for either con-
dition and LP is used to confirm the diagnosis. Hydrocephalus (c)appears as
dilated ventricles on CT scan. If all of the ventricles are patent and dilated, it
is termed communicating hydrocephalus. If part of the ventricular system is
collapsed and the others dilated, an obstructive cause of hydrocephalus is
present. Epidural hematomas (d)are the result of brisk arterial bleeds into
the space between the dura and the calvarium. They are classically caused by
trauma and are associated with a “lucid period” during which level of con-
sciousness is normal prior to neurologic deterioration. On noncontrast CT,
they appear as hyperdense intracranial collections of blood that are bilentic-
ular in shape. Subdural hematomas (SDH) (e)are intracranial blood collec-
tions that result from tearing of the bridging veins between the dura and the
brain. Risk factors for SDH include advanced age and chronic alcohol use.
Both conditions are associated with decreased brain volume and provide
stretch on these delicate veins. On noncontrast CT, SDHs appear as crescent
shaped collections of hyperdense blood.
338.The answer is b.(Tintinalli et al, pp 1434-1435.)The CSF analysis in
this patient is consistent with a viral or atypical cause of meningitis.
Although patients may have a mononuclear predominance and still have
bacterial meningitis, viral causes should be considered. CSF should be sent
for PCR analysis and empiric treatment initiated for herpes encephalitis.
The mortality of meningoencephalitis caused by herpes simplex virus
(HSV) is exceptionally high if untreated.
Tuberculosis (TB) meningitis (a)should be considered in this undomi-
ciled patient. Other risk factors for TB include immunocompromise and
living in an endemic region. However, the patient is recently PPD and chest
x-ray negative, making this possibility less likely. In an immunocompromised
patient PPD may be less reliable so a CSF acid fast stain and mycobacterial cul-
ture should still be sent. Fungal causes (c)of CNS pathology are also a