Neurologic Infections

Supratentorial neurosurgical infections. One is abscess, the second is epidural empyema, and subdural empyema, which statistically is not as common. Whenever you have infection in the supratentorial compartment hitting one side of the brain, always remember Herpes simplex encephalitis as the differential diagnosis. Because the symptoms and signs can be pretty similar. What are they? Focal cerebral signs, hemiplegia, focal seizures, field defects, aphasia, plus fever. Now the weakness, if you have a stroke, tends to be very severe and more abrupt. But if you are dealing with infections, the tempo is a little bit slow, the weakness is not like stroke. Grade IV, maybe grade III, mild or moderate.

Brain abscess. Look for local source of infection; ear, tooth, maybe skin, maybe trauma, maybe systemic. May be endocarditis, maybe IV drug use. If you look at the abscess pathologically or with MRI the pinnar surface is close to the ventricle. You need to remember that. So it kind of ruptures easily into the ventricle. Remember the wall is thinner on the ventricular side. What are the bugs? A whole bunch of them. Very often it’s more than one. Now for exam purposes let me just point out a couple here. If you have local trauma, staphylococcus is the common offending bacteria. In the neonate all these can cause brain abscess. Treatment; if the abscess is small, many books talk about less than 3 cm diameter, antibiotics for 2-3 months is probably enough. If the abscess is big – obviously even those small abscesses you need to follow with MRI or at least CT. Here’s the list of antibiotics for you. Now if the abscess is big, antibiotics and aspiration. So pretty straightforward kind of stuff. The factors that affect the prognosis; size, larger the abscess the worse the outcome, and then when you get them. If the patient is already comatose before treatment is started, prognosis is worse. Of course if their abscess has already ruptured, pretty difficult. If you have ventriculitis, a lot of those people just don’t make it.

If you have pus collection in the meninges, epidural or subdural, these people on the whole tend to be a little younger and seizures are more common. Seizures, in fact in my experience, are almost universal – if you are dealing with empyema – because they get a lot of cortico-thrombophlebitis so you have more irritation of the gray matter, so seizures are more common. Meningeal signs are more common in epidural as well as subdural. The treatment principles are the same. Remove the pus, antibiotics, watch with MRI.

Leave a Reply

Your email address will not be published. Required fields are marked *