00:00
In this lecture, we're going to talk about other types of CNS infections and in particular
opportunistic and exposure-related CNS infections. So let's start with a case. A 58-year-old
woman with headache. This is a 58-year-old Black woman with a past medical history of lupus
who has been managed for over 10 years with multiple immunosuppressing agents;
hydroxychloroquine, mycophenolate, and prednisone requiring prednisone doses up to 40 mg
per day and we think of prednisone doses over 20 mg being immunosuppressive. She presents
with a 1.5-week history of headache, confusion, and episodes of strange stereotypic spells
that could be seizures. And lo and behold this culminated in a generalized tonic clonic seizure
for which she was admitted to the hospital. Examination shows that she is confused, but is
conversant. She has no focal neurologic deficits. And CSF analysis is performed showing
increased white blood cells (pleocytosis), elevated proteins, secondary inflammation, and low
glucose suggesting that if this is an infection, this is a fungal process. The CSF is also tested
for the cryptococcal antigen, evidence of a cryptococcal infection and is elevated with a titer
of 1 and 64. So what's the diagnosis? Well, there are some really important features of this
case that we should key in on. The first is this is a patient who is immunocompromised. She
has been on multiple immunosuppressing medicines for over 10 years which could affect
her immune system's ability to prevent those atypical or rare causes of meningitis,
encephalitis, and cerebritis or brain abscess. The second is there is evidence of cortical
dysfunction. Not a focal deficit. Her exam does not have any focal deficits, but a generalized
brain process with this generalized tonic clonic seizure suggesting an encephalitis or
meningoencephalitis. And the last is the CSF analysis and this is a classic signature for a
fungal encephalitis and even more important we see evidence of cryptococcal antigen
positivity suggesting a possible cryptococcal infection. The patient had imaging to further
evaluate what may be going on and here we're looking at the axial on the left and the coronal
post contrast T1 gadolinium enhanced images. And what we see is very subtle. The brain
in general looks normal, but in the folia of the cerebellum, those potential spaces in between
the gyri of the cerebellum in the sulci, we see enhancement, extra white, extra gadolinium
contrast there indicating that something is in the spinal fluid. And here, this is evidence of a
cryptococcal infection and suggestive of a cryptococcal meningoencephalitis. So what is the
diagnosis? Is this cryptococcus, toxoplasmosis, neurocysticercosis, or a brain abscess?
And as we've discussed, toxoplasmosis has a predilection for the basal ganglia. This doesn't
seem like toxoplasmosis. Neurocysticercosis can be seen in immunocompromised patients
but is more common in patients who have travelled to areas where neurocysticercosis is
endemic and we don't get that history here. We don't see evidence of a brain abscess, there
is not a focal finding on exam and the evidence on imaging doesn't suggest a focal brain
infection. And so this is a classic presentation of cryptococcal meningitis or cryptococcal
meningoencephalitis. The CSF analysis suggests a fungal infection and the positive
cryptococcal antigen establishes the diagnosis. So in this lecture, we're going to talk about
3 types of opportunistic or exposure-related CNS infections. There are many, more than just
the 3 we'll discuss but these 3 are particularly common, we see them in patients or tested in
clinical vignettes. So I'd like you to understand how to apply what we learn with each of these
3 organisms to any opportunistic or exposure related infection in the brain. As you can see
here, there are a variety of these opportunistic infections that if primarily been described
in AIDS patients, but increasingly we see them in patients on immunocompromising or
immuno-active medications. We also need to think about exposure associated infections.
04:35
Infections that occur in certain types of the world and certain areas over the country and in
patients who have travelled to those areas. Today, we're going to talk about cryptococcus,
toxoplasmosis, and neurocysticercosis.