Cerebral Toxoplasmosis, Neurocysticercosis and Parasitic Meningoencephalitis

by Carlo Raj, MD

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    00:01 So let’s talk about that one parasitic known as cerebral toxoplasmosis.

    00:06 First and foremost, who's your patient? A greater importance once again in AIDS epidemic unfortunately and the organism, gondii, Toxoplasma gondii, is one of the most common causes of neurologic symptoms in AIDS patients.

    00:25 What is CT or MRI going to show you? You should know a list of differentials that will give you ring-enhanced lesions.

    00:37 We’ll talk about brain abscess coming up.

    00:39 Toxoplasma will give you ring-enhanced lesion.

    00:43 What does that mean? I’ll show you a picture later, whereupon CT, you find this ring around the brain parenchyma.

    00:51 You could have toxoplasma.

    00:53 It could be brain abscess.

    00:55 Later on, we’ll talk about gliobastoma multiforme, but that is a heterogeneous type of ring-enhanced lesion.

    01:02 At this point, we’ll go with the basics.

    01:05 Ring-enhanced lesion is a very important point or description or finding for further differentials and pathology.

    01:12 A similar findings with CNS lymphoma, tuberculosis, or fungal infection.

    01:17 Toxo.

    01:19 There is a trial of toxo therapy if necessary.

    01:21 Toxo is the most common cause of cerebral mass lesion in patients with AIDS.

    01:27 So as soon as you hear about AIDS and you see a ring-enhanced lesion upon imaging, you should be thinking about toxo.

    01:35 If you take a look at this particular imaging, what do you find? A ring-enhanced lesion.

    01:42 You find a ring-enhanced lesion such as this apart from toxoplasmosis.

    01:47 You should be thinking about abscess formation.

    01:49 You see that, right there? Perfectly, perfectly ring-like structure.

    01:55 If this patient has a CD4 count less than 50 and AIDS, in fact, has unfortunately settled in, most likely toxoplasmosis.

    02:06 In laboratory workup, what are you going to do? CSF findings, if negative, a trial of therapy may still be attempted though.

    02:14 Okay. So once again, can send serum and CSF serology, but if negative, still if you know your patient has AIDS, you still do empiric type of therapy.

    02:26 Treatment, avoid steroids.

    02:28 It actually hampers differential diagnosis.

    02:31 Your pyrimethamine, sulfadiazine or folinic acid.

    02:35 Life-long maintenance is required here if patient most likely immunocompromised.

    02:43 Another type of parasitic infection here, apart from toxoplasmosis, would be neurocysticercosis.

    02:50 This is a tapeworm and this is your soul pig.

    02:54 "I’m sorry what?" Take a look Taenia solium and think of this pig, pork is what you should be thinking, right? And I’ll go ahead and call this soul pig if that helps you.

    03:05 There are different types of Taenia.

    03:07 At least know solium, please.

    03:09 The most common parasitic infection of the CNS worldwide.

    03:13 Look at this, not necessarily, immunocompromised really for the first time in a long time.

    03:20 We talked about Cryptococcus, meningoencephalitis and that was immunocompromised.

    03:24 We did toxoplasmosis.

    03:26 That patient was immunocompromised.

    03:28 Here, we have neurocysticercosis.

    03:31 Most common parasitic infection of CNS worldwide.

    03:34 Notice, we do not have an immunocompromised patient.

    03:38 Are we clear? Endemic in Mexico and Central America.

    03:43 Brain involvement in 50-70% of your cases.

    03:47 Let’s talk about the clinical presentation of neurocysticercosis.

    03:51 I’m going to bring in a couple of integration points here.

    03:55 Seizures.

    03:58 Headaches due to increased intracranial pressure.

    04:00 So worldwide, most common parasitic CNS infection, right? And your patient is exposed to what organism? Taenia solium.

    04:12 And what was I being silly about? Pork.

    04:17 What’s interesting is that you might then form -- Take a look at the middle portion of this name.

    04:23 Neuro-, cyst-, -cercosis.

    04:28 What if this cyst ruptures in the brain? Now, what do we call this technically? Good.

    04:35 Whenever you have a cyst that ruptures, you call this separately “chemical meningitis”.

    04:42 Is that clear? The last time we saw a cyst that were rupturing is when we talked about dermoid tumor or for that matter any type of cyst that may rupture.

    04:52 Here, exactly the same thing.

    04:55 With neurocysticercosis, here is an imaging and an arrow particularly pointing to that cyst-like structure.

    05:03 "Dr. Raj, how can I tell that this is a cyst and not a ring-like structure?" This is not a ring-enhancing lesion.

    05:10 Why? If it was a ring-enhancing lesion, then in the middle of that ring, it would be more transparent, right? But here, it’s a cyst.

    05:18 So the entire darn thing, it looks like a ball, right? It looks like a ball that is a cyst in the brain.

    05:25 Be careful of abscess.

    05:29 If it’s an abscess, it will be a ring-enhanced lesion.

    05:32 This is not a ring-enhancing lesion.

    05:35 Is that clear? The imaging studies and that information which is being given to you should speak volumes in terms of making sure that you’re going down the right track of differentials.

    05:47 With neuroimaging, I want you to be really careful with this statement.

    05:52 Now, the ring-enhancing cystic lesion, we've had an active cyst, remember in the middle, you’re going to be completely, well for the most part, it would be filled with fluid, it could be a cyst.

    06:06 The parenchymal calcification, you have an older cyst.

    06:09 And you have vasogenic edema.

    06:10 Now, this is quite interesting here and you want to pay attention in the detail here.

    06:15 Why do you want to know so much detail about this? Because it is the most common parasitic CNS infection worldwide, okay? And you don’t have to be immunocompromised.

    06:25 So, if it’s an active lesion and there is a cyst, granted maybe it’s ring enhancing, okay? But more commonly, the presentation, the picture that I gave you earlier, that imaging study, if you took a look at the middle, it wasn’t transparent, right? It was not lucent.

    06:43 And so therefore, it was calcified.

    06:45 Most commonly, that is a presentation that you might be given.

    06:48 But just to be technical, yes, it could be ring-enhanced if it’s an active cyst.

    06:54 But usually by the time the patient is going to present, you’re going to find that the cyst has now become calcified, which means that you have a very, very opaque structure.

    07:03 Is that clear? And finally, a type of edema will be vasogenic.

    07:08 What does that mean to you? It means that this is an inflammatory process.

    07:12 And if it’s an inflammatory process, vasodilation, and you then will have release of fluid or escape of fluid from your blood vessel resulting in what’s known as vasogenic edema.

    07:25 In the cerebrospinal fluid, usually normal and may show mononuclear pleocytosis, maybe mild increase in protein, but there is enough information here without CSF analysis to know that you’re dealing with neurocysticercosis.

    07:43 Treatment: Seizures with antiepileptics: That is important.

    07:47 What does this seizure mean to you? Well, obviously, you have a patient that is going into all kinds of jerky movements, but the seizure means to you that there might be a space-occupying lesion in the brain.

    07:58 What do you think a cyst is? A space-occupying lesion, may then result in seizures.

    08:04 You’ll have albendazole to kill the parasite and steroid to maybe control the inflammation.

    About the Lecture

    The lecture Cerebral Toxoplasmosis, Neurocysticercosis and Parasitic Meningoencephalitis by Carlo Raj, MD is from the course CNS Infection—Clinical Neurology. It contains the following chapters:

    • Cerebral Toxoplasmosis
    • Neurocysticercosis
    • Parasitic Meningoencephalitis

    Included Quiz Questions

    1. Intracerebral hemorrhage
    2. Brain abscess
    3. Cerebral toxoplasmosis
    4. Glioblastoma multiforme
    5. CNS lymphoma
    1. Trial of toxo therapy
    2. Trial of steroids
    3. Trial of antibiotics
    4. Trial of INH
    5. Trial of rifampicin
    1. Toxoplasma gondii
    2. Histoplasmosis
    3. Tuberculosis
    4. Treponema pallidum
    5. Cryptococcus
    1. Taenia solium
    2. Toxoplasma gondii
    3. Histoplasma capsulatum
    4. Cryptococcus neoformans
    5. Ascaris lumbricoides
    1. Inhalation of spores from pigeon excreta
    2. Hydrocephalus due to rupture of intraventricular cyst
    3. Chemical meningitis due to rupture of intraventricular cyst
    4. Old cysts due to parenchymal calcification
    5. Mild mononuclear pleocytosis on CSF
    1. Toxoplasmosis gondii
    2. Cryptococcus neoformans
    3. Taenia solium
    4. Histoplasma capsulatum
    5. Ascaris lumbricoides

    Author of lecture Cerebral Toxoplasmosis, Neurocysticercosis and Parasitic Meningoencephalitis

     Carlo Raj, MD

    Carlo Raj, MD

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