 Our next case is a 23-year-old with worsening headache, inguinal rash, and arthralgia. We're scrolling three sequences, an axial T1 contrast MR, an axial T2, and an axial flare. I'm going to pause on the relevant findings so that you can gaze at them and formulate your differential diagnosis. And as you do, now let's return to the questions. First question, the most likely diagnosis is A, Lyme disease, B, sarcoid, C, Ramsey-Hunt syndrome, D, Talusa-Hunt syndrome, E, Gradinigo's syndrome. Before I go on to the next question, spoiler alert. You're going to get the answer, so if you want to pause the educational program, I'd urge you to do so. But I'm going to move on. Question number two, which of the following regarding Lyme disease is false? A, Borrelia burgdoffi, spirochete, is the organism, a gram-negative bacterial flagellate. That's a lot of words. B, deer tick-borne disease in northeastern United States, Ohio, Tennessee Valley, and Rocky Mountains. C, presents as skin rash, erythema chronicum migrans, athralgias, meningitis, neuritis including cranial nerves, vasculitis and cardiac, the latter two occurring early. D, imaging signs include multifocal white matter lesions with or without enhancement, similar in appearance to MS or multiple sclerosis. E, likes the subcortical frontal white matter. Now, let's return to our images. As we scroll through them, the axial flare shows some nondescript, nonperiventricular and periventricular white matter lesions, which are not very specific at all. Cradial nerve enhancement is a feature of the diagnosis here, which is Lyme disease, but it occurs, unfortunately, in the minority of cases, but fortunate for the patient. When we look at the seventh and eighth nerve complexes and we blow them up, there's no enhancement of either seventh or eighth nerve complex. And occasionally, Lyme may even present with Bell's palsy syndrome or facial nerve paralysis. Let's go back to our questions and answer the questions and evaluate each choice. Let's begin with question number one. The most likely diagnosis is Lyme disease based on the imaging findings and the history. It's true that sarcoidosis could produce headaches, a rash, an arthralgia, but the rash in sarcoid is typically in the face, known as lupus perneo. So that wouldn't fit so well for sarcoid. Sarcoid can do anything. It could present with multiple white matter lesions, but typically you're gonna get some enhancement associated with sarcoid. Lyme disease, the enhancement is extremely variable, although when the cranial nerves are involved, they will enhance, but the white matter lesions typically don't enhance with any regularity. Ramsey Hunt syndrome is an infection caused by herpes zoster ophthalmicus, so it doesn't fit the history at all. You may see enhancing vesicles in the external auditory canal, but the typical findings of Ramsey Hunt should include enhancement of the seventh and eighth nerve pathway. You might even get cochlear enhancement. There are multiple cranial nerves involved. Often the clinical syndrome is far more severe at presentation than it is with Bell's palsy, but the external vesicles, both by history and on imaging are an important tip off to the diagnosis. You shouldn't confuse choice C Ramsey Hunt with Lyme disease. Tolusa Hunt, also known as granulomatous involvement of the cavernous sinus. There is no cavernous sinus disease here, so that wouldn't fit at all. That's a silly choice. And Grad Nigo syndrome, which is a form of apical petrocytis. The patients are extremely ill and the findings are associated with the anatomy that passes over the Petrus apex. We haven't shown you any abnormality of the Petrus apex or adjacent anatomy, so Grad Nigo is not a reasonable choice. The most logical choice with the history and amorphous nondescript imaging findings is Lyme disease. Question number two, which of the following regarding Lyme disease is false? And the answer, which you might find a little surprising is C. Lyme disease does present with a skin rash called erythema, chronicum migrans. It is typically an inguinal rash in the creases. They do have arthritis pretty early on. The neural findings come a bit later, including the cranial nerve enhancement. The vasculitis and cardiac findings come latest. Therefore, the statement, the latter two occurring early, namely neural and cardiac, is totally untrue. Those are findings that occur in the end game or chronically in Lyme disease. The other choices are true. Borrelia burgdorfy, a spirochete, is a gram negative bacterial flagellate. It is a deer tick-borne disease that is found in three major areas in the United States, the Ohio, Tennessee Valley, the Northeastern United States, Lyme being a small city or town in Connecticut and the Rocky Mountains. There are many other tick-borne infections that occur in the Rocky Mountains, one you are very familiar with, Rocky Mountains spotted fever. Then we have choice D. The imaging signs do include multifocal white matter lesions, which we have here. The enhancement is variable, similar in appearance to MS, but MS is a multifasic disease, waxing and waning. It has a predilection for the septiclosal region. Neither of those factors are compatible with Lyme disease. And finally, likes the subcortical frontal white matter is true and we did have innumerable frontal white matter lesions in this case. Let's move on to our next case since that concludes our discussion of Lyme disease. Shall we?