Neurology | Brain Abscess

0:00Hi, everyone. Welcome back to the Med Bullets Step 2 and 3 podcast. In today's episode, we covered the topic of brain abscess found under the neurology section, medbullets.com. Let's begin with a clinical snapshot. A 59-year-old man presents to the emergency department with a headache. He has never had headaches in the past and reports his headache worsens with cough. He describes his headaches as severe and located on the right side of his head. His headaches are unresponsive to over-the-counter analgesics. Physical exam is notable for four minus out of five power in the left-sided upper extremity. An MRI brain with contrast demonstrates a ring-enhancing lesion in the right primary motor cortex. Neurosurgery has been consulted for removal of the mass in order to time empiric antibiotic administration. Let's continue with an introduction to brain abscess. This is defined as a focal, purulent collection in the brain perincoma.

1:00Risk factors include infection of contiguous structures, such as otitis media, dental infection, mastoiditis, and sinusitis. Other risk factors include skull trauma or surgery, such as a ventricular peritoneal shunt, endocarditis leading to hematogenous spread, and an immunocompromised state. In terms of etiology, pathogens include streptococcus most commonly, stafloococcus aureus, and epidermidis, and gram-negative enteric organisms. Also remember that infections are often polymicrobial. In terms of the pathophysiology, there is an immune-mediated response to the microbial pathogen. Moving on to the presentation, symptoms will often include headache, which is the main chief complaint. On exam, one may note a fever, though this is not a reliable clinical indicator. There may be focal neurological deficits, such as extremity weakness, and one may note seizures. In terms of further imaging, MRI brain with contrast is indicated as the imaging study of choice

2:05in patients in which there is a strong suspicion for a brain abscess. Remember that a CT head with contrast can also be used. Findings may include a round-like encapsulated mass with central necrosis and surrounding edema. Remember that the differential diagnosis for a ring-enhancing lesion can be remembered with the mnemonic magic doctor. This stands for metastasis, abscess, glioblastoma, infarct and inflammatory, such as neuro-systems or cosis, and tuberculoma, contusion, demyelinating disease, and radiation necrosis, are resolving hematoma. When making the diagnosis, remember that this can be suggested based on neuro-imaging, but is confirmed with surgical removal in histopathology. In terms of the differential, make sure to think about neuro-systems or cosis. Also think about glioblastoma. Differen shading factors for glioblastoma include that biopsy results will demonstrate cellular polymorphism and microvascular proliferation with the central area of necrosis.

3:08In terms of treatment, medical options include empiric antibiotics. This is indicated as a component of the mainstay of treatment for brain abscess. Specific medications include sub-triaxone or cephotaxime with metronidazole. Vancomycin can be considered if the patient is at risk of developing staphlocaxine infection, such as from a recent brain surgery. Operative options include neurosurgical removal. This is indicated as a component of the mainstay of treatment for brain abscess. Remember that the approach may involve stereotactic neurosurgical aspiration, or surgical excision, but this is less commonly used. And lastly, complications related to brain abscess include seizures, brain herniation, ventriculitis secondary to abscess rupture and seeding in the ventricles, and meningitis. Now that we've discussed the major points relating to brain abscess, let's walk through a question to apply what we've learned and get a sense of how the topic might be tested. For this question, consider the following clinical scenario. A 37-year-old Mexican man

4:13presents to his neurologist for new onset seizures. The patient began having seizures one week ago, just prior to when he immigrated to the United States. The patient otherwise has a past medical history of two emergency department admissions for substance detoxification. His current medications include ginkgo baloba. His temperature is 99.5 degrees Fahrenheit, or 37.5 degrees Celsius. Blood pressure is 160 over 105. Pulse is 90 beats per minute, respirations are 15 breaths per minute, and oxygen saturation is 98% on room air. On physical exam, you note an obese man who appears to be in no distress. Cardiopominary exam is within normal limits. Neurological exam reveals cranial nerves 2 through 12 as grossly intact, with 5 out of 5 strength in the upper and lower extremities. That patient's gate is stable, and his rhomburg sign is negative. An MRI of the brain is performed, which demonstrates

5:17multiple cysts. Which of the following is the next best step in management? In the answer choices are, choice one, safe triaxone, and vancomycin. Choice two, neurosurgical evacuation and excision. Choice three, lorazapam. Choice four, albendazole, or choice five, detoxification. The best answer to this question is, choice four, albendazole. This patient is presenting with new onset seizures in the setting of a head MRI demonstrating multiple fluid-filled cysts, suggesting a diagnosis of neurosistocercosis. The best treatment for this pathology is albendazole or prizee-quantle. Neurosistocercosis typically occurs in patients who have eaten undercooked meat, typically pork, infected liteniasolium. Suspect this diagnosis in patients who have new onset neurological symptoms, such as seizures, who have been exposed to questionable meat,

6:22or come from a background that could involve poor sanitation or preparation of food, such as immigrants from developing countries. Imaging of the head will demonstrate cysts throughout the brain. Treatment should be started with albendazole and prizee-quantle. Let's also discuss whether their choices are incorrect. Choice one, safe triaxone and vancomycin are appropriate initial antibiotics for bacterial meningitis, which presents with fever, photophobia, and neck stiffness or pain. Choice two, neurosurgical evacuation and excision would not be appropriate management. The cystic lesions are occurring secondary to an infectious process. Choice three, lorazapam is an appropriate initial therapy for patients having seizures, such as from alcohol withdrawal seizures. Choice five, detoxification is appropriate management if this patient is presenting with acute intoxication. However, his seizures are more likely due to neurosurcosis based on his MRI. Finally, a bullet summary. Neurosurcosis should

7:26be treated with albendazole or prizee-quantle. That's all for this review about brain abscess. We hope that was helpful. This is the Med Bullets Step Two and Three Podcast, a daily audio review session for Med Bullets, the free learning and collaboration community for medical student education. As a reminder, you can follow along with these podcast episodes by reviewing the topics directly on medbullets.com. You can listen to these episodes on the Med Bullets website or phone app while reading through the topic. If the Med Bullets podcast has been valuable to you, we'd be thrilled if you consider leaving us a five-star rating and writing us a review on Apple Podcasts. It will help us spread the word and increase our discoverability tremendously. Thanks for tuning in. We'll see you out tomorrow, right here on the Med Bullets Step Two and Three Podcast.