CNS Infections | Clinical Medicine

Premium Member Resources: https://ninjanerd.org Ninja Nerds! In this lecture, Professor Zach Murphy will present on CNS Infections. We will begin by establishing a clear framework for localizing infection within the central nervous system, then rapidly narrowing the differential based on timing, immune status, and key clinical clues that distinguish meningitis, encephalitis, and focal intracranial infections. We will begin with acute meningitis, focusing on how meningeal inflammation produces fever, headache, neck stiffness, and altered mental status, and how to use bedside findings and initial laboratory results to determine when to initiate immediate empiric antibiotics. We will walk through the diagnostic approach with lumbar puncture and CSF interpretation, including patterns for bacterial, viral, fungal, and tuberculous meningitis, and how to recognize situations where brain imaging is needed before LP. We will also review common organisms by age and risk factors, as well as the role of adjunctive dexamethasone in select cases. Next, we will cover encephalitis, emphasizing the difference between meningeal irritation and true parenchymal brain involvement. We will connect clinical findings like seizures, focal deficits, and behavioral changes to the underlying pathophysiology and highlight high-yield etiologies such as HSV encephalitis. We will also review the key studies that support diagnosis, including CSF testing and neuroimaging patterns, and the time-sensitive decision to start acyclovir when encephalitis is suspected. From there, we will transition to focal CNS infections such as brain abscess, reviewing how contiguous spread, hematogenous seeding, and predisposing conditions shape the presentation. We will focus on warning signs, such as focal neurologic deficits and signs of increased intracranial pressure, as well as imaging findings that guide management, including when neurosurgical drainage is indicated in conjunction with targeted antimicrobial therapy. Finally, we will pull everything together into a practical step-by-step algorithm for boards and clinical practice, covering stabilization, isolation considerations when indicated, empiric therapy selection, and the complications you cannot miss, including cerebral edema, herniation risk, seizures, hydrocephalus, and long-term neurologic injury. Enjoy the lecture and support us below! Table of Contents: 0:00 Lab 0:51 Pathophysiology of CNS Infections 35:32 Causes of CNS Infections 1:36:06 Classic Findings of CNS Infections 1:52:57 Complications of CNS Infections 2:43:08 Diagnostic Approach to CNS Infections 3:16:26 Treatment of CNS Infections 3:44:10 Comment, Like, SUBSCRIBE! 🌐 Official Links Website: https://www.ninjanerd.org Podcast: https://podcast.ninjanerd.org Store: https://merch.ninjanerd.org 📱 Social Media   / ninjanerdlectures     / ninjanerdlectures     / ninjanerdlectures   https://x.com/ninjanerdsci/   / ninja-nerd   💬 Join Our Community Discord:   / discord   #ninjanerd #infectiousdisease #cnsinfections