PART 4 — MENINGES

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Study use: Rapid revision of meningeal anatomy, meningitis, lumbar puncture, intracranial hemorrhage, subarachnoid hemorrhage, and meningioma. Emergency-management points are intentionally concise and should be interpreted with age, immune status, imaging, and clinical context.

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Priority Guide: 🔴 Core / Must Know | 🟠 Important | 🟡 Additional

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🎯 High-Yield Overview

• Meninges: dura → arachnoid → pia; subarachnoid space contains CSF and major cerebral vessels.
• Bacterial meningitis: neutrophilic CSF + high protein + low glucose; do not delay empiric antibiotics when LP or imaging is delayed.
• Meningococcal disease: petechial/purpuric rash; severe meningococcemia may cause Waterhouse–Friderichsen syndrome.
• Viral meningitis: lymphocytes + usually normal glucose; TB/fungal meningitis: lymphocytes + low glucose + high protein.
• Cryptococcal meningitis: immunocompromised patient + very high opening pressure + positive cryptococcal antigen.
• LP: commonly L3–L4 or L4–L5; defer when mass effect/herniation risk, severe bleeding risk, local infection, or severe instability makes the procedure unsafe.
• EDH: MMA + lucid interval + biconvex collection; SDH: bridging veins + crescentic collection.
• SAH: thunderclap headache → NCCT first; persistent suspicion after nondiagnostic CT may require LP for xanthochromia; secure aneurysm + nimodipine.
• Meningioma: arachnoid cap-cell tumor + dural tail + whorls/psammoma bodies + NF2 association.

1. MENINGEAL ANATOMY, SIGNS & LUMBAR PUNCTURE

2. ACUTE BACTERIAL MENINGITIS & MAJOR BACTERIAL PATHOGENS

3. VIRAL, TUBERCULOUS & CRYPTOCOCCAL MENINGITIS

4. EPIDURAL & SUBDURAL HEMATOMA

5. SUBARACHNOID HEMORRHAGE & ANEURYSM

6. MENINGIOMA

📊 “DON’T CONFUSE” TABLE — MENINGES