Source / episode info
- **Episode:**405
- **Title:**Divine Intervention Episode 405 – USMLE Step 2/3 Rapid Review Series 80
- **Published:**2022-07-28
- Source:Episode page
One-liner
This episode provides a rapid review of key board topics including Normal Pressure Hydrocephalus (NPH) vs. Idiopathic Intracranial Hypertension (IIH), the mechanisms and electrolyte disturbances associated with carbonic anhydrase inhibitors in RTA, the workup of Von Hippel-Lindau Syndrome (VHL), and critical guidelines for solid tumor biopsy.
High-yield summary
- Normal Pressure Hydrocephalus (NPH): Characterized by the triad of wacky (dementia/cognitive decline), wet (urinary incontinence), and wobbly (gait ataxia). Crucially, CSF opening pressures are normal, indicating impaired CSF absorption at the arachnoid granulations.
- Idiopathic Intracranial Hypertension (IIH) / Pseudotumor Cerebri: Presents with symptoms of increased ICP (headache, papilledema). Lumbar puncture reveals elevated CSF opening pressures (>200 mm H₂O), but normal neuroimaging. Treatment involves serial lumbar punctures or acetazolamide.
- Acetazolamide (CAI): Inhibits carbonic anhydrase in the proximal tubule, causing massive bicarbonate wasting and a resulting metabolic acidosis. The subsequent volume depletion activates RAAS, leading to hypokalemia.
- VHL Syndrome: An autosomal dominant disorder caused by VHL gene deletion on chromosome 3. It predisposes patients to bilateral renal cell carcinomas (RCC), hemangioblastomas in the cerebellum (which contain calcifications and produce EPO), and polycythemia.
- Solid Tumor Biopsy Rule: Do NOT biopsy Testicular, Ovarian, Renal, or Adrenal masses/cancers; instead, perform a complete excision (e.g., nephrectomy).
Learning objectives
- Differentiate the pathophysiology and diagnostic findings between Normal Pressure Hydrocephalus (NPH) and Idiopathic Intracranial Hypertension (IIH).
- Understand the mechanism of action and associated electrolyte abnormalities caused by carbonic anhydrase inhibitors.
- Recognize the clinical presentation, genetic basis (VHL gene), and common complications of Von Hippel-Lindau Syndrome.
- Apply critical guidelines regarding the management of solid abdominal/pelvic malignancies (Testicular, Ovarian, Renal, Adrenal).
- Master the initial emergency management steps for acutely elevated intracranial pressure (ICP).
Board exam buzzwords