Source / episode info
- **Episode:**307
- **Title:**Divine Intervention Episode 307 – USMLE Step 2CK Rapid Review Series 55.
- **Published:**2021-04-19
- Source:Episode page
One-liner
This episode provides high-yield rapid reviews covering the differentiation of hyperbilirubinemia causes (overproduction vs. enzyme defect), critical physiological changes in VSD gradients postnatally, management pitfalls like opioid-induced GI dysfunction, and complex neuroanatomy/neurology topics including hydrocephalus localization, superior colliculus function, and subacute combined degeneration of the spinal cord.
High-yield summary
- Hyperbilirubinemia: In enzyme defects (e.g., Gilbert syndrome), direct bilirubin is very low or absent, while indirect bilirubin is highly elevated. In overproduction states (hemolysis), both indirect and direct bilirubin are elevated, but Indirect > Direct.
- VSD Gradient: Fetal life: Right heart pressure > Left heart pressure (Right-to-Left shunt). Postnatal life: Pulmonary vessels dilate, L side pressure > R side pressure (Left-to-Right shunt).
- Subacute Combined Degeneration (SCD): Characterized by combined degeneration of the spinal cord affecting both the lateral corticospinal tract and the dorsal column/medial lemniscus pathway; classically associated with Vitamin B12 deficiency.
- Hydrocephalus Localization: Obstruction at the cerebral aqueduct of Sylvius causes enlargement of the lateral and third ventricles, but spares the fourth ventricle.
- NSAIDs in Pregnancy: Use of NSAIDs (especially after 20 weeks gestation) is contraindicated due to decreased prostaglandin production, which can lead to premature closure of the ductus arteriosus.
- Superior Colliculus: This structure serves as the vertical conjugate gaze center; compression or infarction leads to paralysis of upward gaze.
Learning objectives
- Differentiate between causes of indirect hyperbilirubinemia based on direct vs. indirect bilirubin levels.
- Explain the physiological shift in cardiac pressures that dictates VSD murmur intensity from fetal life to postnatal life.
- Recognize the clinical triad (ataxia, UMN signs, sensory loss) associated with Subacute Combined Degeneration and its underlying cause (B12 deficiency).
- Identify the anatomical location of obstruction when interpreting ventriculomegaly patterns in hydrocephalus.
- State the contraindications for NSAID use during pregnancy, particularly after 20 weeks gestation.