Flippin’ ‘eck it’s Friday again!
Let’s make it funtabulous with five fantastic frivolous facts…
(This edition will be easy if you’re an assiduous LITFL and TPR reader)
Q1. Why might a patient with an isolated radial nerve palsy also appear to have an ulnar nerve palsy on examination of the hand?
- A patient with a radial nerve palsy cannot extend at the MCP joints. It is difficult to abduct the fingers with the metacarpophalangeal joints (MCPJs) in flexion.
- With the MCPJs in flexion, the dorsal interossei (innervated by the ulnar nerve) are ineffective at abducting the fingers.
- Test it on yourself — try abducting your fingers (moving them apart) when your MCPJs are extended (fingers straight at the knuckles) and when the MCPJs are flexed (fingers bent 90 degrees at the knuckles).
Q2. What is Parinaud syndrome?
- Parinaud syndrome is also called dorsal midbrain syndrome.
- It is characterized by vertical gaze palsy (can’t look up) and near-light dissociation (pseudo-Argyll Robertson pupils: the pupils show brisk accommodation but no reaction to light)
- It results from direct or compressive injury to the dorsal midbrain, affecting regions such as the superior colliculus adjacent to the oculomotor (CN3) and Edinger-Westphal nuclei (see diagram here).
- Causes of Parinaud syndrome include: neoplasms (especially pinealomas), multiple sclerosis, brainstem strokes, and other causes including: toxoplasmosis of the brainstem, hydrocephalus, trauma, midbrain hemorrhage, and arteriovenous malformations.
- You might have remembered this one from Ophthalmology Befuddler 017 — Pupils and Prostitutes.
Q3. What toxic substance might causes a patient to ‘internally combust’?
- Aluminium phosphide
- When this agent, widely used as a pesticide in Asia, contacts stomach acid, small amounts of diphosphine are formed. This gas can burn spontaneously in contact with air.
- Learn more from Leon Gussow’s Poison Review post: What toxin causes a patient to spontaneously combust?
Q4. Do redheads bleed more than ‘non-redheads’?
- Probably not.
- Red-heads are often (according to some members of the anesthetic and surgical professions) said to be more likely to bleed perioperatively that patients with hair of other colours. There is no good evidence that this is the case (as detailed in Are Redheads Bleeders?)
- However, they may have higher anesthetic requirements due to a melanocortin-1 receptor mutation…
Q5. Who discovered that cocaine can be used to anethetise the urethra?
- Dr H. Knapp
- Knapp was an ophthalmologist who published some bizarre self-experiments on the uses of cocaine in 1884 — you can read more (and I suggest you do so!) at TPR: The Most Amazing Medical Article Ever Published.