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)
Questions
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.
About Chris Nickson
Chris:
I recently realized another amazing thing about Knapp’s 1884 paper describing the anesthetic effects of cocaine on the urethra. His article starts:
“As soon as I had read the very remarkable communication on cocaine, by Dr. H.D. Noyes, in The Medical Record, October 11, 1884, p. 417, I procured specimens of the new remedy from different sources.”
The issue of The Medical Record in which Knapp’s article appears is October 25, 1884. That means that Knapp had read the original article, obtained specimens of cocaine, performed his self-experiments, written them up, and gotten his paper published over the course of TWO WEEKS! Even with the internet and world wide web today, research doesn’t move that fast. Really amazing.
BTW, I’ve described the article to two ophthalmologist friends, and they had both heard of Knapp. Apparently he was quite a well-known and historically important eye doctor in New York.
Great stuff Leon -
I wonder how many of the self-experiments he thought of before he started using the cocaine, and how many he thought of while under the influence?… and how much of his productivity over the 2 weeks was a side effect of his subject matter?
If the study was on benzo’s instead of cocaine I expect he would have been considerably less productive…
C