aka Ophthalmology Befuddler 017
On examining a patient’s eyes you note that the pupils are small, irregular, non-reactive to light and constrict when focused on a near object.
Questions
Q1. What is the name of this abnormality?
Argyll Robertson pupils
Q2. What does this abnormality have in common with prostitutes?
“They both accommodate, but don’t react”, and both are associated with neurosyphilis.
You may have remembered the answer from an old Funtabulously Frivolous Friday Five question. It may be politically incorrect, but it sure helps remember the key facts about Argyll Robertson pupils.
Q3. What are the features of this abnormality?
- small, irregular, unequal pupils
- near-light dissociation (brisk accommodation but no light reaction)
These features are demonstrated in this classic video:
Q4. What other causes of near-light dissociation are there?
Near-light dissociation is generally a feature of midbrain lesions that somehow affect iridodilator nerve fibers. the causes include:
- syphilis (true Argyll Robertson pupils — the precise anatomic lesion is poorly understood)
- diabetes mellitus
- alcoholic midbrain degeneration (rare)
- other midbrain lesions, e.g. sarcoidosis, encephalitis, Parinaud syndrome
- abnormal regeneration of the oculomotor (CN3) nerve
- tonic phase of the Holmes-Adie pupil
Sometimes the non-syphilitic pupillary abnormalities are called pseudo-Argyll Robertson pupils.
Q5. How did this ocular abnormality get its name?
Douglas Moray Cooper Lamb Argyll Robertson (1837-1909) was a Scottish ophthalmologist. He was the first to describe his eponymous pupillary abnormality among patients with tabes dorsalis.
Argyll Robertson was also the first to demonstrate the cholinergic ocular effects of an extract from the Calabar bean, the drug physostigmine. Later he was consulted by a patient who lived in ‘Old Calabar’ (in modern day Nigeria) about the ‘Calabar swellings’ that affected her eyes. He extracted filiarial Loa loa worms from these lumps and was thus one of the first to describe ocular loasis.
Q6. What is Parinaud syndrome?
Parinaus syndrome is also called dorsal midbrain syndrome, it is another cause of near-light dissociation.
Parinaud syndrome is characterised by the following features:
- vertical gaze palsy
- near-light dissociation
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 CVA
- other causes including: toxoplasmosis of the brainstem, hydrocephalus, trauma, midbrain hemorrhage, and arteriovenous malformations
References
- Bhidayasiri R, Waters MF, Giza CC. Neurological differential diagnosis: a prioritized approach, Blackwell Publishing 2005.
- Gupta A, Kedha S. Images in Clinical Medicine: Eye Worm. N Engl J Med 2005; 353:e22 [free online]
- Patten J. Neurological differential diagnosis (2nd edition), Springer-Verlag 1996.
About Chris Nickson
