🎧MSRA Podcast:Argyll-Robertson Pupil – A Small Sign with Big Implications

In today’s DeepDive, we explore the Argyll-Robertson pupil– a classic and high-yield neurological sign that can unlock insight intoserious underlying conditions like neurosyphilis.

This is the “light-near dissociation” you absolutely needto know for the MSRA.

🧠What is theArgyll-Robertson Pupil?

• Bilateral, small, irregular pupils

• Do not react to light

• But constrict normally to accommodation (near focus)

• Classic for neurosyphilis, but also seen in otherneurological conditions

🧠Mnemonic: “ARP” =Accommodation Reflex Present, Pupillary Reflex Absent

🔍Key Causes to Know

• Tertiary syphilis (neurosyphilis) – most commoncause

• Diabeticneuropathy

• Midbrain lesions(e.g., Parinaud syndrome)

• Alcoholic midbraindegeneration

• Encephalitis

• Multiple sclerosis

• Pineal glandtumours

🔬Pathophysiology – WhyDoes This Happen?

• Damage to the pretectal area of the midbrain

• Disrupts light reflex pathway

• Accommodation reflex pathway is either sparedor takes an alternate route

• A brilliantclinical example of how localised neurologicaldamage can dissociate reflexes

🧪DifferentialDiagnoses

Don’t forget to ruleout:

• Adie’s (tonic) pupil

• Horner’s syndrome (with ptosis and anhidrosis)

• Opioid overdose (pinpoint pupils)

• Pharmacologic causes – e.g. miotic agents

📊Epidemiology

• Rare in the modern UK due to earlydiagnosis/treatment of syphilis

• Still important tospot in undiagnosed or inadequately treatedlate syphilis

• May be seen in global health contexts, or in patients with complex neurological presentations

🔎Clinical Features

• Bilateral, small, irregular pupils

• Poor or absentlight reflex

• Normalconstriction to near stimulus

• No direct visualcomplaint – diagnosis based on clinicalexamination

🧪Investigations

• Detailed eye exam including light and near reflex testing

• Syphilis serology: treponemal-specific andnon-specific tests

• Neuroimaging (MRI) if other midbrain pathologysuspected

• Consider CSF analysis if neurosyphilis is suspected

💉Management

• Treat the underlying cause, not the pupil abnormalityitself

• For neurosyphilis:

– IV high-dose penicillin G is the treatment ofchoice

– Monitor for Jarisch-Herxheimer reaction

• Addressco-existing neurological or infectious complications

📈Prognosis &Complications

• ARP itself causes no direct harm

• But underlyingneurosyphilis can lead to:

– General paresis

– Tabes dorsalis

– Cognitiveimpairment

– Vision and hearingloss

• Early detectionand treatment improve outcomes

🧠Quick Summary – Whatto Remember

• ARP = small, irregular pupils, poor light response,good near response

• Strongly associated with neurosyphilis

• Test with light and accommodation reflexes

• Confirm with syphilis serology

• Manage the underlying cause, not the pupil itself

• MSRA loves classicsigns – and this one is gold

📚Argyll-RobertsonPupil MSRA Resources

📝 Revision Notes:

https://www.passthemsra.com/topic/argyll-robertson-pupil-revision-notes/

🃏 Flashcards:

https://www.passthemsra.com/topic/argyll-robertson-pupil-flashcards/

📖 Accordion Q&A Notes:

https://www.passthemsra.com/topic/argyll-robertson-pupil-accordion-qa-notes/

🧠 Rapid Quiz:

https://www.passthemsra.com/topic/argyll-robertson-pupil-rapid-quiz/

🎯 Quiz Link:

https://www.passthemsra.com/quizzes/argyll-robertson-pupil/

📘 Explore more high-yield revision at:

🌐https://www.passthemsra.com

🌐https://www.freemsra.com

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