Abnormal pupils Flashcards
Abnormal pupils
Examine this patient’s eyes.
- Horner’s pupil
- Holmes–Adie (myotonic) pupil
- Argyll Robertson pupil
- Oculomotor (III) nerve palsy
Clinical signs of Horner’s pupil
‘PEAS’
1. Ptosis (levator palpebrae is partially supplied by sympathetic fibres)
2. Enophthalmos (sunken eye)
3. Anhydrosis (sympathetic fibres control sweating)
4. Small pupil (miosis)
5. May also have flushed/warm skin ipsilaterally to the Horner’s pupil due to loss of vasomotor sympathetic tone to the face.
Extra points
* Look at the ipsilateral side of the neck for
1. Scars (trauma, e.g. central lines, carotid endarterectomy surgery or aneurysms) and
2. Tumours (Pancoast’s).
Cause of Horner’s according to the sympathetic tract’s anatomical course
1. Brain stem: MS; Stroke (Wallenberg’s)
2. Spinal cord: Syrinx
3. Neck: Aneurysm; Trauma; Pancoast’s
Clinical signs of Holmes–Adie (myotonic) pupil
Moderately dilated pupil that has a poor response to light and a sluggish response to accommodation (you may have to wait!)
Extra points
- Absent or diminished ankle and knee jerks
Discussion of Holmes–Adie (myotonic) pupil
A benign condition that is more common in females. Reassure the patient that nothing is wrong.
Clinical signs of Argyll Robertson pupil
- Small irregular pupil
- Accommodates but doesn’t react to light
- Atrophied and depigmented iris
Extra points
* Offer to look for sensory ataxia (tabes dorsalis)
Discussion of Argyll Robertson pupil
- Usually a manifestation of quaternary syphilis, but it may also be caused by diabetes mellitus
- Test for quaternary syphilis using TPHA (Treponema pallidum hemagglutination assay) or FTA (fluorescent treponemal antibody), which remain positive for the duration of the illness
- Treat with penicillin
Tabes dorsalis
- Caused by 3° syphilis.
- Results from degeneration (demyelination) of dorsal columns and roots => impaired sensation and proprioception, progressive sensory ataxia (inability to sense or feel the legs => poor coordination).
-
Associated with Charcot joints, shooting pain, Argyll
Robertson pupils. - Exam will demonstrate absence of DTRs and ⊕ Romberg sign.
Clinical signs of Oculomotor (III) nerve palsy
- Ptosis usually complete
- Dilated pupil
- The eye points ‘down and out’ due to the unopposed action of lateral rectus (VI) and superior oblique (IV)
- Test for the trochlear (IV) nerve
» On looking nasally the eye will intort (rotate towards the nose) indicating that the trochlear nerve is working
Extra points
1. If the pupil is normal consider medical causes of III palsy
2. Surgical causes often impinge on the superficially located papillary fibres running in the III nerve
Medical Causes of Oculomotor (III) nerve palsy
- Mononeuritis multiplex, e.g. DM
- Midbrain infarction: Weber’s
- Midbrain demyelination (MS)
- Migraine
Surgical Causes of Oculomotor (III) nerve palsy
- Communicating artery aneurysm (posterior)
- Cavernous sinus pathology: thrombosis, tumour or fistula (IV, V and VI may also be affected)
- Cerebral uncus herniation