Question about physiological anisocornia...?!
Question: My eye doctor just performed a series of tests on me and told me that the reason I have differently sixed pupils is because of physiological anisocornia. However, I as just wondering a few things...
1. Is it normal for the bigger pupils to sometimes be the smaller one, and vice versa? And can they sometimes be normal sized?
2. The eye doctor told me that because both pupils react equally to light, I must have physiological anisocornia and not a tumor or aneurysm. Do you think that the eye doctor is an efficient enough source of informatio to feel safe, or should I be worried and still get an MRI/other brain scan. Honestly.
Thanks a lot.
**Serious answers only please. Only answer if you've got an answer. Thanks.**
Answers: My eye doctor just performed a series of tests on me and told me that the reason I have differently sixed pupils is because of physiological anisocornia. However, I as just wondering a few things...
1. Is it normal for the bigger pupils to sometimes be the smaller one, and vice versa? And can they sometimes be normal sized?
2. The eye doctor told me that because both pupils react equally to light, I must have physiological anisocornia and not a tumor or aneurysm. Do you think that the eye doctor is an efficient enough source of informatio to feel safe, or should I be worried and still get an MRI/other brain scan. Honestly.
Thanks a lot.
**Serious answers only please. Only answer if you've got an answer. Thanks.**
An interruption of the oculo-sympathetic pathway leading to sympathetic inactivity
= Horner's syndrome (HS)
Clinical Triad of (Click HERE to see picture):
1. Miosis
2. Ptosis
3. Anhidrosis
Anatomy:
Sympathetic pathway extends from hypothalamus via lateral brainstem and cervical cord, with first-order neuron synapsing in ciliospinal center (of Budge) at level of C8-T2, in interomediolateral cell columns
- exits out of T1 nerve root in thoracic sympathetic trunk, over apex of lung and near subclavian artery, passing through stellate ganglion
- synapses in superior cervical ganglion (near bifurcation of common carotid artery)
- sudomotor and vasoconstrictor fibres to face travel then with external carotid artery
- fibres to pupillary dilators and eyelid retractor muscles travel with internal carotid artery to long ciliary nerve and nasociliary nerve (3rd order neuron, post-ganglionic)
- divide from ICA and travel transiently with abducens nerve within cavernous sinus, then with V1 branch of trigeminal nerve
Etiology and Localization of HS:
1. First-order neuron (brainstem and spinal cord) 50-60%
- Stroke (commonly Wallenberg's lateral medullary infarction)
- Neoplasm
- Demyelinating disease
- Syringomyelia
- Transverse myelitis
2. Second-order neuron (pre-ganglionic) 20-30%
- thoracic or neck tumor esp Pancoast's tumor at apex of lung, breast malignancy
- "Rowland-Payne" syndrome with HS + paresis of phrenic, vagus, and recurrent laryngeal nerve (elevation of hemidiaphragm, hoarse voice)
- neck trauma and disc protrusion at C8-T1
- compression from cervical ribs, lower plexus avulsions (eg obstetric), aortic aneurysms, thyroid malignancy, lymphadenopathy
- iatrogenic from thyroidectomy, radical neck exploration / surgery, carotid angiography (in days of direct carotid puncture !), vascular catheters, chest tubes, pacemaker insertion
3. Third-order neuron (post-ganglionic) 20%
NB: will not see facial anhidrosis in this localization
- some similar causes to #2
- vascular headaches (as in autonomic cephalgias, cluster headache)
- cavernous sinus / superior orbital fissure lesion (eg. tumor, aneurysm)
- carotid-cavernous fistula ... usually associated ophthalmoplegia, facial pain
- internal carotid artery dissection (with headache, represents Raeder's paratrigeminal neuralgia)
- nasopharyngeal carcinoma (or tumors at jugular foramen)
- complicated otitis media
- trauma with basal skull fracture
Congenital HS usually due to early brachial plexus injury (at birth), post-viral or with some early tumors
- may see straight hair on side of HS in patients with naturally curly hair !!
Differential Diagnosis:
Anisocoria:
- physiologic anisocoria (up to 0.5-1 mm in 20% of population)
- pharmacologic (eyedrops)
- if greater in light then parasympathetic defect such as CN III palsy, Adie's pupil, iris trauma or scopolamine / atropine effects
Ptosis:
- myasthenia gravis
- CN III palsy (with dilated pupil, may be unreactive, +/- ophthalmoplegia)
- levator dehiscence
Coincidental occurrence of physiological anisocoria and age-related ptosis can mimic closely a Horner's syndrome, but dilatation lag and other subtle features will be absent
History:
- notice pupillary asymmetry (affected side smaller, esp in dark)
- drooping of the eyelid (usually mild)
- when first noticed?
- does the ptosis fluctuate (suggesting neuromuscular dysfunction, not HS)
- is there any double vision (absent in isolated HS; suggests either another cause or associated damage to brainstem / cranial nerve structures by lesion causing HS)
- noticed any change in sweating on affected side of face (implies lesion proximal to carotid bifurcation in post-ganglionic neuron, or pre-ganglionic lesion)
- was the eye ever red (seen in acute stages of HS)?
- any associated brainstem features such as dysarthria, dysphagia, ataxia, vertigo, facial weakness, sensory abnormality (on face or in limbs)?
- any neck symptoms including neck pain (eg carotid dissection), masses palpated?
- pulmonary symptoms such as cough, hemoptysis, dyspnea or pain (suggestive of apical lung tumor)
- ipsilateral arm symptoms including pain, numbness / paresthesias, weakness, wasting suggesting involvement of brachial plexus
- headache (if ipsilateral and facial pain consider carotid dissection; if occipital consider vertebral artery dissection with brainstem infarct)
- any Hx of prior neurological events (such as strokes or demyelinating episodes)
Examination:
Confirmation of Horner's syndrome (Click HERE to see picture):
1. Miosis
- affected pupil smaller, more apparent in dark or dim illumination than in light (where it may be inapparent); also stimulate sympathetics with sudden noise (accentuating anisocoria)
- anisocoria usually mild (0.5 - 1 mm) with paresis of iris dilators
- pupil reacts normally to light and accommodation
- dilation lag found when darken room (affected pupil dilates more slowly)
- may see paradoxical pupillary dilatation on affected side in states of adrenergic hyperactivity (eg emotional excitement or stress) due to denervation supersensitivity to circulating catecholamines
- look for heterochromia iridis (iris is different, lighter color in congenital HS due to depigmentation of iris; rarely can occur in acquired lesions)
- conjunctival injection in acute phase may be seen (loss of vasoconstrictor activity) as can hemi-facial flushing and nasal stuffiness
+/- reduced intraocular pressure and increased accommodation
2. Ptosis:
- usually subtle (2-3 mm) and may be variable (slight fluctuations)
- due to weakness of Muller's muscle (smooth muscle, involuntary retractor of upper lid)
- also get upside-down ptosis of lower lid on that side (due to paresis of inferior tarsal muscle) leading to lower lid drawn up higher (hiding bottom of cornea) vs other side
- may have apparent enophthalmos (eye looks sunken) with narrowed palpebral fissure
3. Anhidrosis:
- check sweating (by palpation) on both sides of face, seeing if less on affected side
- also see if hemibody involved (found with central lesions) vs hemi-face and neck down to clavicle in pre-ganglionic lesions
Looking for Etiology / Localization:
1. Brainstem testing:
- cranial nerve abnormalities (incl. CN V, VII, IX, X) may be seen in BS lesions
- ipsilateral ataxia if cerebellum or its connections affected
2. Examination of the Neck:
- palpate for masses, tenderness
- auscultate for carotid bruits and palpate for pulse present (absent if occlusion)
3. Examination of Limbs:
- look at ipsilateral arm for wasting or weakness suggestive of lower plexus involvement
- loss of reflexes and sensory loss can also be found
Diagnosis:
- initial clinical suspicion confirmed (if necessary) by pharmacologic stimulation of sympathetic pathways
1. Cocaine test
- 2 drops of 10% cocaine instilled into each eye
- prolongs action of norepinephrine on dilator muscle by blocking reuptake (requires its release from nerve terminals by intact oculosympathetic pathway)
- normal pupil will dilate while HS pupil will fail to dilate after 45 minutes (confirming diagnosis of HS); but still need to examine in dim room else bright light will overpower effect as PSNS intact - both eyes look constricted !
NB: metabolites of cocaine will be found in urine for 1-2 days afterwards !
2. 1% Hydroxyamphetamine:
- done only after confirming dx with cocaine test (or clinically) and waiting 24-28 hrs to allow cornea and pupils to recover
- 2 drops to also create sympathomimetic effect but does so by stimulating release of norepinephrine from nerve endings, stimulating dilator muscle
- requires that post-ganglionic (3rd-order) neuron be intact and have normal axoplasmic activity so norepinephrine available for release
- normal pupil will dilate, and also normal or accentuated in HS pupil if pre-ganglionic (first- or second-order) while incomplete dilatation seen if post-ganglionic lesion
NB: direct-acting topical adrenergic agents will dilate pupils of HS (eg. epinephrine solution)
- often becomes larger than unaffected side due to supersensitivity from denervation (in subacute to chronic, but not acute phase)
Localization:
1. First-order (central):
- MRI of head and cervical spine
2. Second-order (pre-ganglionic)
- Chest x-ray +/- CT of chest
- CT or MRI of neck
3. Post-Ganglionic:
- MRA for carotid dissection
- MRI for cavernous sinus lesions
References:
Kline LB, Bajandas FJ. Neuro-Ophthalmology review manual. 4th ed. 1996.
Miller NR, Newman N. Walsh & Hoyts Clinical Neuro-Ophthalmology. 5th ed. 1999.
Last update: July 2004
Reviewed by: pending
Neurological Medicine Pocketbook
? 2003-2004 UWO Neurology Residents