Horner's Syndrome Flashcards
Where is the pathophysiology most likely to be?
- Abducens nerve (VI)
- Midbrain
- Oculomotor nerve (III)
- Soft tissue of orbit
- Sympathetic chain
Answer: Oculomotor nerve III - this single lesion can cause both ptosis and an eye movement disorder.
The sixth nerve controls only abduction of the eye.
A lesion of the sympathetic chain causes a Horner’s syndrome with ptosis but does not affect eye movement.
Orbital lesions (e.g. Graves’) can restrict eye movement but would cause proptosis if anything rather than ptosis.
Technically a midbrain lesion is possible, but is much less common and you would expect a variety of other symptoms and signs from it.
Which three features, could *not* be caused by a third nerve palsy alone?
- Complete ptosis
- Enlarged pupil
- Facial weakness
- Hoarse voice
- Restricted eye abduction
- Facial weakness
- Hoarse voice
- Restricted eye abduction
A complete third nerve palsy causes a complete ptosis and a dilated pupil unreactive to light. Facial movements are controlled largely by the facial nerve, voice by the tenth, and eye abduction by the sixth.
Which three are differentials for a third nerve palsy?
- Internal carotid artery dissection
- Intracranial aneurysm pressing on nerve
- Raised intracranial pressure
- Thrombotic occlusion of blood supply to nerve
- Varicella zoster infection of nerve
- Internal carotid artery dissection
- Intracranial aneurysm pressing on nerve
- Thrombotic occlusion of blood supply to nerve
A rapidly expanding intracranial aneurysm is the most serious cause of an acute third nerve palsy, feared because it can herald rupture of the aneurym. Occlusion of the small vasa nervorum, a ‘microvascular third’, is a very common cause, especially in elderly individuals with hypertension. A carotid artery dissection can also cause ischaemia of the nerve. Raised ICP can cause a third nerve palsy, but not in an otherwise well patient, and this typically involves the pupil early. VZV can cause facial palsy mimicking Bell’s palsy (Ramsay-Hunt syndrome), but does not commonly affect the third nerve.
Which three of these features favour a serious cause over a benign cause of third nerve palsy?
- Loss of pupillary light reflex
- Mother died of ‘bleed on the brain’
- Onset over hours or less
- Patient has diabetes
- Pain around the affected eye
- Loss of pupillary light reflex
- Mother died of ‘bleed on the brain’
- Pain around the affected eye
Acute onset is characteristic of both serious and benign causes; an insidious-onset third nerve palsy may well also be due to a serious cause such as cancer. An ischaemic third nerve palsy will usually spare the pupil and is more likely in patients with vascular risk factors, while a compressive cause (e.g. aneurysm) usually affects the pupil early, is more likely in patients with a family history of intracranial aneurysm, and is more likely to be painful.
What three investigations could rule out a rapidly expanding aneurysm as the cause?
- CT brain
- MRI brain
- CT angiogram
- MRI angiogram
- Catheter angiogram
- CT angiogram
- MRI angiogram
- Catheter angiogram
Neither CT nor MRI alone are sufficiently sensitive to rule out an aneurysm in this context. Non-invasive angiography (CTA, MRA) is less sensitive for small aneurysms than formal catheter angiography, but is sufficient to rule out a rapidly expanding aneurysm causing a third nerve palsy.
Define Horner’s syndrome.
1 miosis (pupil constriction)
2 partial ptosis (drooping upper eyelid) + apparent enophthalmos (sunken eye)
3 anhydrosis (ipsilateral loss of sweating).
EVERYTHING REDUCES: PUPIL, EYE, SWEATING
What is the aetiology of anhydrosis in Horner’s syndrome?
Interruption of the face’s sympathetic supply, eg at:
- brainstem (demyelination, vascular disease),
- cord (syringomyelia),
- thoracic outlet (Pancoast’s tumour,)
- on the sympathetic’s trip on the internal carotid artery into the skull and orbit.
How many orders of neurones are involved in the pathways involved in Horner’s syndrome?
First-order sympathetic fibres start in the hypothalamus → descend through brainstem to C8-T2 of the spinal cord → synapse on preganglionic sympathetic nerve fibres.
Second-order fibres leave the cord at T1 → ascend in the sympathetic chain over the apex of the lung → synapse in the superior cervical ganglion at the level of bifurcation of common carotid artery (C3-C4).
Third-order (postganglionic) fibres pass alongside internal carotid → branches to vessels and sweat glands of face → via the cavernous sinus to enter the eye. Then via long ciliary nerves to supply the iris dilator and Müller’s muscle.
Name 3 causes of Horner’s from a central (first order) nerve lesion.
- CVA
- MS
- Pituitary/basal skull tumours
- Basal meningitis
- Neck trauma
- Syringomyelia
- Arnold-Chiari malfromations
- Spinal cord tumours
Name 3 causes of Horner’s resulting from a preganglionic (second-order) nerve lesion.
- Apical lung tumours (e.g. Pancoast)
- Lymphadenopathy (lymphoma, leukaemia, tuberculosis, mediastinal tumours)
- Lower brachial plexus trauma or cervical rib
- Aneurysms of aorta, subclavian or common carotid arteries.
- Trauma or surgical injury to neck/chest
- Neuroblastoma
- Mandibular dental abscess
Name 3 causes of Horner’s resulting from a postganglionic (third-order) nerve lesion.
- Cluser headache/migraine
- Herpes zoster infection
- Internal carotid artery dissection may be traumatic
- Raeder’s syndrome (paratrigeminal syndrome)
- Carotic-cavernous fistula
- Temporal arteritis
What is Pancoast tumour/syndrome?
Apical lung cancer which
- invades the sympathetic plexus in the neck (→ipsilateral Horner’s)
- ± brachial plexus (→arm pain ± weakness)
- ± recurrent laryngeal nerve (→hoarse voice/bovine cough).
What are the clinical features of Horner’s?
- Inability to open eye fully
- Loss of sweating
- Facial flushing (if preganglionic lesion)
- Orbital pain/headache (if postgangionic)
- Other symptoms of underlying cause e.g. head, neck or facial pain on affected side if associated with carotid artery dissection
What investigations would you do for Horner’s?
Physical examination
- Extraocular movements
- Pupils
- Fundoscopy - for neuroblastoma
- Observation for the presence of nystagmus, facial swelling, lymphadenopathy, or vesicular eruptions
Laboratory testing - not v helpful
- Urine test for VMA in paediatric Horner’s
- FBC
- PPD placement
Imaging
- CXR - apical bronchogenic carcinoma
- CT head - if stroke suspected
- MRA - if carotid artery dissection suspected
What pharmacological tests can be done to investigate Horner’s?
Distinguish pre and postganglionic lesions (associated with malignancy).
Topical cocaine test - cocaine is sympathomimetic by inhibiting NA reuptake. Cocaine is added into each eye. Pupils should dilate but the affected side in Horner’s will dilate poorly. Anisocoria >0.8mm = Horner’s
Topical apraclonidine test - alpha1-agonist and strong alpha2-agonist. Has little to no effect on a normal pupil but has a mydriatic effect on an abnormal pupil. Alternative to cocaine test.
Topical hydroxyamphetamine test - stimulates the release of stored endogenous NA from the postganglionic axons into NMJ at iris dilator muscles. May distinguish a postganglionic third-order neuron lesion from a presynaptic second-order or first-order neuron lesion - dilation of affected pupil with intact postganglionic fibers(1st/2nd order) but no dilation if damaged.
