Jagdish Dukre

Anatomy First-order central sympathetic

fibers arise from the posterolateral hypothalamus, descend uncrossed through the mid brain and pons, and terminate in the intermediolateral cell column of the spinal cord at the level of C8-T2 (ciliospinal center of Budge).

Second-order preganglionic pupillomotor fibers exit the spinal cord at the level of T1, and enter the cervical sympathetic chain, where they are in close proximity to the pulmonary apex and the subclavian artery.

The fibers ascend through the sympathetic chain and synapse in the superior cervical ganglion at the level of the bifurcation of the common carotid artery (C3-C4).

Postganglionic pupillomotor fibers exit the superior cervical ganglion and ascend along the internal carotid artery.

Shortly after the postganglionic fibers leave the superior cervical ganglion vasomotor and the sudomotor fibers branch off, they travel along the external carotid artery to innervate the blood vessels and sweat glands of the face.

The pupillomotor fibers ascending along the internal carotid artery enter the cavernous sinus.

Then, the fibers leave the carotid plexus briefly to join the abducens nerve (cranial nerve VI) in the cavernous sinus and enter the orbit through the superior orbital fissure along with the ophthalmic branch of the trigeminal nerve (V1) via the long ciliary nerves.

Then, the long ciliary nerves innervate the iris dilator and the Müller muscle.

SignsThe vast majority of cases are unilateral.

Miosis

Mild ptosis

Anhydrosis

Loss of ciliospinal reflex

Apparent enophthalmos

Miosis due to the unopposed action of the sphincter pupillae with resultant anisocoria.

Paresis of Dilator muscles can be detected by

1. Dilation lag : When lights turn off affectedpupil dilates more slowly.

2. Psychosensory stimulus like noise whichcauses normal pupil to dilate

anisocoria is due to

• Inhibition of Edinger westphal nucleus

• Sympathetic discharge to dilator muscle.

• There is palsy of iris dilator muscle in this but, ifdilator muscle is stimulated by adrenergic drug pupil dilates widely.

• Endogenous catecholamines can produce a similarphenomenon as the muscles are supersensitivebecause of denervation.

• In intense emotional excitement pupil on the sideof lesion becomes larger than the normal pupil k/a"paradoxical pupillary Reaction" is because ofdenervation supersensitivity to circulating adrenergicsubstances.

Mild ptosis (usually 1–2 mm) as a result of weakness of Müller muscle,

Slight elevation of the inferior eyelid as a result of weakness of the inferior tarsal muscle.

This along with partial ptosis results in apparent enophthalmos.

Reduced ipsilateral sweating, but only if the lesion is below the superior cervical ganglion, because the sudomotor fibers supplying the skin of the face run along the external carotid artery.

Hypochromic heterochromia (irises of different colour –Horner is lighter) may be seen if congenital or long-standing.

Pharmacological tests Cocaine

Hydroxyamphetamine (Paredrine)

Adrenaline

Apraclonidine

CocaineCocaine 4% is instilled into both eyes.

Result:

The normal pupil will dilate but the Horner pupil will not.

The maximum response is seen 40-60 minutes after instillation of the drops.

A post-cocaine anisocoria of >0.8 mm in a dimly lit room is significant.

Rationale:

NA released at the post-ganglionic sympathetic nerve endings is reuptaken by the nerve endings, thus terminating its action.

Cocaine blocks this uptake.

NA therefore accumulates and causes pupillary dilatation.

In Horner syndrome, there is no NA being secreted.

Cocaine thus confirms the diagnosis of Horner syndrome by continued constriction of the affected pupil.

HydroxyamphetamineHydroxyamphetamine 1%

is instilled into both eyes the next day, after the effects of cocaine have worn off.

Result:

• In a preganglionic lesion both pupils will dilate.

• In a postganglionic lesion the Horner pupil will not dilate.

Rationale:

Hydroxyamphetamine potentiates the release of NA from postganglionic nerve endings.

If this neurone is intact (a lesion of the first or second order neurone, and also the normal eye) NA will be released and the pupil will dilate.

In a lesion of the third order neurone(postganglionic) there can be no dilatation since the neurone is destroyed.

Adrenaline

Adrenaline 0.1% is instilled into both eyes.

Result:

In a preganglionic lesion neither pupil will dilate because adrenaline is rapidly destroyed by monoamine oxidase

In a postganglionic lesion, the Horner pupil will dilate and ptosis may be temporarily relieved because adrenaline is not broken down due to the absence of monoamine oxidase.

Rationale:

A muscle deprived of its motor supply manifests heightened sensitivity to the excitatory neurotransmitter secreted by its motor nerve.

In Horner syndrome the dilator pupillae muscle similarly manifests ‘denervation hypersensitivity’ to adrenergic neurotransmitters.

Therefore adrenaline, even in minute concentration produces marked dilatation of the Horner pupil.

Apraclonidine Apraclonidine 0.5% or 1.0% is instilled into both eyes in

order to confirm the diagnosis, similar to the cocaine test.

Result: Horner pupil will dilate but a normal pupil is unaffected.

Rationale: alpha-1 receptors are upregulated in the denervated dilator pupillae.

Horner's Types :

Central HS : There is involvement of 1st orderneuron. Lesion located between hypothalmus andCiliospinal centre of budge.

Preganglionic HS : Lesion is located from C–8 to T–2and the superior cervical ganglion i.e., second orderneurons.

Post ganglionic HS : 3rd order neurons involvementfrom superior cervical ganglion to the dilator pupillae

Causes of Horner syndrome Central (first-order neurone)

• Brainstem disease (tumour, vascular, demyelination)

• Syringomyelia

• Lateral medullary (Wallenberg) syndrome

• Spinal cord tumor

• Diabetic autonomic neuropathy

Preganglionic (second-order neurone)

• Pancoast tumor

• Carotid and aortic aneurysm and dissection

• Neck lesions (glands, trauma, postsurgical)

Postganglionic (third-order neurone)

• Cluster headaches (migrainous neuralgia)

• Internal carotid artery dissection

• Nasopharyngeal tumour

• Otitis media

• Cavernous sinus mass

Localization Central Horner's syndrome

Almost always unilateral

Often associated with hemihypohydrosis of entire body.

Patients with cervical spondylosis may present with only Horner’s syndrome and neck pain

Associated with Wallenberg’s syndrome.

Wallenberg syndrome :

ipsilateral impairment of pain and temperature over the face and bulbar involvment

With contralatral impairment of pain and temperature over trunk and limbs.

Pre-ganglionic Horner’s syndrome

Ptosis and miosis are nonspecific but anhyrosis is characteristic.

Face and neck down to clavicle are involved.

Maliganancy is most common cause.

Rowland Payne syndrome :

Horner’s syndrome associated with paralysis of phrenic and recurrent laryngeal nerve.

Post-ganglionic Horner’s syndrome

Atherosclerosis of internal carotid artery

Nasopharyengeal tumor

Cavernous sinus pathology

Cluster headaches

Congenital Horner’s syndrome Patients have h/o perinatal head

trauma.

h/o use of high forceps or rotation of for fetal malpostion.

Associated signs related to birth trauma are also present.

Parents report that child develops hemifacial flushing.

Hypochromic heterochromia is seen in these cases due to anterograde ganglionicdysgenesis.