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Horner’s sydrome is a classic neurologic syndrome whose signs include:-
Horner’s syndrome is also called oculosympathetic paresis, a horners syndrome can be produced by a lesion anywhere along the sympathetic pathway that supplies the head,eye and neck.
Horner’s syndrome can result from a lesion anywhere along a three neuron sympathetic pathway that originates in the hypothalamus.
The first order neuron:
Descends caudally from the hypothalamus to the first synapse, which is located in the cervical spinal cord (level C8-T2, also called ciliospinal center of Budge).
The second order neuron:
Travels from the sympathetic trunk, though the brachial plexus over the lung apex. It then ascends to the superior cervical ganglion, located near the angle of the mandible and the bifurcation of the common carotid artery.
The third order neuron:
Then ascends the adventitia of the internal carotid artery, through the cavernous sinus, where it is in close relation to the sixth cranial nerve.
The oculosympathetic pathway then then joins the ophthalmic division of the fifth cranial nerve(trigeminal nerve)
In the orbit and the eye, the oculosympathetic fibres innervate the iris dilator muscle as well as Muller’s muscle, a small smooth muscl e in the eyelids responsible for minor portion of the upper lid elevation and lower lid retraction.
The classic signs of a horner’s syndrome are:-
The degree of anisocoria is more marked in the dark than in light.
There is associated dilation lag, an asymmetry in papillary redilation between the two eyes when he light source is moved away from the eye.
The horner’s pupil will redilate more slowly(by 15 to 20 seconds) than the normal pupil.
The ptosis is minor(less than 2mm) and occurs as a result of paralysis of Muller’s muscle, which is innervated by the sympathetic pathway. the lower as well as upper lid is affected producing the so called “upside-down ptosis”.
Anhidrosis is present in central or preganglionic(first or second order) lesions. The sympathetic fibres responsible for facial sweating and vasodilation, branch off at the superior cervical ganglion from the remainder of the oculo sympathetic pathway; thus, anhidrosis is not a feature of postganglionic or third order lesions. This sign is frequently not apparent to patients or clinicians.
A congenital Horner’s syndrome should be suspected when anisocoria is associated with heterochromia(unequal iris colour, with the affected being lighter).
This occurs because of formation of iris pigment in the first several months of age is under sympathetic control. This may only be apparent if the natural colour is relatively dark.
The etiology of horner’s syndrome in adults relates to the lesion location.
Lesions of the sympathetic tracts in the brain stem or cervicothoracic spinal cord can produce a first-order Horner’s syndrome
lateral medullary syndrome
Cervical cord trauma
Spinal cord tumour
Diabetic autonomic neuropathy
Second Order Syndrome(pre-ganglionic)
Trauma or surgery involving spinal cord, thoracic outlet lung apex
Caotid and Aortic anneurysm and dissection
Lumbar epidural anaesthesia
Third Order Syndrome(post-ganglionic)
Lesions of internal carotid artery
Cavernous sinus mass
Horner’s Syndrome- Eye Drop Testing
Horner’s syndrome Case Discussion
Horner’s Syndrome Images:
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