Horner syndrome. Horner's syndrome

This is a detailed lecture about Horner's syndrome.

1. Horner syndrome Dr. Jwan Ali Ahmed AlSofi

2. Contents:- Definition Neuroanatomy Clinical presentation Pathophysiology Causes Classification Investigation

3. Definition:- Horner’s syndrome is the clinical picture resulting from dysfunction of sympathetic nerve supply to the eye . Most commonly is acquired. The congenital or familial form exists, often associated with lack of pigmentation of the iris. The lesion site is unknown.

4. Anatomy:- Sympathetic nerve supply originates in the hypothalamus and emerges in the root of the neck before innervating the pupil: Posterior hypothalamus ( 1 st order neuron)  ciliospinal center of Budge C8-T2 ( 2 nd order neuron, preganglionic )  superior cervical ganglion ( 3 rd order neuron, postganglionic)  plexus around ICA and ophthalmic arteries  ciliary ganglion without interruption  ciliary nerves  dilator pupillae and Muller’s muscle . **Damage at any point in this pathway will result in Horner’s syndrome

5. Neural pathway in Horner syndrome :- First-order neurons Originate in hypothalamus Travel in spinal cord Synapse in ciliospinal center of Budge Second-order neurons (pre-ganglionic neurons) Originate at Budge center Exit spinal cord Travel in sympathetic chain Synapse in superior cervical ganglion – the stellate ganglion . Third-order neurons (post-ganglionic neurons) Originates in superior cervical ganglion Travels with internal carotid artery intocavernous sinus

6. CLINICAL FEATURES OF Horner syndrome:-

7. Partial ptosis (drooping of the upper eyelid)  Muller muscle and smooth muscle of levator palpebral superiors paralysis . Miosis (constriction of the pupil)  pupil dilator paralysis. Anhidrosis (decreased sweating)  occurs when the lesion is proximal to fibre separation along the internal and external carotid arteries. Enophthalmus (sinking of the eyeball into the face)  The enophthalmos of Horner syndrome is often apparent but not real and is caused by the ptosis. facial flushing  vasodilation of skin arterioles loss of ciliospinal reflex . The pupil's light reflex is maintained as this is controlled via the parasympathetic nervous system.

8. Pathophysiology:- In Horner’s syndrome there is only  partial  ptosis since control of the upper eyelid is controlled by two sets of nerves: the IIIrd nerve supplies the levator palpebrae superioris and sympathetic fibres supply the Muller muscle. In Horner’s syndrome, despite the weakness owing to a dysfunctional Muller muscle, the IIIrd nerve is still intact meaning the ptosis is not complete. Interestingly, voluntary upward gaze overcomes the partial ptosis. IIIrd nerve palsies and Myaesthenia gravis are two important differentials of Horner’s syndrome to exclude.

9. Pathophysiology:- Presentation of Horner’s is dependent on the site of the lesion due to the anatomy of the sympathetic supply to the face. Sympathetic supply to the face is composed of the connection of three separate neurons: First order neurone: Hypothalamus → Brainstem → Cervical Cord à T1 root ganglion. Second order neurone: T1 root ganglion → cervical sympathetic chain → superior cervical ganglion. Third order neurone: Superior cervical ganglion → Muller muscles + pupil + sweat glands

10. Pathophysiology:- Central lesions affect the First order neurones. Peripheral lesions are those which affect the Second (pre-ganglionic) and Third (post ganglionic) order neurones. The ganglion is the superior cervical ganglion. Locating the lesion is dependent on identifying the pattern of anhidrosis :

11. Causes of Horner syndrome:-

12. Classification of Horner syndrome:-

13. First order neuron Second order neuron Third order neuron

14. FON:- Anatomy

15. FON:- causes

16. FON:- Associated features

17. FON :- Lesions

18. FON:- Imagings

19. Second order neurons :- Anatomy

20. Second order neurons :- Causes

21. Second order neurons :- Associated features

22. Second order neurons :- Lesions

23. Third order neurons :- Anatomy

24. Third order neurons :- Causes

25. Third order neurons :- Associated features

26. Third order neurons :- Lesions

27. Third order neurons :- Lesions

28. Third order neurons :- Lesions

29. first-neuron defect ( central Horner syndrome ) second-neuron involvement ( preganglionic Horner syndrome ) third-neuron involvement ( postganglionic Horner syndrome ) Clinical signs contralateral hyperesthesia of the body loss of sweating of the entire half of the body. loss of sweating limited to the face and neck the presence of flushing or blanching of the face and neck. facial pain or ear, nose, or throat disease. Usually not associated with anhidrosis .  because sympathetic projections to the face and neck emerge from the sympathetic chain prior to the superior cervical ganglion. Causes Arnold-Chiari malformation Pituitary tumour Wallenberg (lateral medullary) syndrome Hypothalamic stroke High cervical myelopathy Syringomyelia Pancoast’s tumour Subclavian artery dissection / aneurysm Thyroid masses / LAP Cervical rib Aortic aneurysm / dissection Neck surgery Central venous catheterization Shoulder dystocia (trauma to brachial plexus) Internal carotid artery dissection Cluster headache Cavernous sinus thrombosis

30. Investigative approach :-

31. Confirmatory test ( apraclonidine test); can also use 1:1000 adrenaline eye drops Apraclonidine is a weak alpha-1 and strong alpha-2 agonist Due to hypersensitivity of the denervated pupil dilator and Muller muscles Apraclonidine application hence results in reversal of miosis and lid elevation Little or no response in normal eye False negatives: acute Horner’s when alpha-2 receptors have yet to be up-regulated Cocaine test: cocaine inhibits noradrenaline re-uptake. In normal eye, pupil will dilate. There will be no reaction in the affected eye due to sympathetic denervation. First-order: MRI brain (structural lesions, stroke) MRI cervical spine (syrinx, cervical myelopathy) Second-order: Chest radiograph (apical lung tumour) Angiogram for large artery aneurysm / dissection Third-order: CT venogram (cavernous sinus thrombosis)

32. The END