Horners syndrome in ICU

 Components
 Reason/relevant clinical anatomy
 Etiology
 Diagnosis

Components- Ptosis, miosis, anhydrosis(classic triad), enophthalmus, chemosis of conjunctiva, nasal stuffiness.

Reason- lesion anywhere in the sympathetic neural pathway supplying the head and neck(oculo sympathetic defect)
Relevant clinical anatomy- ocular sympathetics is a 3 neuron ipsilateral pathway:
1st order neurons- arise from hypothalamus and synapse with
2nd order neurons- pre-ganglionic fibres located in the intermediolateral spinal cord, C8-T2 (cilio spinal centre of Budge)- they exit in the anterior roots and pass over the pulmonary apex to synapse in the superior cervical ganglia (located near the angle of jaw).
3rd order neurons- Post ganglionic fibres- run along with the internal carotid artery as sympathetic plexus surrounding it & enter the skull. They exit the skull via orbit in the ophthalmic division of trigemminal nerve and supply the following- Mullers muscle (levator palpebrae superioris) of the upper eyelid, radial muscle of iris (dilator pupilae) and sweat gland of face.


- Horner's syndrome + brain stem/cerebellar signs => suspect a brain stem or cerebellar stroke syndrome affecting the first neuron eg. Wallenberg' syndrome
(* a "central" Horner's syndrome affecting the first neuron does not respond to cocaine and the diagnosis must be made by the associated neurological signs - nearly always associated with pain and temperature loss on the opposite side of the body)

- Horner's syndrome + sensory and/or motor deficit of the limbs => suspect cervical spinal cord pathology affecting the first neuron

- Horner's syndrome + hoarseness => compressive lesion in the chest or neck affecting the second neuron and recurrent laryngeal nerve

- Horner's syndrome + paralysis of the ipsilateral phrenic, vagus and recurrent layngeal nerve => tumor behind the carotid sheath at the C6 level affecting the second neuron

All patients with an unexplained unilateral Horner's syndrome + face/head pain should be presumed to have a carotid artery dissection until proved otherwise

- the sympathetic nerves to the eye travel with the ophthalmic nerve (V1) and a lesion affecting V1 in the region of the orbit is also likely to affect to neighbouring nerves

- Horner's syndrome + cranial nerve 3 and/or 4 and/or 6 and/or V1/V2 dysfunction (and not affecting V3) => suspect cavernous sinus pathology

- Horner's syndrome + cranial nerves 3 and/or 4 and/or 6 and/or V1 (and not affecting V2 and V3) dysfunction => suspect superior orbital fissure pathology

- Horner's syndrome + cranial nerves 2 (optic nerve), 3, and/or 4 and/or 6 and V1 (and not affecting V2 and V3) dysfunction => suspect orbital apex pathology

- Horner's syndrome + optic nerve II dysfunction +/- incomplete cranial nerve 3 dysfunction (and not affecting cranial nerves 3, 4 and 6 and V2 and V3) => suspect posterior orbit pathology

- all patients with an asymptomatic, unexplained Horner's syndrome (especially if they have ipsilateral anhidrosis of the face and neck, which implies a preganglionic Horner's syndrome), who are going to be discharged from the ED for pre-arranged follow-up as an outpatient, should have a chest X-ray performed prior to ED discharge - to exclude a mediastinal or apical lung tumor (Pancoast's tumor) or thoracic aneurysm affecting the second neuron


Etiology-
In general- brain stem lesions (stroke, tumour, trauma), cervical cord lesions, pancoast syndrome & iatrogenic
In ICU- iatrogenic causes are more important (10% of all cases of horners syndrome admitted to hospital)- neck surgery, carotid angiography/endartrectomy/surgeries(are well recognized causes), IJV cannulation and ICC placement. Other causes are- brachial plexus block and thoracic epidural anesthesia. The close proximity of cervical sympathetic trunk to the IJV may result in damage to the trunk by either trauma from the needle or pressure from a hematoma with he development of Horners syndrome. The risk of damaging the sympathetic fibres is increased with a higher approach to the IJV and if the angle between the needle and the skin is great. In the ICU patients with sudden onset of U/L miosis, the d/d is between carotid dissection vs. horners syndrome; the relevant clinical context becomes important to
differentiate.

Clinical Tests for diagnosis-
Dilation lag of miotic pupil- where in dark, the miotic pupil initially fails to dilate increasing the degree of anisocoria- considered specfic test
Cocaine test- Gold std- failure of cocaine drops to dilate the miotic pupil

Differentiation between physiological anisocoria and Horner's syndrome