Pathway:

Posterolateral hypothalamus --> 1st order neurone

1st order neuron terminates at ciliospinal center of BUDGE at C8-T2 (T1)

2nd order neuron: from Ciliospinal centre of BUDGE enters cervical sympathetic chain

Terminates at the superior cervical ganglion at the bifurcation of CCA at C3-C4

3rd order neuron (post ganglionic pupillomotor fibres) exit the ganglion and ascends via ICA entering cavernous sinus, briefly joining CN6 before entering orbit via SOF with CNV1 via the long ciliary nerve which innervates the pupillary dilator and Mullers

3rd order neuron (post ganglionic sudomotor and vasomotor) branch off the ganglion and travel along ECA to innervate the face.

Clinical S/S:

- miosis (paralysis of pupillary dilator)

- enopthalmos (loss of tone of the muscles of the floor of orbit

- partial ptosis (loss of tone of superior tarsal muscle of Muellers)

- slight elevation of lower lid (upside down ptosis due to loss of tone of lower tarsal muscles)

Features would be seen in congenital horners: heterochromia

Diagnosis:

2 tests: cocaine 4% or adrenaline 1:1000

These tests help us determine whether it is above or below the superior cervical ganglion

For example, with a lesion distal to the superior cervical ganglion:

addition of cocaine 4% will:

affected eye --> no changes

unaffected eye --> dilates

for a lesion proximal to the superior cervical ganglion:

affected eye --> dilates

unaffected eye --> dilates

Another example with adrenaline 1:1000 eyedrops:

Distal lesion:

affected eye --> dilates

unaffacted eye --> no changes

Proximal lesions:

affected eye: no change

unaffected eye: no change

Thus if a patient presents with unilateral partial ptosis with upside down ptosis: check for vasomotor and sudomotor changes to determine level. If you suspect the patient having a lesion proximal to the superior cervical ganglion: look at the neck. In the local context, most probably due to pancoast tumour. So what you should do:

1. ask about sudomotor and vasomotor symptoms (to confirm suspicion of level)

2. offer to do and actually inspect and examine the lower neck for signs of SVCO and cervical lymphadenopathy

3. offer to examine the upper chest

4. offer confirmatory tests: 4% cocaine and 1:1000 adrenaline, of which the affected eye will dilate with 4% cocaine but will not with 1:1000 adrenaline