hi let's talk about horner syndrome in this video we'll discuss horner syndrome and how its symptoms
help to illustrate the targets and functions of the sympathetic nervous system in the head
so horner syndrome is the effect of an interruption of the sympathetic pathway
this may either be congenital so at birth or acquired there are different types of
syndromes depending on which part of the pathway is affected so for instance if it's a disruption
within the central nervous system it is a first order if it's a disruption of the pathway of the
preganglionic fibers it's a second order or of the postganglionic fibers it is a third order
keep in mind that all of the preganglionic fibers that are going to serve any of the cervical
sympathetic ganglia ascend from the thoracic spine so that means that it's not just the cervical
region that can produce Horner's but it's also an interruption in the thoracic region which could
produce horners and it is that superior cervical ganglion which is providing the exclusive
postganglionic fibers to the head either via the internal or external carotid plexuses
so let's take a look at the symptomology with Horner's we have several potential
symptoms they all aren't necessarily present it's going to depend on what order of horners
but um Horner's is generally characterized as unilateral that means on one side
meiosis meiosis is a constricted pupil so if we look here we can see that this pupil
is smaller than that pupil it's harder to tell on brown eyed individuals
that pupil is smaller than that people so this is the affected side
within the eye there are two sets of muscles that control the pupil there are the dilator pupillae
under sympathetic control and then the sphincter pupillae under parasympathetic control if the
dilator pupillae muscle are denervated then the sphincter pupillae muscle are unbalanced
thus that is why the constricted pupil or meiosis is present with Horner's on one side the other
symptoms include ptosis ptosis is a droopy eyelid so controlling the superior eyelid or the superior
palpebra is a muscle called levator palpebrae superioris and a tiny slip of that muscle
is smooth muscle embedded within the tarsal plate there which when sympathetically
activated really opens the eyes wide but there's generally some sympathetic tone to it
when that muscle is denervated the eyelid droops the next symptom is more of a consequence of
the previous symptom ptosis and that's pseudo enophthalmus which means a pseudo sunken globe
when the eyelids become droopy it gives the eyes an appearance of being sunken
the next symptom is hyperemia hyperemia is a flushed appearance to the skin
this occurs because the vasomotor fibers are denervated without the tone on those five
coming from the fibers to the walls of the blood vessels the walls of the blood vessels relax and
as a result more blood flows through them near the surface of the skin this gives a flushed
appearance hence hyperemia emia means blood hyper more so more blood leads to flushed skin
the next symptom is anhidrosis and not or lack of hidrosis sweating so this is a
lack of sweating sweat glands are exclusively supplied by the sympathetic division of the
autonomic nervous system when the sudomotor fibers that serve them are denervated they cease
to excrete and as a consequence there's unilateral anhidrosis so if you see any cluster of unilateral
miosis ptosis pseudoenophthalmus hyperemia or anhidrosis you'll understand given the sympathetic
pathways to these various target tissues why so we've discussed the types of horner syndrome
where the interruptions may occur and how this might affect target tissues and how this may
present unilaterally as a cluster of symptoms this is your summary slide i thank you for your time