Horner Syndrome Caused by Dissected Internal Carotid Artery

choi

Lisa Sanders, A Knife in the Ear Solved! New York Times Magazine, Aug 16, 2015.
well.blogs.nytimes.com/2015/08/07/think-like-a-doctor-a-knife-in-the-ear-solved/

Note:
(a) The patient presented with (localized) earache, Yet headache, neck or face pain is most common.

(b) artery dissection
(i) Alicia Peterson and Amer Aldeen. Headache and Neck Pain - When to Suspect Cervical Artery Dissection. American College of Emergency Physicians, undated (under the heading CME, which stands for CME or continuing medical education (as shown in the URL).
www.acep.org/Education/Continuing-Medical-Education-(CME)/Focus-On/Focus-On--Headache-and-Neck-Pain---When-to-Suspect-Cervical-Artery-Dissection/

Quote:

Partial Horner syndrome "is caused by ischemia or compression of sympathetic fibers that run from the internal carotid artery plexus [of sympathetic system]. ['Partial' because] Facial sweating is preserved because the external carotid plexus is not affected. Almost a third of patients have a partial Horner syndrome.

"Historically, cerebral angiography has been the 'gold standard' for diagnosis of dissection. * * * However, cerebral angiography is less commonly used today due to the invasive nature and the risks of the procedure. Conventional angiography has been replaced in the ED by the faster and more readily available magnetic resonance angiography (MRA) and computed tomography angiography (CTA). * * *
The general consensus among experts is that CTA is the better screening test [than MRA] because it is faster, cheaper, and shows excellent visualization of large vessels"

(ii) Carotid Artery Dissection. Cleveland Clinic, undated
my.clevelandclinic.org/services/heart/disorders/hic_Carotid_Artery_Disease/Carotid-Artery-Dissection

says things similarly, and thus you need not read it.

choi

(c) “Dr Slamovits immediately sent his patient to the Hackensack University Medical Center for a type of MRI [called MRA] that focuses on the blood vessels. It was a good call. The patient had a dissection.”

imaging
(i) magnetic resonance angiography
https://en.wikipedia.org/wiki/Magnetic_resonance_angiography
(MRA)

Vessels are white, because contrast agents, which is radio-opaque, is injected directly into the vessel at question.
(ii) computed tomography angiography
https://en.wikipedia.org/wiki/Computed_tomography_angiography
(CTA)

There is no need to read the text. Just view the photo, which demonstrates the descending portion of an aorta 主動脈, whose lower end is occluded somewhat, surrounded by a huge, round clot in the lumen of aneurysm. The aorta is opaque, due to contrast agent in it.
(d) common carotid artery
https://en.wikipedia.org/wiki/Common_carotid_artery
(divide in the neck to form the external and internal carotid arteries [supplying blood to face and brain, respectively])

carotid artery  頸動脈

(e)
(i) Quotation 1 of (b)(i) above mentions “internal carotid artery plexus.” See the illustrations in
internal carotid plexus
https://en.wikipedia.org/wiki/Internal_carotid_plexus

, which depicts a plexus (Latin for ‘braid’) on the surface of internal carotid artery.

Take notice that in the top illustration, sympathetic system (red) is made up of three-neuron pathway --whereas parasympathetic system is blue. (In the dissection of internal carotid artery, the sympathetic plexus is stretched and partially loses function (to muscle “dilator pupillae”) therefore can not counter parasympathetic system which constrict the muscle called “sphincter pupillae” (Latin) to make the pupil smaller in diameter.  
(ii) For three-neuron pathway, see
tcooper, Neuro-ophthalmology. Stanford University, Sept 24, 2013.
ophthalmology.stanford.edu/blog/archives/2013/09/neuro-ophthalmo-59.html
http://ophthalmology.stanford.ed ... o-ophthalmo-59.html

View Figure 2 only.