Horner syndrome
00:00 / 00:00
Videos
Notes
Horner syndrome
Pathology
Pathology
Pathology
Assessments
Horner syndrome
Flashcards
0 / 12 complete
USMLE® Step 1 questions
0 / 2 complete
High Yield Notes
3 pages
Flashcards
Horner syndrome
of complete
Questions
USMLE® Step 1 style questions USMLE
of complete
Memory Anchors and Partner Content
External References
First Aid
2022
2021
2020
2019
2018
2017
2016
Anhidrosis
Horner syndrome p. 559, 719
Brown-Séquard syndrome p. 549
Horner syndrome p. 549
Horner syndrome p. 530, 536, 559
labs/findings p. 723
lung cancer p. 709
Pancoast tumor p. 710
presentation p. 719
Miosis
Horner syndrome p. 549, 719
Pancoast tumor p. 710
Horner syndrome and p. 559
Ptosis (eyelids)
Horner syndrome p. 560, 719
Syringomyelia p. 506
Horner syndrome p. 559
External Links
Transcript
Horner’s syndrome, named after the ophthalmologist Johann Friedrich Horner, is caused by a problem with the sympathetic nerve supply to one side of the face.
This disruption results in miosis, which is constricted pupil; ptosis, a droopy eyelid; and anhidrosis, a failure to sweat.
Broadly speaking, the autonomic nervous system is a part of the nervous system that controls involuntary body functions like the heart rate, blood pressure and digestion.
The autonomic nervous system can be subdivided into the sympathetic and parasympathetic nervous system, which have opposite effects.
The sympathetic nervous system controls functions like increasing heart rate, blood pressure, and slowing digestion. All of this maximizes blood flow to the muscles, and can help you either run away from a threat or fight it which is why it’s also called the fight-or-flight response.
The parasympathetic nervous system has the opposite effect; it slows heart rate, decreases blood pressure, and stimulates digestion - the effects can be summarized as 'rest and digest'.
Now, with regard to the face and eye, there’s an oculosympathetic pathway with three groups of neurons called first-order, second-order and third-order neurons.
The body of the first-order neuron is located in the hypothalamus, and it’s axon extends down into the spinal cord, where it synapses with the second-order neuron.
The body of the second-order neuron is located in the cervical region of the spinal cord, and it’s axon exits the spinal cord and enters the sympathetic chain, which is a structure full of sympathetic ganglions or nerve cell bodies, and it runs along both sides of the spine.
Summary
Horner syndrome is a neurological disorder characterized by the combination of three main symptoms: ptosis (drooping eyelid), miosis (constricted pupil), and anhidrosis (lack of sweating on one side of the body).
Most cases of horner syndrome are caused by damage to the sympathetic nervous system, which can be due to a stroke, tumor, or injury. Less common causes include infections, autoimmune disorders, and medications. Some people also develop horner syndrome as a side effect of cancer treatment.
Sources
- "Robbins Basic Pathology" Elsevier (2017)
- "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
- "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
- "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
- "Enophthalmos Is Not Present in Horner Syndrome" PLoS Medicine (2005)
- "Neuroimaging Strategies for Three Types of Horner Syndrome with Emphasis on Anatomic Location" American Journal of Roentgenology (2007)
For Institutions
Copyright © 2023 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
Cookies are used by this site.
USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.
