Horner's Sign

Historical Overview

• In 1854, French physiologist Claude Bernard described a condition found in animals in which disruption of sympathetic innervation to the eye gave rise to miosis, ptosis, and anhidrosis.¹
• In 1869, Swiss ophthalmologist Johann Friedrich Horner provided a more complete assessment of this condition and correctly attributed it to oculosympathetic paresis, which led to creation of the honorific term “Horner’s syndrome.”^1,2

Description

• Horner’s sign, or syndrome, is actually a combination of classical clinical signs—the triad of ipsilateral ptosis, pupillary miosis, and facial anhidrosis—that occur secondary to damage or interruption of the oculosympathetic pathway.^2,3

Pathophysiology

• Horner’s syndrome may develop from lesions at any point along the sympathetic pathway, and it can be either acquired or congenital. Classically, the cause of congenital Horner's syndrome has been birth trauma resulting in brachial plexus injury (Klumpke's palsy), but more aggressive etiologies, such as neuroblastoma and carotid artery thrombosis, have also been seen.⁴
• Potential causes of acquired Horner’s syndrome include: primary or preganglionic neuron lesions, stroke, tumor, migraine, carotid artery ischemia, brachial plexus trauma, dissecting carotid aneurysm, middle cranial fossa neoplasm, and iatrogenic injury.
  • The long anatomical pathway of the oculosympathetic chain makes it vulnerable to many pathological processes. 
  • In most cases, the cause of isolated Horner’s syndrome is benign or from a previously identified cause, such as surgery, but it’s important to also consider the possibility of carotid dissection and neoplasm.³

Instructions

1. Obtain an accurate and complete patient history, including prior trauma, sensory loss, and pain in the face, neck, shoulders, or arms. Also ask if the patient has recently undergone an interventional procedure that has the potential to cause relevant neurologic damage.
2. Measure the pupillary diameter in dim and bright light and the reactivity of the pupils to light and accommodation.
3. Examine for dilation lag of the pupil immediately after dimming the lights.
4. Examine the upper lids for ptosis and the lower lids for upside-down ptosis.
5. Observe for extraocular movements.
6. Perform a biomicroscopic examination of the pupillary margin and iris structure and color.
7. Perform a visual field testing and test of facial sensation.
8. Observe for the presence of nystagmus, facial swelling, lymphadenopathy, or vesicular eruptions.⁵

Related Signs and Tests^3,4

• The “harlequin” sign: asymmetric facial flushing
• Pharmacological testing
  • 4% cocaine drops
  • Apraclonidine
  • Hydroxyamphetamine
  • Pholedrine
• Carotid Doppler ultrasound
• Chest X-ray
• Cervical spine X-ray
• MRI

Diagnostic Performance Characteristics

• A diagnosis of Horner’s syndrome should be considered in any patient with anisocoria associated with what appears to be normal pupillary constriction to light in both the larger and smaller pupil. The presence of dilation lag of the smaller pupil, when present, is also helpful in making the diagnosis.
  • Patients in whom Horner’s syndrome is suspected should be evaluated for evidence of cranial nerve dysfunction, particularly an ipsilateral abducens nerve paresis that may indicate a lesion of the cavernous sinus or, in very rare cases, of the brain stem.¹

• A positive result occurs when the clinician observes the classic triad of ipsilateral ptosis, pupillary meiosis, and facial anhydrosis with enophthalmos (sunken globe).⁷

• A negative result occurs when the clinician does not observe the classic triad of ipsilateral ptosis, pupillary miosis, and facial anhydrosis with enophthalmos (sunken globe).⁷

• The etiologies of Horner’s syndrome are numerous, with some being life-threatening. Therefore, clinicians evaluating a possible Horner’s syndrome must carefully assess the patient for other neurologic manifestations that may help confirm the diagnosis and localize the site of injury. This is why in addition to a complete physical examination, pharmacological testing should also be used to accomplish this.¹
  • The diagnosis of Horner’s syndrome characteristics is not straightforward, as the clinical signs may be subtle and it is not common for patients to present with the classic triad of signs; however, the diagnosis will be more likely if it is suspected, as failing to recognize the condition might cause permanent, long-term disability.^3,6
  • Since these signs are often subtle, additional testing is often needed.³
• It has been suggested that pharmacological methods of localizing sympathetic lesions may be less reliable in congenital Horner's syndrome than acquired Horner's syndrome. Such atypical responses are not widely acknowledged and may have implications in the management of congenital Horner's syndrome.⁴

1. Kanagalingam, S and Miller, NR. Horner syndrome: clinical perspectives. Eye Brain 2015;7:35-46. PMID: 28539793
2. Nasser, BA, Mesned, A, Moazamy, YE, et al. Horner's syndrome after paediatric cardiac surgery: case report and review of the literature. Cardiol Young 2015;25(3):569-72. PMID: 24717921
3. Davagnanam, I, Fraser, CL, Miszkiel, K, et al. Adult Horner's syndrome: a combined clinical, pharmacological, and imaging algorithm. Eye (Lond) 2013;27(3):291-8. PMID: 23370415
4. Morrison, DA, Bibby, K and Woodruff, G. The "harlequin" sign and congenital Horner's syndrome. J Neurol Neurosurg Psychiatry 1997;62(6):626-8. PMID: 9219751
5. Bardorff, C. Horner Syndrome-Clinical Presentation. Medscape. 2017.
6. Lazar, I, Cavari, Y, Rosenberg, E, et al. Horner's syndrome in patients admitted to the paediatric intensive care unit: epidemiology, diagnosis and clinical practice. Anaesth Intensive Care 2013;41(1):20-3. PMID: 23362886
7. Hentz VR, Narakas A. The result of microsugical management of brachial plexus palsy.   Assessing outcome and predicting results Orthop Clin North Am 1988: 19(1): 107