Acute Painful Horner Syndrome as the First Presenting Sign of Carotid Artery Dissection
Background: Horner syndrome is a rare neurologic disorder that can arise from severe neurologic and systemic conditions, which may require immediate diagnosis with radiologic imaging and treatment with antiplatelet and anticoagulant therapy. Horner syndrome is often asymptomatic but can have distinct, easily identified characteristics seen with an ophthalmic examination.
Case Presentation: A 61-year-old woman presented with periorbital pain localized around and behind the right eye that she rated as 7 on a 10-point scale with onset 3 days prior. She reported light sensitivity, syncope, dizziness, and a recent history of transient ischemic attacks of unknown etiology. The patient had acute, slight ptosis with pathologic miosis and pain in the ipsilateral eye with no reports of exposure to miotic pharmaceutical agents and no history of trauma to the globe or orbit eliminated other differentials, leading to a diagnosis of right-sided Horner syndrome. She was referred for emergency department evaluation where radiography was indicative of an internal carotid artery dissection.
Conclusions: Due to possible life-threatening complications that can arise in patients with Horner syndrome, clinicians must have a thorough understanding of the condition, appropriate treatment, and management modalities. Determining the underlying etiology of Horner syndrome can help prevent a decrease in a patient’s vision or quality of life and in some cases prevent death. Magnetic resonance imaging and computed tomography should be used to rule out carotid artery dissection and other severe conditions.
Pathologic Miosis
Pathologic miotic pupils can result from dysfunction in the sympathetic nervous system and can be related to blunt or penetrating trauma to the orbit, Horner syndrome, and pharmacologic miosis.2 Horner syndrome will be accompanied by a slight ptosis and sometimes anhidrosis on the ipsilateral side of the face. To differentiate between traumatic and pharmacologic miosis, a detailed history should be obtained, paying close attention to injuries to the eyes or head and/or possible exposure to chemical or pharmaceutical agents, including prostaglandins, pilocarpine, organophosphates, and opiates.2
Horner Syndrome
Horner syndrome is a neurologic condition that results from damage to the oculosympathetic pathway.4 The oculosympathetic pathway is a 3-neuron pathway that begins in the hypothalamus and follows a circuitous route to ultimately innervate the facial sweat glands, the smooth muscles of the blood vessels in the orbit and face, the iris dilator muscle, and the Müller muscles of the superior and inferior eyelids.1,5 Therefore, this pathway’s functions include vasoconstriction of facial blood vessels, facial diaphoresis (sweating), pupillary dilation, and maintaining an open position of the eyelids.1
Oculosympathetic pathway anatomy. To understand the findings associated with Horner syndrome, it is necessary to understand the anatomy of this 3-neuron pathway.5 First-order neurons, or central neurons, arise in the posterolateral aspect of the hypothalamus, where they then descend through the midbrain, pons, medulla, and cervical spinal cord via the intermediolateral gray column.6 The fibers then synapse in the ciliospinal center of Budge at the level of cervical vertebra C8 to thoracic vertebra T2, which give rise to the preganglionic, or second-order neurons.6
Second-order neurons begin at the ciliospinal center of Budge and exit the spinal cord via the central roots, most at the level of thoracic vertebra T1, with the remainder leaving at the levels of cervical vertebra C8 and thoracic vertebra T2.7 After exiting the spinal cord, the second-order neurons loop around the subclavian artery, where they then ascend close to the apex of the lung to synapse with the cell bodies of the third-order neurons at the superior cervical ganglion near cervical vertebrae C2 and C3.7
After arising at the superior cervical ganglion, third-order neurons diverge to follow 2 different courses.7 A portion of the neurons travels along the external carotid artery to ultimately innervate the facial sweat glands, while the other portion of the neurons combines with the carotid plexus and travels within the walls of the internal carotid artery and through the cavernous sinus.7 The fibers then briefly join the abducens nerve before anastomosing with the ophthalmic division of the trigeminal nerve.7 After coursing through the superior orbital fissure, the fibers innervate the iris dilator and Müller muscles via the long ciliary nerves.7
