From the Guidelines
Horner's syndrome is a neurological condition that requires a thorough clinical examination, including a complete ophthalmic examination with emphasis on sensorimotor evaluation, to identify the underlying cause and guide treatment. The syndrome is characterized by a triad of symptoms: miosis (pupil constriction), ptosis (drooping eyelid), and anhidrosis (reduced sweating) on one side of the face, occurring due to disruption of the sympathetic nerve pathway from the brain to the face and eye 1. According to the adult strabismus preferred practice pattern, a careful check for other neuro-ophthalmic signs and symptoms, including Horner’s syndrome, cranial nerve palsy, INO, nystagmus, and hearing loss, is essential during the examination 1.
Key elements of the examination include:
- Complete ophthalmic examination with emphasis on sensorimotor evaluation
- Complete three-step test and consideration of the additional upright-supine test
- Fundus examination to check for papilledema or optic atrophy
- Visual field testing to provide additional information on the etiology
- Checking for abnormalities in the rostral pons and midbrain, which can result in contralateral hypotropia and head tilt, whereas abnormalities in the vestibular periphery, medulla, and more caudal pons will result in ipsilateral hypotropia and head tilt 1.
The comprehensive adult medical eye evaluation preferred practice pattern also highlights the importance of identifying signs of systemic diseases or other serious medical conditions during the ocular comprehensive ophthalmic evaluation, including pupillary function to identify Horner’s syndrome, pharmacologic toxicity, midbrain tumor, or aneurysm 1. Treatment of Horner's syndrome focuses on addressing the underlying cause, and patients with unexplained Horner's syndrome should undergo thorough evaluation, including imaging studies of the brain, neck, and chest, to identify potentially serious underlying conditions.
From the Research
Definition and Symptoms of Horner's Syndrome
- Horner's syndrome refers to the clinical triad of ptosis, miosis, and anhidrosis resulting from disruption of the ocular and facial sympathetic pathways 2.
- The syndrome consists of unilateral ptosis, an ipsilateral miotic but normally reactive pupil, and in some cases, ipsilateral facial anhidrosis, all resulting from damage to the ipsilateral oculosympathetic pathway 3.
Causes of Horner's Syndrome
- A myriad of etiologies can lead to Horner's syndrome, including trauma, cervical artery dissection, and infarction 2.
- Procedures in the neck, chest, skull base, and paraspinal region accounted for most of the identified causes, with cervical carotid dissection the next most common cause 4.
- Tumors, such as Pancoast tumors, are also a possible cause, although they are discovered only in a small minority of Horner's syndrome cases 2.
Diagnosis and Investigation
- The diagnosis of Horner's syndrome can be difficult, as patients rarely present with the classic triad of ptosis, miosis, and anhydrosis 5.
- Pharmacologic testing, such as with apraclonidine, can confirm the presence of Horner's syndrome and direct further testing and management 3, 4.
- A practical and safe combined clinical and radiological diagnostic protocol for Horner's syndrome can be applied in most clinical settings 5.
Clinical Significance
- Awareness of the underlying anatomy and array of possible etiologies can assist physicians in identifying potential causes and initiating appropriate care 2.
- In an important minority of cases, the identification of Horner's syndrome is critical to the discovery of underlying conditions such as carotid dissection or tumor 4.