From the Research
Enophthalmos in Horner's syndrome is caused by paralysis of the sympathetic innervation to Müller's muscle, leading to a relaxation of the muscle and a slight sinking of the eyeball backward into the orbit. This occurs because Müller's muscle normally provides a small amount of forward tension on the globe when functioning properly. The sympathetic pathway disruption in Horner's syndrome can occur at various points along the three-neuron pathway from the hypothalamus to the eye, resulting from conditions such as stroke, tumor, trauma, or other lesions affecting the sympathetic chain 1.
Key Points
- The enophthalmos is typically mild (1-2 mm) and is often accompanied by other classic signs of Horner's syndrome including ptosis (drooping of the upper eyelid), miosis (constricted pupil), and anhidrosis (reduced sweating) on the affected side of the face.
- No specific treatment is needed for the enophthalmos itself, as management focuses on addressing the underlying cause of the sympathetic disruption.
- Pharmacological testing with apraclonidine eye drops can help diagnose Horner's syndrome and may also have an elevating effect on the upper eyelid, which can be useful in managing ptosis associated with the condition 1.
- The use of apraclonidine testing can improve the diagnostic accuracy of Horner's syndrome, with a decrease of inter-eye difference in the aperture of >0.42 mm being discriminative of Horner's syndrome compared to physiological anisocoria 1.
Management
- Management of Horner's syndrome focuses on addressing the underlying cause of the sympathetic disruption, which may involve treatment of underlying conditions such as stroke, tumor, or trauma.
- Pharmacological testing with apraclonidine can be useful in diagnosing and managing Horner's syndrome, particularly in cases where the diagnosis is uncertain or the patient has significant ptosis 1.