From the Research
Yes, Horner syndrome can cause isolated ptosis without swelling. Horner syndrome is characterized by a classic triad of symptoms that includes ptosis (drooping of the upper eyelid), miosis (constriction of the pupil), and anhidrosis (reduced sweating) on the affected side of the face. The ptosis in Horner syndrome is typically mild (1-2 mm) compared to other causes of ptosis and occurs due to paralysis of the Müller's muscle, which is innervated by sympathetic nerves, as described in 1. This happens because Horner syndrome results from an interruption of the sympathetic nerve pathway somewhere between its origin in the hypothalamus and its termination in the eye and face. The ptosis occurs without inflammation or swelling because it's purely neurogenic in nature, caused by the loss of sympathetic tone rather than by any inflammatory process. Other distinguishing features that may accompany the ptosis include apparent enophthalmos (the eye appears sunken), elevation of the lower lid (upside-down ptosis), and in some cases, heterochromia (different colored irises) if the condition is congenital or long-standing. If Horner syndrome is suspected, further evaluation is necessary to determine the underlying cause, which could range from benign to serious conditions like stroke, tumor, or trauma affecting the sympathetic pathway, as noted in 2, which is the most recent and highest quality study on the topic.
Some key points to consider in the diagnosis of Horner syndrome include:
- The presence of ptosis, miosis, and anhidrosis on the affected side of the face
- The absence of inflammation or swelling
- The potential for underlying serious conditions, such as stroke or tumor
- The importance of further evaluation to determine the underlying cause, as discussed in 3 and 4.
It's also important to note that isolated ptosis can have other causes, such as myasthenia gravis or orbital myositis, as described in 5, but Horner syndrome is a possible cause of isolated ptosis without swelling.