All of the following are components of Horner’s syndrome except –
**Core Concept**
Horner's syndrome is a neurologic disorder characterized by the disruption of sympathetic nerves supplying the eye, resulting in a triad of symptoms: ptosis (drooping eyelid), miosis (pupillary constriction), and anhidrosis (absence of sweating). The condition can be caused by lesions affecting the sympathetic pathway from the hypothalamus to the orbit.
**Why the Correct Answer is Right**
Horner's syndrome involves the interruption of sympathetic innervation to the eye. This occurs due to the disruption of the oculosympathetic pathway, which includes the hypothalamus, the Edinger-Westphal nucleus, the superior cervical ganglion, and the nasociliary nerve. The affected structures lead to decreased sympathetic tone, resulting in ptosis, miosis, and anhidrosis.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as ptosis is a characteristic feature of Horner's syndrome, caused by the paralysis of the superior tarsal muscle due to the interruption of sympathetic innervation.
**Option B:** This option is incorrect as miosis is a hallmark of Horner's syndrome, resulting from the disruption of the sympathetic pathway that normally dilates the pupil.
**Option C:** This option is incorrect as anhidrosis is a component of Horner's syndrome, manifesting as reduced or absent sweating on the affected side of the face.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that Horner's syndrome can be caused by a variety of conditions, including stroke, trauma, tumors, and congenital anomalies. The presence of Horner's syndrome should prompt a thorough evaluation to identify the underlying cause.
**Correct Answer: A. Enophthalmos**