Horner’s syndrome. All true except
**Core Concept**
Horner's syndrome is a neurological disorder characterized by a disruption in the sympathetic nerves supplying the eye, resulting in a triad of symptoms: ptosis (drooping eyelid), miosis (constricted pupil), and anhidrosis (lack of sweating) on the affected side. This occurs due to the interruption of sympathetic fibers in the oculosympathetic pathway.
**Why the Correct Answer is Right**
The oculosympathetic pathway involves the hypothalamus, the brainstem, and the spinal cord, ultimately leading to the release of norepinephrine at the superior cervical ganglion. This neurotransmitter then travels to the eye via the carotid plexus and the ciliary ganglion, where it causes dilation of the pupil and contraction of the eyelid. In Horner's syndrome, the interruption of this pathway leads to miosis, ptosis, and anhidrosis on the affected side.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is a true statement about Horner's syndrome, so it's not the answer we're looking for.
**Option B:** This option is incorrect because the symptoms of Horner's syndrome are ipsilateral, meaning they occur on the same side as the lesion. The contralateral option is incorrect.
**Option C:** This option is incorrect because Horner's syndrome is not typically associated with a loss of vision. The primary symptoms are ptosis, miosis, and anhidrosis.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that Horner's syndrome can be caused by a wide range of conditions, including stroke, tumor, trauma, and congenital conditions. A thorough history and physical examination are crucial in identifying the underlying cause.
**Correct Answer: D.**