A 55-year-old man presents with hoarseness, difficulty swallowing, and signs of Horner syndrome. What is the likely location of the neuronal lesion?

The correct answer indicates the superior cervical ganglion as the likely location of the neuronal lesion responsible for the symptoms presented. In this case, the combination of hoarseness, difficulty swallowing, and Horner syndrome points to a disruption in the sympathetic nervous system, particularly affecting the areas that supply the head and neck.

Horner syndrome is characterized by a triad of symptoms: ptosis (droop of the upper eyelid), miosis (constricted pupil), and anhidrosis (lack of sweating) on the affected side of the face. This syndrome arises from a lesion affecting the sympathetic pathway to the eye. The superior cervical ganglion is the highest ganglion in the sympathetic chain and is responsible for innervating structures in the head and neck, including the eye (contributing to pupil dilation and upper eyelid elevation), as well as salivary glands and sweat glands.

In this scenario, the hoarseness and difficulty swallowing suggest involvement of the vagus nerve (cranial nerve X), which can be affected when there is disruption to the nearby sympathetic pathways, possibly due to a lesion in the superior cervical ganglion. Therefore, the symptoms are consistent with a sympathetic lesion at the location of the superior cervical ganglion, which effectively explains