Does a Pancoast tumor affect preganglionic or postganglionic sympathetic fibers?

Does a Pancoast tumor affect preganglionic or postganglionic sympathetic fibers?

• A. Preganglionic
• B. Postganglionic
• C. Both
• D. Neither

Answer: (A)

Sympathetic innervation to the head travels from the spinal cord via preganglionic neurons that exit at T1–T2, ascend in the sympathetic trunk, and synapse in the superior cervical ganglion with postganglionic neurons that reach the eye, forehead, and facial sweat glands. A Pancoast tumor at the lung apex sits beside the lower part of the sympathetic chain and can compress these fibers as they travel toward the ganglion. When the preganglionic fibers are disrupted before they synapse, the downstream postganglionic signaling to the eye and face is lost, producing Horner’s syndrome features. While postganglionic fibers could be involved if the ganglion itself were affected, the apex tumor’s location most classically interrupts the preganglionic input, making preganglionic involvement the best explanation.

Sympathetic innervation to the head travels from the spinal cord via preganglionic neurons that exit at T1–T2, ascend in the sympathetic trunk, and synapse in the superior cervical ganglion with postganglionic neurons that reach the eye, forehead, and facial sweat glands. A Pancoast tumor at the lung apex sits beside the lower part of the sympathetic chain and can compress these fibers as they travel toward the ganglion. When the preganglionic fibers are disrupted before they synapse, the downstream postganglionic signaling to the eye and face is lost, producing Horner’s syndrome features. While postganglionic fibers could be involved if the ganglion itself were affected, the apex tumor’s location most classically interrupts the preganglionic input, making preganglionic involvement the best explanation.