Lung cancers are prone to early local and distant spread.  Intrathoracic expansion of a tumor can cause a number of distinctive syndromes, including phrenic nerve irritation and palsy.

The phrenic nerve arises from the C3-C5 cervical segments and descends through the neck and thorax to innervate the ipsilateral hemidiaphragm.  Phrenic nerve irritation can cause dyspnea, hiccups (diaphragmatic irritation), and referred pain to the shoulder (area innervated by supraclavicular nerve originating from C3 and C4).  Phrenic nerve palsy is associated with respiratory distress and diminished breath sounds on the affected side, with elevation of the affected hemidiaphragm on chest x-ray.  Upward movement of the affected hemidiaphragm with inspiration is seen on fluoroscopy.

Other syndromes that may occur due to local spread of a lung tumor include:

• Horner syndrome (ipsilateral miosis, ptosis, and anhydrosis) occurs in association with tumors of the lung apex (Pancoast tumor) that disrupt the oculosympathetic nerve pathway.  Lung cancer in this location can also invade the rami of the brachial plexus (C5-T1) and cause shoulder pain (Choices D and E).
• A centrally located tumor or mediastinal spread of a more distant tumor can cause superior vena cava (SVC) syndrome, which is commonly associated with small cell lung carcinoma.  SVC syndrome causes headache, facial and upper-extremity edema, and dilated veins of the upper torso.
• Involvement of the recurrent laryngeal nerve may cause hoarseness.
• Dysphagia may result if the tumor compresses the esophagus.

(Choice A)  The brainstem, which is the site of origin of most cranial nerves, contains the respiratory center (in the medulla oblongata) and is traversed by spinal tracts.  Brainstem strokes typically present with vertigo and, in extreme cases, can lead to locked-in syndrome (spastic quadriplegia and paralysis of most cranial nerves with preserved consciousness).

(Choice B)  C1 is unique among the spinal nerves in that it carries only motor fibers.  C1-C3 lesions could affect neck musculature but would not explain this patient's hiccups or dyspnea.

Educational objective:
The phrenic nerve arises from the C3-C5 segments of the spinal cord and innervates the ipsilateral hemidiaphragm.  Intrathoracic spread of lung cancer may affect the phrenic nerve, causing hiccups and diaphragmatic paralysis with dyspnea.  Brachial plexus involvement can cause pain in the distribution of the C8, T1, and T2 nerve roots.  Involvement of the recurrent laryngeal nerve may cause hoarseness.