DISCUSSION:
Our patient had a lung malignancy presenting as hemifacial pain syndrome and vocal cord palsy. In addition, the pain had the features of vagal cephalalgia, a type of atypical facial pain syndrome.
This facial pain is characterized by its unilateral nature, an aching quality that worsens over minutes and is localized around the ear, jaw, and temple. One of the causes of this type of pain is lung cancer, with the pain occurring ipsilateral to the cancer site, showing a dextral dominance [5]
The clinical characteristics of several documented cases of facial pain associated with lung cancer can be found in the literature. The ear, the mandible, and the temporal region are the most typical locations for face pain, which is nearly invariably unilateral. The discomfort may be constant or intermittent and is commonly described as intense and painful. Digital clubbing, an elevated ESR, and hypertrophic osteopathy may also influence the diagnosis. Treatment of face pain with radiotherapy and tumor removal via vagotomy is quite successful. Lung cancer should be considered when making a differential diagnosis for facial pain that is unusual or unresponsive to treatment. Face pain related to non-metastatic lung cancer may be caused by referred pain from vagal nerve invasion or compression and paraneoplastic syndrome brought on by the generation of circulatory humoral factors by the cancerous cells.
This is an uncommon presentation of lung malignancy. This pain arises as a referred pain from the lung via the vagus nerve. The visceral and somatic afferents terminate in the trigeminal nucleus. Due to the convergence of somatic and visceral afferents in the central nervous system (CNS), visceral pain is referred to as the somatic segment where they enter the CNS. Dextral dominance can be explained by the relationship of the right vagus nerve with the main bronchus and trachea, as the tumor can directly infiltrate the nerve.
In contrast, the left vagus is separated by the great vessels. Afferent impulses travel via the visceral afferents and connect with their somatic counterparts. Due to the extensive synapsing of cranial nerves V, VII, IX, and X in the trigeminal nucleus, a larger area of the face can be involved [6].
Sarlani E et al. also postulated the role of circulating humoral factors produced by the tumor causing a paraneoplastic syndrome as a possible explanation of facial pain in lung carcinoma [7].
A few similar cases in the literature are described below: