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: