syncope is defined as a transient loss of consciousness that occurs spontaneously and is rapidly reversible with minimal intervention . it is caused by a wide variety of disorders that range from common benign disorders to severe life - threatening diseases . even when an extensive evaluation of syncope is undertaken , its cause may be difficult to diagnose ; data from sarasin et al . show unexplained syncope in 20% or more of patients with syncope in the emergency department despite standardized evaluation . carotid sinus syndrome , a variety of neurally mediated syncope , is rarely associated with malignancy . we describe a patient who suffered from recurrent syncope due to tumor compression of the carotid sinus by metastases of a carcinoma of the esophagus , successfully treated with radiotherapy . a 76-year - old man was admitted to our hospital for recurrent syncope occurring while sitting or standing , preceded by headache and followed by circumstantial amnesia without neurological deficits . two years before the admission , he was treated with chemotherapy and radiotherapy for a squamous cell carcinoma of the middle third of the esophagus with mediastinal lymph node metastasis ; after 16 months , he received second - line chemotherapy because of tumor recurrence . on admission , temperature was 36.5c , pulse 90 beats / min , and blood pressure 134/78 mm hg . the laboratory tests and chest x - ray were unremarkable ; the ekg showed an atrial fibrillation and signs of ventricular hypertrophy without ischemia . during hospitalization , one episode , characterized by loss of consciousness for 30 s associated with a gaze deviation to the left , diaphoresis , pallor , and hypotension ( 60/30 mm hg ) without bradycardia , occurred during a 24-hour electrocardiographic monitoring . a transthoracic echocardiography showed a low - gradient aortic stenosis ( valve area 1 cm , mean gradient 16 mm hg , aortic jet velocity 3.1 m / s ) and normal ejection fraction of the left ventricle with important concentric hypertrophy ; an exercise spect study with thallium and cardiac mri excluded myocardial ischemia . as symptoms were not typical for valvular abnormality as a single etiology and the patient had a past history of ischemic stroke , neurological investigations were completed by eeg , brain mri , and carotid - vertebral duplex doppler sonography : all these investigations yielded normal results . finally , an upright tilt - table test was performed , showing a fall in the arterial blood pressure reproducing symptoms without any change in heart rate , consistent with reflex syncope of vasodepressor type ( fig . a cervical computed tomography ( ct ) showed the presence of a cervical mass infiltrating the sheath of the right common carotid artery just below and in contact with the carotid bifurcation , without involvement of the retropharyngeal space . we renounced to any histological samples of this mass because an upper gastrointestinal endoscopy confirmed a relapse of the esophageal cancer ( fig . 3 ) . given the poor condition of the patient , we opted for a targeted radiotherapy treatment on the right carotid sheath . he finally received 5 sessions ( 30 gy in total ) and eventually died 6 weeks later of an episode of severe broncho - aspiration . the initial evaluation of a patient presenting with syncope consists of careful history , physical and electrocardiographic examination . our patient presented many clinical features that initially suggested a cardiovascular syncope , like abnormal ekg and presence of definite valvular heart disease . however , because of an atypical presentation for a syncope due to valvular disease , we continued the investigations , according to the recently published esc guidelines for the diagnosis and management of syncope . we performed an upright tilt - table test which turned out positive and led us to look for a malignant etiology in the context of this patient . neurally mediated syncope ( also named reflex syncope ) is the most common group of disorders causing syncope . these disorders result from reflex - mediated modifications in vascular tone or heart rate characterized by a sudden failure of the autonomic nervous system to maintain blood pressure and sometimes heart rate at a sufficient level to insure cerebral perfusion and consciousness . conditions in this group comprise neurocardiogenic ( vasovagal ) syncope , situational syncope , carotid sinus syndrome and glossopharyngian neuralgia . malignancy - related reflex syncope is rare : in a series of 4,500 patients with cancer of the head and neck , the prevalence of syncope was estimated at 0.4% . patients with advanced tumoral disease at diagnosis and those with a history of neck surgery appear to be at greater risk of developing syncope . syncope may be an early sign of neck or cervical cancer   and even the sole sign of recurrent disease . however , cases of lymphomas , neurofibromas or metastatic breast   or lung   malignancies have been reported . to our knowledge , the reflex arc of the carotid sinus is composed of an afferent pathway arising from baroreceptors located just above the bifurcation of the carotid artery . in case of arterial wall stretching , the information is transmitted by the carotid sinus nerve [ a branch of the glossopharyngeal nerve ( 9th cranial nerve ) ] to brainstem centers in the caudal nucleus of the solitary tract . interneurons then activate the efferent pathways resulting in the stimulation of the parasympathetic and the inhibition of the sympathetic systems leading to lower blood pressure and heart rate ( fig . 4 ) . overstimulation of this reflex caused by mechanical traction or invasion of the carotid sinus by a tumor , or caused by tumor - induced irritation of the glossopharyngeal nerve ( glossopharyngeal neuralgia ) may produce symptoms . patients with glossopharyngeal neuralgia usually have acute unilateral head or neck pain prior to syncopal attacks . the cardiovascular responses of neurally mediated syncope are classified into three types : cardioinhibitory response ( asystole or symptomatic bradycardia associated with hypotension or not ) , vasodepressor response ( hypotension without bradycardia ) , and a mixed response with features of both . pure vasodepressor form , as evidenced in our patient by the upright tilt - table test , is thought to account for only 510% of cases of reflex syncope , although its prevalence increases up to 59% in the context of malignant forms . a large variety of medications have been used , including anticholinergics , vasoconstrictors , volume expanders , such as fludrocortisone , and antiepileptic drugs , such as carbamazepine , especially in case of glossopharyngeal neuralgia . cardiac pacing may be ineffective in reflex syncope due to malignancy in which a mixed - response type ( cardioinhibitory and vasodepressor ) is usually present and may even promote emergence of vasodepressor manifestation . surgical treatment includes intracranial glossopharyngeal and vagal neurectomy   and is reserved for patients in whom standard treatment failed . depending on the type of cancer , several cases of complete resolution of symptoms with chemotherapy have been reported [ 12 , 13 ] . in our case , the patient could not be treated with chemotherapy , because the disease progressed despite multiple prior courses of chemotherapy . radiation therapy may be effective by reducing the frequency of syncope , pain , and tumor size , but the procedure itself carries the risk of causing symptoms due to the application of pressure on the carotid sinus during the installation of the patient . in conclusion , we reported the case of a patient with reflex vasodepressor syncope due to hypersensitivity carotid sinus secondary to recurrent , metastatic esophageal carcinoma , successfully relieved by radiotherapy . because syncope may be an early sign of neck or cervical cancer and even the sole sign of recurrent disease , the diagnostic approach of syncope in patients with past history of cancer should include the possibility of neck tumor recurrence or metastasis and an oncologic workout should be considered .
syncope is caused by a wide variety of disorders . 
 recurrent syncope as a complication of malignancy is uncommon and may be difficult to diagnose and to treat . 
 primary neck carcinoma or metastases spreading in parapharyngeal and carotid spaces can involve the internal carotid artery and cause neurally mediated syncope with a clinical presentation like carotid sinus syndrome . 
 we report the case of a 76-year - old man who suffered from recurrent syncope due to invasion of the right carotid sinus by metastases of a carcinoma of the esophagus , successfully treated by radiotherapy . in such cases , surgery , chemotherapy or radiotherapy can be performed . because syncope may be an early sign of neck or cervical cancer , 
 the diagnostic approach of syncope in patients with a past history of cancer should include the possibility of neck tumor recurrence or metastasis and an oncologic workout should be considered .