a 66-year - old man was transferred to our hospital on february 29 , 2009 , after an episode of syncope during sleep . he had a history of acute pancreatitis at the age of 25 , and diabetes , hypertension , and dyslipidemia from his early 60s . on february 27 , 2008 , at 10:15  pm , his wife noticed he was snoring abnormally in bed , and he did not respond to her voice until after she tried many times to wake him . when the paramedic examined him at home , his consciousness level was jcs ii-20 and his bp 109/70  mmhg . his bp recovered to 121/71  mmhg in the ambulance . upon his arrival at the emergency room , there were no particular findings to cause syncope , but he was found to have a thoracic aortic aneurism and bilateral peripheral artery disease . according to his wife , he had experienced presyncopal episodes several times in the supine position recently . there were severe stenotic lesions of bilateral iliac arteries , and he was scheduled to receive percutaneous transluminal angioplasty . after admission , when he lay in the supine position for 10  min for a baroreflex function test , he experienced a sense of upper abdominal pressure , which developed into hypotension , a cold sweat , and an unpleasant feeling . during a physical exam , his face was pale , he was yawning , and he was generally sweating . his bp could not be measured , but his pulse was 60 and there was tenderness in the upper abdomin . he felt better after sitting up , but he was then admitted to our hospital . a 24-hour holter ecg presented no findings to cause syncope , and echocardiography was normal except for mild lvh . during the hospitalization , the syncope and its attendant symptoms were fully reproduced on three separate occasions when he was in the supine position ( figure 1 ) . however , we could not detect any cause of upper abdominal pain or subsequent presyncope during his hospitalization . on july 3 , 2009 , he revisited the clinic with similar complaints , which had developed to include right lateral voluntary abdominal pain with a sense of chest filling . chest - enhanced ct showed multiple metastatic tumors in the liver ( figure 2 ) originating from a small - cell carcinoma in the lung ( ct4 , n3 , m1 , stage iv ) . we did not perform an autopsy because his condition changed very much since he first visited the hospital . we experienced a reproducible supine syncope followed by upper abdominal pain . in this case , a presyncopal attack and a sense of ill - feeling were provoked by the patient lying in a prolonged supine position . because few cases of syncopal attack have been reported in the supine position [ 1 , 2 ] , its underlying mechanisms deserve consideration . neurally mediated syncope is induced in a standing position such as in the head - up tilt test . the principal mechanism of syncope is a lack of central and peripheral vasoconstriction against gravity with venous pooling . therefore , syncope attack is easily resolved by placing the patient in the supine position . on the other hand , vasovagal fainting can be induced by various circumstances , such as an unpleasant sight , emotional upset , unanticipated pain , venipuncture , prolonged upright posture , and excessive heat or dehydration . marrison and parry reported an interesting case in which nms was observed in the supine position at night . in that case , gerd was provoked by food intake at night , which caused upper abdominal pain and psychological stress , resulting in vasovagal syncope . reported a case with a systemic disease ; just after the patient lay   supine in the head - up tilt test , a syncope attack developed . unlike these reports , in the present case the patient had had diabetes , hypertension , dyslipidemia , and peripheral artery disease , but there had been no definitive trigger of upper abdominal pain , such as gastrointestinal tract disease or tumors . the cause of the pain could have been related to occult metastatic liver tumor before it was detected by contrast ct . to the best of our knowledge , there are only two reports of three cases of supine syncope , each of which had a complex medical history , such as hodgkin 's disease in the first case of iskos 's report , systemic lupus erythematosus complicated by arthritis , renal insufficiency , and anemia in the second case of iskos 's report , and atrial fibrillation , hypogonadism , osteoporosis , and arthritis in the third case . although rare , supine syncope could be a precursor of critical diseases , and thus careful followup is needed for this condition .   in the present case , metastatic liver disease was found 5 months after the patient 's first er visit , but no tumor was found at that time . there is a report that paraneoplastic syndrome ( pns ) , accompanied by small - cell carcinoma , induced nms . with regard to pns , neurological symptoms such as lambert - eaton myasthenic syndrome and encephalomyelitis would be possible , but nms is the least possible manifestation of pns . therefore , a possible explanation would be a tumor microinvasion at the liver that was undetectable by ct scan presented at the liver membrane and caused the pain . namely , nms with the patient in the supine position could have been an alarm of the pain of small - cell carcinoma . in conclusion , what we learned from this case would be that a careful malignancy survey is important when we see a rare case of autonomic neuropathy .
we experienced a reproducible supine syncope followed by upper abdominal pain . 
 a 66-year - old man was transferred to our hospital after an episode of syncope during sleep . 
 he had a history of acute pancreatitis , diabetes , hypertension , and dyslipidemia , but no history of presyncopal attack . 
 one night , his wife noticed he was snoring abnormally in bed , and he did not respond to her voice until after she tried many times to wake him . 
 the same attack was reproduced three times in the same situation . 
 one of the attacks was recorded under a continuous ecg and radial tonometry . in this case , a presyncopal attack and a sense of ill - feeling were provoked by the patient lying in a prolonged supine position . 
 he was eventually diagnosed as metastatic liver tumor 5 months after the first attack . because few cases of syncopal attack have been reported in the supine position , its underlying mechanisms deserve consideration .