Are syncopes in sitting and supine positions different? Body positions and syncope: A study of 111 patients
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0028-3886.115060
Source of Support: None, Conflict of Interest: None
Context: Syncope is a common cause of transient loss of consciousness. In the analysis of patients having syncope, body position has not been systematically studied and correlated with triggers, prodromal symptoms and circumstances. This correlation is important in differentiating syncope from its mimics. Aims: To study syncope with respect to body positions, triggers, prodromal symptoms and circumstances. Settings and Design: Prospective study set in Neurology Department of Tertiary Care Center. Materials and Methods: Patients fulfilling guidelines set by The Task Force for the Diagnosis and Management of Syncope of the European Society of Cardiology (ESC) were recruited. Detailed clinical history, examination and investigations (ECG, 2D-ECHO, Head Up Tilt Test, Holter monitor, EEG, MRI Brain) were carried out. Results: Out of the 111 recruited patients, 67 developed syncope in standing, 16 in sitting, 23 in both standing and sitting, 1 in both sitting and supine and 4 in all three positions. Prodromal symptoms were present in 81% while triggers in 42% and circumstances in 41% of patients. Black out, sweating, dizziness and headache were most common prodromal symptoms. Intense pain, smell and fear were most common triggers while prolonged standing, hot crowded room and fasting were most common circumstances associated with syncope. Conclusions: Against common belief, syncope can occur in sitting as well as in supine position. Emotional triggers were commoner in patients with syncope in supine and sitting positions while prodromal symptoms and circumstances were similar for all positions. Syncope should be considered in body positions other than standing.
Keywords: Body position, circumstances, prodromal symptoms, syncope, triggers
Syncope or transient loss of consciousness (T-LOC) due to transient global cerebral hypoperfusion can be confused with disorders producing transient neurological dysfunction like seizures, metabolic disorders, vertebrobasilar ischemia, migraine, and intoxications.  Syncope tends to occur in standing position due to gravitational effects. In supine position, it is uncommon because of absence of orthostatic stress and presence of gravitational effects, which maintains adequate cerebral perfusion.  Triggers, prodromal symptoms, and circumstances in relation to body positions have received less attention. Here, we studied 111 patients with particular attention to body position and its correlates.
This is a prospective study carried out at a tertiary care neurology department from January 2011 to July 2012; consecutive patients fulfilling guidelines given by The Task Force for the Diagnosis and Management of Syncope of the European Society of Cardiology 2009  were included.
Inclusion and exclusion criteria:
Patients were investigated with electrocardiography, 2D echocardiography, electroencephalography, 24-h holter monitoring, head-up tilt test, and brain imaging. Head-up tilt test was carried out with standardized protocol and provocation was done in indicated patients over the age of 15 years.  Whenever transient loss of awareness was likely to be attributed to functional causes like phobia, psychiatric evaluation was done.
In patients with supine syncope, special attention was given to exclude cardiac arrthythmia and epilepsy. Scoring system developed by Sheldon  was used to distinguish syncope from seizures. These 5 patients underwent 24-h holter monitoring. As yield of 24-h holter monitor is 1-2% in unselected population,  we used following parameters given by Calkins et al.  : Male sex, age >54 years, ≤2 episodes of syncope, and duration of warning of ≤5 s-as predictors of syncope due to AV block or ventricular tachycardia. To select patients for prolonged holter monitoring, we used criteria developed by Bass et al. 
A total of 111 patients fulfilled the inclusion criteria. There were 67 males and 44 females in this study with a mean age of 35.91 years (± standard deviation 19.78).
Out of 111 patients, 67 patients developed syncope only in standing position, 16 patients only in sitting position, and the rest developed syncope in more than one body position at different events. E.g., 23 patients in both standing and sitting positions, 1 patient in both sitting and supine positions, and 4 patients in all three positions. No patient developed syncope only in supine position.
Prodromal symptoms were present in 81% patients, while triggers were present in 42% and circumstances in 41%. These were analyzed in relation to body positions. The percentages were calculated keeping the total number of positive events as denominator and not from total number of patients for accurate reflection.
Darkening of vision (48.65%) was the most common prodromal symptom in all positions. Sweating (36.94%), dizziness (33.33%), and headache (15.32%) were common prodromal symptoms in syncope during standing as well as in sitting position. Headache (20%) was more common than sweating (13.33%) and dizziness (13.33%) in supine position. In addition, we found rare prodromal symptoms like shoulder pain, throat pain, irritability, and chocking sensation [Figure 1].
Common triggers for syncope in standing positions in decreasing order of frequency were intense pain (12.77%), smell (10.64%), fear (8.51%), and blood sight (4.26%). While in supine and sitting positions, smell (50% and 18.75%, respectively) and intense pain (16.67% and 12.50%, respectively) were common triggers. Situational syncope was seen in standing (17.12%) and sitting position (4.5%). Micturation (16.22%) was common trigger among various cause of situational syncope, while cough (12.50%), micturation (6.25%), laughing (6.25%), and defecation (6.25%) were encountered in sitting positions. Other triggers like head movements, sleep deprivation, seeing blood, alcohol intoxication, weight lifting, reading, concentration, anxiety, playing, and ear cleaning were rare [Table 1].
Prolonged standing (35.59%) was common circumstance, preceding syncopal episodes, mainly while standing in queue in crowded temple, especially in summer season. Hot crowded closed space and fasting and summer season were common during episodes in standing as well as in sitting positions. Prolonged fasting (50%) was relatively common in episodes during supine position, followed by hot crowded closed space and summer season. Prolonged sun exposure, postprandial state, fatigue, after awakening, hospital environment, febrile illness, and diarrheal illness were other common circumstances preceding syncope [Table 1].
Four out of the 5 patients who developed syncope in supine position also experienced syncopal events in standing and sitting positions, and the fifth patient had events in sitting and supine positions. Triggers were different in different body positions in the same patient. For example, weight lifting in standing and unpleasant smell in supine position, and, similarly, abdominal pain in sitting position and unpleasant smell in supine position. Prodromal symptoms remained consistent in individual patients for all events in all positions. Prolonged standing was the most frequent circumstance in syncope while standing in all four patients who also had supine syncope.
During spell, common observations were limb movements (8.11%), followed by color changes (5.41%) and uprolling of eye balls (3.6%) in both standing and sitting positions. Color changes (28.57%) were more frequently observed, followed by injury (28%), limb movements (14.29%) and urinary incontinence (14.29%) in supine syncope. Hyperventilation (0.9%), urinary incontinence (0.9%), and vomiting (0.9%) were very rare.
After syncope, headache (9.91%) was commonest complaint in all three positions, followed by weakness (7.21%) in standing and sitting position, while vomiting (40%) was quite common in supine position. Rarely patients had experienced dizziness (3.6%), fever (3.6%), hyperventilation (0.9%), palpitation (0.9%), and abdominal pain (0.9%).
We studied 5 patients with supine syncope in further details to excluded seizure and cardiac causes. Sheldon scoring system  in these patients suggested syncope and not seizure. Calkin et al.  and Bass et al.  parameters were applied to these 5 patients, and they scored in the low yield group for cardiac causes and for long-term holter monitoring. Hence, loop recorder was not used for them. Four out of these 5 patients had concomitant migraine.
We found more than one mechanism operating for syncope in same patient during different episodes like emotional stress, orthostatic stress, and situational syncope.
Nature of syncope in different body positions are mentioned in [Table 2]. Patients have syncope in more than one position and more than one mechanism of syncope, hence the total exceeds 111 in [Table 2].
In the present study, syncope was not uncommon in sitting and supine positions (20.72% in both sitting and standing positions, 14.41% had in only sitting position, 3.6% had in all positions and 0.9% had in both sitting and supine positions). This fact needs to be highlighted, as events in body positions other than standing often take the neurologist away from the diagnosis of syncope. There are limited references for body positions during syncope; only three series ,, and anecdotal case reports ,, are available regarding the same. Graham et al.  reported 19% syncope to occur in sitting position, which is comparable to that in the present study; however, there were no patients of supine syncope in Graham's study. Sorajja et al.  studied syncope during driving and found 9.8% of patients getting syncope while driving [sitting]. This study does not comment on sitting syncope besides driving. The sole study on supine syncope seems different  as they enrolled patients who had syncope during sleep only. This study did not evaluate other body positions. Moreover, all these three series are not strictly comparable to the present study as prodrome, triggers, and circumstances had not been fully analyzed in these studies.
In the present study, we analyzed prodrome, triggers, and circumstances at the time of occurrence of syncope in relation to body positions, in particular, supine and sitting.
Prodromal symptoms were important for their consistent presence (81%) in all patients of syncope, irrespective of their body positions. Also, analysis of individual prodromes in relation to a particular body position did not yield any differences. Thus, prodromes were consistent and similar in all body positions. This finding is not unexpected as the pathophysiological sequences in all body positions would remain the same, as they lead to syncope. Comparing the available literature, ,, it is interesting that the frequency of individual prodromal symptoms was different in various studies of syncope. [Table 3] highlights these differences. The significance of these differences is unclear.
Intense pain, smell, fear, and anxiety were the main triggers in patients having syncope in sitting and supine positions. It is well known that strong emotional stimuli by themselves may induce a vasovagal reaction in susceptible individuals, even in the absence of gravitational stress.  This is the most likely explanation in our patients having syncope in sitting and supine positions. The same pathophysiological mechanism of emotional stimulation triggering vasovagal reaction has been postulated for syncope while driving.  Situational syncope like micturition, coughing, laughing, and defecation formed the other group of triggers in sitting position.
Circumstances were encountered in 41% patients. When present, they were hot crowded closed space, prolonged fasting, and summer season. They are believed to aggravate the process by causing dehydration, cutaneous vasodilatation, and venous pooling, which decreases the cerebral perfusion, leading to syncope in sitting and supine positions even in the absence of gravity. Sorajja et al.  postulated a hypothesis that these factors can trigger syncope while driving. Thus, when present, circumstances help in diagnosis, because such circumstances rarely lead to other conditions mimicking syncope.
During and after spell, events did not differ according to the body position at the time of syncope suggesting that the sequence of events, once set in, is similar irrespective of the body position.
Syncope can occur in all body positions and in more than one position in individual patients. Prodromal symptoms are more consistent than triggers and circumstances preceding syncope. While prodromes tend to be similar to all body positions, triggers can be different in different body positions in the same patient. Triggers related to emotional disturbances are common for syncope in sitting and supine positions. Circumstances for occurrence of syncope are uniform for all body positions and are helpful in differential diagnosis. During spell and after spell events are uniform in all body positions.
Syncope should be considered as a differential diagnosis of T-LOC in supine and sitting positions after exclusion of more serious diagnosis such as structural heart disease, cardiac arrthymias, and epilepsy.  Presence of specific prodromal symptoms, triggers, and circumstances of syncope; history of syncope in standing position; and a positive tilt test further helps the diagnosis of syncope in sitting and supine positions.
Due to the retrospective nature of inquiry into the event, it is sometimes difficult to clarify the nature of prodromal symptoms and circumstances of occurrence, even with witnesses available. Most of our patients had prodromal symptoms of more than 5 s duration, so they were able to describe them, and triggers and circumstances were less dependent on history. A larger series may bring out further differences in prodromal symptoms, triggers, and circumstances of syncope in relation to body position and allow further statistical analysis.
We thank Dr. Amit Vora for his help in the head-up tilt test and cardiac evaluation of patients and Dr. Namit Gupta for his help in the preparation of the manuscript.
[Table 1], [Table 2], [Table 3]