piercings ( body art ) are more and more widespread , and can induce various complications such as infections , allergies , headaches , various skin , cartilage , or dental problems which will lead to economic effects on health - care systems ( e.g. , mayers et al . , 2002 ; stirn , 2003 ; bone et al . , 2008 ) . to maintain the center of body mass in equilibrium while standing , the central nervous system performs coordinated transformations of visual , vestibular and somaesthetic inputs ( see lvanenko et al . , 1999 ) , and permanently generates muscular response adapted as corrective torque through the action of a feedback control system ( peterka , 2002 ; todorov , 2004 ) . vertical heterophoria ( vh ) and vertical orthophoria are respectively the presence or the absence of a relative deviation of the vertical visual axes when the retinal images are dissociated , i.e. , each eye views a different image ( see amos and rutstein , 1987 ) . vh can be induced by eye refraction problems ( amos and rutstein , 1987 ) , but without refraction problems , vh of small size ( < 1  dpt , i.e. , 0.57 ) could exist indicating a perturbation of the somatosensory loops involved in postural control ( matheron and kapoula , 2008 , 2011 ) . in subjects with vh in this normal range , postural stability was impaired relative to subjects with vertical orthophoria ; the cancelation of the vh with an appropriate vertical prism improved postural stability ( matheron and kapoula , 2008 , 2011 ) . the influence of vh was explained by among other possibilities : the colliculus superior , the brainstem nuclei , and the cerebellum receiving visual , extraocular muscles and somatosensory inputs , implied to the vestibuloocular , the vestibulospinal and the reticulospinal systems required in phoria adjustment , vertical binocular alignment , and postural control while standing ( see bttner - ennever , 2006 ; matheron and kapoula , 2008 ) . we hypothesized that pierced facial jewelry disturbed somaesthetic signals driven by the trigeminal nerve , and might be related to interference in central integration processes leading to various complaints . here , we draw attention to the possible side effects resulting from facial piercing ( with jewelry ) complications such as eye misalignment , decreased postural stability , and non - specific chronic back pain . four subjects wearing facial jewelry pierced in eyebrow , tragus , upper lip , and nose ( figure 1 ) retained our attention ; they suffered from non - specific chronic back pain with an additional comorbidity such as dizziness , headache , or eyestrain known in non - specific chronic back pain ( von korff et al . , 2003 ; hagen et al . , 2006 ) , they did not wear glasses , so there were no prismatic effects and thus no induced vertical eye deviation . vision was normal with no history of strabismus , double vision , nor any other manifest ocular disease . medical consultation and complementary examination ( e.g. , radiographic imaging , magnetic resonance imaging , or blood analysis ) did not report any findings ( anatomical , neuropathy , or rheumatism ) . pierced jewelry on the face of each subject . pain score evaluated with a subjective analogical scale on the first day before the jewelry was removed ( a ) , and when each subject was checked on average 3  weeks later without the jewelry ( b ) . pain was evaluated using a subjective visual analogical scale of 10  cm ( 010 ,  0  as no pain and  10  as the extreme of pain ; huskisson , 1974 ) validated for chronic pain ( price et al . , 1983 ) . vertical heterophoria was detected , and measured for all the subjects as less than 0.57 with the maddox rod test , combined with an appropriate prism value , which is one of the most appropriate tests ( wong et al . , postural performance during quiet standing was investigated through the center of pressure ( cop ) displacements recorded using a force platform ( principle of strain gage ) consisting of two dynamometric clogs ( technoconcept , creste , france ) . the excursions of the cop were measured over a period of 25.6  s while the subjects looked at a target , a letter  x  ( angular size  =  1 ) , 200  cm away at eye level ; the equipment contained an analog  digital converter of 16 bits and the sampling frequency of the cop was 40  hz . the subjects wore a special spectacle into which one could easily insert or not a vertical prism , and were placed barefoot on the force platform . they stood in a quiet upright and standardized position ( feet placed side by side , forming a 30 angle with heels separated 4  cm ) . they were asked to look at the  x  target in the straight ahead position . the conditions were : ( 1 ) with jewelry : eyes open , eyes open with a prism to cancel the vh , and eyes closed ; ( 2 ) jewelry removed : eyes open and eyes closed . a check was done on average 3  weeks later , the conditions were eyes open and eyes closed . each testing condition over the period of 25.6  s was done twice and was counterbalanced , and data averaged . the investigation adhered to the tenets of the declaration of helsinki and was approved by the institutional human experimentation committee , the written informed consent was obtained from all subjects after the nature of the procedure had been explained . here , we presented the body sway area ( mm ) , the parameter known for reporting on postural stability ( e.g. , tagaki et al . , 1985 ; vuillerme et al . , was strongly lower when eyes were closed , indicating a strong visual dependency for body stabilization . yet the values with eyes open were still higher than corresponding values of healthy subjects with eyes open . when an appropriate prism canceled the vh , postural stability increased further approaching normal values ( matheron and kapoula , 2008 ) . more surprising , removal of jewelry immediately improved postural stability and restored eye alignment . the difference between eyes open and eyes three weeks later , back pain had either diminished or ceased entirely ( figure 1 ) . interestingly , one subject then agreed to put the jewelry back in temporarily ( figure 2b ) . five minutes later , vh was found , postural stability decreased . when the jewelry was removed again ( a ) reporting on postural stability , means of the surface area of the center of pressure excursions ( mm ) for each subject for each condition with jewelry , when jewelry is removed and when on average 3  weeks later the check is done . eyes open ( eo ) , eyes closed ( ec ) , and eo with a prism to cancel the vertical heterophoria ( eo  +  pc ) . triangle symbols indicate eo control data from the study of matheron and kapoula ( 2008 ) of healthy subjects with vertical orthophoria , and with no jewelry or back pain . ( b ) results for subject 3 who agreed to put the jewelry back on temporarily during the second session . the results of four cases are of course not sufficient to generalize , but suggest that piercings could thus create more complications than those currently described in literature ; we found binocular misalignment , reduced postural control efficiency , and non - specific chronic back pain . to our knowledge , aside from our conference abstract ( matheron and kapoula , 2009 ) , and that of zanchetta et al . ( 2009 ) reporting on the influence of lingual piercing on postural control , the lack of studies on such from piercings in literature is surprising . indeed , jewelry in body piercings is widespread , psychological , sociological , or culturally dependent , for instance nasal piercing is very frequent in india ( for review , see stirn , 2003 ) . maybe because body pierced jewelry is so common and the link to numerous side effects ( beyond immediate pain , local infection , or other skin modifications as necrosis ) has not yet sufficiently been established , its detrimental role remains underestimated . for face pierced jewelry , it is important to emphasize that trigeminal primary afferent neurons and their sensory receptors provide information for the perception of the orofacial region , and contribute to various types of sensorimotor integration ( capra and dessem , 1992 ; shankland , 2000 ) such as postural control while quiet standing ( gangloff et al . , 2000 ; gangloff and perrin , 2002 ) . these afferences project to the cerebellum , the reticular formation , and the vestibular nucleus ( see capra and dessem , 1992 ) which are located at the base of the spinal motor neurons and oculomotor efferents ( see bttner - ennever , 2006 ) . previous studies reported that vh could indicate a conflict between somaesthetic signals , here produced by jewelry in the trigeminal territory , involved in sensorimotor loops required in postural control ( matheron and kapoula , 2008 , 2011 ) . persistent conflict between vision and somaesthetic cues could lead to non - specific chronic back pain ( mccabe et al . , 2005 ; matheron and kapoula , 2011 ) , modify perception , or even induce pain and unpleasant sensations in healthy subjects ( mccabe et al . this novel observation can be understood in this context . the next step is to investigate the influence of piercings on the face , and other body parts in a larger number of cases . for instance , experimental studies of postural control in quiet stance are needed before and after body pierced jewelry . postural control is also the basis for body stability during movements and gait ( gurfinkel et al . , 1995 ) . furthermore , postural control is involved in the control of body segment orientation and body stabilization , which is a prerequisite for perception and action ( amblard et al . , 1985 ) . investigations on movement performance , eye  hand or eye  foot coordination would be of interest , as well as studies with eye movement recordings and visual stereoscopic tests , because small vh can alter vergence eye movements , stereopsis depth perception , and distance evaluation ( see saladin , 1995 , 2005 ) . we hope that this preliminary study will stimulate research in these fields . as mentioned , recent studies ( stirn , 2003 ; laumann and derick , 2006 ) have reported that body piercing as body art , i.e. , with jewelry , has a high incidence of medical complications . here as previously proposed , prolonged sensory  motor conflict could exacerbate pain and other symptoms , or could act after an undetermined precipitating event on a pre - existing conflict , or as a precipitating event in the trigeminal territory ( matheron and kapoula , 2011 ) . health professionals and researchers should be aware of the possible side effects of piercings , i.e. , impaired motor control , body pain , and additional comorbidity  known in chronic back pain ( von korff et al . , 2003 ; hagen et al . , 2006 ) including postural disorders ( gagey et al . , 1980 ; da cunha , 1987 ) , and the presence of vh ( amos and rutstein , 1987 ; scheiman and wick , 1994 ) , and heterophoria . epidemiological and longitudinal studies of such side effects would be of interest . body piercings with jewelry , at least on the face , could more or less rapidly induce other complaints than the medical complications described in the relevant literature ; we report here body pain , impaired postural control , and vertical eye misalignment ( heterophoria ) . if these side effects were confirmed in a larger population , health professionals need to deal with them taking into account sociological and psychological aspects as recommended by stirn ( 2003 ) . we hope this study of a few cases could stimulate further experimental and clinical research to complete the investigation on risk factors linked to body piercing , and lead to public health recommendations and prevention . more knowledgeable clinicians could thus better inform patients thus helping to reduce possible future complaints . the authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest .
piercings ( body art , i.e. , with jewelry ) are more and more widespread 
 . they can induce various complications such as infections , allergies , headaches , and various skin , cartilage , or dental problems , and represent a public health problem . 
 we draw attention to possible side effects resulting from face piercing complications observed on four young adults such as eye misalignment , decreased postural control efficiency , and non - specific chronic back pain with associated comorbidity . 
 we found that the origin was pierced jewelry on the face . removing the jewelry restored eye alignment , improved postural control , and alleviated back pain in a lasting way . 
 we suggest that pierced facial jewelry can disturb somaesthetic signals driven by the trigeminal nerve , and thus interfere with central integration processes , notably in the cerebellum and the vestibular nucleus involved in postural control and eye alignment . 
 facial piercings could induce sensory 
 motor conflict , exacerbate , or precipitate a pre - existing undetermined conflict , which leads pain and complaints . 
 these findings are significant for health ; further investigations would be of interest .