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== Pathogenesis ==

===Sensazioni fantasma dolorose e non===

PhantomLe painsensazioni dolorose ande non-painful phantomdolorose sensationsderivano resultda fromcambiamenti changesnel insistema thenervoso centralcentrale, nervousa systemcausa duedella todenervazione denervationdi ofuna aparte bodydel part.corpo<ref name="Ramachandran">{{citecita journalpubblicazione |firstquotes=Vilayanur S. |lastcognome=Ramachandran |authorlinknome=Vilayanur S. |linkautore=Vilayanur S. Ramachandran |coauthorscoautori=W. Hirstein |titleanno=1998 |mese=settembre |titolo=The perception of phantom limbs. The D. O. Hebb lecture |journalrivista=[[Brain (journal)|Brain]] |volume=121 |issuenumero=9 |pagespagine=1603–301603-1630 |year=1998 |month=September |pmidid=9762952 {{doi|doi= 10.1093/brain/121.9.1603}} |url=http://brain.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=9762952 {{pdf}} |accessdatelingua=2008{{en}} |accesso=17-0907-232010 |abstract= }}</ref><ref name="Nikolajsen">{{citecita journalpubblicazione |firstquotes=L. |lastcognome=Nikolajsen |coauthorsnome= |linkautore= |coautori=T. S. Jensen |titleanno=2001 |mese=luglio |titolo=Phantom limb pain |journalrivista=[[British Journal of Anaesthesia]] |volume=87 |issuenumero=1 |pagespagine=107–16107-116 |year=2001 |month=July |pmidid=11460799 {{doi|doi= 10.1093/bja/87.1.107}} |url=http://bja.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=11460799 |accessdatelingua=2008-09-23{{en}}</ref> Phantom|accesso=17-07-2010 eye|abstract= pain is considerably less common than phantom limb pain. The prevalence of phantom pain after limb [[amputation]] ranged from 50% to 78%. The prevalence of phantom eye pain, in contrast, is about 30%.}}

</ref>. La sindrome dell'occhio fantasma è molto meno comune della [[sindrome dell'arto fantasma]]. Dopo l'[[amputazione]] di un arto, la percentuale dei pazienti che lamentano tale sindrome è tra il 50% e il 78%, mentre nel caso di perdita di un occhio, la percentuale scende a circa il 30%.

Si pensa che le sensazioni dolorose e non agli arti mancanti siano dovuti a cambiamenti post-amputazione nella [[omuncolo motorio|rappresentazione corticale delle parti del corpo]] adiacenti all'arto amputato. Una ragione per la minore incidenza di casi di occhio fantasma si pensa possa essere la rappresentazione corticale [[tattile]] più piccola dell'occhio, in confronto alla rappresentazione degli arti.

Alcuni studi

=== Phantom pain and non-painful phantom sensations ===

Phantom pain and non-painful phantom sensations result from changes in the central nervous system due to denervation of a body part.<ref name="Ramachandran">{{cite journal |first=Vilayanur S. |last=Ramachandran |authorlink=Vilayanur S. Ramachandran |coauthors=W Hirstein |title=The perception of phantom limbs. The D. O. Hebb lecture |journal=[[Brain (journal)|Brain]] |volume=121 |issue=9 |pages=1603–30 |year=1998 |month=September |pmid=9762952 |doi= 10.1093/brain/121.9.1603|url=http://brain.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=9762952 |accessdate=2008-09-23}}</ref><ref name="Nikolajsen">{{cite journal |first=L. |last=Nikolajsen |coauthors=T. S. Jensen |title=Phantom limb pain |journal=[[British Journal of Anaesthesia]] |volume=87 |issue=1 |pages=107–16 |year=2001 |month=July |pmid=11460799 |doi= 10.1093/bja/87.1.107|url=http://bja.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=11460799 |accessdate=2008-09-23}}</ref> Phantom eye pain is considerably less common than phantom limb pain. The prevalence of phantom pain after limb [[amputation]] ranged from 50% to 78%. The prevalence of phantom eye pain, in contrast, is about 30%.

Post-amputation changes in the [[Cortical homunculus|cortical representation of body parts]] adjacent to the amputated limb are believed to contribute to the development of phantom pain and nonpainful phantom sensations. One reason for the smaller number of patients with phantom eye pain compared with those with phantom limb pain may be the smaller cortical [[somatosensory]] representation of the eye compared with the limbs.

In limb amputees, some<ref name="Nikolajsen">{{cite journal |author=Nikolajsen L, Ilkjaer S, Krøner K, Christensen JH, Jensen TS |title=The influence of preamputation pain on postamputation stump and phantom pain |journal=Pain |volume=72 |issue=3 |pages=393–405 |year=1997 |month=September |pmid=9313280 |doi= 10.1016/S0304-3959(97)00061-4|url=http://linkinghub.elsevier.com/retrieve/pii/S0304395997000614 |accessdate=2008-09-23}}</ref> but not all studies have found a correlation between preoperative pain in the affected limb and postoperative phantom pain. There is a significant association between painful and nonpainful phantom experiences and preoperative pain in the symptomatic eye and [[headache]].<ref name="Nicolodi">{{cite journal |first=M. |last=Nicolodi |coauthors=R. Frezzotti, A. Diadori, A. Nuti and F. Sicuteri |title=Phantom eye: features and prevalence. The predisposing role of headache |journal=Cephalalgia |volume=17 |issue=4 |pages=501–4 |year=1997 |month=June |pmid=9209770 |doi= 10.1046/j.1468-2982.1997.1704501.x|url=http://www.blackwell-synergy.com/openurl?genre=article&sid=nlm:pubmed&issn=0333-1024&date=1997&volume=17&issue=4&spage=501 |accessdate=2008-09-23}}</ref> Based on the present data it is difficult to determine if headaches or preoperative eye pain play a causal role in the development of phantom phenomena, or if headache, preoperative eye pain, and postoperative phantom eye experiences are only epiphenomena of an underlying factor. However, a study in humans demonstrated that experimental pain leads to a rapid reorganization of the [[somatosensory cortex]].<ref name="Soros2">{{cite journal |first=Peter |last=Sörös |coauthors=Stefan Knechta, Carsten Bantelb, Tanya Imaia, Rainer Wüstenb, Christo Pantevc, Bernd Lütkenhönerc, Hartmut Bürkleb and Henning Henningsen |title=Functional reorganization of the human primary somatosensory cortex after acute pain demonstrated by magnetoencephalography |journal=Neuroscience Letters |volume=298 |issue=3 |pages=195–8 |year=2001 |month=February |pmid=11165440 |doi= 10.1016/S0304-3940(00)01752-3|url=http://linkinghub.elsevier.com/retrieve/pii/S0304394000017523 |accessdate=2008-09-23}}</ref> This study suggests that preoperative and postoperative pain may be an important cofactor for somatosensory reorganization and the development of phantom experiences.