The
phantom eye syndrome is a
phantom painPhantom pain sensations are described as perceptions that an individual experiences relating to a limb or an organ that is not physically part of the body. Limb loss is a result of either removal by amputation or congenital limb deficiency . However, phantom limb sensations can also occur following...
in the eye and visual hallucinations, after the removal of an eye (enucleation,
eviscerationAn evisceration is the removal of the eye's contents, leaving the scleral shell and extraocular muscles intact. The procedure is usually performed to reduce pain or cosmesis in a blind eye, as in cases of endophthalmitis unresponsive to antibiotics...
).
Many patients experience one or more phantom phenomena after the removal of the eye:
- Phantom pain
Phantom pain sensations are described as perceptions that an individual experiences relating to a limb or an organ that is not physically part of the body. Limb loss is a result of either removal by amputation or congenital limb deficiency . However, phantom limb sensations can also occur following...
in the (removed) eye (prevalence: 26%)
- Non-painful phantom sensations
- Visual hallucinations. About 30% of patients report visual hallucinations of the removed eye.
The
phantom eye syndrome is a
phantom painPhantom pain sensations are described as perceptions that an individual experiences relating to a limb or an organ that is not physically part of the body. Limb loss is a result of either removal by amputation or congenital limb deficiency . However, phantom limb sensations can also occur following...
in the eye and visual hallucinations, after the removal of an eye (enucleation,
eviscerationAn evisceration is the removal of the eye's contents, leaving the scleral shell and extraocular muscles intact. The procedure is usually performed to reduce pain or cosmesis in a blind eye, as in cases of endophthalmitis unresponsive to antibiotics...
).
Symptomatology
Many patients experience one or more phantom phenomena after the removal of the eye:
- Phantom pain
Phantom pain sensations are described as perceptions that an individual experiences relating to a limb or an organ that is not physically part of the body. Limb loss is a result of either removal by amputation or congenital limb deficiency . However, phantom limb sensations can also occur following...
in the (removed) eye (prevalence: 26%)
- Non-painful phantom sensations
- Visual hallucinations. About 30% of patients report visual hallucinations of the removed eye. Most of these hallucinations consist of basic perceptions (shapes, colors). In contrast, visual hallucinations caused by severe visual loss (Charles Bonnet syndrome
Charles Bonnet syndrome is a condition that causes patients with visual loss to have complex visual hallucinations, first described by Charles Bonnet in 1760 and first introduced into English-speaking Psychiatry in 1982.-Characteristics:...
) are less frequent (prevalence 10%) and often consist of detailed images.
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. Phantom eye pain is considerably less common than phantom limb pain. The prevalence of phantom pain after limb
amputationAmputation is the removal of a body extremity by trauma or surgery. As a surgical measure, it is used to control pain or a disease process in the affected limb, such as malignancy or gangrene. In some cases, it is carried out on individuals as a preventative surgery for such problems...
ranged from 50% to 78%. The prevalence of phantom eye pain, in contrast, is about 30%.
Post-amputation changes in the
cortical representation of body partsA cortical homunculus is a physical representation of the primary motor cortex, i.e., the portion of the human brain directly responsible for the movement and exchange of sense and motor information of the rest of the body.The resulting image is a grotesquely disfigured human with...
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 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
headacheIn medicine a headache or cephalalgia is a symptom of a number of different conditions of the head. Some of the causes are benign while others are medical emergencies.There are a number of different classification systems for headaches...
. 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. This study suggests that preoperative and postoperative pain may be an important cofactor for somatosensory reorganization and the development of phantom experiences.
Visual hallucinations
Enucleation of an eye and, similarly, retinal damage, lead to a cascade of events in the cortical areas receiving visual input. Cortical
GABAGabâ or gabaa, for the Cebuano people , is the concept of a non-human and non-divine, imminent retribution. A sort of negative karma, it is generally seen as an evil effect on a person because of their wrongdoings or transgressions...
ergic (GABA: Gamma-aminobutyric acid) inhibition decreases and cortical glutamatergic excitation increases, followed by increased visual excitibility or even spontaneous activity in the
visual cortexThe term visual cortex refers to the primary visual cortex and extrastriate visual cortical areas such as V2, V3, V4, and V5. The primary visual cortex is anatomically equivalent to Brodmann area 17, or BA17...
. It is believed that spontaneous activity in the denervated visual cortex is the neural correlate of visual hallucinations.
External links
- http://psy.ucsd.edu/chip/ramabio.html Homepage of Vilayanur S. Ramachandran
Vilayanur Subramanian "Rama" Ramachandran is a neurologist best known for his work in the fields of behavioral neurology and psychophysics. He is currently the Director of the Center for Brain and Cognition, Professor in the Psychology Department and Neurosciences Program at the University of...