Phantom eye syndrome: a review of the literature

Pain in the Context of Sensory Deafferentation

Pain that accompanies deafferentation is one of the most mysterious and misunderstood medical conditions. Prevalence rates for the assorted conditions vary considerably but the most reliable estimates are greater than 50% for strokes involving the somatosensory system, brachial plexus avulsions, spinal cord injury, and limb amputation, with controversy surrounding the mechanistic contributions of deafferentation to ensuing neuropathic pain syndromes. Deafferentation pain has also been described for loss of other body parts (e.g., eyes and breasts) and may contribute to between 10% and upwards of 30% of neuropathic symptoms in peripheral neuropathies. There is no pathognomonic test or sign to identify deafferentation pain, and part of the controversy surrounding it stems from the prodigious challenges in differentiating cause and effect. For example, it is unknown whether cortical reorganization causes pain or is a byproduct of pathoanatomical changes accompanying injury, including pain. Similarly, ascertaining whether deafferentation contributes to neuropathic pain, or whether concomitant injury to nerve fibers transmitting pain and touch sensation leads to a deafferentation-like phenotype can be clinically difficult, although a detailed neurologic examination, functional imaging, and psychophysical tests may provide clues. Due in part to the concurrent morbidities, the physical, psychologic, and by extension socioeconomic costs of disorders associated with deafferentation are higher than for other chronic pain conditions. Treatment is symptom-based, with evidence supporting first-line antineuropathic medications such as gabapentinoids and antidepressants. Studies examining noninvasive neuromodulation and virtual reality have yielded mixed results.

[Chronic eye pain]

Numerous conditions in the field of ophthalmology are associated with pain in or around the eye. Chronic pain associated with the eye is a common finding in the daily routine of ophthalmologists and can be associated with primary ocular or extraocular diseases as well as with other conditions. Appropriate diagnostic assessment and management of people with chronic pain requires an understanding of the condition based on the biopsychosocial model in which the interactions of biological/somatic, psychological and social factors are determining pain and suffering. Beyond the ophthalmological findings,  close interdisciplinary cooperation and assessment are required. Therefore, if eye pain is insufficiently responsive to treatment or if symptoms of chronic pain are evident, pain medicine expertise should be involved. The management of chronic ocular pain is based on interdisciplinary multimodal approaches, in addition to the ophthalmologist-specific approaches. These focus on self-efficacy, patient competence and acceptance of pain as central goals of treatment rather than pain relief. Patient information, education and the development of a suitable concept by the interdisciplinary team are essential therapeutic aspects in this context.

Persistent socket pain in a dog after the enucleation of the eye and its clinical management

Persistent socket pain is a condition described in humans after enucleation of the eye. This report aims at describing this condition in dogs. A 10-year-old male-neutered crossbreed was presented to the referral veterinary surgeon for enucleation of the right ocular globe. Anaesthesia and surgery were uneventful although during the postoperative period the dog was reluctant to open the mouth and to be explored by the referral veteterinary surgeon. Despite treatment with meloxicam, paracetamol and tramadol, no improvements were observed. Ten weeks after surgery, the dog was referred to the Dick White referrals for further investigations. Ophthalmic examination was normal, though palpation of the wound triggered an avoidance response. Magnetic resonance imaging showed changes compatible with orbital cellulitis. The area of interest was evaluated with the use of the mechanical Von Frey filaments. A response, characterised by sudden turning of the head and attempts to withdraw it, was evoked with filament 4.93 (8.0 g) during stimulation of the periorbital area. After induction of anaesthesia, an ultrasound-guided injection containing levobupivacaine 0.5% and methylprednisolone was performed within the retrobulbar area. Three hours after recovery from anaesthesia, no discomfort was observed during palpation of the area. Re-evaluation was performed with the Von Frey filaments; no response could be evoked during testing with all 20 filaments (from 2.36 to 6.65) applied on either side of the face. The patient was discharged with a course of gabapentin and, 3 weeks after the intervention, the dog showed no clinical signs of pain. Persistent socket pain is an unpleasant sensation at the level of the enucleated orbit, and it should be regarded as a challenging condition to diagnose and treat. The MRI findings appeared to be essential to select the most appropriate interventional treatment. The injection of local anaesthetic and steroid into the retrobulbar space was useful for both confirming the diagnosis and treating pain by reducing the peripheral signalling and decreasing the residual inflammation.

[Principles of acute pain therapy-An overview taking special features in the patient collective of ophthalmology into consideration]

For many years the quality of perioperative pain management in general has been repeatedly reported as inadequate and there is significant evidence to indicate that this is also true after surgical procedures in ophthalmology. The patient population in ophthalmology is quite challenging due to numerous comorbidities and a high average age resulting in numerous contraindications and organ dysfunctions and requiring special knowledge to ensure high quality acute pain management. The following overview covers basic knowledge of acute pain management, with a particular focus on analgesic approaches and the specifics of the patient population and the associated limitations in terms of analgesic and co-analgesic pharmacological options.

Cerebral processing of emotions in phantom eye pain patients: An event related potential study

Purpose

Phantom eye pain (PEP) is a major clinical problem after eye removal with no standard treatment protocol to date. As pain is a multidimensional experience associated with emotional and cognitive components, this study aimed to explore the possible neuropsychological mechanisms of PEP in a perspective of emotional cognition, in order to provide a basis for clinical treatment.

Methods

Visual oddball event-related potentials (ERPs) under different external emotional stimuli (Disgust, Fear, Sadness, Happiness, Erotica and Neutral) were tested in 12 patients and 12 healthy volunteers. Participants' affective states were measured with the Mood Disorder Questionnaire (MDQ), the Hypomania Checklist-32 (HCL-32), and the Plutchik-van Praag Depression Inventory (PVP). The amplitudes and latencies of N1, P2, N2 and P3 components were analyzed by three-way ANOVA, i.e., group (2) ​× ​emotion (6) ​× ​electrode (3). Multiple comparisons were performed using Bonferroni's test.

Results

Longer N1 latencies, increased N1 amplitudes; shorter P2 latencies under Disgust and Happiness, decreased P2 amplitudes; shorter N2 latencies under Erotica, increased N2 amplitudes were found in patients compared with controls. There was no main effect of group or interaction effect on P3 latencies and P3 amplitudes. The MDQ and HCL-32 scores were lower, and the N1 latencies under Sadness were negatively correlated with PVP scores in patients.

Conclusions

PEP patients showed reversed patterns in exogenous attention allocation and enhanced involuntary attention to emotional stimuli compared with controls. This study demonstrated cortical processing of emotions in PEP patients and could provide a basis for developing emotional intervention therapy.

Anophthalmic Socket Syndrome: Prevalence, Impact and Management Strategies

Anophthalmic socket syndrome determines functional deficits and facial deformities, and may lead to poor psychological outcomes. This review aims to comprehensively evaluate the features of the syndrome, based on literature review and authors’ clinical and surgical experience. An electronic database (PubMed,MEDLINE and Google Scholar) search of all articles written in English and non-English language with abstract translated to English on anophthalmic socket syndrome was performed. Data reviewed included demographics, presentations, investigations, management, complications and outcomes. Different types of orbital implants were evaluated; the management of implant exposure was examined; different orbital volume enhancement procedures such as secondary implantation, subperiosteal implants and the use of fillers in anophthalmic patients were described; the problems related to socket contraction were outlined; the treatment options for chronic anophthalmic socket pain and phantom eye syndrome were assessed; the most recent advances in the management of congenital anophthalmia were described. Current clinical evidence does not support a specific orbital implant; late exposure of porous implants may be due to pegging, which currently is seldom used; filler absorption in the orbit appears to be faster than in the dermis, and repeated treatments could be a potential source of inflammation; socket contraction results in significant functional and psychological disability, and management is challenging. Patients affected by anophthalmic socket pain and phantom eye syndrome need specific counseling. It is auspicable to use a standardized protocol to treat children affected by clinical congenital anophthalmia; dermis fat graft is a suitable option in these patients as it helps continued socket expansion. Dermis fat graft can also address the volume deficit in case of explantation of exposed implants and in contracted sockets in both children and adults. Appropriate clinical care is essential, as adequate prosthesis wearing improves the quality of life of anophthalmic patients.

Phantom eye pain: a multicentric study in 100 patients

PURPOSE

Phantom eye syndrome (PES) is an underestimated complication of eye amputation (EA) characterized by phantom eye pain (PEP), phantom visions and/or phantom sensations. The aim of this study was to assess PEP prevalence, features, risk factors, social and psychological consequences and associated quality of life.

METHODS

A questionnaire study was conducted in three oculoplastic departments between April 2016 and July 2017. Patients >18 years who had undergone EA ≥3 months earlier were included and asked to complete a prestamped questionnaire. Patient's characteristics, preoperative, surgical and postoperative data were collected.

RESULTS

Of the 185 questionnaires given, 115 (62%) were returned for analysis. Hundred patients with a mean age of 65.1 years (29-92; SD = 13.0) were included. Eye amputation (EA) indications were uveal melanoma (n = 24, 24%), trauma (n = 20, 20%), retinal detachment (n = 20, 20%), glaucoma (n = 14, 14%) and endophthalmitis (n = 12, 12%). Forty-seven (47%), 30 (30%) and 38 (38%) patients experienced PEP, phantom visions and phantom sensations, respectively. Anxiety and depression [Hospital Anxiety Depression scale (HADS) score ≥8 for both] were diagnosed in 34 (34%) and 42 (42%) patients, respectively. The mean EQ-5D-3L and EQ-5D visual analogue scale scores were 0.8 (0.06-1; SD = 0.2) and 68 (0-100; SD = 22), respectively. Preoperative eye pain (p = 0.031), glaucoma (p = 0.027), postoperative anxiety with HADS score ≥8 (p = 0.012) and ≥11 (p = 0.014), aesthetic discomfort (p = 0.002) and EQ-5D-3L score <0.8 (p < 0.001) were significantly associated with PEP in the univariate analysis. In the multivariate analysis, only anxiety (HADS score ≥8) was significantly associated with PEP (p = 0.009).

CONCLUSION

Phantom eye pain (PEP) is a common complication of EA strongly associated with postoperative anxiety.

Phantom vision after eye removal: prevalence, features and related risk factors

AIM

Phantom eye syndrome is a poorly understood and underestimated complication of eye removal (ER). Seeing with the amputated eye, referred to as phantom vision (PV), is undoubtedly the most intriguing and confusing complication experienced by anophthalmic patients. The aim of the study was to assess PV prevalence, clinical features and risk factors after ER.

METHODS

A multicentric questionnaire-based study was conducted between April 2016 and July 2017. Patients >18 years who underwent ER >3 months ago had a socket examination before inclusion. Data recorded included patients' demographics, and preoperative, surgical and postoperative features.

RESULTS

One hundred patients (53 men) with a mean age of 65.1 years (29-92; SD=13.0) were included. ER indications were: uveal melanoma (n=24, 24%), trauma (n=20, 20%), retinal detachment (n=20, 20%), glaucoma (n=14, 14%) and endophthalmitis (n=12, 12%). Thirty (30%) patients experienced PV. Elementary and complex visual hallucinations were experienced by 80% and 20% of patients, respectively. PV usually appeared within the first postoperative month and tended to decrease over time. Risk factors for PV were the preoperative use of proton beam therapy (p=0.006), uveal melanoma (p=0.014), enucleation (p=0.015), anxiety with a Hospital and Anxiety Depression (HAD) score ≥8 (p=0.042), depression with a HAD score ≥8 (p=0.030), phantom eye pain (p=0.044) and phantom eye sensations (p=0.002).

CONCLUSION

PV was reported by one-third of our patients. Despite being widely misunderstood, ophthalmologists and neurologists should be aware of this complication to adequately reassure patients.

The Phantom Satiation Hypothesis of Bariatric Surgery

The excitation of vagal mechanoreceptors located in the stomach wall directly contributes to satiation. Thus, a loss of gastric innervation would normally be expected to result in abrogated satiation, hyperphagia, and unwanted weight gain. While Roux-en-Y-gastric bypass (RYGB) inevitably results in gastric denervation, paradoxically, bypassed subjects continue to experience satiation. Inspired by the literature in neurology on phantom limbs, I propose a new hypothesis in which damage to the stomach innervation during RYGB, including its vagal supply, leads to large-scale maladaptive changes in viscerosensory nerves and connected brain circuits. As a result, satiation may continue to arise, sometimes at exaggerated levels, even in subjects with a denervated or truncated stomach. The same maladaptive changes may also contribute to dysautonomia, unexplained pain, and new emotional responses to eating. I further revisit the metabolic benefits of bariatric surgery, with an emphasis on RYGB, in the light of this phantom satiation hypothesis.

Clinical updates on phantom limb pain

Phantom limb pain is highly prevalent after amputation. Treatment results will probably benefit from an interdisciplinary team and individually adapted surgical, prosthetic and pain medicine approaches.

Introduction:

Most patients with amputation (up to 80%) suffer from phantom limb pain postsurgery. These are often multimorbid patients who also have multiple risk factors for the development of chronic pain from a pain medicine perspective. Surgical removal of the body part and sectioning of peripheral nerves result in a lack of afferent feedback, followed by neuroplastic changes in the sensorimotor cortex. The experience of severe pain, peripheral, spinal, and cortical sensitization mechanisms, and changes in the body scheme contribute to chronic phantom limb pain. Psychosocial factors may also affect the course and the severity of the pain. Modern amputation medicine is an interdisciplinary responsibility.

Methods:

This review aims to provide an interdisciplinary overview of recent evidence-based and clinical knowledge.

Results:

The scientific evidence for best practice is weak and contrasted by various clinical reports describing the polypragmatic use of drugs and interventional techniques. Approaches to restore the body scheme and integration of sensorimotor input are of importance. Modern techniques, including apps and virtual reality, offer an exciting supplement to already established approaches based on mirror therapy. Targeted prosthesis care helps to obtain or restore limb function and at the same time plays an important role reshaping the body scheme.

Discussion:

Consequent prevention and treatment of severe postoperative pain and early integration of pharmacological and nonpharmacological interventions are required to reduce severe phantom limb pain. To obtain or restore body function, foresighted surgical planning and technique as well as an appropriate interdisciplinary management is needed.

Ocular Neuropathic Pain: An Overview Focusing on Ocular Surface Pains

Objective

This paper reviews ocular pain with the main focus on ocular surface discomfort and dry eye pain. Anatomy, physiology, epidemiology, assessment, and treatment are discussed in this paper.

Methods

A PubMed search was conducted for studies published from 2000 to 2019 on the anatomy, pathophysiology, epidemiology, assessment, and treatment of ocular pain. Reviews, meta-analyses, and randomized clinical trials were included. Inclusion criteria focused on ocular surface discomfort, dry eye pain and neuropathic pain.

Results

A total of 112 articles were found through searches, 45 of which were selected and studied in this review.

Discussion

Pain in general can be acute or chronic. Acute pain is usually a physiologic response to a serious damage to the tissues and alleviates with pain relief treatments. Chronic pain is defined as the persistence of pain for more than three months. From another point of view, pain has been classified into either nociceptive or neuropathic. Nociceptive pain is a physiologic response to a noxious stimulus. Both central and peripheral nervous systems can be involved in the development of a neuropathic pain, which is characterized by positive or negative sensory signs, a pain perceived disproportionate to a noxious stimulus, and/or not responsive to analgesics. Chronic pain usually has a neuropathic component. Ocular surface pain is a well-known complaint after any corneal surgery. This is mainly due to abnormal regeneration of damaged corneal nerve endings and abnormal connections with adjacent nerve endings which produce spontaneous activity. Tear hyperosmolarity and the resultant ocular surface inflammation can also trigger voluntary activity of corneal nerve endings. Referral pain to the first and second division of the trigeminal nerve has been reported. Interference with vision and even sleep, which is out of proportion to the examination are among patients' complaints. All of these elements proposed the new concept of ocular neuropathic pain syndrome. The first step in conventional evaluation of ocular discomfort is search for tear insufficiency. Pathologies of lid and blinking as well as conjunctival irregularities should be addressed. Anti-inflammatory agents and, in resistant cases, systemic neuromodulators are shown to be helpful. Education on behavioral changes and reassurance are essential steps. Considering the neuropathic origin for the ocular pain, treatment modalities used for such pain in other parts of the body can be considered for this syndrome.

Phantom eye syndrome. Case report and literature review

A frequent complication after limb amputation is the appearance of phantom limb syndrome, a phenomenon that has also been studied in the amputation of different body parts. Cases reported in relation to ophthalmologic surgery are few and evidence is limited in terms of specific management, which makes this a very important study. We report the case of a patient diagnosed with phantom eye syndrome in the post-operative period of an orbital exenteration surgery. A comprehensive approach was taken with multimodal symptom management, including intervention treatment. Significant improvement regarding the pain was achieved; however, non-painful ghost sensations persisted. Upon reviewing the available literature on the subject, its pathophysiology is not fully elucidated. Its incidence is highly variable, as well as the symptoms’ appearance. The presence of headache and eye pain prior to surgery seem to be risk factors. Climate and psychological stress are exacerbating factors of the symptomatology. No high-quality evidence was found in terms of management guidelines, with the use of antidepressants, anticonvulsants and opioids being the most recommended. Interventional management is an option according to the characteristics of the pain and associated symptoms.

Analgesic effects of intraorbital insertion of an absorbable gelatin hemostatic sponge soaked with 1% ropivacaine solution following enucleation in dogs

OBJECTIVE

To evaluate analgesic effects and complications associated with intraorbital insertion of an absorbable gelatin hemostatic sponge (AGHS) soaked with 1% ropivacaine solution following enucleation in dogs.

ANIMALS

20 client-owned dogs undergoing enucleation.

PROCEDURES

Dogs were randomly assigned to receive an AGHS soaked with 1% ropivacaine solution (n = 10) or saline (0.9% NaCl) solution (control group; 10) inserted intraorbitally prior to skin closure following enucleation. Carprofen (2 mg/kg [0.9 mg/lb]) was administered SC once after orotracheal extubation and then PO twice a day for 5 days. During the postoperative recovery period, apparent pain level was scored at various points with a modified short-form Glasgow Composite Pain Scale (score range, 0 to 19), and methadone was administered for rescue analgesia if any score was ≥ 5. After dogs returned home, owners recorded their behavior and apparent pain level for the first 3 days following enucleation.

RESULTS

At extubation, the median (range) pain score was significantly higher in the control group (8 [2 to 14]) versus the ropivacaine group (3 [1 to 7]). A greater proportion of dogs in the control group received methadone (7/10 vs 1/10) and had crying or attention-seeking behavior on the first day following enucleation (7/10 vs 1/10). No complications were observed in either group.

CONCLUSIONS AND CLINICAL RELEVANCE

Addition of intraorbital insertion of a ropivacaine-soaked AGHS to the analgesic protocol for dogs undergoing enucleation provided better analgesia than was achieved without this treatment as measured immediately and the first day after surgery, with no noted adverse effects.

Persistent socket pain postenucleation and post evisceration: a systematic review

PURPOSE

To investigate causes, diagnostics and treatment modalities for persistent socket pain (PSP) after enucleation and evisceration.

METHODS

A systematic search was undertaken in accordance with the PRISMA Statement, in PubMed, Embase.com and Thomson Reuters/Web of Science. We searched for relevant papers until the 28th of July 2016. Inclusion criteria were (1) patients with a history of enucleation or evisceration, (2) PSP, (3) report of the cause and/or used diagnostics and/or treatment modality, (4) full text in English, Dutch or Spanish language. Excluded were (1) review articles, (2) comments, and publications concerning, (3) nonhumans, (4) exenterated patients, (5) acute postoperative pain, or (6) periorbital pain without pain in the socket. Given the lack of high quality evidence from randomized controlled trials, we examined all available evidence from primary observational studies and assessed quality within this lower level of evidence.

RESULTS

A total of 32 studies were included. Causes of PSP found were prosthesis-related (n = 5), dry socket (n = 2), trochleitis (n = 3), compression of the trigeminal nerve (n = 2), implant-related (n = unknown), inflammation (n = 5), surgery-related (n = 4), neuromas (n = 8), malignant tumours (n = 3), psychiatric/psychosocial (n = 2), phantom pain (n = 149), rarer entities (n = 3) or unknown (n = 14). Nonsurgical treatments suffice for conditions as trochleitis, prosthesis-related pain, dry socket and for phantom pain. Other causes of pain may require more invasive treatments such as implant removal.

CONCLUSION

Careful history and examination can give some direction in the diagnostic procedure; however, PSP is probably multifactorial and the specific origin(s) may remain uncertain. Implant replacement can be an effective treatment. Studies to identifiy less invasive procedures are required.

Head Transplantation: The Immune System, Phantom Sensations, and the Integrated Mind

The principal focus of this paper is to consider the implications of head and neck transplantation surgery on the issue of personal identity. To this end, it is noted that the immune system has not only been established to impose a level of self-identity on bodily cells, it has also been implicated in mental development and the regulation of mental state. In this it serves as a paradigm for the mind as the product of cephalic and extracephalic systems. The importance of bodily systems in identity is then discussed in relation to phantom tissue syndrome. The data strongly indicate that, even if surgically successful, head and neck transplantation will result in the loss of the continuity of personal identity.

Maladaptive change of body representation in the brain after damage to central or peripheral nervous system

Our brain has great flexibility to cope with various changes in the environment. Use-dependent plasticity, a kind of functional plasticity, plays the most important role in this ability to cope. For example, the functional recovery of paretic limb motor movement during post-stroke rehabilitation depends mainly on how much it is used. Patients with hemiparesis, however, tend to gradually disuse the paretic limb because of its motor impairment. Decreased use of the paretic hand then leads to further functional decline brought by use-dependent plasticity. To break this negative loop, body representation, which is the conscious and unconscious information regarding body state stored in the brain, is key for using the paretic limb because it plays an important role in selecting an effector while a motor program is generated. In an attempt to understand body representation in the brain, we reviewed animal and human literature mainly on the alterations of the sensory maps in the primary somatosensory cortex corresponding to the changes in limb usage caused by peripheral or central nervous system damage.