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Practical Neurology Feb 2018Persistent postural-perceptual dizziness (PPPD) is a newly defined diagnostic syndrome that unifies key features of chronic subjective dizziness, phobic postural vertigo... (Review)
Review
Persistent postural-perceptual dizziness (PPPD) is a newly defined diagnostic syndrome that unifies key features of chronic subjective dizziness, phobic postural vertigo and related disorders. It describes a common chronic dysfunction of the vestibular system and brain that produces persistent dizziness, non-spinning vertigo and/or unsteadiness. The disorder constitutes a long-term maladaptation to a neuro-otological, medical or psychological event that triggered vestibular symptoms, and is usefully considered within the spectrum of other functional neurological disorders. While diagnostic tests and conventional imaging usually remain negative, patients with PPPD present in a characteristic way that maps on to positive diagnostic criteria. Patients often develop secondary functional gait disorder, anxiety, avoidance behaviour and severe disability. Once recognised, PPPD can be managed with effective communication and tailored treatment strategies, including specialised physical therapy (vestibular rehabilitation), serotonergic medications and cognitive-behavioural therapy.
Topics: Dizziness; Humans; Perceptual Disorders; Postural Balance; Vertigo; Visual Perception
PubMed: 29208729
DOI: 10.1136/practneurol-2017-001809 -
Expert Opinion on Drug Safety Jun 2022Hallucinogen persisting perception disorder (HPPD) affects a subset of persons who use hallucinogens and is defined as the repeated experience of hallucinations and... (Review)
Review
INTRODUCTION
Hallucinogen persisting perception disorder (HPPD) affects a subset of persons who use hallucinogens and is defined as the repeated experience of hallucinations and other perceptual disturbances as a result of prior intoxications. As select hallucinogens are under development for the treatment of selectmental disorders, there is a need to better characterize this disorder.
AREAS COVERED
A scoping review of the literature on HPPD was completed from inception to July 2021. Topics covered in the review herein include treatments for HPPD, prevalence or incidence data on HPPD among different classes of hallucinogens, risk factors for HPPD, and data pertaining to the pathophysiology of HPPD.
EXPERT OPINION
Hallucinogen persisting perception disorder appears to be an uncommon yet serious event associated with prior hallucinogen exposure. The renewed interest in psychedelics as potential treatment options for select mental disorders, especially agents with hallucinogenic potential, provides the impetus to characterize HPPD in its frequency, risk and protective factors, key characteristics, as well as other clinical and treatment-related factors.
Topics: Hallucinations; Hallucinogens; Humans; Perceptual Disorders; Prevalence; Risk Factors
PubMed: 35426769
DOI: 10.1080/14740338.2022.2063273 -
Frontiers of Neurology and Neuroscience 2018In 1955, English psychiatrist John Todd defined the Alice-in-Wonderland syndrome (AIWS) as self-experienced paroxysmal body-image illusions involving distortions of the... (Review)
Review
In 1955, English psychiatrist John Todd defined the Alice-in-Wonderland syndrome (AIWS) as self-experienced paroxysmal body-image illusions involving distortions of the size, mass, or shape of the patient's own body or its position in space, often accompanied by depersonalization and/or derealization. AIWS had been described by American Neurologist Caro Lippman in 1952, but Todd's report was the most influential. Todd named the syndrome for the perceptual disorder of altered body image experienced by the protagonist in Alice's Adventures in Wonderland (1865) by Lewis Carroll (Charles Lutwidge Dodgson). In Carroll's original story, Alice experienced several dramatic changes in body size and shape (e.g., shrinking to 10 inches high, growing unnaturally tall but not any wider, and growing unnaturally large). Todd reported 6 cases of AIWS, all of whom had episodic body-image distortions like those experienced by Lewis Carroll's Alice character; some also had visual perceptual disturbances, but none had visual perceptual disorders without body-image distortions. Therefore, AIWS may be accompanied by visual perceptual disorders (e.g., micropsia, macropsia, telopsia, pelopsia), but basing the diagnosis of AIWS on isolated visual perceptual disorders, as has subsequently been done by a number of authors, is inaccurate and misleading. Cases of isolated visual illusions without self-perceived distortions of body size, shape, or form, do not meet Todd's original criteria, nor are they commensurate with the experiences of the protagonist in Alice's Adventures in Wonderland. Furthermore, such cases differ by age and etiology from those that involve somesthetic perceptual disorders. Therefore, the use of the term AIWS for isolated visual illusions is problematic and should be discouraged. Although Todd's and Lippman's cases were adolescents or adults, AIWS is most commonly reported in children. Reported causes include infection (especially with Epstein Barr virus), migraine, epilepsy, depression, and toxic and febrile delirium.
Topics: Alice in Wonderland Syndrome; Humans
PubMed: 29151098
DOI: 10.1159/000475722 -
Schizophrenia Research Jan 2014The aim of this review is to describe the potential relationship between multisensory disintegration and self-disorders in schizophrenia spectrum disorders. Sensory... (Review)
Review
The aim of this review is to describe the potential relationship between multisensory disintegration and self-disorders in schizophrenia spectrum disorders. Sensory processing impairments affecting multisensory integration have been demonstrated in schizophrenia. From a developmental perspective multisensory integration is considered to be crucial for normal self-experience. An impairment of multisensory integration is called 'perceptual incoherence'. We theorize that perceptual incoherence may evoke incoherent self-experiences including depersonalization, ambivalence, diminished sense of agency, and 'loosening of associations' between thoughts, feelings and actions that lie within the framework of 'self-disorders' as described by Sass and Parnas (2003). We postulate that subconscious attempts to restore perceptual coherence may induce hallucinations and delusions. Increased insight into mechanisms underlying 'self-disorders' may enhance our understanding of schizophrenia, improve recognition of early psychosis, and extend the range of therapeutic possibilities.
Topics: Humans; Perceptual Disorders; Schizophrenia; Schizophrenic Psychology; Sensation Disorders
PubMed: 23973319
DOI: 10.1016/j.schres.2013.07.027 -
Current Opinion in Neurology Feb 2020Visual snow is considered a disorder of central visual processing resulting in a perturbed perception of constant bilateral whole-visual field flickering or pixelation.... (Review)
Review
PURPOSE OF REVIEW
Visual snow is considered a disorder of central visual processing resulting in a perturbed perception of constant bilateral whole-visual field flickering or pixelation. When associated with additional visual symptoms, it is referred to as visual snow syndrome. Its pathophysiology remains elusive. This review highlights the visual snow literature focusing on recent clinical studies that add to our understanding of its clinical picture, pathophysiology, and treatment.
RECENT FINDINGS
Clinical characterization of visual snow syndrome is evolving, including a suggested modification of diagnostic criteria. Regarding pathophysiology, two recent studies tested the hypothesis of dysfunctional visual processing and occipital cortex hyperexcitability using electrophysiology. Likewise, advanced functional imaging shows promise to allow further insights into disease mechanisms. A retrospective study now provides Class IV evidence for a possible benefit of lamotrigine in a minority of patients.
SUMMARY
Scientific understanding of visual snow syndrome is growing. Major challenges remain the subjective nature of the disease, its overlap with migraine, and the lack of quantifiable outcome measures, which are necessary for clinical trials. In that context, refined perceptual assessment, objective electrophysiological parameters, as well as advanced functional brain imaging studies, are promising tools in the pipeline.
Topics: Brain; Functional Neuroimaging; Humans; Perceptual Disorders; Retrospective Studies; Vision Disorders; Visual Perception
PubMed: 31714263
DOI: 10.1097/WCO.0000000000000768 -
Stroke May 2022Perceptual disorders relating to hearing, smell, somatosensation, taste, touch, and vision commonly impair stroke survivors' ability to interpret sensory information,... (Review)
Review
Perceptual disorders relating to hearing, smell, somatosensation, taste, touch, and vision commonly impair stroke survivors' ability to interpret sensory information, impacting on their ability to interact with the world. We aimed to identify and summarize the existing evidence for perceptual disorder interventions poststroke and identify evidence gaps. We searched 13 electronic databases including MEDLINE and Embase and Grey literature and performed citation tracking. Two authors independently applied a priori-defined selection criteria; studies involving stroke survivors with perceptual impairments and interventions addressing those impairments were included. We extracted data on study design, population, perceptual disorders, interventions, and outcomes. Data were tabulated and synthesized narratively. Stroke survivors, carers, and clinicians were involved in agreeing definitions and organizing and interpreting data. From 91 869 records, 80 studies were identified (888 adults and 5 children); participant numbers were small (median, 3.5; range, 1-80), with a broad range of stroke types and time points. Primarily focused on vision (34/80, 42.5%) and somatosensation (28/80; 35.0%), included studies were often case reports (36/80; 45.0%) or randomized controlled trials (22/80; 27.5%). Rehabilitation approaches (78/93; 83.9%), primarily aimed to restore function, and were delivered by clinicians (30/78; 38.5%) or technology (28/78; 35.9%; including robotic interventions for somatosensory disorders). Pharmacological (6/93; 6.5%) and noninvasive brain stimulation (7/93; 7.5%) approaches were also evident. Intervention delivery was poorly reported, but most were delivered in hospital settings (56/93; 60.2%). Study outcomes failed to assess the transfer of training to daily life. Interventions for stroke-related perceptual disorders are underresearched, particularly for pediatric populations. Evidence gaps include interventions for disorders of hearing, taste, touch, and smell perception. Future studies must involve key stakeholders and report this fully. Optimization of intervention design, evaluation, and reporting is required, to support the development of effective, acceptable, and implementable interventions. Registration: URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42019160270.
Topics: Adult; Caregivers; Child; Humans; Perceptual Disorders; Stroke; Stroke Rehabilitation; Survivors
PubMed: 35468001
DOI: 10.1161/STROKEAHA.121.035671 -
British Medical Bulletin May 1981
Review
Topics: Agnosia; Amblyopia; Animals; Humans; Neurons; Perceptual Disorders; Retina; Superior Colliculi; Visual Acuity; Visual Cortex; Visual Pathways; Visual Perception
PubMed: 7032652
DOI: 10.1093/oxfordjournals.bmb.a071698 -
Clinical & Experimental Optometry Nov 2018Traumatic brain injury (TBI) and its associated concussion are major causes of disability and death. All ages can be affected but children, young adults and the elderly... (Review)
Review
Traumatic brain injury (TBI) and its associated concussion are major causes of disability and death. All ages can be affected but children, young adults and the elderly are particularly susceptible. A decline in mortality has resulted in many more individuals living with a disability caused by TBI including those affecting vision. This review describes: (1) the major clinical and pathological features of TBI; (2) the visual signs and symptoms associated with the disorder; and (3) discusses the assessment of quality of life and visual rehabilitation of the patient. Defects in primary vision such as visual acuity and visual fields, eye movement including vergence, saccadic and smooth pursuit movements, and in more complex aspects of vision involving visual perception, motion vision ('akinopsia'), and visuo-spatial function have all been reported in TBI. Eye movement dysfunction may be an early sign of TBI. Hence, TBI can result in a variety of visual problems, many patients exhibiting multiple visual defects in combination with a decline in overall health. Patients with chronic dysfunction following TBI may require occupational, vestibular, cognitive and other forms of physical therapy. Such patients may also benefit from visual rehabilitation, including reading-related oculomotor training and the prescribing of spectacles with a variety of tints and prism combinations.
Topics: Aged; Brain Injuries, Traumatic; Child; Eye Movements; Humans; Perceptual Disorders; Vision Disorders; Visual Acuity; Visual Fields; Young Adult
PubMed: 29488253
DOI: 10.1111/cxo.12670 -
Journal of Affective Disorders Nov 2013Major depression is a neuropsychiatric disorder that can involve profound dysregulation of mood. While depression is associated with additional abnormalities besides... (Review)
Review
BACKGROUND
Major depression is a neuropsychiatric disorder that can involve profound dysregulation of mood. While depression is associated with additional abnormalities besides reduced mood, such as cognitive dysfunction, it is not well established that sensory perception is also altered in this disorder (aside from in psychotic depression). Recent studies have shown that visual processing, in as early a stage as the retina, is impaired in depression. This paper examines the hypothesis that major depression can involve alterations in sensory perception.
METHODS
A Pubmed literature search investigated several lines of evidence: innervation of sensory cortex by serotonin and norepinephrine; antidepressant drugs and depression itself affecting processing of facial expressions of emotion; electroencephalography (EEG) studies of depressed persons and antidepressant drugs; involvement of the serotonergic 5HT2A receptor in both depression and hallucinogenic drug action; psychotic depression involving sensory distortions; dopamine possibly playing a role in depression; and the antidepressant effect of blocking the NMDA receptor with ketamine.
RESULTS
Data from each of these lines of evidence support the hypothesis that major depression can involve sensory perceptual alterations.
CONCLUSIONS
Loss of interest in one's daily activities and inability to experience pleasure, also known as anhedonia, in major depression may in part be mediated by sensory abnormalities, whereby normal sensory perceptions are no longer present to activate reward circuitry.
LIMITATIONS
The data supporting the hypothesis tend to be associative, so further confirmation of the hypothesis awaits additional controlled experiments.
Topics: Depressive Disorder, Major; Humans; Perceptual Disorders
PubMed: 23906865
DOI: 10.1016/j.jad.2013.06.045 -
Developmental Medicine and Child... Jul 2020
Topics: Cerebral Palsy; Humans; Movement Disorders; Perceptual Disorders; Somatosensory Disorders
PubMed: 32484581
DOI: 10.1111/dmcn.14542