Rare perceptual disorders, one visual, one auditory: the neuropsychiatry of visual snow and exploding head syndromes

Abstract

SUMMARY Perceptual disturbances are common in psychiatric and neurological conditions, yet some rare, non-psychotic disorders remain poorly recognised. This review examines two such syndromes: visual snow syndrome (VSS) and exploding head syndrome (EHS). VSS is marked by continuous ‘static’ across the visual field, often accompanied by palinopsia, photophobia and entoptic phenomena. EHS involves sudden, loud auditory sensations – like explosions or crashes – occurring during transitions between sleep and wakefulness. Although distinct in modality, both share common challenges: subjective distressing symptoms, normal investigation findings, frequent misdiagnosis and psychiatric comorbidities such as anxiety, sleep dysfunction and depersonalisation. The article synthesises emerging evidence on their neurobiological underpinnings, including cortical hyperexcitability, thalamocortical dysrhythmia and impaired sensory gating, and on pharmacological and non-pharmacological treatment options. Enhancing clinical awareness and adopting a multidisciplinary approach are essential for improving diagnosis and care. This article aims to support psychiatrists in recognising, differentiating and managing these complex perceptual disorders.