palinacusis

   Also known as palinacousis and auditory perseveration. The term palinacusis comes from the Greek words palin (again) and akouein (to hear). It refers to a rare symptom involving the persistence or paroxysmal recurrence of auditory percepts, analogous to the persistence or recurrence of visual images in *palinopsia, and the recurrence of tactile sensations in * tactile polyaesthesia. As noted by the American neurologists Lawrence D. Jacobs (1938-2001) et al., "Palinacousis is a paroxysmal auditory illusion in which aural sensations produced by diverse environmental sounds, such as speech and music, persist or recur for variable periods of time after the initial acoustic stimulus has ended. The pali-nacoustic sensations, which seem to emanate from a real source located in external auditory space, are usually quite vivid and may be indistinguishable from the sound of the actual acoustic event, whether it be a telephone ring, engine noise, or the yowling of a dog." The first known description of palinacusis was published in 1965 by the Russian-American neurologist Morris Boris Bender (1904-1983) and his colleague Sidney P. Diamond. Jacobs et al. have been credited with publishing the most extensive and detailed description of palinacusis to date, based on their observations in seven affected individuals. The perseverative auditory percepts in palina-cusis tend to be designated as * illusions, but they can also be classified as hallucinations. In general, however, they are classified as * reduplicative phenomena. Of the sounds reported by individuals with palinacusis, human voices are the most prevalent, with utterances varying in length from a single word to a whole phrase. Palinacoustic percepts are reported as commencing immediately after the original acoustic event, or up to 24 h later. They may persist for days to months, typically recurring several times a day. The quality of the perseverated sounds can be poorer or richer than the original acoustic event (i.e. either 'muffled', or 'louder' and 'sharper'). The perse-verated sounds may or may not be accompanied by additional nonverbal sounds such as ringing, hissing, whistling, rushing, tinkling, and cracking. They may be restricted to a single sound, but the account of a person with more than 30 different palinacoustic experiences was also reported by Jacobs et al. Sometimes palinacous-tic experiences can be stopped by covering the ear. Pathophysiologically, palinacusis is associated primarily with focal temporal seizure discharges occurring in the context of an *aura or a * dreamy state. It has also been reported in the aftermath of epileptic seizures, i.e. as a pos-tictal or interictal event. Comorbid symptoms in palinacusis may include * déjà vu and déjà entendu experiences, illusions and hallucinations in anyofthe othersensorymodalities, palinopsia, * synaesthesias, paroxysmal agitation, confusion, aphasia, and amnesia. Episodes of palinacusis may be followed by a generalized epileptic seizure. When the seizures are managed appropriately, the palinacoustic experiences tend to vanish as well. Etiologically, palinacusis is associated primarily with organic lesions affecting the temporal lobe, such as a tumour, haemorrhage, or infection. Palinacusis has also been reported in an individual with a thalamus infarction, and in individuals with a clinical diagnosis of hysteria or *psychotic disorder. Phenomenologically, palinacusis bears a certain similarity to * Gedankenlautwerden or thought echoing, a phenomenon characterized by the echoing of one's own conscious thoughts. Pathophysiologically, however, the two phenomena would seem to be quite different.

   References

   Bender, M., Diamond, S.P. (1965). An analysis of auditory perceptual defects with observations on the localisation of dysfunction. Brain, 88, 675-686.

   Di Dio, A.S., Fields, M.C., Rowan, A.J. (2007). Palinacousis - Auditory perseveration: Two cases and a review of the literature. Epilepsia, 48,1801-1806.

   Jacobs, L., Feldman, M., Diamond, S.P., Bender, M.D. (1973). Palinacousis: Persistent or recurring auditory sensations. Cortex, 9, 275-287.