TACTILE HALLUCINATION

tactile hallucination: translation

Also known astactile phantasma, haptic hallucination, touch hallucination, andhallucination of touch. The term tactile hallucination is indebted to the Latin verbtangere, which means to touch. It refers to a bodily sensation seemingly evoked by a stimulus from outside the body (such as a pat on the shoulder, a blow to the head, or a stab in the back) which occurs in the absence of an appropriate source in the extracorporeal environment. The above terms are used in opposition to the term * somatic hallucination, which is reserved for a hallucination of bodily sensations that would seem to come from inside the body. Together, tactile and somatic hallucinations are referred to as * bodily hallucinations. Historically, tactile hallucinations have been divided mainly in accordance with the type of sensation evoked. Thus the term * stereognosic hallucination is used to denote a type of tactile hallucination in which one or more solid objects are perceived, and the term * spontaneous stereognosic sensation to denote a tactile hallucination mimicking the feeling of an object held in the palm of one's hand, while the hand is actually empty. The term * hygric hallucination is used to denote the hallucinated sensation of water, experienced in the tactile modality. When tactile hallucinations mimic the feeling of bugs crawling upon or beneath the skin, they are designated as *formicative hallucinations. Drug-induced variants of formication are known under the names *cocaine bugs, *Magnan's sign, Magnan-Saury's sign, and * crank bugs. Tactile hallucinations experienced in erogenic zones are referred to as *genital or *sexual hallucinations. The complete inability to feel one's body is designated as * acenesthesia, whereas painful sensations attributed to hallucinatory activity are referred to as * hallucinated pain. Some of the sensory deceptions experienced in the tactile modality should perhaps be classified as tactile illusions rather than hallucinations.Some examples are *tactile polyaesthesia (in which a single tactile stimulus is at first perceived and localized properly, and then perceived again in one or more improperly localized places), *allachaesthesia (i.e. a mislocation of tactile sensations), *phantom alloaesthesia (i.e. a tactile sensation perceived below the stump ofan amputated limb, following stimulation of the remaining - contralateral -limb), and * allochiria (i.e. a mislocation of sensory stimuli to the corresponding opposite half of the body). Pathophysiologically, tactile hallucinations are associated primarily with aberrant neurophysiological activity in sensory cortical areas representing the skin and subcutaneous tissues. In clinical practice, it is not always easy to distinguish them from other somatosensory phenomena. The differential diagnosis of tactile hallucinations includes such diverse phenomena as somatic hallucinations, hallucinated pain, *sensed presence, * distortions of vital sensation, *coenesthetic hallucinations, *body schema illusions, *paraesthesiae, *alloesthaesia, *allodynia, *hyperaesthesia, * hyperalgesia, * hyperpathia, referred pain, and actual parasitosis.

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