- formicative hallucination
- Also referred to as formication, dermatozoic hallucination, and insect hallucination. The terms formication and formicative hallucination are indebted to the Latin noun formica, which means ant. All of the above four terms are used more or less interchangeably to denote the hallucinated feeling of ants or other bugs crawling upon or beneath the skin. Formicative hallucinations may be accompanied by pruritus and scratching, which may entail even more pruritis, and hence an aggravation of the formicative hallucinations. Their occurrence is associated primarily with the use of (or more likely, withdrawal from) substances such as cocaine, amphetamines (including the therapeutic methylphenidate), and alcohol. They can also occur in the context of *alcoholic hallucinosis, and in association with a variety of somatic conditions such as * delirium, high fever, diabetic neuropathy, herpes zoster, and peripheral nerve regeneration or neuropathy, as in * Tinel's sign of formication. They have also been described in association with psychiatric disorders such as bipolar disorder and somato-form disorder. Formicative hallucinations may be accompanied by delusional parasitosis, a condition also referred to as Ekbom's syndrome, after the Swedish neurologist Karl Axel Ekbom (1907-1977). They may also be accompanied by *visual hallucinations of insects, which may be regarded by the affected individual as confirmation of an actual bug infestation. The term *chronic tactile hallucinosis is used to denote a syndrome characterized by formicative hallucinations, parasitic or other dermatozoic delusions, and a chronic course which is believed to occur mainly in women of 50 years of age and older. When formicative hallucinations are attributed to the chronic use of cocaine, they are referred to as * cocaine bugs, * Magnan's sign, or Magnan-Saury's sign. When they occur in the context of amphetamine use they are known as * crank bugs. Formicative hallucinations are classified either as * tactile hallucinations or as *paraesthesias. They should not be confused with hallucinations due to * ant ingestion.ReferencesBers, N., Conrad, K. (1954). Die chronische tak-tile Halluzinose. Fortschritte der Neurologie und Psychiatrie, 22, 254-270.Ekbom, K.A. (1938). Praeseniler Dermatozoen-wahn. Acta Psychiatrica Scandinavica, 13, 227-259.
Dictionary of Hallucinations. J.D. Blom. 2010.