Formication

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Template:DiseaseDisorder infobox Template:Search infobox Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Luke Rusowicz-Orazem, B.S. Cafer Zorkun, M.D., Ph.D. [2]

Overview

Formication is a somewhat unusual, but medically well-known, abnormal sensation. This sensation closely resembles the feeling of insects crawling on and/or under the skin, and can also include sensations which resemble those of insects stinging or biting. There are many known causes of formication.

The word is derived etymologically from the Latin word formica, meaning "ant", precisely because of this similarity in sensation to that of crawling insects.

Formication is a specific form of the general set of abnormal skin sensations known as paresthesia, and thus it is related to the sensation known as "pins and needles", and other tingling sensations.

Some people suffering the sensation of formication find it to be annoying, others find it painful, and some find it itchy. Those who find it to be itchy may in some cases repeatedly scratch themselves until they bleed, causing skin damage and sores. (In the subset of cases where the sufferer is delirious or intoxicated because of high fever, substance abuse, or extreme alcohol withdrawal, this repeated scratching is very common indeed.)

Formication can on occasion lead to people becoming fixated on the sensation and its possible meaning, and these people may develop delusional parasitosis. This is a situation where individuals are convinced that there are real insects crawling on and/or under their skin, whereas in reality there are no insects involved, just a crawling sensation. It is fairly easy to misunderstand the significance and causality of the "creepy crawly" sensation of formication.

Causes

Formication is a somewhat unusual, but medically well-known, abnormal sensation. This sensation closely resembles the feeling of insects crawling on and/or under the skin, and can also include sensations which resemble those of insects stinging or biting. There are many known causes of formication.

The word is derived etymologically from the Latin word formica, meaning "ant", precisely because of this similarity in sensation to that of crawling insects.

Formication is a specific form of the general set of abnormal skin sensations known as paresthesia, and thus it is related to the sensation known as "pins and needles", and other tingling sensations.

Some people suffering the sensation of formication find it to be annoying, others find it painful, and some find it itchy. Those who find it to be itchy may in some cases repeatedly scratch themselves until they bleed, causing skin damage and sores. (In the subset of cases where the sufferer is delirious or intoxicated because of high fever, substance abuse, or extreme alcohol withdrawal, this repeated scratching is very common indeed.)

Formication can on occasion lead to people becoming fixated on the sensation and its possible meaning, and these people may develop delusional parasitosis. This is a situation where individuals are convinced that there are real insects crawling on and/or under their skin, whereas in reality there are no insects involved, just a crawling sensation. It is fairly easy to misunderstand the significance and causality of the "creepy crawly" sensation of formication.

Life Threatening Causes

Common Causes

Causes by Organ System

Cardiovascular Cerebrovascular accident, Compartment syndrome, Limb ischaemia, Posterior inferior cerebellar artery syndrome, Volkmann ischaemic contracture
Chemical/Poisoning 4-aminopyridine, Carbon monoxide toxicity, Mercury poisoning, Pesticide
Dental No underlying causes
Dermatologic Lepromatous leprosy, Melanoma
Drug Side Effect Adderall use, Amifampridine, Amiodarone, Benzodiazepine withdrawal, Cocaine intoxication, Colistimethate, Digoxin, Dimercaprol, Lanatoside c, Lidocaine, Lunesta, Mefloquine, Palifermin, Riluzole, Ritalin use, Tetrodotoxin, Thallium, Topiramate
Ear Nose Throat No underlying causes
Endocrine Gopalan syndrome, Hypothyroidism, Osteomalacia
Environmental No underlying causes
Gastroenterologic No underlying causes
Genetic Ito syndrome
Hematologic Hypocalcaemia
Iatrogenic No underlying causes
Infectious Disease Herpes zoster, Lepromatous leprosy, Lyme disease, Syphilis
Musculoskeletal/Orthopedic Carpal tunnel syndrome
Neurologic Causalgia, Cerebrovascular accident, Compartment syndrome, Delirium tremens, Diabetic neuropathy, Gopalan syndrome, Guillain-barre syndrome, Multiple sclerosis, Notalgia paraesthetica, Peripheral neuropathy, Posterior inferior cerebellar artery syndrome, Thoracic outlet syndrome, Transverse myelitis
Nutritional/Metabolic Diabetic neuropathy
Obstetric/Gynecologic Menopause
Oncologic Melanoma
Ophthalmologic No underlying causes
Overdose/Toxicity Alcohol withdrawal, Benzodiazepine withdrawal, Cocaine intoxication, Delirium tremens, Lidocaine, Methamphetamine intoxication, Opiate use, Ritalin use
Psychiatric No underlying causes
Pulmonary Respiratory alkalosis
Renal/Electrolyte Respiratory alkalosis
Rheumatology/Immunology/Allergy Causalgia, Respiratory alkalosis
Sexual Herpes zoster, Syphilis
Trauma No underlying causes
Urologic No underlying causes
Miscellaneous No underlying causes

Causes in Alphabetical Order

Referenced

Formication was neatly described in 1890:

A variety of itching, often encountered in the eczema of elderly people, is formication; this is described as exactly like the crawling of myriads of animals over the skin. It is probably due to the successive irritation of nerve fibrils in the skin. At times patients who suffer from it will scarcely be persuaded that it is not due to insects. Yielding to the temptation to scratch invariably makes the disease worse.[1]

The term formication has been in use for several hundred years. In the 1797 edition of the Encyclopædia Britannica, a description of the condition raphania includes the symptom:

...a formication, or sensation as of ants or other small insects creeping on the parts.[2]

Depictions of formication in fiction

  • The novel A Scanner Darkly by Philip K Dick contains a scene where the character Jerry Fabin (and Charles Freck in the movie of the same name) suffers from formication and attempts to remedy the condition by showering for hours on end.
  • In the movie Old Boy, the main character experiences formication while imprisoned for 15 years.

References



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