Parrot's sign refers to at least two

medical signs Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...

; one relating to the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, t ...

and another to a

pupil The pupil is a black hole located in the center of the iris of the eye that allows light to strike the retina.Cassin, B. and Solomon, S. (1990) ''Dictionary of Eye Terminology''. Gainesville, Florida: Triad Publishing Company. It appears black ...

reaction.

Background

Marie Jules Parrot was a French physician in Paris, whose early work concentrated on the

brain The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head ( cephalization), usually near organs for special ...

, followed by

tuberculosis Tuberculosis (TB) is an infectious disease usually caused by ''Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, in w ...

and later syphilis.

Skull

Parrot's sign, also known as 'Parrot's nodes' and 'Parrot's bosses', refers to the bony growth noted at

autopsy An autopsy (post-mortem examination, obduction, necropsy, or autopsia cadaverum) is a surgical procedure that consists of a thorough examination of a corpse by dissection to determine the cause, mode, and manner of death or to evaluate any dis ...

by Marie Jules Parrot and

Jonathan Hutchinson Sir Jonathan Hutchinson (23 July 1828 – 23 June 1913), was an English surgeon, ophthalmologist, dermatologist, venereologist, and pathologist. Life He was born in Selby, Yorkshire, of Quaker parents and educated in the local school. Then he ...

on the skulls of children with

congenital syphilis Congenital syphilis is syphilis present ''in utero'' and at birth, and occurs when a child is born to a mother with syphilis. Untreated early syphilis infections results in a high risk of poor pregnancy outcomes, including saddle nose, lower ext ...

(CS) in the 19th century. Later publications also describe it as the

frontal bossing Skull bossing is a descriptive term in medical physical examination indicating a protuberance of the skull, most often in the frontal bones of the forehead ("frontal bossing"). Although prominence of the skull bones may be normal, skull bossing m ...

that presents in the late type CS. Initially thought to be

indicative A realis mood ( abbreviated ) is a grammatical mood which is used principally to indicate that something is a statement of fact; in other words, to express what the speaker considers to be a known state of affairs, as in declarative sentences. Mo ...

of congenital syphilis, it was noted to be present in other conditions, particularly

rickets Rickets is a condition that results in weak or soft bones in children, and is caused by either dietary deficiency or genetic causes. Symptoms include bowed legs, stunted growth, bone pain, large forehead, and trouble sleeping. Complications ma ...

. A description of bone findings in CS by Parrot was published in ''The Lancet'' in 1879 following his presentation at a meeting hosted by

and Thomas Barlow in London. In 1883 Barlow referred to the overgrowth of skull bone seen in CS as 'Parrot's swellings' and 'Parrot's bosses'. The nodes were said to be indicative of CS. In

Timothy Holmes Timothy Holmes FRCS (9 May 1825 in Islington, Greater London – 8 September 1907) was an English surgeon, known as the editor of several editions of '' Gray's Anatomy''. Life Holmes was educated at Merchant Taylors' School and then at Pembroke ...

' and Thomas Pickering 's '' A Treatise on Surgery: Its Principles and Practice'' (1889) it was noted that Parrot's nodes could co-exist with thinning bone in the same skull. The nodes were described in '' Gray's Anatomy'' (1893) as appearing like

buttocks The buttocks (singular: buttock) are two rounded portions of the exterior anatomy of most mammals, located on the posterior of the pelvic region. In humans, the buttocks are located between the lower back and the perineum. They are compose ...

hot cross bun A hot cross bun is a spiced sweet bun usually made with fruit, marked with a cross on the top, and has been traditionally eaten on Good Friday in the United Kingdom, Ireland, Australia, New Zealand, South Africa, Canada, India, Pakistan and ...

depending on which skull bones were affected. According to

D'Arcy Power Sir D'Arcy Power, (11 November 1855 in Pimlico, London - 18 May 1941) was a British surgeon, medical historian, and contributor of some 200 articles on famous surgeons and other related figures to the ''Dictionary of National Biography''. Me ...

in 1895, they were first reported by Parrot and Hutchinson, and also found in

, and therefore could not strictly make them indicative of congenital syphilis. In Hamilton and Love's '' A Short Practice of Surgery'' (1959), Parrot's nodes were said to consist of patches of

periostitis Periostitis, also known as periostalgia, is a medical condition caused by inflammation of the periosteum, a layer of connective tissue that surrounds bone. The condition is generally chronic, and is marked by tenderness and swelling of the bone an ...

in CS.

Pupil

Parrot's sign was described in some ophthalmology textbooks of the 19th century as the dilatation of a

when the back of the neck is pinched in some cases of

meningitis Meningitis is acute or chronic inflammation of the protective membranes covering the brain and spinal cord, collectively called the meninges. The most common symptoms are fever, headache, and neck stiffness. Other symptoms include confusion ...

Background

Skull

Pupil

See also

References

Further reading