Ainhum

Alternate names

Spontaneous dactylolysis

Definition

• Ainhum is the autoamputation of a finger or toe as a result of a fibrotic band that constricts the finger or toe until it falls off.
• (in'-hum) [negro word, meaning to saw]. A disease of Guinea and Hindustan, peculiar to negroes, in which the little toes are slowly and spontaneously amputated at about the digitoplantar fold.
• The process is very slow, is unaccompanied by any constitu- tional symptoms, and its cause is unknown.
• It sometimes attacks the great toe.

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Epidemiology

Ainhum has a prevalence worldwide but is most common in African countries. Despite this, the prevalence may be as low as 0.015 of the population of African countries.

Cause

• The cause of ainhum is not known. By definition, “true ainhum” must be idiopathic.
• This etiology is the differentiating feature from various forms of pseudoainhum which may be congenital, late-onset, or secondary to trauma.
• The common relationship between constricting bands of the feet and rural areas of Africa and South America has led to speculation about the trauma of walking barefoot in tropical regions.

Signs and symptoms

Clinically, the main feature is the progressive development of a circumscribed fibrotic ring at the base of the toes, or less frequently, the fingers. The most common location occurs over the fifth toe and may be bilateral.[1].

Clinical criteria include three findings:

• Soft tissue constriction
• Bulbous distal enlargement
• Distal thinning or lysis of phalangeal bones

Stages

• The disease may manifest through four clinical stages that are visible with radiography.
• First, a small callus develops and transforms into a circumferential groove or fissure.
• Next, the portion distant to the band becomes bulbous or globular secondary to impaired lymph and venous drainage with arterial narrowing.
• The third stage is typified by pain as the bone becomes separated in an intra-osseous or intra-articular location.
• The last stage is that of bloodless, spontaneous, auto-amputation.

Diagnosis

• Although primarily a clinical diagnosis, radiography can be useful to identify the extent of disease.
• Also, ainhum has correlations with progressive features that may be identifiable with plain films, ultrasound, computed tomography, or even magnetic resonance imaging. [2].

Treatment

• In early lesions, there have been attempts made with topical and injectable corticosteroids, retinoids, or salicylates.
• Reports exist of a case of pseudoainhum secondary to psoriasis responding to topical pimecrolimus, and low-dose narrowband UVB.
• Treatment of the constricting rings of fibrous tissue in stage-I and early stage-II disease may be treated similarly to scars and contractures.
• Resection of the band with subsequent z-plasty may prevent progression if performed early.
• Once stage-III and stage-IV disease have developed, surgical amputation or allowance for auto-amputation are the expected outcomes.[3].

NIH genetic and rare disease info

• NIH info on Ainhum

Ainhum is a rare disease.

Ainhum Resources
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Ainhum Resources
Latest articles Most recent articles Ongoing trials	Wikipedia