Slight pain is present in the earliest stage of ainhum, caused by pressure on the underlying nerves. Fracture of the phalanx or chronic sepsis is accompanied with severe pain. Cause
The true cause of ainhum remains unclear. It is not due to infection by parasites, fungi, bacteria or virus, and it is not related to injury. Walking barefoot in childhood had been linked to this disease, but ainhum also occurs in patients who have never gone barefoot. Race seems to be one of the most predisposing factors and it may have a genetic component, since it has been reported to occur within families. Dent et al. discussed a genetically caused abnormality of the blood supply to the foot. It has been related to inadequate posterior tibial artery circulation and absence of plantar arch. Diagnosis
Histolopathology
Histology shows a change in the prickle cell layer, and this is responsible for the laying down of condensed keratin causing the groove. The junctional tissue is reduced to a slender fibrous thread, almost avascular, and all the tissues beyond the constricting band is repressed by a fibro-fatty mass covered by hyperkeratotic integument. Imaging
Soft tissue constriction on the medial aspect of the fifth toe is the most frequently presented radiological sign in the early stages. Distal swelling of the toe is considered to be a feature of the disease. In grade III lesions osteolysis is seen in the region of the proximal interphalangeal joint with a characteristic tapering effect. Dispersal of the head of the proximal phalanx is frequently seen.
In Nigeria it is a common disease with an incidence of 1.7 per thousand. In tropical and subtropical climates, its incidence has been reported as between 0.015 percent and 2.0 percent of the population. Up to now only a few cases had been reported in Europe. Ainhum usually affects people between 20 and 50 years. The average age is about thirty-eight. The youngest recorded patient was seven years old. It is more common in men than in women (2:1), and is often familial. History
The first description of ainhum in the West appears to have been provided by English surgeon Robert Clarke, who made a passing reference to "dry gangrene of the little toe" as a common occurrence in the Gold Coast in an 1860 report to the Epidemiological Society of London, but did not recognize it as a distinct entity and believed it to be a consequence of "suppressed yaws". Ainhum was first recognized as a distinct disease and described as such in detail by Brazilian physician Jose Francisco da Silva Lima (1826–1910), in 1867. The name "ainhum" (from the Yoruba ayùn, meaning "to saw" or "to file") was used to refer to the disease by Yoruba speakers in Bahia, Brazil, where Silva Lima practiced.The first histological studies of ainhum were conducted by O. E. H. Wucherer and published in 1872, and the first imaging studies were conducted in 1924. References


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