Continuing Education Activity
Ainhum, also called dactylolysis spontanea, is a rare disease of fibrotic constricting bands that most commonly occur over digits. These rings of fibrous tissue may result in significant morbidity and auto-amputation. Although historically a disease of South American and African individuals, it is recognized in more broad literature and White and rarely in India. The disease requires differentiation from other hereditary and secondary constricting band diseases. This activity outlines the epidemiology, clinical manifestations, diagnosis, and treatment of ainhum.
- Identify the etiology of ainhum medical conditions and emergencies.
- Outline the appropriate evaluation of ainhum.
- Review the management options available for ainhum.
- Summarize interprofessional team strategies for improving care coordination and communication to improve outcomes in patients with ainhum.
Ainhum, also known by the name dactylolysis spontanea, is a disease of constricting fibrous bands and possible resultant auto amputation. Historically, ainhum is a rare condition that has occurred most frequently in those of African males. The name “ainhum” is thought to have a meaning similar to a fissure from early published Brazilian reports or maybe from an Africa meaning “to saw or cut.”
Ainhum, by definition, is a constricting band disease without an identifiable cause. If a secondary cause is identified, whether a systemic condition or trauma, the disease would be classified as pseudoainhum. Unfortunately, in the absence of an underlying trigger, the pathophysiology of the progressive constricting fibrous bands is not understood.
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. In Brazil, another endemic area has a higher incidence in individuals with lighter phenotypes due to historical interracial marriages and offspring.
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.
Although biopsies are usually unnecessary to establish a diagnosis, if done, findings reveal dermal fibrosis with longitudinally oriented connective tissue. Electron micrographic findings reveal findings similar to keloidal tissue.
History and Physical
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.
A fibrotic band classically begins within a flexural groove. The lesion is circumferential and often slowly progresses with resultant changes distal to the constriction. Clinical criteria include three findings:
- Soft tissue constriction
- Bulbous distal enlargement
- Distal thinning or lysis of phalangeal bones
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. As the initial stage is a non-specific diagnosis usually arouses clinical suspicion after forming the constricting band.
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. The earliest phase demonstrates a deep sulcus along with the soft tissue of the phalanx; this has been likened to having the appearance of a “sand-glass.” The second phase occurs as a result of lymphedema and appears as increased volume distal to the constricting band. The third phase corresponds with the presence of bone resorption distal to the band, and the fourth phase is that of spontaneous amputation.
Treatment / Management
There has as yet been no consistent treatment established for ainhum. As the inciting event is often unidentified, there are no targeted therapies to date. There have been attempts made with topical and injectable corticosteroids, retinoids, or salicylates in early lesions. Reports exist of a case of pseudoainhum secondary to psoriasis responding to topical pimecrolimus and low-dose narrowband UVB. However, extrapolation of this to idiopathic ainhum seems unlikely as this patient responded to treatment of the underlying causal condition. 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.
- Primary pseudoainhum: Auto-amputation that is congenital and presents early in life with an identifiable associated process. Excludes cases that are secondary to amniotic bands.
- Secondary pseudoainhum: Auto-amputation later in life with an identifiable associated process. Excludes cases that are secondary to amniotic bands.
- Traumatic pseudoainhum: Auto-amputation resembling ainhum with a clear traumatic origin.
- Amniotic band syndrome:
- Caused by intrinsic developmental defects of germ plasma and vascular disruption or extrinsic insults with resulting extrusion of fetal body parts into the chorionic cavity.
- Variable clinical manifestations including constricting rings, digital amputations, or visceral involvement.
- Porokeratosis of Mibelli
- Hansens disease
- Neuropathic plica
- Raynaud’s disease
- Factitious pseudoainhum (from tourniquet application)
- Keratoderma hereditarium mutilans (Vohwinkel syndrome)
Dactylolysis spontanea often progresses over time, and spontaneous amputation occurs fur to six years after the disease onset.
After amputation of the digit(s) occurs, complications may include pain, secondary infection, and locomotor imbalance.
Postoperative and Rehabilitation Care
Although not specifically reported, there are clinicians of the opinion that patients with ainhum or other constricting band syndromes would likely benefit from physical and occupational therapy. In patients with early disease, occupational therapy may improve mobility or even promote fine motor function after amputation has occurred. In patients with surgical or spontaneous amputation of the digits of the foot, physical therapy or custom, orthotics would likely benefit patients with locomotor dysfunction and balance.
As the diagnosis is clinical, dermatologists are often the most acquainted with the constricting band syndromes. If surgical amputation is desired or is a consideration, orthopedic surgeons would also be well adapted to manage these patients.
Deterrence and Patient Education
As no distinct behaviors have demonstrated consistent links to ainhum, preventative counseling is not feasible. If pseudoainhum or secondary ainhum occurs, patients should avoid any identifiable triggers and underlying disease processes treated.
Enhancing Healthcare Team Outcomes
Ainhum is a disease process that is often under-recognized and may not be caught early enough to implicate effective treatment. As nurses, medical assistants, and non-physician healthcare members are often the first to see patients in the social and medical setting, increasing awareness in this community may prompt patients to seek care before symptoms occur. In addition to the physician’s interpretation of diagnostic studies and ultimate surgical treatment, physical therapists and occupational therapists can help maximize an affected individual's quality of life. Researchers have not explored the social and mental effects of ainhum, but psychiatrists, psychologists, counselors, or pastoral care may help alleviate underappreciated psychological consequences of this disease.
Although historically a disease of rural South America, Africa, and India, as migratory patterns continue to change, physicians in the western world and developed nations may be more likely to encounter ainhum.
All studies at this time are evidence level 5 or lower. As the disease is so infrequently encountered, there have been no well-organized trials performed.