Medical Care
In patients with thrombocytopenia-absent radius (TAR) syndrome, general thrombocytopenic precautions during times of clinically significant thrombocytopenia with a platelet count < 80 X 109/L (usually during the first year of life) should include avoidance of trauma (with use of a soft helmet if needed), avoidance of certain antiplatelet drugs (eg, aspirin, nonsteroidal anti-inflammatory drugs [NSAIDs]), and prolonged pressure on injection sites (especially after intramuscular injections). [23]
Prehospital care should involve first aid for visible acute hemorrhage. Apply firm steady pressure to the site of bleeding. Keep the patient warm. Elevate the bleeding limb.
The mainstay of hospital treatment is supportive care. By far, the most important treatment is platelet transfusion. The goal of platelet transfusion is to maintain a sufficient volume of platelet to prevent bleeding without adverse effects.
Prophylactic transfusions with leukocyte-reduced platelet concentrates are used in patients at high risk of clinically significant hemorrhage.
A transfusion target extrapolated from thrombocytopenia associated with acute leukemia is a platelet count < 40 X 109/L. Platelet counts greater than this level are associated with a decreased risk of major vascular bleeding. Melena, epistaxis, hematuria, mucosal bleeding, and hematemesis are controlled in 80% of patients with acute leukemia when a posttransfusion increment of >40 X 109/L is used.
Potential risks of platelet transfusion include infection, anaphylaxis, formation of antiplatelet antibodies, and hemolytic reactions.
Hepatitis viruses (B, C, other) and HIV are the most common infective pathogens potentially transmitted with the transfusion of blood products.
A further risk with transfusion is human leukocyte antigen (HLA) alloimmunization. However, platelets themselves are not highly immunogenic, and contaminating lymphocytes are most likely to cause HLA alloimmunization. Therefore, leukocyte-reduced platelet concentrates should always be used. Alloimmunization can be delayed by using random single-donor platelets and, ideally, by identifying a limited number of dedicated donors.
Treatment of conditions refractory or nonresponsive to transfusion is difficult but may include the use of HLA-matched platelets from family members. However, the refractory state can occur even in patients receiving HLA-matched platelets, a finding that suggests a non-HLA, platelet-specific antigen.
Splenectomy may be partially effective for the treatment of thrombocytopenia in adults.
Hematopoietic stem cell transplantation (HSCT) is an option for patients who remain thrombocytopenic with bleeding despite platelet transfusions.
Patients with thrombocytopenia have responded to cytokine treatment with erythropoietin and interleukin-6. The side effects of the latter, however, do not justify such therapy. [24, 25]
Surgical Care
Splinting of the hands (and legs, if indicated) during infancy improves future function. If surgical correction of the arm deformities is indicated, it should be undertaken after the patient is hemodynamically stable. If surgery is not a feasible option to manage deformities of the upper limb as patients age, adaptive devices to assist with activities of daily living (eg, dressing, toileting, feeding) are helpful. Prostheses are less useful than adaptive devices because the patient often has a weak upper extremity because of poorly developed musculature and because a functional 5-digit hand diminishes the need for a long limb.
Management of lower-extremity deformities must be individualized given the wide spectrum of anomalies. Intervention can range from no treatment if the deformity is mild (eg, mild varus deformity) and if it causes no functional impairment to the use of a power wheelchair or a motorized cart if the anomaly is severe and if it limits ambulation. Overall, the goal is to improve functioning and enhance independence.
Splenectomy may be partially effective for the treatment of thrombocytopenia in adults.
Consultations
The patient with suspected TAR syndrome should be examined by a hematologist, orthopedic surgeon, plastic surgeon, and cardiologist, all of whom specialize in treating children.
Diet
Patients should avoid ingesting cow's milk for the first year of life because cow's milk allergy is associated with TAR and may precipitate thrombocytopenic episodes.
The frequency of thrombocytopenic episodes and the risk of complications are typically highest during the first 2 years of life, and recurrences decrease as the child ages.
Bloody diarrhea is reported in 20% of patients. Removal of milk from the diet alleviates this symptom.
Activity
Careful handling of the patient, with padding of his or her crib and with the application of soft helmets, can be used in the first year of life. Most patients are adequately hemostatic after the first year of life to allow them to perform normal activities. Patients should avoid trauma (eg, contact sports) during periods of thrombocytopenia.
A study by Al Kaissi et al indicated that optimal treatment of TAR syndrome can allow patients to participate in most activities of daily living, albeit with some ulnar deviation and with limitations on wrist extension and on total active range of digital motion. The study included five patients, in whom the wrists underwent realignment and stabilization and whose ulnar forearm bows were reversed through rebalancing of the musculotendinous forces around the wrist. [26]
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Infant with thrombocytopenia-absent radius syndrome. The arms and forearms are shortened, with radial deviation of both hands because of the absence of bilateral radii. The legs are normal. See also Media files 2 and 3.
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Same infant as in Media files 1 and 3. Close-up photograph of arm and forearm (volar aspect). Note the petechiae.
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Same infant as in Media files 1 and 2. Close-up photograph of arm and forearm (dorsal aspect).
