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Managing the dental patient with sickle cell anemia: a review of the literature.

In 1910, a black West Indian student was found by JB Herrick to have strange sickle-shaped cells within his bloodstream (Barnhart et al. 1979). In 1929, a similar observation was documented in a white individual (Benjamin and Gootenberg 1987). However, it was not until 1949 that Linus Pauling actually identified hemoglobin S as the abnormal hemoglobin associated with sickle cell anemia (SCA; Barnhart et al. 1979). Sickle cell anemia is a genetic disease that primarily affects the black population. This anemia is due to a homozygous state of the abnormal hemoglobin S (Rose and Kaye 1983). An alteration occurs on the DNA molecule involving the substitution of the amino acid valine for glutamic acid at the sixth position on the beta polypeptide chain (Rose and Kaye 1983). This biochemical variation on the DNA molecule creates a physiological change that causes sickle-shaped red blood cells to be produced. The sickle-shaped cells are the result of the hemoglobin S being deoxygenated. With a decrease in affinity of oxygen to an abnormal hemoglobin, deoxygenation will occur, again producing more sickle-shaped cells. This leads to obstruction or microvasculature erythrostasis, causing vasocclusion and extensive organ damage (Rose and Kaye 1983). It is a cyclic process. Sickle cell anemia may be diagnosed in the sixteenth week of gestation, but manifestations normally do not appear until the sixth month after birth. Newer techniques for hemoglobin electrophoresis can be used to diagnose the abnormal hemoglobin at birth. Painful episodes or "crises" characteristic of this disease are vasocclusion, sequestration, aplastic, and to a lesser degree, hyperhemolysis. The vasocclusive or infarctive type crisis most commonly is associated with excrutiating pain (Rose and Kaye 1983). Barnhart et al. (1979) have reported that infection, dehydration, acidosis, exposure to cold, some forms of stress, rigorous exercise, or an emotional disorder may be precipitating factors for a crisis. Symptoms may include increased breathing, abnormal heart rate, jaundice, fever, or abdominal tenderness (Rose and Kaye 1983). An early indication of SCA in infancy is the symmetrical hand-foot syndrome (sickle-cell dactylitis), which is described as the swelling of the hands and feet due to vasocclusion of the microvasculature in the small bones. Sickle cell dactylitis frequently occurs around two years of age; however, it may be diagnosed as early as six months of age (Barnhart et al. 1979). Sequestration crises occur mainly in the young child. One symptom is the sudden enlargement of the liver and spleen caused by massive accumulation of blood in these organs. The enlarged liver leads to an increase in unconjugated bilirubin, and eventually is associated with jaundice and scleral icterus in SCA patients (Barnhart et al. 1979). Gallstones may be detected SCA patients in the first and second decades of their lives, and are common in the third decade. A palpable spleen is common in children. After age six, however, the spleen decreases in size because of fibrosis and the presence of scar tissue resulting from the frequent occurrence of infarctions. The reduction in size or loss of the spleen may be a contributing factor to the likelihood of widespread bacterial infections, especially in infants and young children who have not developed adequate immunity to certain bacterial pathogens (Barnhart et al. 1979). Rose and Kaye (1983) report that aplastic crisis results from the nonproductive function of bone marrow, which leads to severe anemic conditions. The less common type of crisis, hyperhemolytic, is sometimes associated with glucose-6-phosphatase (G-6-PD) deficiency. This deficiency can cause lactic acidosis which could precipitate a crisis for the SCA patient (Behrman and Vaughan 1987). Painful crises are common with the SCA patient and affect the entire body; moreover, changes are seen in the renal, central nervous (CNS), cardiovascular (CVS), and pulmonary systems. Evidence of renal lesions indicates that sickle-shaped cells