Page 711 - Hematology_ Basic Principles and Practice ( PDFDrive )

Chapter 42 Sickle Cell Disease 603

A B
Fig. 42.13 Postmortem microangiographic studies of the vasa recta in a normal individual (A) and a patient
with sickle cell anemia (B). (Reproduced with permission from Elsevier. From LW Statius van Eps et al., Nature of
concentrating defect in sickle-cell nephropathy. Microradioangiographic studies, The Lancet, 1970, 295, 450-452.)

Preventing recurrent priapism is an important component of space and subperiosteal hemorrhage has been observed to result in
management. Strategies include HU administration; chronic transfu- headache, fever, and palpebral edema. In this situation, culture, CT
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sion; the antiandrogen bicalutamide; self-administration of the scan, and MRI should be used to rule out infectious, neoplastic,
α-adrenergic agent etilefrine orally and for episodes lasting over 1 and other hemorrhagic etiologies. Conservative therapy, including
hour, by intracavernous injection; and monthly administration of local measures, analgesia, fluids, transfusion, and careful ophthal-
intramuscular gonadotropin-releasing hormone analogue. 218,219 Pro- mologic surveillance, is recommended unless compression of the
phylactic pseudoepinephrine (Sudafed) appears beneficial in prevent- optic nerve ensues, in which case surgical decompression should be
ing recurrent mild episodes. considered.
Surgical creation of shunts is reserved for severe cases resistant to
the above interventions. As many as 45% of patients who have pria-
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pism develop some degree of impotence. When impotence persists Bone Complications
for 12 months, a semirigid penile prosthesis may be implanted.
Chronic tower skull, bossing of the forehead, and fish-mouth defor-
mity of the vertebrae are the result of extended hematopoietic bone
Ocular Complications 221 marrow, causing widening of the medullary space, thinning of the
trabeculae and cortices, and osteoporosis. Osteonecrosis may cause a
The retina is particularly vulnerable to vasoocclusion, and annual steplike depression of the vertebrae, selected shortening of the cuboi-
retinal examination is part of routine health care maintenance for dal bones of the hands and feet, and acute aseptic or avascular
patients with SCD. Superficial retinal hemorrhages have a pink necrosis. The excruciating pain of bone infarction in the “hand–foot
“salmon patch” appearance. Deeper retinal hemorrhages have a syndrome” that occurs around 2 years of age is often the first symptom
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“black sunburst” appearance. Other manifestations of sickle cell of SCD (Fig. 42.15). This dactylitis resolves spontaneously and is
retinopathy include iridescent spots, retinal neovascularization, and treated with hydration and analgesia. Bone infarcts are demonstrable
retinal detachment. More subtle signs of sickle cell retinopathy using nuclear medicine scintigraphy or MRI. Serial scans specific for
are optic nerve head vascular changes, vascular tortuosity, macular bone osteoclasts, bone marrow macrophages, and inflammatory cells
changes (e.g., microaneurysms and vascular loops), and peripheral may be useful adjuncts for distinguishing bone marrow infarction
arteriovenous anastomoses. Other ophthalmologic complications from osteomyelitis, but it is essential to obtain cultures directly from
are anterior chamber ischemia, tortuosity of conjunctival vessels, the affected tissue before starting antibiotics. Treatment of osteomy-
retinal artery occlusion, and angioid streaks. Sickle cell retinopathy elitis is addressed in the Infection sections.
is best seen by fluorescein angiography (Fig. 42.14). The earlier Bone necrosis occurs with equal frequency in the femoral and
onset and greater frequency of proliferative retinopathy in Hb SC humeral heads, but the femoral heads more commonly undergo
+
disease and sickle cell–β -thalassemia compared with sickle cell progressive joint destruction as a result of chronic weight bearing.
anemia and sickle cell–β°-thalassemia suggest that retinal vessels The process is associated with increased intraosseous pressure and is
are more susceptible to occlusion by more viscous blood than by most sensitively detected by MRI. Aggressive physical therapy appears
more rigid individual cells. Peripheral sickle retinopathy may require to prevent progression in mild cases and should be considered in
vision-saving therapy with laser photocoagulation. Orbital compres- the therapy of avascular necrosis. Core decompression surgery to
sion syndrome caused by vasoocclusion of the periorbital marrow relieve increased intraosseous pressure can be used in early-stage