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  • Updated 05.14.2024
  • Released 04.03.2006
  • Expires For CME 05.14.2027

Polycythemia vera and its neurologic manifestations



Polycythemia vera is the commonest of chronic myeloproliferative disorders, which are a group of bone marrow stem cell neoplasms characterized by an autonomous expansion of the cellular elements of the marrow and the peripheral blood. In polycythemia vera, the increase in red cell mass predominates the clinical picture, with other cell lines showing lesser increases. The presenting symptoms are frequently vague and consist of fatigue, headaches, dizziness, bleeding, pruritus, dyspepsia, and thrombosis. Many patients have neurologic symptoms, such as headaches, dizziness or vertigo, visual problems, and paresthesias, at the time of diagnosis. Neurologic complications are seen in 50% to 80% of the cases during the course of the disease and include headaches, dizziness, visual changes, transient ischemic attack, cerebral thrombosis and hemorrhage, and cerebral venous sinus thrombosis. The causes of neurologic (and other) complications are increased blood viscosity and associated coagulopathy. An elevated white blood cell count is associated with a higher risk of complications. Virtually all patients with polycythemia vera are treated with phlebotomy to keep hematocrit under 45% in men and 40% in women. This simple therapy improves patient survival to near normal. Aspirin therapy is useful in the prevention of arterial thrombosis. Some patients, such as those with elevated white cell and platelet counts or symptomatic splenomegaly, require treatment with hydroxyurea. In over 90% of patients with polycythemia vera, JAK2 (Janus kinase 2) mutations can be demonstrated, and these mutations constitute a major diagnostic criterion of this disorder.

Key points

• Polycythemia vera is the commonest of myeloproliferative neoplasms and is associated with elevated hemoglobin, white cell, and platelet counts.

• Virtually all patients with polycythemia vera harbor JAK2 mutations.

• The neurologic complications of polycythemia vera result primarily from increased viscosity of the blood.

• Therapeutic phlebotomy is the mainstay of treatment, but newer agents such as JAK2 inhibitors appear promising.

Historical note and terminology

At the turn of the 20th century, French internist Louis Henri Vaquez (1860-1938) and Canadian-born internist Sir William Osler (1849-1919) described polycythemia vera as a distinct disease entity and made it a formal diagnosis (113; 72).

In 1938, Rosenthal and Bassen described polycythemia as part of the spectrum of myeloproliferative disorders (87). Because of the widely varying opinions regarding diagnosis and treatment options proposed for primary polycythemia, an international Polycythemia Vera Study Group was formed in 1967 with the goal of providing a unifying diagnostic algorithm and treatment regimen for polycythemia vera, or primary polycythemia (117).

Polycythemia vera is also known as polycythemia rubra vera, primary polycythemia, erythremia, Vaquez disease, and Osler-Vaquez disease.

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