Delayed manifestation and slow progression of cerebral infarction caused by polycythemia rubra vera

Background. Polycythemia rubra vera is often found after the manifestation of cerebral infarction, though the pathogenesis is still controversial. We present a case of cerebral infarction secondary to polycythemia rubra vera, which presented a slow expansion on magnetic resonance imaging despite severe hemiplegia. This case suggests a possible mechanism for development of cerebral infarction in polycythemia rubra vera. Methods: This case report was conducted in a university hospital. Magnetic resonance imaging and diffusion-weighted imaging were performed to assess the evolution of infarction, and the total blood volume and cerebral blood flow were determined with the use of isotopes, Cr-51 and Tc-99m, respectively. Phlebotomy was performed, but intervention was not applicable. The manual muscle test and sensory disturbance were assessed by the same physiotherapist throughout the clinical course. Results: A 64-year-old male patient with polycythemia rubra observed on CT scan on the third day after the onset of infarction, and a small signal was demonstrated on magnetic resonance imaging on the fourth day. The cerebral infarction expanded slowly in size and reached a maximum on day 24. A diagnosis of cerebral infarction secondary to polycythemia rubra vera was made, and treatment by phlebotomy, hydration, and hydroxyurea was begun. Though the hemiplegia remained, he became ambulatory with a brace, as do patients with atherosclerotic infarction. Conclusions: It is suggested that the delayed manifestation and slow expansion of cerebral infarction caused by elevated hematocrit might be derived from a pathogenesis different from atherosclerotic infarction.