“…[1] Hyperviscosity manifests as cerebral infarction caused by monoclonal immunoglobulinm (IgM) protein in the blood. [2] Clinical manifestations: Patients may develop symptoms associated with infiltration of hematopoietic or other tissues (such as anemia, lymphadenopathy, hepatosplenomegaly), or symptoms associated with monoclonal IgM protein in the blood (such as hyperviscosity, peripheral neuropathy). [3] Hyperviscosity syndrome: up to 30% of patients experience symptoms related to hyperviscosity, resulting in blurred or lost vision, headache, dizziness, nystagmus, tinnitus, sudden deafness, diplopia, or often neurological deficits, ataxia and other systemic diseases.…”