Neurologic complications of primary systemic amyloidosis

Amyloid is a botanical term that denotes a waxy, amorphous, eosinophilic material and is used to describe similar pathological findings in humans. The deposits in primary systemic amyloidosis are derived from monoclonal serum proteins in plasma cell dyscrasia, which are degraded locally in tissues and deposited in insoluble sheets that damage organs. The cause of organ damage in amyloidosis is unclear but most likely due to the direct toxic effects of amyloid. Symptoms of the disorder include neuropathy, myopathy, and cardiac or renal insufficiency; there is often multiple-organ involvement. Congestive heart failure and nephrotic syndrome are predominant causes of death. Differential difficulties exist in diagnosing the disorder, and familial amyloid polyneuropathy directly mimics the disease. Diagnostic tools include electromyography, laboratory testing for abnormalities in serum and urine, and histological investigation of appropriate tissue. The median survival of patients is 2 years. However, melphalan and prednisone treatment for at least 1 year has resulted in increased survival rates. There have also been reports of benefit from high-dose chemotherapy followed by peripheral blood stem cell transplantation. Without early therapy, however, the disease has a dismal prognosis, and peripheral neuropathy usually persists or worsens despite therapy and improvement in other organs.