Background: Primary systemic amyloidosis is an uncommon disorder associated with the desposition of fragments of immunoglobulin light chains in a variety of tissues. Some patients present with peripheral neuropathy. The prognosis of these patients is not clear.
Methods: We searched the medical records of all patients seen at the Mayo Clinic between January 1, 1978 and December 31, 1994 with the diagnosis of amyloidosis. Twenty-six patients with sural nerve biopsy-proven amyloid neuropathy and a documented monoclonal protein in the serum or urine were studied.
Results: The most common symptoms that led to the diagnosis of primary amyloid neuropathy were paresthesias (81%), muscle weakness (65%), and numbness (58%). The median duration of symptoms before diagnosis was 29 months. Symptoms of autonomic neuropathy were present at diagnosis in 17 patients (65%). Other organs were involved in most patients. The monoclonal light chain protein detected was lambda in 18 patients (69%) and kappa in 8 (31%). The neuropathy was chronic, debilitating, and showed relentless progression. Twenty-two patients (85%) died (median survival 25 months) and 4 patients were alive at a median follow-up of 4.5 years. Progressive amyloidosis was the cause of death in most patients. Survival was significantly better in the patients with a serum albumin level >3 g/dL (median survival 31 months compared with 18 months; P <0.01, log-rank test).
Conclusions: Patients with primary systemic amyloidosis in whom neuropathy is the dominant clinical manifestation often do not receive a diagnosis until years after the onset of symptoms. The prognosis is worse than previously indicated. Neuropathy does not improve with therapy.