Prognosis of patients with primary systemic amyloidosis who present with dominant neuropathy

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.

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.

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).

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.