Autonomic Dysfunction in a Patient Initially Diagnosed With Parkinson's Disease Who Subsequently Developed Systemic Amyloidosis.

Parkinson's disease and closely related Parkinsonian neurodegenerative diseases are frequently associated with neurogenic orthostatic hypotension. In many cases, the dysautonomia would be attributed to Parkinson's disease or its closely related neurodegenerative mimics. We present our experience diagnosing and managing a patient with dysautonomia attributed to an initial diagnosis of Parkinson's disease and systemic amyloidosis, which the coexistence of these two diseases have not been previously reported in the literature. Our 73-year-old patient developed levodopa-responsive symptoms initially suggestive of Parkinson's disease. Within three years, he developed progressively worsening neurogenic orthostatic hypotension and, eventually, symptomatic bradycardia requiring a pacemaker, and was found to have a condition causing the dysautonomia other than Parkinson's. Further workup led to a concurrent diagnosis of amyloid light-chain amyloidosis, which was successfully treated with chemotherapy. Despite being in remission of the amyloidosis and having satisfactory control of the Parkinson's motor symptoms, his neurogenic orthostatic hypotension continued to be severely disabling, and overall functioning continued to decline. Although neurogenic orthostatic hypotension is common in Parkinson's disease and closely related neurogenerative disorders, there may be clinical features discordant with a neurodegenerative disorder that could lead to an alternative explanation for the dysautonomia. This patient not only fell into the usual Parkinsonism with dysautonomia differential diagnosis but also suggests that Parkinsonian conditions and systemic amyloidosis may exert a synergistic effect on morbidity, explaining why management of dysautonomia in these patients and reducing disability may be a significant challenge.