Small (autonomic) and large fiber neuropathy in Parkinson disease and parkinsonism

BACKGROUND Recent studies have reported that peripheral neuropathy (PN) is common in patients with Parkinson's disease (PD) and raised the possibility that levodopa neurotoxicity is the main culprit. METHODS We evaluated the presence of large & small (autonomic) fiber PN in 54 consecutive patients with PD or parkinsonism in a tertiary outpatient clinic from Brazil. Initial PN screening consisted of history/neurological exam and skin wrinkling test (SWT). In addition, we also performed Nerve conduction studies/Electromyography (NCS/EMG) in all patients with PN signs/symptoms and/or abnormal SWT. RESULTS Thirty eight patients with PD (10 women, mean age: 63 ± 2.1 years, P < 0.05 versus parkinsonism, mean disease duration: 8 ± 0.8 years) and 16 patients with other forms of parkinsonism [7 women, mean age: 50.1 ± 3.9 years, mean disease duration: 6.9 ± 1.1 years] completed clinical neuromuscular evaluation. SWT was performed in 48 patients (33 PD, 15 parkinsonism). In the PD group, SWT was abnormal in 57.6% of the tested patients (comprising 50% of all PD patients). In the parkinsonism group, SWT was abnormal in 37.5% (comprising 35.3% of all parkinsonism patients). NCS/EMG was performed in 39 patients (26 PD and 13 parkinsonism). Twelve out of the 26 PD (34.2% of all PD) and 4 out of the 13 parkinsonism (23.5% of all parkinsonism) had abnormal NCS/EMG results. Neuropathy prevalence was similar in PD and parkinsonism groups as detected either by NCS/EMG or SWT. CONCLUSIONS Large fiber and small (autonomic) fiber PN are common in patients with PD and parkinsonism. The etiology for the neuropathy was likely to be multifactorial and may be secondary to PD itself.