Small Fiber Sensory Neuropathy in Parkinson Disease with Autonomic Failure (P06.056)

Abstract

Objective: To answer the question whether a small fiber neuropathy (SFN) in Parkinson disease (PD) is restricted to autonomic fibers or it represents more widespread degenerative process that also affects sensory small fibers. Background There is large evidence about damage of the autonomic small fibers but there is limited knowledge about involvement of sensory small fibers in PD. Design/Methods: 55 PD patients with symptomatic autonomic failure (PD-AF) were subjected to quantitative autonomic testing (AT). Sensory SFN was tested using skin biopsies for determination of epidermal nerve fiber density (ENFD). AT included deep breathing, Valsalva maneuver, tilt and quantitative axon sudomotor test. Three mm punch biopsies were done at proximal thigh and distal leg sites. Severity of parkinsonism was evaluated by the UPDRS. Severity of dysautonomia was evaluated using Composite Autonomic Severity Score (CASS). Results: CASSs were: 5.4+-2.2 total, 1.6+-1.1 cardiovagal, 2.2+-1.3 adrenergic and 1.7+-1.0 sudomotor. Abnormal CASSs were obtained in 100% of subjects (cardiovagal in 80%, adrenergic in 95% and sudomotor in 86%). Mild GAF was detected in 23%, moderate in 38% and severe in 29% of subjects. Reduced ENFD consistent with sensory SFN was detected overall in 44 subjects (80%); in 7(54%) subjects with mild GAF, in 13 (62%) with moderate GAF and in 12 (75%) subjects with severe GAF. There were significant correlations between total and adrenergic CASS and UPDRS. ENFD at distal leg correlated with sudomotor volumes at foot, with UPDRS and with CASS (total and adrenergic). Conclusions: Sensory SFN is common in PD-AF. The severity of sensory SFN correlates both with severity of parkinsonism and severity of dysautonomia. Sensory SFN is probably a part of more generalized SFN that affects both sensory and autonomic fibers. Autonomic involvement may precede sensory involvement. Proper recognition of sign of SFN can lead to more optimal treatment of autonomic and sensory symptoms in PD. Disclosure: Dr. Novak has nothing to disclose. Dr. Ravin has received research support from Kyowa, Juvantia-Santhera, Acadia Pharmaceuticals. Dr. Qin has nothing to disclose.