Sensory Neuropathy in Parkinson Disease: Electrodiagnostic Evaluation

ABSTRACT

The relationship between Parkinson Disease (PD) and peripheral neuropathy (PN) has gained attention in recent years. There is increasing evidence of a-synuclein deposition and pointing to a form of small fiber neuropathy intrinsic to PD, medium-large fiber PN is also a relatively frequent and potentially severe complication in advanced levodopa-treated PD, but degenerative factors and vitamin deficiency were related. Objective: To determine the neurophysiological characteristics of patients with PD and the clinical manifestations of suspected PN. Methods: We performed a cross-sectional study between January 2014 and December 2017, of 36 patients diagnosed with PD who were referred for electrodiagnostic studies (EDX) with suspected clinical PN. We performed electromyography of five muscle or more (brachial biceps, first dorsal interosseous, thumb abductor, anterior tibial, medial gastrocnemius and short finger extensor), and nerve conduction/velocity studies on fibular and tibial nerves (motor) sural and superficial fibular nerves (sensory) and median and ulnar, (both motor and sensory). Results: Twenty-one females (58.3%) with an average age of 69.6 years and fifteen males (41.7%) with an average age of 68.0 years who were submitted for EDX were included in this study. All had a tremor and the average evolution of PD was 5 years. Thirty-two patients were receiving oral levodopa treatment. EDX of twenty-two patients demonstrated neuropathy abnormalities, and in 90.9% of these patients, sensory neuropathy was confirmed. The most common nerve found to be compromised was the superficial fibular nerve (55.0%), followed by the sural (50.0%). Conclusions: Sensory neuropathy was the main finding. Diagnosing PN based on symptom prevalence assessed by checklists and questionnaire has a risk of overestimating the prevalence of PN. The age and the time of disease evolution were factors related to neuropathy. In our study we found that 39% of the patients did not have neuropathic alterations despite clinical suspicion, which opens up new questions about the mechanisms of PD neuropathy and the possibility of fine fiber neuropathy in these patients, motivating further research.

KEY WORDS:

• Electrodiagnostic
• Parkinson disease
• polyneuropathy
• sensory neuropathy
• superficial fibular nerve
• sural nerve

Disclosure Statement

There is no conflict of interest to declare.