Can Parkinson's Disease Cause Neuropathy?
Yes: there is a positive correlation between Parkinson's disease (PD) and peripheral neuropathy (PN). Peripheral neuropathy is a neurological condition which results from damage to the nerves outside of the central nervous system (CNS). Dysfunctions in peripheral nerve signaling can cause sensory symptoms including numbness, skin sensitivity, prickling, tingling, pain, or muscle weakness [1]. Peripheral neuropathy has also been associated with broader impairments in sensorimotor function among patients with Parkinson's disease. This may cause difficulties with mobility and balance, which can increase one’s risk of injury due to falls [2]. As such, peripheral neuropathy is a notable comorbidity for patients with PD.
While peripheral neuropathy has been reliably observed in connection with Parkinson's disease, estimates of its prevalence are highly variable. It is approximated that anywhere between 4.8% to 55% of Parkinson's patients experience peripheral neuropathy [2].
The underlying mechanism which links peripheral neuropathy and Parkinson's disease is an ongoing topic of debate. One hypothesis is that the neurodegeneration that characterises Parkinson's causes peripheral neuropathy as a collateral symptom [3]. However, others suggest that peripheral nerve damage may be a side effect of levodopa, a dopamine-like molecule which is frequently used as a medication to treat PD [3].