Polyneuropathy (PNP) remains a common comorbidity among patients with chronic obstructive pulmonary disease (COPD), and better screening strategies are needed to identify the condition and improve patients' quality of life, according to authors of a recent review.
"Recent advances demonstrate that the relationship between COPD and the nervous system is extensive, and patients are at increased risk of stroke, dementia, depression, and other neurological and psychiatric conditions even after controlling for the main confounding risk factors, such as age and smoking," write Irina Odajiu, MD, of Colentina Clinical Hospital, Bucharest, Romania, and colleagues. However, data on the relationship between COPD and peripheral nervous system pathology are limited, they write.
PNP is distinct from peripheral neuropathy and neuropathy, the researchers emphasize.
"Polyneuropathy implies a homogeneous process affecting peripheral nerves, specifically distal nerves, more severely than proximal ones," while peripheral neuropathy refers to any disorder of the peripheral nervous system, they explain.
In an article published in Respiratory Medicine, the authors summarize the latest data on the association between COPD and polyneuropathy. They reviewed data from 21 studies published between 1981 and 2021. All studies included adults with COPD. The mean age of the patients was 55–65 years.
Peripheral neuropathy represents a significant comorbidity among patients with COPD. The percentage of cases of peripheral neuropathy among patients in the study populations ranged from 15% to 93.8%. Of these cases, the majority were of axonal sensory polyneuropathy. In most of the studies, the neuropathy affected the lower limbs more than the upper limbs.
"Additionally, in most presented studies, peripheral neuropathy correlated with disease duration and hypoxemia severity; the longer the duration and the more severe hypoxia, the more severe peripheral neuropathy was," the researchers note.
Overall, potential predisposing factors for PNP among patients with COPD (in addition to chronic hypoxemia) included older age, poor nutrition, systemic inflammation, COPD medications, smoking, and increased partial pressure of carbon dioxide (hypercapnia).
Several strategies for managing peripheral neuropathy for patients with COPD were described. Prophylaxis options include neuroprotection with hormones such as progesterone, neuronal growth factors, and corticosteroids, although none have shown high levels of effectiveness, the researchers write. Topical treatment with muscarinic antagonists has shown some potential and may be a practical therapeutic choice, they say. Oxygen support, including hyperbaric oxygen therapy, has demonstrated healing of diabetic leg ulcers associated with PNP and has led to improvements in pain-related symptoms and quality-of-life scores, they add.
Although PNP is often present in patients with COPD, no association between COPD severity and PNP has been determined, the researchers write in their discussion section.
"Moreover, the current data do not indicate a relationship between COPD stages, GOLD classification, or degree of obstruction and PNP," they say.
The data support screening of all COPD patients for PNP, both clinically and with electrodiagnostic studies, despite the absence of current specific COPD-related PNP screening tools, they write.
The study received no outside funding. The researchers have disclosed no relevant financial relationships.
Respir Med. Published online August 11, 2022. Full text
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