Panagiotis Zis

Introduction: Vitamin B6 is a water-soluble vitamin that is naturally present in many foods and is accessible in many dietary supplements. The three natural forms are pyridoxine, pyridoxal, and pyridoxamine. Both vitamin B6 deficiency and high B6 intake have been described as risk factors for developing peripheral neuropathy (PN). The aim of this systematic review is to characterize and comprehensively describe B6-related PN. Method: A systematic, computer-based search was conducted using the PubMed database. Twenty articles were included in this review. Results: Higher vitamin B6 levels, which usually occur following the taking of nutritional supplements, may lead to the development of a predominantly, if not exclusively, sensory neuropathy of the axonal type. After pyridoxine discontinuation, such patients subjectively report improved symptoms. However, although low vitamin B6 levels can be seen in patients suffering from peripheral neuropathy of various etiologies, there is no firm evidence that low B6 levels have a direct causal relationship with PN. Many studies suggest subjective improvement of neuropathy symptoms in patients suffering from PN of various etiologies after receiving B6 supplementation; however, no data about B6 administration as a monotherapy exist, only as part of a combination treatment, usually with other vitamins. Therefore, the potential therapeutic role of B6 cannot be confirmed to date. Supplementation with vitamin B6, even as part of a nutritional multivitamin supplement, has not been proven harmful at permitted daily doses in patients who already suffer from PN. Conclusion: Current scientific evidence supports a neurotoxic role of B6 at high levels. Although some studies suggest that low B6 is also a potential risk factor, further studies in this area are needed.

Introduction: Chronic pain is increasingly recognized as part of long COVID syndrome, mainly in the form of myalgias. However, chronic pain has several forms, and according to our clinical experience, COVID-19 survivors suffer from numerous painful syndromes, other than myalgias. The aim of our study was to estimate the prevalence of chronic pain, describe the commonest painful syndromes and identify pain determinants in a random population of COVID-19 survivors. Methods: This was a cross-sectional study conducted at the Medical School, University of Cyprus. A random population of 90 COVID-19 survivors was recruited. Demographic and COVID-19 related clinical characteristics were recorded. The painDETECT and DN4 questionnaires were used to evaluate the painful syndromes. Results: The prevalence of chronic pain was estimated to be 63.3%. The most common site of pain was low back (37.8%), followed by joints (28.9%) and neck (12.2%). Patients with chronic pain compared to subjects without pain were older (50.5 ± 15.9 versus 42.2 ± 12.6, p = 0.011) and more likely to be female (71.9% versus 45.5%, p = 0.013). One in six subjects (16.7%) reported new-onset pain post COVID-19. The prevalence of neuropathic pain was estimated to be 24.4%. After adjusting for age and gender, headache during COVID-19 was a statistically significant predictor of neuropathic pain, increasing 4.9 times (95% 1.4–16.6, p = 0.011) the odds of neuropathic pain. Conclusion: Chronic pain—especially neuropathic—is widely prevalent in COVID-19 survivors. One in six subjects will develop new-onset pain that will persist beyond the acute phase of the disease and, therefore, should be considered a symptom of long COVID syndrome.