2. Current Insights
In this study, complaints that are typical for the small fiber neuropathy were described in 60% of the patients with sarcoidosis. Small fiber neuropathy can manifest with a wide range of symptoms, including autonomic and sensory dysfunction. The most common clinical manifestations that were observed in our study in the patients with sarcoidosis were impaired cardiovascular regulation (36% of cases), e.g., the development of palpitations and dizziness. In 32% of cases, patients noted pain in the chest or limbs, which was often accompanied by allodynia, a subjective perception of tactile touch as pain. In some cases, this can result in sleep disturbances due to the pain sensations that are caused by bed linen touching the skin. Another symptom that is often noted by patients with sarcoidosis is blurred vision, which is described in 20% of cases. A physician needs to clarify whether these visual impairments are transient or permanent in nature in order to determine a differential diagnosis of ophthalmic pathology. In the neuropathy of small fibers, blurred vision is transient, arising while overworking or during physical exertion. Gastrointestinal tract disorders are less commonly reported with patients with sarcoidosis. In 12% of the cases, the patients complained of impaired intestinal motility, with the development of both diarrhea and constipation, which occurred simultaneously with the onset of sarcoidosis. This also includes subjective complaints of swallowing dysfunction, which is associated with both impaired muscle innervation and with the progression of mouth dryness.
While a negative, statistically significant correlation between the IEND and SFN-SL scores was described in both groups (Spearman coefficient, r = −0.3508, p = 0.0102, and r = −0.7382, p = 0.0064), a decrease in the density of the small nerve fibers in patients with pulmonary sarcoidosis was more prominent.
Thus, the neuropathy of small fibers seems to be a widespread pathology that results in the development of multiple organ dysfunction. Disorders in small fiber neuropathy, along with the typical complaints of patients with lung sarcoidosis, such as cough and shortness of breath, can significantly contribute to a decrease in the quality of life. At the same time, when focusing on the main complaints as well as on instrumental and laboratory deviations, clinicians often do not attach the necessary importance to the manifestations of SFN. It is necessary to identify the main causes that are responsible for a patient’s quality of life deteriorating in order to determine a treatment strategy and to improve the prognosis of the patient’s disease
[31][32].
Given the low awareness of both medical specialists and patients about the development of this complication and the difficulties that are involved in its diagnosis, further study into this issue is required.
In patients with pulmonary sarcoidosis, small fiber neuropathy may develop as a result of systemic immune-mediated inflammation. The validated questionnaires and histologic verification of the diagnosis help to establish the severity of the neuropathy of small fibers to determine the prognosis and to plan the treatment strategy.