@article{JaenschEvdokimovEgenolfetal.2024,
  author    = {J{\"a}nsch, Sarah and Evdokimov, Dimitar and Egenolf, Nadine and Meyer zu Altenschildesche, Caren and Kreß, Luisa and {\"U}{\c{c}}eyler, Nurcan},
  title     = {Distinguishing fibromyalgia syndrome from small fiber neuropathy: a clinical guide},
  series = {Pain Reports},
  volume    = {9},
  journal   = {Pain Reports},
  number    = {1},
  doi       = {10.1097/PR9.0000000000001136},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350306},
  year      = {2024},
  abstract  = {Introduction: Fibromyalgia syndrome (FMS) and small fiber neuropathy (SFN) are distinct pain conditions that share commonalities and may be challenging as for differential diagnosis. Objective: To comprehensively investigate clinical characteristics of women with FMS and SFN to determine clinically applicable parameters for differentiation. Methods: We retrospectively analyzed medical records of 158 women with FMS and 53 with SFN focusing on pain-specific medical and family history, accompanying symptoms, additional diseases, and treatment. We investigated data obtained using standardized pain, depression, and anxiety questionnaires. We further analyzed test results and findings obtained in standardized small fiber tests. Results: FMS patients were on average ten years younger at symptom onset, described higher pain intensities requiring frequent change of pharmaceutics, and reported generalized pain compared to SFN. Pain in FMS was accompanied by irritable bowel or sleep disturbances, and in SFN by paresthesias, numbness, and impaired glucose metabolism (P < 0.01 each). Family history was informative for chronic pain and affective disorders in FMS (P < 0.001) and for neurological disorders in SFN patients (P < 0.001). Small fiber pathology in terms of skin denervation and/or thermal sensory threshold elevation was present in 110/158 (69.7 \%) FMS patients and 39/53 (73.6 \%) SFN patients. FMS patients mainly showed proximally reduced skin innervation and higher corneal nerve branch densities (p<0.001) whereas SFN patients were characterized by reduced cold detection and prolonged electrical A-delta conduction latencies (P < 0.05). Conclusions: Our data show that FMS and SFN differ substantially. Detailed pain, drug and family history, investigating blood glucose metabolism, and applying differential small fiber tests may help to improve diagnostic differentiation and targeted therapy.},
  language  = {en}
}
@article{KressEgenolfSommeretal.2023,
  author    = {Kreß, Luisa and Egenolf, Nadine and Sommer, Claudia and {\"U}{\c{c}}eyler, Nurcan},
  title     = {Cytokine expression profiles in white blood cells of patients with small fiber neuropathy},
  series = {BMC Neuroscience},
  volume    = {24},
  journal   = {BMC Neuroscience},
  number    = {1},
  doi       = {10.1186/s12868-022-00770-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-300619},
  year      = {2023},
  abstract  = {Background The role of cytokines in the pathophysiology, diagnosis, and prognosis of small fiber neuropathy (SFN) is incompletely understood. We studied expression profiles of selected pro- and anti-inflammatory cytokines in RNA from white blood cells (WBC) of patients with a medical history and a clinical phenotype suggestive for SFN and compared data with healthy controls. Methods We prospectively recruited 52 patients and 21 age- and sex-matched healthy controls. Study participants were characterized in detail and underwent complete neurological examination. Venous blood was drawn for routine and extended laboratory tests, and for WBC isolation. Systemic RNA expression profiles of the pro-inflammatory cytokines interleukin (IL)-1ß, IL-2, IL-8, tumor necrosis factor-alpha (TNF) and the anti-inflammatory cytokines IL-4, IL-10, transforming growth factor beta-1 (TGF) were analyzed. Protein levels of IL-2, IL-8, and TNF were measured in serum of patients and controls. Receiver operating characteristic (ROC)-curve analysis was used to determine the accuracy of IL-2, IL-8, and TNF in differentiating patients and controls. To compare the potential discriminatory efficacy of single versus combined cytokines, equality of different AUCs was tested. Results WBC gene expression of IL-2, IL-8, and TNF was higher in patients compared to healthy controls (IL-2: p = 0.02; IL-8: p = 0.009; TNF: p = 0.03) and discriminated between the groups (area under the curve (AUC) ≥ 0.68 for each cytokine) with highest diagnostic accuracy reached by combining the three cytokines (AUC = 0.81, sensitivity = 70\%, specificity = 86\%). Subgroup analysis revealed the following differences: IL-8 and TNF gene expression levels were higher in female patients compared to female controls (IL-8: p = 0.01; TNF: p = 0.03). The combination of TNF with IL-2 and TNF with IL-2 and IL-8 discriminated best between the study groups. IL-2 was higher expressed in patients with moderate pain compared to those with severe pain (p = 0.02). Patients with acral pain showed higher IL-10 gene expression compared to patients with generalized pain (p = 0.004). We further found a negative correlation between the relative gene expression of IL-2 and current pain intensity (p = 0.02). Serum protein levels of IL-2, IL-8, and TNF did not differ between patients and controls. Conclusions We identified higher systemic gene expression of IL-2, IL-8, and TNF in SFN patients than in controls, which may be of potential relevance for diagnostics and patient stratification.},
  language  = {en}
}
@article{OezdağAcarlıKleinEgenolfetal.2022,
  author    = {{\"O}zdağ Acarl{\i}, Ay{\c{s}}e Nur and Klein, Thomas and Egenolf, Nadine and Sommer, Claudia and {\"U}{\c{c}}eyler, Nurcan},
  title     = {Subepidermal Schwann cell counts correlate with skin innervation - an exploratory study},
  series = {Muscle \& Nerve},
  volume    = {65},
  journal   = {Muscle \& Nerve},
  number    = {4},
  doi       = {10.1002/mus.27496},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-318726},
  pages     = {471 -- 479},
  year      = {2022},
  abstract  = {Introduction/Aims Schwann cell clusters have been described at the murine dermis-epidermis border. We quantified dermal Schwann cells in the skin of patients with small-fiber neuropathy (SFN) compared with healthy controls to correlate with the clinical phenotype. Methods Skin punch biopsies from the lower legs of 28 patients with SFN (11 men, 17 women; median age, 54 [range, 19-73] years) and 9 healthy controls (five men, four women, median age, 34 [range, 25-69] years) were immunoreacted for S100 calcium-binding protein B as a Schwann cell marker, protein-gene product 9.5 as a pan-neuronal marker, and CD207 as a Langerhans cell marker. Intraepidermal nerve fiber density (IENFD) and subepidermal Schwann cell counts were determined. Results Skin samples of patients with SFN showed lower IENFD (P < .05), fewer Schwann cells per millimeter (P < .01), and fewer Schwann cell clusters per millimeter (P < .05) than controls. When comparing SFN patients with reduced (n = 13; median age, 53 [range, 19-73] years) and normal distal (n = 15, median age, 54 [range, 43-68] years) IENFD, the number of solitary Schwann cells per millimeter (p < .01) and subepidermal nerve fibers associated with Schwann cell branches (P < .05) were lower in patients with reduced IENFD. All three parameters correlated positively with distal IENFD (P < .05 to P < .01), whereas no correlation was found between Schwann cell counts and clinical pain characteristics. Discussion Our data raise questions about the mechanisms underlying the interdependence of dermal Schwann cells and skin innervation in SFN. The temporal course and functional impact of Schwann cell presence and kinetics need further investigation.},
  language  = {en}
}
@article{EgenolfAltenschildescheKressetal.2021,
  author    = {Egenolf, Nadine and Altenschildesche, Caren Meyer zu and Kreß, Luisa and Eggermann, Katja and Namer, Barbara and Gross, Franziska and Klitsch, Alexander and Malzacher, Tobias and Kampik, Daniel and Malik, Rayaz A. and Kurth, Ingo and Sommer, Claudia and {\"U}{\c{c}}eyler, Nurcan},
  title     = {Diagnosing small fiber neuropathy in clinical practice: a deep phenotyping study},
  series = {Therapeutic Advances in Neurological Disorders},
  volume    = {14},
  journal   = {Therapeutic Advances in Neurological Disorders},
  issn      = {1756-2864},
  doi       = {10.1177/17562864211004318},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-232019},
  year      = {2021},
  abstract  = {Background and aims: Small fiber neuropathy (SFN) is increasingly suspected in patients with pain of uncertain origin, and making the diagnosis remains a challenge lacking a diagnostic gold standard. Methods: In this case-control study, we prospectively recruited 86 patients with a medical history and clinical phenotype suggestive of SFN. Patients underwent neurological examination, quantitative sensory testing (QST), and distal and proximal skin punch biopsy, and were tested for pain-associated gene loci. Fifty-five of these patients additionally underwent pain-related evoked potentials (PREP), corneal confocal microscopy (CCM), and a quantitative sudomotor axon reflex test (QSART). Results: Abnormal distal intraepidermal nerve fiber density (IENFD) (60/86, 70\%) and neurological examination (53/86, 62\%) most frequently reflected small fiber disease. Adding CCM and/or PREP further increased the number of patients with small fiber impairment to 47/55 (85\%). Genetic testing revealed potentially pathogenic gene variants in 14/86 (16\%) index patients. QST, QSART, and proximal IENFD were of lower impact. Conclusion: We propose to diagnose SFN primarily based on the results of neurological examination and distal IENFD, with more detailed phenotyping in specialized centers.},
  language  = {en}
}