Study on the relationship between peripheral nerve fiber types and levodopa usage in Parkinson's disease.

Background and purpose:

The aim of this study is to comprehensively determine the types of affected fibers in Parkinson’s disease (PD) patients by employing nerve conduction studies (NCS), sympathetic skin response (SSR) examinations, and current perception threshold (CPT) testing and to analyze the correlation between levodopa use and nerve involvement.

This retrospective study included 36 clinically diagnosed PD patients who were recruited between January 2018 and April 2019. All patients underwent NCS, SSR testing, and CPT sensory examinations. Additionally, the PD patients were assessed for disease staging using the Hoehn and Yahr (H-Y) scale. 

Fifteen patients were included in the tremor-dominant subtype, ten patients in the rigid-dominant subtype, and eleven patients in the mixed subtype. Eleven patients were using levodopa, while twenty-five patients had never used any anti-Parkinson’s medication. Ten patients (28%) showed abnormal sympathetic skin responses (SSR). The CPT examination revealed sensory abnormalities in twenty-four patients (67%), with eighteen patients (75%) experiencing sensory hypersensitivity and six patients (25%) experiencing sensory hypoesthesia. Twelve patients (33%) had normal CPT results. Among the patients with abnormal CPT findings, seven cases (29%) involved large myelinated fiber damage, twenty-two cases (92%) involved small myelinated fiber damage, and nineteen cases (79%) involved unmyelinated fiber damage. The rate of sensory abnormalities was 64% (7/11) in the levodopa group and 68% (17/25) in the non-levodopa group, with no statistically significant difference between the two groups. 

The incidence of abnormal CPT findings in PD patients was higher than that of abnormal SSR responses, suggesting that nerve fiber damage primarily affects small fiber nerves (SFN).

Preoperative prediction of perineural invasion of rectal cancer based on a magnetic resonance imaging radiomics model: A dual-center study.

BACKGROUND: Perineural invasion (PNI) has been used as an important pathological indicator and independent prognostic factor for patients with rectal cancer (RC). Preoperative prediction of PNI status is helpful for individualized treatment of RC. Recently, several radiomics studies have been used to predict the PNI status in RC, demonstrating a good predictive effect, but the results lacked generalizability. The preoperative prediction of PNI status is still challenging and needs further study. AIM: To establish and validate an optimal radiomics model for predicting PNI status preoperatively in RC patients. METHODS: This retrospective study enrolled 244 postoperative patients with pathologically confirmed RC from two independent centers. The patients underwent pre-operative high-resolution magnetic resonance imaging (MRI) between May 2019 and August 2022. Quantitative radiomics features were extracted and selected from oblique axial T2-weighted imaging (T2WI) and contrast-enhanced T1WI (T1CE) sequences. The radiomics signatures were constructed using logistic regression analysis and the predictive potential of various sequences was compared (T2WI, T1CE and T2WI + T1CE fusion sequences). A clinical-radiomics (CR) model was established by combining the radiomics features and clinical risk factors. The internal and external validation groups were used to validate the proposed models. The area under the receiver operating characteristic curve (AUC), DeLong test, net reclassification improvement (NRI), integrated discrimination improvement (IDI), calibration curve, and decision curve analysis (DCA) were used to evaluate the model performance. RESULTS: Among the radiomics models, the T2WI + T1CE fusion sequences model showed the best predictive performance, in the training and internal validation groups, the AUCs of the fusion sequence model were 0.839 [95% confidence interval (CI): 0.757-0.921] and 0.787 (95%CI: 0.650-0.923), which were higher than those of the T2WI and T1CE sequence models. The CR model constructed by combining clinical risk factors had the best predictive performance. In the training and internal and external validation groups, the AUCs of the CR model were 0.889 (95%CI: 0.824-0.954), 0.889 (95%CI: 0.803-0.976) and 0.894 (95%CI: 0.814-0.974). Delong test, NRI, and IDI showed that the CR model had significant differences from other models (P < 0.05). Calibration curves demonstrated good agreement, and DCA revealed significant benefits of the CR model. CONCLUSION: The CR model based on preoperative MRI radiomics features and clinical risk factors can preoperatively predict the PNI status of RC noninvasively, which facilitates individualized treatment of RC patients.

The prognostic and predictive significance of perineural invasion in stage I to III colon cancer: a propensity score matching-based analysis.

BACKGROUND: Colorectal cancer (CRC) presents with varying prognoses, and identifying factors for predicting metastasis and outcomes is crucial. Perineural invasion (PNI) is a debated prognostic factor for CRC, particularly in stage I-III patients, but its role in guiding adjuvant chemotherapy for node-positive colon cancer remains uncertain. METHODS: We conducted a single-center study using data from the Colorectal Section Tumor Registry Database at Chang Gung Memorial Hospital, Taiwan. This prospective study involved 3,327 CRC patients, 1,536 of whom were eligible after application of the exclusion criteria, to investigate the prognostic value of PNI in stage I-III patients and its predictive value for node-positive/negative cancer patients receiving adjuvant chemotherapy. Propensity score matching (PSM) was used to minimize selection bias, and follow-up was performed with standardized procedures. RESULTS: PNI-positive (PNI+) tumors were associated with higher preoperative CEA levels and more frequent adjuvant chemotherapy. After PSM, PNI + tumors were associated with marginally significantly lower 5-year disease-free survival (DFS) and significantly lower overall survival (OS) rates in stages III CRC. However, no significant differences were observed in stages I and II. Subgroup analysis showed that among PNI + tumors, only poorly differentiated tumors had higher odds of recurrence. PNI did not predict outcomes in node-negative colon cancer. Adjuvant chemotherapy benefited PNI + patients with node-positive but not those with node-negative disease. CONCLUSIONS: Our study indicates that PNI is an independent poor prognostic factor in stage III colon cancer but does not predict outcomes in node-negative disease. Given the potential adverse effects of adjuvant chemotherapy, our findings discourage its use in node-negative colon cancer when PNI is present.

Unique clinical and electrophysiological features in the peripheral nerve system in patients with sialidosis - a case series study.

BACKGROUND: To investigate the peripheral nervous system involvement in S sialidosis with typical features of myoclonus, seizure, and giant waves in somatosensory evoked potentials suggesting hyperexcitability in the central nervous system. METHODS: The clinical presentation of patients with genetically confirmed sialidosis was recorded. Neurophysiological studies, including nerve conduction studies (NCSs), F-wave studies, and needle electromyography (EMG), were performed on these patients. RESULTS: Six patients (M/F: 2:4) were recruited. In addition to the classical presentation, intermittent painful paresthesia was noted in four patients, and three of whom reported it as the earliest symptom. In the NCSs, one patient had reduced compound muscle action potential amplitudes in the right ulnar nerve, while another patient had prolonged distal motor latency in the bilateral tibial and peroneal nerves. Prolonged F-wave latency (83.3%), repeater F-waves (50%), and neurogenic polyphasic waves in EMG (in 2 out of 3 examined patients) were also noted. Interestingly, a very late response was noted in the F-wave study of all patients, probably indicating lesions involving the proximal peripheral nerve or spinal cord. CONCLUSION: In addition to the central nervous system, the peripheral nervous system is also involved in sialidosis, with corresponding clinical symptoms. Further study on these phenomena is indicated.

Mitochondrial DNA and Electron Transport Chain Protein Levels Are Altered in Peripheral Nerve Tissues from Donors with HIV Sensory Neuropathy: A Pilot Study.

Distal sensory polyneuropathy (DSP) and distal neuropathic pain (DNP) remain significant challenges for older people with HIV (PWH), necessitating enhanced clinical attention. HIV and certain antiretroviral therapies (ARTs) can compromise mitochondrial function and impact mitochondrial DNA (mtDNA) replication, which is linked to DSP in ART-treated PWH. This study investigated mtDNA, mitochondrial fission and fusion proteins, and mitochondrial electron transport chain protein changes in the dorsal root ganglions (DRGs) and sural nerves (SuNs) of 11 autopsied PWH. In antemortem standardized assessments, six had no or one sign of DSP, while five exhibited two or more DSP signs. Digital droplet polymerase chain reaction was used to measure mtDNA quantity and the common deletions in isolated DNA. We found lower mtDNA copy numbers in DSP+ donors. SuNs exhibited a higher proportion of mtDNA common deletion than DRGs in both groups. Mitochondrial electron transport chain (ETC) proteins were altered in the DRGs of DSP+ compared to DSP- donors, particularly Complex I. These findings suggest that reduced mtDNA quantity and increased common deletion abundance may contribute to DSP in PWH, indicating diminished mitochondrial activity in the sensory neurons. Accumulated ETC proteins in the DRG imply impaired mitochondrial transport to the sensory neuron's distal portion. Identifying molecules to safeguard mitochondrial integrity could aid in treating or preventing HIV-associated peripheral neuropathy.

Systemic and Neurosarcoidosis With Rare Involvement of the Extremities' Peripheral Nerves.

ABSTRACT: We present a case of sarcoidosis with a rare presentation of involvement of peripheral nerves of the lower limbs and subcutaneous nodules detected on 18 F-FDG PET/CT. The patient also had involvement of the spinal nerves and dura, histologically proven to be sarcoidosis. There were other manifestations of systemic sarcoidosis like metabolically active cervical and mediastinal lymphadenopathy. This case highlights the role of 18 F-FDG PET/CT in evaluating the uncommon sites of sarcoid involvement. Although many cases of sarcoid involvement of central nervous system have been reported, peripheral nerves involvement in the extremities was not found on a literature search.

Implications of Pretreatment Serum Carcinoembryonic Antigen Levels and Perineural Invasion with Staging, Prognosis, and Management in Stage I-III Colon Cancer after Surgery: A Retrospective Cohort Study in the SEER Database.

BACKGROUND: Pretreatment levels of serum carcinoembryonic antigen (CEA) and perineural invasion (PNI) are related to poor prognosis in colon cancer. We analyzed the CEA and PNI (defined as incorporation of carcinoembryonic antigen and perineural invasion (CP)-stage), which are included in the Tumor-Node-Metastasis (TNM) staging system of the American Joint Committee on Cancer (AJCC), and evaluated the survival prognosis of patients treated with surgery in I-III stage colon carcinoma. MATERIALS AND METHODS: We employed a retrospective study for eligible colon carcinoma patients obtained from the Surveillance, Epidemiology, and End Results (SEER) database between 2010 and 2015. Kaplan-Meier curve and Multivariate Cox regression analysis were used to analyze different TNM-CP stages for the cancer-specific survival (CSS) probabilities in colon cancer. RESULT: In our study, CEA levels and PNI were significant prognostic factors (p < 0.05), and the newly proposed CP-stage was an independent prognostic index in stage I-III colon carcinoma after surgery. Multivariate Cox regression analyses indicated that CP1-stage was related to a 63.9% increased risk of cancer-specific mortality (hazard ratio (HR): 1.639, 95% confidence interval (CI): 1.544-1.739, p < 0.001), compared with CP0-stage in colon cancer. In respective TNM stages, the CP0-stage had an advantage over the CP1-stage for CSS (p < 0.001). Moreover, CP1-stage patients with node-negative colon cancer were contacted with similar or worse survival in comparison to CP0-stage patients with node-positive. CONCLUSION: For postoperative patients with stage I-III colon cancer, our study indicated that the CP stage is a significant prognostic factor for CSS, which deserves more clinical attention. It's worth noting that including the CP stage in the AJCC TNM staging system of colon carcinoma is beneficial to the survival prediction and clinical treatment.

The depth of perineural invasion is an independent prognostic factor for stage II colorectal cancer.

BACKGROUND: Perineural invasion (PNI) is the invasion of nerves by cancer cells and is associated with poor survival in stage II colorectal cancer. However, PNI can be further subdivided according to the depth of invasion, and the depth of PNI has not been clearly linked to prognosis. METHOD: This study aimed to assess the prognostic value of different depths of PNI in stage II colorectal cancer. We defined PNI in the submucosal plexus and myenteric plexus as superficial perineural invasion (sup-PNI) and PNI in the subserous plexus as deep perineural invasion (deep-PNI). Patients were divided into three groups based on the depth of PNI: sup-PNI, deep-PNI and non-PNI. Then, univariate and multivariate Cox regression analyses were conducted to evaluate the role of PNI in the prognosis of stage II colorectal cancer. RESULTS: This study enrolled 3508 patients with stage II colorectal cancer who underwent resection for primary colorectal lesions between January 2013 and September 2019. Clinicopathological features, including elevated carcinoembryonic antigen (CEA) levels, T4 stage, poor differentiation, deficient DNA mismatch repair (dMMR), and vascular invasion, were correlated with deep-PNI. Multivariate analyses revealed that deep-PNI was associated with worse overall survival (OS; hazard ratio [HR], 3.546; 95% confidence interval [CI], 2.307-5.449; P < 0.001) and disease-free survival (DFS; HR, 2.921; 95% CI, 2.032-4.198; P < 0.001), compared with non-PNI. Conversely, no significant difference in OS or DFS was observed between the sup-PNI and non-PNI groups in multivariate analyses. CONCLUSIONS: The study demonstrated that the depth of PNI was an independent prognostic factor for patients with stage II colorectal cancer, and patients with deep PNI had a worse prognosis. Thus, patients with PNI require further subdivision according to the depth of invasion.

Perineural invasion in cervical cancer: A multicenter retrospective study.

OBJECTIVE: The study aimed to evaluate the accuracy of perineural invasion (PNI) diagnosis in cervical cancer, and to analyze the impact of PNI on the prognosis and postoperative adjuvant treatment decisions for cervical cancer. METHODS: A retrospective pathological review of PNI in cervical cancer was conducted from 2004 to 2016 in 15 hospitals. RESULTS: This study included a total of 1208 cases, comprising 273 cases with PNI and 935 cases without. The false positive rate and false negative rate of PNI diagnosis were 5.35% (50/935) and 33.33% (91/273), respectively. Adenocarcinoma, deep stromal invasion, lymphovascular space invasion (LVSI) (+), and margin involvement were independent risk factors for PNI. Both 5-year overall survival rate (OS) and 5-year disease-free survival rate (DFS) of PNI group were worse than non-PNI group. PNI was an independent risk factor for 5-year OS and 5-year DFS. In cases receiving standard postoperative adjuvant treatment, among those with two intermediate-risk factors, both 5-year OS and DFS were worse in the PNI group. Among cases with three intermediate-risk factors or at least one high-risk factor, there was no difference in 5-year OS between the two groups, but 5-year DFS was worse in the PNI group. CONCLUSION: The diagnosis of PNI in cervical cancer was not accurate. Adenocarcinoma, deep stromal invasion, LVSI, and margin involvement were independent risk factors for PNI. PNI was an independent risk factor for 5-year OS and DFS. PNI has the potential to serve as a new high-risk factor, thus providing guidance for postoperative adjuvant therapy.

Diagnostic value of lower extremity ultrasonographic nerve enlargement for differentiating demyelinating Charcot-Marie-Tooth disease from chronic inflammatory demyelinating polyneuropathy.

BACKGROUND AND PURPOSE: We previously reported that nerve enlargement assessment by nerve ultrasonography of the intermediate upper limb is applicable for distinguishing demyelinating Charcot-Marie-Tooth disease (CMT) from chronic inflammatory demyelinating polyneuropathy (CIDP). However, differences in the severity and distribution patterns of lower extremity nerve enlargement have not been established for either disease. Therefore, we examined the utility of lower extremity nerve ultrasonography for differentiating between CMT and CIDP. METHODS: Twelve patients with demyelinating CMT and 17 patients with CIDP were evaluated. The median, ulnar, tibial, and fibular nerves were evaluated in three regions: the distal upper extremity, intermediate upper extremity, and lower extremity. Of the 14 selected screening sites, the number of sites that exhibited nerve enlargement (enlargement site number, ESN) in each region was determined. RESULTS: The screening ESNs in the intermediate region and lower extremities were greater in patients with demyelinating CMT than in patients with CIDP and greater than the ESN in the distal region (p = 0.010, p = 0.001, and p = 0.101, respectively). The ESNs in the intermediate region and lower extremities significantly differed among patients with typical CIDP, CIDP variants, and demyelinating CMT (p = 0.084 and p < 0.001). Among the 14 selected screening sites, the combined upper and lower extremity ESNs exhibited the highest AUC (0.92; p < 0.001). CONCLUSIONS: Combining the upper and lower extremities for ultrasonographic nerve measurement more accurately distinguishes CIDP from demyelinating CMT.

Perineural invasion score system and clinical outcomes in resected pancreatic cancer patients.

BACKGROUND/OBJECTIVES: Perineural invasion (PNI), classified according to its presence or absence in tumor specimens, is recognized as a poor prognostic factor in pancreatic ductal adenocarcinoma (PDAC) patients. Herein, we identified five histological features of PNI and investigated their impact on survival outcomes of PDAC resected patients. METHODS: Five histopathological features of PNI (diameter, number, site, sheath involvement, and mitotic figures within perineural invasion) were combined in an additional final score (ranging from 0 to 8), and clinical data of PDAC patients were retrospectively analyzed. PNI + patients were stratified in two categories according to the median score value (<6 and ≥ 6, respectively). Impact of PNI on disease-free survival (DFS) and overall survival (OS) were analyzed. RESULTS: Forty-five patients were enrolled, of whom 34 with PNI (PNI+) and 11 without PNI (PNI-). The DFS was 11 months vs. not reached (NR) (p = 0.258), while the OS was 19 months vs. NR (p = 0.040) in PNI+ and PNI- patients, respectively. A ≥6 PNI was identified as an independent predictor of worse OS vs. <6 PNI + patients (29 vs. 11 months, p < 0.001) and <6 PNI+ and PNI- patients (43 vs. 11 months, p < 0.001). PNI ≥6 was an independent negative prognostic factor of DFS vs. <6 PNI+ and PNI- patients (13 vs. 6 months, p = 0.022). CONCLUSIONS: We report a PNI scoring system that stratifies surgically-treated PDAC patients in a graded manner that correlates with patient prognosis better than the current dichotomous (presence/absence) definition. However, further and larger studies are needed to support this PNI scoring system.

Neuropathy in ARSACS is demyelinating but without typical nerve enlargement in nerve ultrasound.

BACKGROUND: To specify peripheral nerve affection in autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) by correlating high-resolution nerve ultrasound and nerve conduction studies. METHODS: We assessed a cohort of 11 ARSACS patients with standardized nerve conduction studies and high-resolution ultrasound of peripheral nerves and compared nerve ultrasound findings to a healthy control group matched for age, sex, size and weight. RESULTS: Mean age of patients was 39.0 (± 14.1) years and disease duration at assessment 30.6 (± 12.5) years. All patients presented with a spasticity, ataxia and peripheral neuropathy. Neuropathy appeared to be primarily demyelinating in 9/11 cases and was not classifiable in 2/11 cases due to not evocable potentials. Nerve ultrasound revealed a normal ultrasound pattern sum score (UPSS) in each ARSACS patient and no significant nerve enlargement compared to the control group. CONCLUSIONS: Peripheral neuropathy in ARSACS showed primarily demyelinating rather than axonal characteristics and presented without nerve enlargement. As demyelinating neuropathies do commonly present enlarged nerves we recommend further genetic testing of the SACS gene in patients who present with this combination of demyelinating neuropathy without nerve enlargement. ARSACS cases that initially presented only with neuropathy without spasticity or ataxia and therefore were misdiagnosed as Charcot-Marie-Tooth disease are supporting this suggestion.

Autoreactive T cells target peripheral nerves in Guillain-Barré syndrome.

Guillain-Barré syndrome (GBS) is a rare heterogenous disorder of the peripheral nervous system, which is usually triggered by a preceding infection, and causes a potentially life-threatening progressive muscle weakness1. Although GBS is considered an autoimmune disease, the mechanisms that underlie its distinct clinical subtypes remain largely unknown. Here, by combining in vitro T cell screening, single-cell RNA sequencing and T cell receptor (TCR) sequencing, we identify autoreactive memory CD4+ cells, that show a cytotoxic T helper 1 (TH1)-like phenotype, and rare CD8+ T cells that target myelin antigens of the peripheral nerves in patients with the demyelinating disease variant. We characterized more than 1,000 autoreactive single T cell clones, which revealed a polyclonal TCR repertoire, short CDR3ß lengths, preferential HLA-DR restrictions and recognition of immunodominant epitopes. We found that autoreactive TCRß clonotypes were expanded in the blood of the same patient at distinct disease stages and, notably, that they were shared in the blood and the cerebrospinal fluid across different patients with GBS, but not in control individuals. Finally, we identified myelin-reactive T cells in the nerve biopsy from one patient, which indicates that these cells contribute directly to disease pathophysiology. Collectively, our data provide clear evidence of autoreactive T cell immunity in a subset of patients with GBS, and open new perspectives in the field of inflammatory peripheral neuropathies, with potential impact for biomedical applications.

When biopsy goes wrong: a case series of misdiagnoses and complications from biopsies of masses of unknown origin potentially originating from a peripheral nerve.

OBJECTIVE: Biopsies of peripheral nerve tumors (PNTs) are often used to plan an efficient treatment strategy. However, performing a biopsy is controversial when the mass is likely to be a benign PNT (BPNT). The aim of this study was to evaluate the side effects of biopsies in patients with potential PNTs. METHODS: A retrospective and cross-sectional study was conducted on 24 patients who underwent biopsy of a mass of unknown origin potentially originating from a peripheral nerve (MUOPON), performed in nonspecialty services, and who were later referred to the authors' service for resection of their lesion between January 2005 and December 2022. The patients were evaluated for pain score, presence of a motor or sensory deficit, biopsy diagnosis, and definitive histopathological postsurgical diagnosis. RESULTS: The location of the tumor was supraclavicular in 7 (29.2%) patients, in the axillary region in 3 (12.5%), in the upper limb in 7 (29.2%), and in the lower limb in 7 (29.2%). Twenty-one (87.5%) patients were evaluated by MRI before biopsy, and 3 (12.5%) underwent ultrasound. One patient did not have an examination before the procedure. Based on the biopsy findings, 12 (50%) analyses had an inconclusive histopathological result. The preexisting pain worsened, as measured 1 week after biopsy, in all patients and had remained unchanged at the first evaluation by the authors (median 3 months, range 2-4 months). In 1 case, the open biopsy had to be interrupted because the patient experienced excruciating pain. Four (16.7%) patients developed motor deficits. Subsequent surgery was hampered by scar formation and intratumoral hemorrhage in 5 (20.8%) patients. The initial diagnosis obtained by biopsy differed from the final histopathological diagnosis in all patients, of whom 21 (87.5%) had BPNTs, 2 (8.3%) malignant peripheral nerve sheath tumors, and 1 (4.2%) an ancient schwannoma. CONCLUSIONS: Biopsies of PNTs are controversial and may result in misdiagnosis, neuropathic pain, or neurological deficit due to axonal damage, and they may also hinder microsurgical resection when if performed when not indicated. Indications for biopsy of an MUOPON must be carefully considered, especially if BPNT is a possible diagnosis.

Subcategorization of Perineural Invasion Stratifies Oral Cavity Squamous Cell Carcinoma Prognosis.

OBJECTIVE: To evaluate whether subcategorization of perineural invasion (PNI) improves the prognostic resolution of the American Joint Committee on Cancer, Eighth Edition (AJCC8) staging system in oral cavity squamous cell carcinoma (OCSCC). METHODS: OCSCC tumor specimens from patients seen at a tertiary care institution who underwent primary surgical resection between January 2019 and June 2021 were sorted into four PNI categories: negative, intratumoral, peripheral, and extratumoral. The prognostic effect of these PNI categories were assessed through Kaplan-Meier, Cox regression, and log-rank testing using recurrence-free survival (RFS) and overall survival (OS) as primary and secondary outcomes respectively. RESULTS: A total of 158 patients were examined. The median follow-up time was 21 months. PNI subcategorization further stratified RFS (p = 0.007) and OS (p = 0.002). Extratumoral PNI was associated with a 4.5-fold increase in recurrence risk (adjusted hazards ratio [aHR]: 4.53; 95% confidence interval [CI]: 1.1-18.66) and worse OS when compared with PNI negative disease (aHR: 5.71; 95% CI: 1.0-32.67). Peripheral PNI was associated with worse OS (aHR: 5.7; 95% CI: 1.35-24.08) but not worse RFS (p = 0.18) when compared with PNI negative disease. Interestingly, intratumoral PNI was not associated with significant differences in RFS (p = 0.087) or OS (p = 0.22) when compared with PNI negative disease. CONCLUSIONS: Subcategorization of OCSCC tumors into extratumoral, peripheral, and intratumoral PNI stratifies RFS and OS when compared with patients with PNI negative disease in an incremental fashion. This pilot study suggests that there may be added benefit in subcategorization of PNI in the prognostic evaluation of OCSCC. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:1656-1662, 2024.

Granuloma, vasculitis, and demyelination in sarcoid neuropathy.

BACKGROUND: Despite the suggestion that direct compression by granuloma and ischemia resulting from vasculitis can cause nerve fiber damage, the mechanisms underlying sarcoid neuropathy have not yet been fully clarified. METHODS: We examined the clinicopathological features of sarcoid neuropathy by focusing on electrophysiological and histopathological findings of sural nerve biopsy specimens. We included 18 patients with sarcoid neuropathy who had non-caseating epithelioid cell granuloma in their sural nerve biopsy specimens. RESULTS: Although electrophysiological findings suggestive of axonal neuropathy were observed, particularly in the lower limbs, all but three patients showed ≥1 abnormalities in nerve conduction velocity or distal motor latency. Additionally, a conduction block was observed in 11 of the 16 patients for whom waveforms were assessed; five of them fulfilled motor nerve conduction criteria strongly supportive of demyelination as defined in the European Academy of Neurology/Peripheral Nerve Society (EAN/PNS) guideline for chronic inflammatory demyelinating polyneuropathy (CIDP). In most patients, sural nerve biopsy specimens revealed a mild to moderate degree of myelinated fiber loss. Fibrinoid necrosis was observed in one patient, and electron microscopy analysis revealed demyelinated axons close to granulomas in six patients. CONCLUSIONS: Patients with sarcoid neuropathy may meet the EAN/PNS electrophysiological criteria for CIDP due to the frequent presence of conduction blocks. Based on our results, in addition to the ischemic damage resulting from granulomatous inflammation, demyelination may play an important role in the mechanism underlying sarcoid neuropathy.

M2 macrophage-derived cathepsin S promotes peripheral nerve regeneration via fibroblast-Schwann cell-signaling relay.

BACKGROUND: Although peripheral nerves have an intrinsic self-repair capacity following damage, functional recovery is limited in patients. It is a well-established fact that macrophages accumulate at the site of injury. Numerous studies indicate that the phenotypic shift from M1 macrophage to M2 macrophage plays a crucial role in the process of axon regeneration. This polarity change is observed exclusively in peripheral macrophages but not in microglia and CNS macrophages. However, the molecular basis of axonal regeneration by M2 macrophage is not yet fully understood. Herein, we aimed to identify the M2 macrophage-derived axon regeneration factor. METHODS: We established a peripheral nerve injury model by transection of the inferior alveolar nerve (IANX) in Sprague-Dawley rats. Transcriptome analysis was performed on the injured nerve. Recovery from sensory deficits in the mandibular region and histological reconnection of IAN after IANX were assessed in rats with macrophage depletion by clodronate. We investigated the effects of adoptive transfer of M2 macrophages or M2-derived cathepsin S (CTSS) on the sensory deficit. CTSS initiating signaling was explored by western blot analysis in IANX rats and immunohistochemistry in co-culture of primary fibroblasts and Schwann cells (SCs). RESULTS: Transcriptome analysis revealed that CTSS, a macrophage-selective lysosomal protease, was upregulated in the IAN after its injury. Spontaneous but partial recovery from a sensory deficit in the mandibular region after IANX was abrogated by macrophage ablation at the injured site. In addition, a robust induction of c-Jun, a marker of the repair-supportive phenotype of SCs, after IANX was abolished by macrophage ablation. As in transcriptome analysis, CTSS was upregulated at the injured IAN than in the intact IAN. Endogenous recovery from hypoesthesia was facilitated by supplementation of CTSS but delayed by pharmacological inhibition or genetic silencing of CTSS at the injured site. Adoptive transfer of M2-polarized macrophages at this site facilitated sensory recovery dependent on CTSS in macrophages. Post-IANX, CTSS caused the cleavage of Ephrin-B2 in fibroblasts, which, in turn, bound EphB2 in SCs. CTSS-induced Ephrin-B2 cleavage was also observed in human sensory nerves. Inhibition of CTSS-induced Ephrin-B2 signaling suppressed c-Jun induction in SCs and sensory recovery. CONCLUSIONS: These results suggest that M2 macrophage-derived CTSS contributes to axon regeneration by activating SCs via Ephrin-B2 shedding from fibroblasts.

Indolent Multinodular Synovial Sarcoma of Peripheral Nerves Mimicking Schwannoma: A Case Report and Literature Review.

BACKGROUND/AIM: Most cases of synovial sarcoma (SS) are aggressive and large-sized; only few show indolent behavior, having a small size. Nerves are rare sites of SS occurrence. An atypical case of SS can lead to its misdiagnosis as a benign tumor and delay its treatment. CASE REPORT: Here, we report a case of primary SS of indolent multinodular synovial sarcoma of peripheral nerves. Considering the clinical and imaging findings at the first visit, we suspected a benign tumor and continued careful follow-up. Three years later, marginal resection was performed and SS was suspected. We then performed an additional wide resection using a free flap. Histopathologically, the proximal tumor showed a diffuse proliferation of spindle cells without pleomorphism, whereas the distal tumor showed a similar histology with more hypercellularity. Additional wide-resection specimens showed remnant tumors derived from the peripheral nerve. Immunohistochemistry (IHC) showed positive staining for SS18:SSX and SSX in both tumors and fluorescence in situ hybridization showed positive staining for the SS18 split in both tumors. Finally, SS of the peripheral nerve was diagnosed. Owing to FNCLCC grade 2 tumor and tumor size, adjuvant chemotherapy was not performed. CONCLUSION: In cases of SS or other sarcomas with atypical clinical courses, with imaging findings mimicking benign tumors, we recommend marginal resection along with pathological examination for correct diagnosis.

Unraveling the Mysteries of Perineural Invasion in Benign and Malignant Conditions.

Perineural invasion (PNI) is defined as the dissemination of neoplastic cells within the perineural space. PNI can be a strong indicator of malignancy and is linked to poor prognosis and adverse outcomes in various malignant neoplasms; nevertheless, it can also be seen in benign pathologic conditions. In this review article, we discuss various signaling pathways and neurotrophic factors implicated in the development and progression of PNI. We also describe the methodology, benefits, and limitations of different in vitro, ex vivo, and in vivo models of PNI. The spectrum of presentation for PNI can range from diffuse spread within large nerves ("named" nerves) all the way through localized spread into unnamed microscopic nerves. Therefore, the clinical significance of PNI is related to its extent rather than its mere presence or absence. In this article, we discuss the guidelines for the identification and quantification of PNI in different malignant neoplasms based on the College of American Pathologists (CAP) and World Health Organization (WHO) recommendations. We also describe benign pathologic conditions and neoplasms demonstrating PNI and potential mimics of PNI. Finally, we explore avenues for the future development of targeted therapy options via modulation of signaling pathways involved in PNI.