Neurophysiological, nerve imaging and other techniques to assess chemotherapy-induced peripheral neurotoxicity in the clinical and research settings

Using ultrasound shear wave elastography to characterize peripheral nerve mechanics: a systematic review on the normative reference values in healthy individuals

Ultrasound shear wave elastography (SWE) is an emerging non-invasive imaging technique for peripheral nerve evaluation. Shear wave velocity (SWV), a surrogate measure of stiffness, holds promise as a biomarker for various peripheral nerve disorders. However, to maximize its clinical and biomechanical value, it is important to fully understand the factors that influence nerve SWV measurements. This systematic review aimed to identify the normal range of SWV for healthy sciatic and tibial nerves and to reveal the factors potentially affecting nerve SWV. An electronic search yielded 17 studies eligible for inclusion, involving 548 healthy individuals (age range, 17 to 72 years). Despite very good reliability metrics, the reported SWV values differed considerably across studies for the sciatic (1.9-9.9 m/s) and tibial (2.3-9.1 m/s) nerves. Factors such as measurement proximity to joint regions, limb postures inducing nerve axial stretching, and transducer alignment with nerve fiber orientation were associated with increased SWV. These findings suggest regional-specific nerve mechanical properties, non-linear elastic behaviour, and marked mechanical anisotropy. The impact of age and sex remains unclear and warrants further investigation. These results emphasize the importance of considering these factors when assessing and interpreting nerve SWE. While increased SWV has been linked to pathological changes affecting nerve tissue mechanics, the significant variability observed in healthy nerves highlights the need for standardized SWE assessment protocols. Developing guidelines for enhanced clinical utility and achieving a comprehensive understanding of the factors that influence nerve SWE assessments are critical in advancing the field.

Neurosarcoidosis with enlargement of the dorsal root ganglia: A case report

We report the case of a woman in her 40s who presented with sensory disturbances in all 4 limbs and left facial palsy. MRI revealed asymmetric enlargement of the dorsal root ganglia, which was enhanced by gadolinium-a chest CT scan identified enlarged supraclavicular, mediastinal, and hilar lymph nodes. A biopsy of a hilar lymph node showed noncaseating epithelioid granulomas, confirming a sarcoidosis diagnosis. Prednisolone treatment led to symptomatic improvements. In sarcoidosis of the peripheral nervous system, there might be observable enlargement of the dorsal root ganglion alongside enhanced gadolinium contrast. Obtaining a biopsy from the dorsal root ganglion poses challenges, and radiologists should be mindful of this specific imaging characteristic.

The Efficacy of Neuromodulation Interventions for Chemotherapy-Induced Peripheral Neuropathy: A Systematic Review and Meta-Analysis

Purpose

To determine the efficacy and safety of a neuromodulation intervention regimen in the treatment of chemotherapy-induced peripheral neuropathy (CIPN).

Patients and Methods

Systematic searches were conducted in seven English databases. Randomized controlled trials of all neuromodulation interventions (both invasive and non-invasive) for the treatment of CIPN were selected. Group comparisons of differences between interventions and controls were also made. We divided the outcomes into immediate-term effect (≤3 weeks), short-term effect (3 weeks to ≤3 months), and long-term effect (>3 months).

Results

Sixteen studies and 946 patients with CIPN were included. Among immediate-term effects, neuromodulation interventions were superior to usual care for improving pain (SMD=-0.77, 95% CI -1.07~ 0.47), FACT-Ntx (MD = 5.35, 95% CI 2.84~ 7.87), and QOL (SMD = 0.44, 95% CI 0.09~ 0.79) (moderate certainty); neuromodulation loaded with usual care was superior to usual care for improving pain (SMD=-0.47, 95% CI -0.71 ~ -0.23), and QOL (SMD = 0.40, 95% CI 0.12 ~ 0.69) (moderate certainty). There were no statistically significant differences between the neuromodulation interventions regimen vs usual care in short- and long-term outcomes and neuromodulation vs sham stimulation from any outcome measure. There were mild adverse events such as pain at the site of stimulation and bruising, and no serious adverse events were reported.

Conclusion

Neuromodulation interventions had significant immediate-term efficacy in CIPN but had not been shown to be superior to sham stimulation; short-term and long-term efficacy could not be determined because there were too few original RCTs. Moreover, there are no serious adverse effects of this therapy.

Axonal degeneration in chemotherapy-induced peripheral neurotoxicity: clinical and experimental evidence

Multiple pathological mechanisms are involved in the development of chemotherapy-induced peripheral neurotoxicity (CIPN). Recent work has provided insights into the molecular mechanisms underlying chemotherapy-induced axonal degeneration. This review integrates evidence from preclinical and clinical work on the onset, progression and outcome of axonal degeneration in CIPN. We review likely triggers of axonal degeneration in CIPN and highlight evidence of molecular pathways involved in axonal degeneration and their relevance to CIPN, including SARM1-mediated axon degeneration pathway. We identify potential clinical markers of axonal dysfunction to provide early identification of toxicity as well as present potential treatment strategies to intervene in axonal degeneration pathways. A greater understanding of axonal degeneration processes in CIPN will provide important information regarding the development and progression of axonal dysfunction more broadly and will hopefully assist in the development of successful interventions for CIPN and other neurodegenerative disorders.

Gait analysis in chemotherapy-induced peripheral neurotoxicity rodent models

Gait analysis could be used in animal models as an indicator of sensory ataxia due to chemotherapy-induced peripheral neurotoxicity (CIPN). Over the years, gait analysis in in vivo studies has evolved from simple observations carried out by a trained operator to computerised systems with machine learning that allow the quantification of any variable of interest and the establishment of algorithms for behavioural classification. However, there is not a consensus on gait analysis use in CIPN animal models; therefore, we carried out a systematic review. Of 987 potentially relevant studies, 14 were included, in which different methods were analysed (observation, footprint and CatWalk™). We presented the state-of-the-art of possible approaches to analyse sensory ataxia in rodent models, addressing advantages and disadvantages of different methods available. Semi-automated methods may be of interest when preventive or therapeutic strategies are evaluated, also considering their methodological simplicity and automaticity; up to now, only CatWalk™ analysis has been tested. Future studies should expect that CIPN-affected animals tend to reduce hind paw support due to pain, allodynia or loss of sensation, and an increase in swing phase could or should be observed. Few available studies documented these impairments at the last time point, and only appeared later on respect to other earlier signs of CIPN (such as altered neurophysiological findings). For that reason, gait impairment could be interpreted as late repercussions of loss of sensory.

Acupuncture May Help to Prevent Chemotherapy-Induced Peripheral Neuropathy: A Randomized, Sham-Controlled, Single-Blind Study

OBJECTIVE

This study investigated the efficacy of acupuncture in preventing chemotherapy-induced peripheral neuropathy (CIPN) in patients with colorectal cancer (CRC).

METHODS

This single center, randomized, controlled, single-blind clinical trial randomly assigned patients with stage 3 CRC attending outpatient clinics in China Medical University Hospital to either verum or sham acupuncture treatment concurrently with chemotherapy. Primary outcomes were nerve conduction velocity (NCV) and touch thresholds of limb terminals. Secondary outcomes were total and subdomain scores on the Functional Assessment of Cancer Therapy-General (FACT-G), and scores on the FACT/GOG-Ntx subscale and the Brief Pain Inventory-Short Form (BPI-SF), at baseline, weeks 12, 36, and follow-up (week 48).

RESULTS

Thirty-two patients met the inclusion criteria and received verum acupuncture (N = 16) or sham acupuncture (N = 16). Under the -intent-to-treat principle, 26 participants were analyzed. Significant changes from baseline for questionnaire scores and sensory NCV were observed in both study groups. Sham acupuncture was associated with significant reductions from baseline in motor NCV and sensory touch thresholds; no such changes were observed with verum acupuncture. No serious adverse events were reported.

CONCLUSION

Prophylactic acupuncture may exert neuroprotective effects on mechanical or tactile touch thresholds during chemotherapy regimens in patients with CRC, with evidence of this protectiveness persisting at 6 months' follow-up. The lack of change in motor NCV values with verum acupuncture indicates neuroprotective effects. Sensory NCV values and patient-reported outcomes did not differ significantly between the study groups.

Metabolic and lifestyle risk factors for chemotherapy-induced peripheral neuropathy in taxane and platinum-treated patients: a systematic review

PURPOSE

Chemotherapy-induced peripheral neurotoxicity (CIPN) is a common dose-limiting toxicity of cancer treatment causing functional impairment and impacting quality of life. Effective prevention and treatment of CIPN are lacking, and CIPN risk factors remain ill-defined. Metabolic syndrome and associated conditions have emerged as potential risk factors, due to their high prevalence and independent association with nerve dysfunction. This systematic review aimed to investigate the association between these common metabolic-lifestyle factors and CIPN.

METHODS

Searches were undertaken using Medline, Embase, CINAHL, Scopus, and Web of Science databases, with additional studies identified from bibliographic references cited by original and review articles. Articles that analyzed metabolic-lifestyle risk factors associated with CIPN for patients treated with platinum- or taxane-based chemotherapy were included.

RESULTS

Searches identified 6897 titles; 44 articles had full text review, with 26 studies included. Overall incidence of neuropathy ranged from 16.9 to 89.4%. Obesity had the most consistent patient-oriented evidence as a risk factor for CIPN, with moderate evidence suggesting diabetes did not increase CIPN incidence or severity. A limited number of studies supported an association with low physical activity and greater CIPN risk.

CONCLUSIONS

Comorbidities and lifestyle factors, particularly obesity and low physical activity, may contribute to the development of CIPN. The implementation of sensitive outcome measures in large-scale clinical trials is required to further elucidate CIPN risk factors and evaluate if changes in lifestyle would improve long-term CIPN outcomes for cancer survivors.

IMPLICATIONS FOR CANCER SURVIVORS

Better understanding of CIPN risk profiles may inform personalized medicine strategies and help elucidate pathophysiological mechanisms which could be targeted for neuroprotection.

Serum neurofilament levels correlate with electrodiagnostic evidence of axonal loss in paclitaxel-induced peripheral neurotoxicity

INTRODUCTION

Paclitaxel-induced peripheral neurotoxicity (PIPN) typically manifests as a predominantly sensory axonopathy. Nerve conduction studies (NCS) represent the gold standard method to quantify axonal impairment in PIPN. Serum neurofilament light chain (sNfL) levels are emerging biomarkers for quantifying axonal damage in peripheral neuropathies. To date, the association between NCS abnormalities and sNfL levels during paclitaxel-based chemotherapy has not been specifically addressed.

METHODS

We prospectively conducted longitudinal measurement of sNfL levels in 27 chemotherapy-naïve breast cancer patients and correlated conventional NCS recordings with sNfL in 22 of them, before (T0) and after (T1) 12 cycles of weekly paclitaxel-based therapy.

RESULTS

PIPN was diagnosed in 24/27 patients (88%) after completion of the 12-week paclitaxel-based chemotherapy regimen. Serum NfL levels (pg/mL) were significantly higher at T1 compared to T0 (T0: 18.50 ± 12.88 vs T1: 255.80 ± 194.16; p < 0.001). The increase of sNfL levels at T1 significantly correlated with the decrease or abolishment of amplitudes recorded from the sural nerve (r = 0.620; p = 0.0035), sensory radial (r = 0.613; p = 0.005), sensory ulnar (r = 0.630; p = 0.005), and peroneal motor (r = 0.568; p = 0.024) nerves.

CONCLUSION

sNfL levels proportionally increase during chemotherapy administration and significantly correlate with NCS axonal abnormalities in patients with PIPN. A multimodal testing approach employing both sNfL and NCS might improve the PIPN diagnostic accuracy.

Chemotherapy-Induced Toxicities: An Imaging Primer

The Coronavirus Disease of 2019 (COVID-19) pandemic has caused significant delays in the delivery of cancer treatments in Canada. As cancer treatment and imaging volumes return to normal, radiologists will encounter more cases of chemotherapy-induced toxicities. These toxicities have varied appearances on imaging, and can affect multiple organ systems. The purpose of this review is to offer a unified resource for general radiologists regarding the imaging appearances of chemotherapy-induced toxicities.

Comparison of Clinical Symptoms and Neurophysiological Findings in Patients With Chemotherapy Induced Peripheral Neuropathy

Introduction

Taxanes are associated with a distal sensory neuropathy, significantly affecting cancer survivor quality of life. However, chemotherapy-induced peripheral neuropathy (CIPN) assessments are primarily based on clinical symptoms rather than objective neurophysiologic findings. Therefore, we investigated neurophysiologic changes in symptomatic subjects, comparing them with symptom severity.

Materials and Methods

Medical charts of 111 subjects who were referred for CIPN diagnosis after chemotherapy for breast or ovarian cancer between May 1, 2016, and December 31, 2019, were retrospectively reviewed. Demographics, anthropometric parameters, and Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) pain scale data were collected. The nerve conduction study (NCS) results, including sensory nerve action potentials recorded from sural nerves, were analyzed relative to clinical symptoms. To optimize follow-up (FU) NCS diagnostic sensitivity, relative references of FU sural amplitude reductions to >30% and an absolute reference <10 μV were used.

Results

Eighty-eight female patients met the criteria, and 20 underwent FU NCS. Baseline and FU sural amplitudes showed significant positive correlation with respective LANSS scores (p < 0.01). FU sural amplitude was significantly lower than the initial result (p < 0.05). The FU LANSS score was not different from the initial score. Initial NCS sensitivity and specificity for clinically suspected CIPN diagnoses with LANSS were 69.7 and 47.3%, respectively. All 20 subjects with FU evaluation were clinically compatible with CIPN (LANSS >12) at initial and FU assessments. Among them, only six (30.0%) had abnormal sural amplitudes (<10μV for ≤50 s, <3 μV for 60 s, <1 μV for 70 s) in the initial NCS. In the FU NCS, sural amplitude became abnormal in five additional subjects. Between the initial and FU NCS, sural amplitude was reduced by > 30% in eight subjects (40.0%). NCS sensitivity increased to 65.0% when including either abnormal sural amplitudes or a > 30% reduction in sural amplitude in FU studies.

Conclusions

Although clinical symptoms and NCS results were positively correlated, a single NCS point had limited value for suspected CIPN electrophysiological diagnoses. Serial NCS during chemotherapy might help assess the degree of chemotherapy-induced nerve damage, attain evidence of CIPN prior to symptom aggravation, and monitor the progression of CIPN. Further study is needed to find specific relative references for variable patient factors to increase the sensitivity of electrophysiological studies of clinically suspected CIPN.

Optimal outcome measures for assessing exercise and rehabilitation approaches in chemotherapy-induced peripheral-neurotoxicity: Systematic review and consensus expert opinion

INTRODUCTION

Chemotherapy-induced peripheral neurotoxicity (CIPN) remains a significant toxicity in cancer survivors without preventative strategies or rehabilitation. Exercise and physical activity-based interventions have demonstrated promise in reducing existing CIPN symptoms and potentially preventing toxicity, however there is a significant gap in evidence due to the lack of quality clinical trials and appropriate outcome measures.

AREAS COVERED

We systematically reviewed outcome measures in CIPN exercise and physical rehabilitation studies with expert panel consensus via the Peripheral Nerve Society Toxic Neuropathy Consortium to provide recommendations for future trials. Across 26 studies, 75 outcome measures were identified and grouped into 16 domains within three core areas - measures of manifestations of CIPN (e.g. symptoms/signs), measures of the impact of CIPN and other outcome measures.

EXPERT OPINION

This article provides a conceptual framework for CIPN outcome measures and highlights the need for definition of a core outcome measures set. The authors provide recommendations for CIPN exercise and physical rehabilitation trial design and outcome measure selection. The development of a core outcome measure set will be critical in the search for neuroprotective and treatment approaches to support cancer survivors and to address the gap in the identification of effective rehabilitation and treatment options for CIPN.

Association of electrochemical skin conductance with neuropathy in chemotherapy-treated patients

PURPOSE

Chemotherapy-induced peripheral neuropathy (CIPN) is an adverse event of cancer treatment that can affect sensory, motor, or autonomic nerves. Assessment of autonomic neuropathy is challenging, with limited available tools. Accordingly, it is not routinely assessed in chemotherapy-treated patients. In this study, we aimed to examine whether electrochemical skin conductance (ESC) via Sudoscan, a potential measure of autonomic function, associates with subjective and objective measures of CIPN severity and autonomic neuropathy.

METHODS

A cross-sectional assessment of patients who completed neurotoxic chemotherapy 3-24 months prior was undertaken using CIPN patient-reported outcomes (EORTC-QLQ-CIPN20), clinically graded scale (NCI-CTCAE), neurological examination score (TNSc), autonomic outcome measure (SAS), and Sudoscan. Differences in CIPN severity between participants with or without ESC dysfunction were investigated. Linear regression analyses were used to identify whether ESC values could predict CIPN severity.

RESULTS

A total of 130 participants were assessed, with 93 participants classified with CIPN according to the clinically graded scale (NCI-CTCAE/grade ≥ 1), while 49% demonstrated hands or feet ESC dysfunction (n = 46). Participants with ESC dysfunction did not significantly differ from those with no dysfunction on multiple CIPN severity measures (clinical-grade, patient-report, neurological examination), and no differences on the autonomic outcome measure (SAS) (all p > 0.0063). Linear regression analyses showed that CIPN could not be predicted by ESC values.

CONCLUSIONS

The inability of ESC values via Sudoscan to predict clinically-graded and patient-reported CIPN or autonomic dysfunction questions its clinical utility for chemotherapy-treated patients. The understanding of autonomic neuropathy with chemotherapy treatment remains limited and must be addressed to improve quality of life in cancer survivors.

Management of Side Effects in the Personalized Medicine Era: Chemotherapy-Induced Peripheral Neurotoxicity

Pharmacogenomics is a powerful tool to predict individual response to treatment, in order to personalize therapy, and it has been explored extensively in oncology practice. Not only efficacy on the malignant disease has been investigated but also the possibility to predict adverse effects due to drug administration. Chemotherapy-induced peripheral neurotoxicity (CIPN) is one of those. This potentially severe and long-lasting/permanent side effect of commonly administered anticancer drugs can severely impair quality of life (QoL) in a large cohort of long survival patients. So far, a pharmacogenomics-based approach in CIPN regard has been quite delusive, making a methodological improvement warranted in this field of interest: even the most refined genetic analysis cannot be effective if not applied correctly. Here we try to devise why it is so, suggesting how THE "bench-side" (pharmacogenomics) might benefit from and should cooperate with THE "bed-side" (clinimetrics), in order to make genetic profiling effective if applied to CIPN.

Chemotherapy-Induced Peripheral Neuropathy: Epidemiology, Pathomechanisms and Treatment

PURPOSE

This review provides an update on the current clinical, epidemiological and pathophysiological evidence alongside the diagnostic, prevention and treatment approach to chemotherapy-induced peripheral neuropathy (CIPN).

FINDINGS

The incidence of cancer and long-term survival after treatment is increasing. CIPN affects sensory, motor and autonomic nerves and is one of the most common adverse events caused by chemotherapeutic agents, which in severe cases leads to dose reduction or treatment cessation, with increased mortality. The primary classes of chemotherapeutic agents associated with CIPN are platinum-based drugs, taxanes, vinca alkaloids, bortezomib and thalidomide. Platinum agents are the most neurotoxic, with oxaliplatin causing the highest prevalence of CIPN. CIPN can progress from acute to chronic, may deteriorate even after treatment cessation (a phenomenon known as coasting) or only partially attenuate. Different chemotherapeutic agents share both similarities and key differences in pathophysiology and clinical presentation. The diagnosis of CIPN relies heavily on identifying symptoms, with limited objective diagnostic approaches targeting the class of affected nerve fibres. Studies have consistently failed to identify at-risk cohorts, and there are no proven strategies or interventions to prevent or limit the development of CIPN. Furthermore, multiple treatments developed to relieve symptoms and to modify the underlying disease in CIPN have failed.

IMPLICATIONS

The increasing prevalence of CIPN demands an objective approach to identify at-risk patients in order to prevent or limit progression and effectively alleviate the symptoms associated with CIPN. An evidence base for novel targets and both pharmacological and non-pharmacological treatments is beginning to emerge and has been recognised recently in publications by the American Society of Clinical Oncology and analgesic trial design expert groups such as ACTTION.

Cutaneous pain in disorders affecting peripheral nerves

Our ability to quickly detect and respond to harmful environmental stimuli is vital for our safety and survival. This inherent acute pain detection is a "gift" because it both protects our body from harm and allows healing of damaged tissues [1]. Damage to tissues from trauma or disease can result in distorted or amplified nociceptor signaling and sensitization of the spinal cord and brain (Central Nervous System; CNS) pathways to normal input from light touch mechanoreceptors. Together, these processes can result in nagging to unbearable chronic pain and extreme sensitivity to light skin touch (allodynia). Unlike acute protective pain, chronic pain and allodynia serve no useful purpose and can severely reduce the quality of life of an affected person. Chronic pain can arise from impairment to peripheral neurons, a phenomenon called "peripheral neuropathic pain." Peripheral neuropathic pain can be caused by many insults that directly affect peripheral sensory neurons, including mechanical trauma, metabolic imbalance (e.g., diabetes), autoimmune diseases, chemotherapeutic agents, viral infections (e.g., shingles). These insults cause "acquired" neuropathies such as small-fiber neuropathies, diabetic neuropathy, chemotherapy-induced peripheral neuropathy, and post herpetic neuralgia. Peripheral neuropathic pain can also be caused by genetic factors and result in hereditary neuropathies that include Charcot-Marie-Tooth disease, rare channelopathies and Fabry disease. Many acquired and hereditary neuropathies affect the skin, our largest organ and protector of nearly our entire body. Here we review how cutaneous nociception (pain perceived from the skin) is altered following diseases that affect peripheral nerves that innervate the skin. We provide an overview of how noxious stimuli are detected and encoded by molecular transducers on subtypes of cutaneous afferent endings and conveyed to the CNS. Next, we discuss several acquired and hereditary diseases and disorders that cause painful or insensate (lack of sensation) cutaneous peripheral neuropathies, the symptoms and percepts patients experience, and how cutaneous afferents and other peripheral cell types are altered in function in these disorders. We highlight exciting new research areas that implicate non-neuronal skin cells, particularly keratinocytes, in cutaneous nociception and peripheral neuropathies. Finally, we conclude with ideas for innovative new directions, areas of unmet need, and potential opportunities for novel cutaneous therapeutics that may avoid CNS side effects, as well as ideas for improved translation of mechanisms identified in preclinical models to patients.

A case of spinal nerve neurotoxicity with ropivacaine after combined spinal and epidural anesthesia

Background

Neurotoxicity caused by a local anesthetic after regional anesthesia is a rare but serious problem for anesthesiologists. It is difficult to diagnose neurotoxicity from anesthetics because of the large number of possible diagnoses. In this case report, careful monitoring by neurological examinations helped to diagnose local neurotoxicity caused after epidural anesthesia.

Case description

A 41-year-old pregnant woman who underwent emergency cesarean delivery under combined spinal-epidural anesthesia suffered left leg paralysis after surgery. Multiple neurological examinations (e.g., electromyography, nerve conduction study) revealed that the paralysis was induced by the neurotoxicity of ropivacaine. The neurological examinations were also useful to monitor the recovery process.

Conclusions

This is the first clinical case report that describes the diagnosis of and recovery from local anesthesia-induced neurotoxicity monitored by electromyography and nerve conduction study. Neurological disorders caused by regional anesthetics should be carefully examined and diagnosed using these neurological examinations.

Predictive Biomarkers of Oxaliplatin-Induced Peripheral Neurotoxicity

Oxaliplatin (OXA) is a platinum compound primarily used in the treatment of gastrointestinal cancer. OXA-induced peripheral neurotoxicity (OXAIPN) is the major non-hematological dose-limiting toxicity of OXA-based chemotherapy and includes acute transient neurotoxic effects that appear soon after OXA infusion, and chronic non-length dependent sensory neuronopathy symmetrically affecting both upper and lower limbs in a stocking-and-glove distribution. No effective strategy has been established to reverse or treat OXAIPN. Thus, it is necessary to early predict the occurrence of OXAIPN during treatment and possibly modify the OXA-based regimen in patients at high risk as an early diagnosis and intervention may slow down neuropathy progression. However, identifying which patients are more likely to develop OXAIPN is clinically challenging. Several objective and measurable early biomarkers for OXAIPN prediction have been described in recent years, becoming useful for informing clinical decisions about treatment. The purpose of this review is to critically review data on currently available or promising predictors of OXAIPN. Neurological monitoring, according to predictive factors for increased risk of OXAIPN, would allow clinicians to personalize treatment, by monitoring at-risk patients more closely and guide clinicians towards better counseling of patients about neurotoxicity effects of OXA.

Burst of Corneal Dendritic Cells during Trastuzumab and Paclitaxel Treatment

During breast cancer therapy, paclitaxel and trastuzumab are both associated with adverse effects such as chemotherapy-induced peripheral neuropathy and other systemic side effects including ocular complications. Corneal nerves are considered part of the peripheral nervous system and can be imaged non-invasively by confocal laser scanning microscopy (CLSM) on the cellular level. Thus, in vivo CLSM imaging of structures of the corneal subbasal nerve plexus (SNP) such as sensory nerves or dendritic cells (DCs) can be a powerful tool for the assessment of corneal complications during cancer treatment. During the present study, the SNP of a breast cancer patient was analyzed over time by using large-scale in vivo CLSM in the course of paclitaxel and trastuzumab therapy. The same corneal regions could be re-identified over time. While the subbasal nerve morphology did not alter significantly, a change in dendritic cell density and an additional local burst within the first 11 weeks of therapy was detected, indicating treatment-mediated corneal inflammatory processes. Ocular structures such as nerves and dendritic cells could represent useful biomarkers for the assessment of ocular adverse effects during cancer therapy and their management, leading to a better visual prognosis.

Weekly Paclitaxel-Induced Neurotoxicity in Breast Cancer: Outcomes and Dose Response

BACKGROUND

Paclitaxel treatment produces significant peripheral neuropathy, but the time course of neuropathy development and outcomes are unclear. Dose reduction is the only strategy to prevent neurotoxicity, however, the impact of dose-reduction on neuropathy outcomes remains unknown. This study aimed to prospectively evaluated neuropathy development from weekly paclitaxel treatment and evaluate the impact of dose-reduction on post-treatment neuropathy outcomes.

PATIENTS AND METHODS

Breast cancer patients receiving paclitaxel (80mg/m² ) weekly for 12-weeks were prospectively assessed using patient reported (Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity; FACTGOG-Ntx), clinical (Total Neuropathy Score clinical version; TNSc) and neurophysiological measures up to 12-months post completion. The impact of dose-reduction on post-treatment (3.6 ± 0.1 months) clinical and patient reported outcomes was evaluated in 105 weekly paclitaxel-treated patients.

RESULTS

Significant neuropathy was present by 6-weeks across patient-reported, clinical, and objective neurophysiological assessments, increasing in prevalence and severity over the treatment course. Limited recovery occurred, with significant neuropathy being maintained up to 12 months (p < .05). Patients who received dose reduction had worse patient reported (FACT-GOG-Ntx: 40.2 ± .1.4) and clinical neuropathy outcomes (TNSc: 4.3 ± 0.4) compared to those who received the full dose (FACT-GOG-Ntx: 45.9 ± 0.9; TNSc: 3.3 ± 0.3, p < .05). Patients who ceased treatment early demonstrated the worse deficits (TNSc: 5.0 ± 0.6; FACT-GOG-Ntx: 37.3 ± 2.7) compared to those who received the complete dose (TNSc: 3.5 ± 0.3; FACT-GOG-Ntx: 45.3 ± 0.9, p < .05).

CONCLUSION

Weekly paclitaxel produces symptomatic and objective neuropathy early in the treatment course which can persist. Dose reduction does not necessarily lead to more favorable neuropathy outcomes, with individual risk factors likely important in addition to cumulative dose.

IMPLICATIONS FOR PRACTICE

Weekly paclitaxel schedules are extensively used in breast cancer. Patients may develop symptomatic and objective neuropathy early in the treatment course, with these individuals requiring closer monitoring. Furthermore, neuropathy is a long-term sequela that may impact quality of life and require appropriate supportive services. Results suggest that dose reduction does not necessarily lead to better neuropathy outcomes. Understanding schedule-specific toxicity and risk factors for neuropathy will be critical to determining individualized treatment strategies and improving quality of life in breast cancer survivors.

Mechanisms of Nerve Damage in Neuropathies Associated with Hematological Diseases: Lesson from Nerve Biopsies

Despite the introduction of non-invasive techniques in the study of peripheral neuropathies, sural nerve biopsy remains the gold standard for the diagnosis of several neuropathies, including vasculitic neuropathy and neurolymphomatosis. Besides its diagnostic role, sural nerve biopsy has helped to shed light on the pathogenic mechanisms of different neuropathies. In the present review, we discuss how pathological findings helped understand the mechanisms of polyneuropathies complicating hematological diseases.

A Cross-Sectional Study of Sub-Basal Corneal Nerve Reduction Following Neurotoxic Chemotherapy

Purpose

Sub-basal corneal nerves have been shown to change during neurotoxic chemotherapy treatment. This cross-sectional study investigated corneal nerve morphology in patients who have completed neurotoxic chemotherapy well after treatment cessation and its association with peripheral nerve function.

Methods

Central corneal nerve fiber length (CNFL) and inferior whorl length (IWL), average nerve fiber length (ANFL), corneal nerve fiber density (CNFD) and corneal nerve branch density (CNBD), and nerve fiber area (CNFA) were examined using in vivo corneal confocal microscopy in patients with cancer who had completed treatment with either paclitaxel or oxaliplatin between 3 and 24 months prior to assessment in comparison with 2 separate groups of healthy controls. Neurological assessments were conducted including clinician- and patient-reported outcomes, and neurological grading scales.

Results

Both paclitaxel- (n = 40) and oxaliplatin-treated (n = 30) groups had reduced IWL and ANFL compared to the respective healthy control groups (n = 15 in each group) (paclitaxel: IWL = P = 0.02, ANFL = P = 0.009; and oxaliplatin: IWL = P = 0.008, ANFL P = 0.02). CNFL and CNFD reduction were observed only in the paclitaxel-treated group compared with healthy controls (P = 0.008 and P = 0.02, respectively), whereas CNFA was reduced in the oxaliplatin-treated group (P = 0.04). IWL reduction correlated with worse fine hand dexterity in chemotherapy-treated patients (r = −0.33, P = 0.007).

Conclusions

There is evidence of corneal nerve loss in patients with cancer who have been treated with paclitaxel and oxaliplatin well after treatment cessation associated with worse upper limb function.

Translational Relevance

Sub-basal corneal nerve reduction is evident even after cessation of neurotoxic treatment. In vivo corneal confocal microscopy may be useful in the monitoring of nerve function in patients receiving chemotherapy.

Impact of Cryotherapy on Sensory, Motor, and Autonomic Neuropathy in Breast Cancer Patients Receiving Paclitaxel: A Randomized, Controlled Trial

Introduction: We conducted a randomized controlled trial evaluating the efficacy and tolerability of cryotherapy in preventing chemotherapy-induced peripheral neuropathy (CIPN) in patients with early breast cancer receiving neo/adjuvant weekly paclitaxel.

Methods: Patients were recruited from the National Cancer Centre Singapore and randomized (1:1) to receive either cryotherapy or usual care. Cryotherapy was applied as frozen gloves and socks on all extremities from 15 min before paclitaxel until 15 min post-infusion every cycle. Efficacy was measured by patient-reported outcomes (Patient Neurotoxicity Questionnaire [PNQ] and EORTC QLQ-CIPN20) and electrophysiological assessments. The primary endpoint was PNQ severity at 2 weeks after 12 cycles of weekly paclitaxel.

Results: A total of 46 patients were recruited, of which 8 dropped out before paclitaxel treatment, leaving 38 evaluable. There was no significant difference in PNQ severity between cryotherapy and usual care at 2 weeks after paclitaxel treatment (sensory: p = 0.721; motor: p = 1.000). A benefit was observed at 3 months post-paclitaxel based on PNQ (sensory: 14.3 vs. 41.2%, p = 0.078; motor: 0 vs. 29.4%, p = 0.012) and CIPN20 (sensory: β = −3.6, 95%CI = −10.5–3.4, p = 0.308; motor: β = −7.3, 95%CI = −14.6–0, p = 0.051). Additionally, cryotherapy subjects have lower CIPN20 autonomic score (β = −5.84, 95%CI = −11.15 to −0.524, p = 0.031) and higher sympathetic skin response hand amplitudes (β = 0.544, 95%CI = 0.108–0.98, p = 0.014), suggesting possible autonomic benefits from cryotherapy. Temporary interruption with cryotherapy occurred in 80.9% of the subjects due to cold intolerance.

Conclusions: There is insufficient evidence that cryotherapy prevents sensory neuropathy which may be due to the high rates of cryotherapy interruption in this study. The autonomic benefits of cryotherapy should be further investigated with appropriate outcome measures.

Clinical Trial Registration:ClinicalTrials.gov: NCT03429972.

Oxaliplatin- and docetaxel-induced polyneuropathy: clinical and neurophysiological characteristics

The aim of this study was to evaluate the presence and characterization of chemotherapy-induced neuropathy (CIPN) and neuropathic pain 5 years after adjuvant chemotherapy with docetaxel or oxaliplatin. Patients from an ongoing prospective study, who had received adjuvant chemotherapy with docetaxel or oxaliplatin in 2011 to 2012 were invited to participate. The patients underwent a thorough examination with interview, neurological examination, questionnaires, assessment tools, nerve conduction studies (NCS), quantitative sensory testing, MScan motor unit number estimation (MUNE), and corneal confocal microscopy (CCM). Patients were divided into no, possible, probable, and confirmed CIPN. Out of the 132 eligible patients, 63 agreed to participate: 28 had received docetaxel and 35 had received oxaliplatin. Forty-one percent had confirmed CIPN, 34% possible or probable CIPN, and 22% did not have CIPN. The CIPN was characterized mainly by sensory nerve fiber loss, with a more pronounced large fiber than small fiber loss but also some motor fiber loss identified on NCS and MUNE. In general, patients had mild neuropathy with relatively low scores on assessment tools and no association with mood and quality of life. CCM was not useful as a diagnostic tool. Of the patients with probable or confirmed CIPN, 30% experienced pain, which was most often mild, but still interfered moderately with daily life in 20% to 25% and was associated with lower quality of life. In conclusion CIPN was confirmed in 41% 5 years after chemotherapy. The neuropathy was generally mild, but in patients with neuropathic pain it was associated with lower quality of life.

Evidence of Altered Peripheral Nerve Function in a Rodent Model of Diet-Induced Prediabetes

Peripheral neuropathy (PN) is a debilitating complication of diabetes that affects >50% of patients. Recent evidence suggests that obesity and metabolic disease, which often precede diabetes diagnosis, may influence PN onset and severity. We examined this in a translationally relevant model of prediabetes induced by a cafeteria (CAF) diet in Sprague–Dawley rats (n = 15 CAF versus n = 15 control). Neuropathy phenotyping included nerve conduction, tactile sensitivity, intraepidermal nerve fiber density (IENFD) and nerve excitability testing, an in vivo measure of ion channel function and membrane potential. Metabolic phenotyping included body composition, blood glucose and lipids, plasma hormones and inflammatory cytokines. After 13 weeks diet, CAF-fed rats demonstrated prediabetes with significantly elevated fasting blood glucose, insulin and impaired glucose tolerance as well as obesity and dyslipidemia. Nerve conduction, tactile sensitivity and IENFD did not differ; however, superexcitability was significantly increased in CAF-fed rats. Mathematical modeling demonstrated this was consistent with a reduction in sodium–potassium pump current. Moreover, superexcitability correlated positively with insulin resistance and adiposity, and negatively with fasting high-density lipoprotein cholesterol. In conclusion, prediabetic rats over-consuming processed, palatable foods demonstrated altered nerve function that preceded overt PN. This work provides a relevant model for pathophysiological investigation of diabetic complications.

Overview and critical revision of clinical assessment tools in chemotherapy-induced peripheral neurotoxicity

Chemotherapy-induced peripheral neurotoxicity (CIPN) is a major toxicity of cancer treatment, leading to dose reduction and premature treatment cessation, potentially affecting patient function, and quality of life. The development of accurate and sensitive assessment tools for CIPN is essential to enable clinical monitoring during treatment, follow-up of long-term outcomes and measurement of toxicity in clinical trials. This review examines CIPN clinical assessment scales incorporating clinician-based, composite, and patient-reported outcomes (PROs), providing a systematic review of their properties and an updated critical analysis of recommendations on current evidence for their use. This systematic review of CIPN assessment tools identified 50 papers containing 41 assessment tools, across 4 categories (common toxicity criteria; composite neurological scale; PROs; pain scale). The majority of these tools were PROs, underscoring the importance of patient-based assessment of symptoms. While there has been considerable work in the field over the past 10 years, this review highlights significant gaps, including a lack of evaluation of responsiveness and problematic neuropathic pain evaluation. There remains a need for consensus on the best available tool and the need to modify existing instruments to improve utility.

Electrophysiological and phenotypic profiles of taxane-induced neuropathy

OBJECTIVE

To comprehensively describe patient-reported, functional and neurophysiological outcomes to elucidate the phenotypic profile of taxane-induced neuropathy.

METHODS

Taxane-treated patients (n = 47) completed cross-sectional bilateral clinical and sensory assessments and nerve conduction studies. Patients reported symptom severity via Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity (FACT/GOG-Ntx13) questionnaire.

RESULTS

Symptoms of neuropathy were reported by 81% of patients. On clinical examination, 62% had 2 or more abnormalities, with 20% indicating significant symptomatic and objective neuropathy. Nerve conduction studies were consistent with a sensory predominant axonal neuropathy. However, features more typical of entrapment neuropathy were also present in > 50%, which were not associated with overall severity of chemotherapy-induced peripheral neuropathy (CIPN) or clinical risk factors.

CONCLUSIONS

There is considerable variation in CIPN phenotypes associated with taxane-treatment. Understanding their clinical associations may assist in identification of patients at risk of severe neurotoxicity. This would enable treatment modification decisions but also limit early cessation of effective anti-cancer treatment in patients with less severe neurological sequelae.

SIGNIFICANCE

Understanding the CIPN phenotype may inform treatment decisions which could impact clinical and survival outcomes.

An Experimental Swallow Evoked Potential Protocol to Investigate the Neural Substrates of Swallowing

Advancement in dysphagia intervention is hindered by our lack of understanding of the neural mechanisms of swallowing in health and disease. Evoking and understanding neural activity in response to normal and disordered swallowing is essential to bridge this knowledge gap. Building on sensory evoked potential methodology, we developed a minimally invasive approach to generate swallow evoked potentials (SwEPs) in response to repetitive swallowing induced by citric acid stimulation of the oropharynx in lightly anesthetized healthy adult rats. The SwEP waveform consisted of 8 replicable peaks within 10 milliseconds immediately preceding the onset of electromyographic swallowing activity. Methodology refinement is underway with healthy rats to establish normative SwEP waveform morphology before proceeding to models of advanced aging and age-related neurodegenerative diseases. Ultimately, we envision that this experimental protocol may unmask the pathologic neural substrates contributing to dysphagia to accelerate the discovery of targeted therapeutics.

Methods for in vivo studies in rodents of chemotherapy induced peripheral neuropathy

Peripheral neuropathy is one of the most common, dose limiting, and long-lasting disabling adverse events of chemotherapy treatment. Unfortunately, no treatment has proven efficacy to prevent this adverse effect in patients or improve the nerve regeneration, once it is established. Experimental models, particularly using rats and mice, are useful to investigate the mechanisms related to axonal or neuronal degeneration and target loss of function induced by neurotoxic drugs, as well as to test new strategies to prevent the development of neuropathy and to improve functional restitution. Therefore, objective and reliable methods should be applied for the assessment of function and innervation in adequately designed in vivo studies of CIPN, taking into account the impact of age, sex and species/strains features. This review gives an overview of the most useful methods to assess sensory, motor and autonomic functions, electrophysiological and morphological tests in rodent models of peripheral neuropathy, focused on CIPN. We include as well a proposal of protocols that may improve the quality and comparability of studies undertaken in different laboratories. It is recommended to apply more than one functional method for each type of function, and to perform parallel morphological studies in the same targets and models.

Pathogenesis of paclitaxel-induced peripheral neuropathy: A current review of in vitro and in vivo findings using rodent and human model systems

Paclitaxel (Brand name Taxol) is widely used in the treatment of common cancers like breast, ovarian and lung cancer. Although highly effective in blocking tumor progression, paclitaxel also causes peripheral neuropathy as a side effect in 60-70% of chemotherapy patients. Recent efforts by numerous labs have aimed at defining the underlying mechanisms of paclitaxel-induced peripheral neuropathy (PIPN). In vitro models using rodent dorsal root ganglion neurons, human induced pluripotent stem cells, and rodent in vivo models have revealed a number of molecular pathways affected by paclitaxel within axons of sensory neurons and within other cell types, such as the immune system and peripheral glia, as well skin. These studies revealed that paclitaxel induces altered calcium signaling, neuropeptide and growth factor release, mitochondrial damage and reactive oxygen species formation, and can activate ion channels that mediate responses to extracellular cues. Recent studies also suggest a role for the matrix-metalloproteinase 13 (MMP-13) in mediating neuropathy. These diverse changes may be secondary to paclitaxel-induced microtubule transport impairment. Human genetic studies, although still limited, also highlight the involvement of cytoskeletal changes in PIPN. Newly identified molecular targets resulting from these studies could provide the basis for the development of therapies with which to either prevent or reverse paclitaxel-induced peripheral neuropathy in chemotherapy patients.

Taxane-induced peripheral neuropathy: differences in patient report and objective assessment

PURPOSE

Chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting side-effect of neurotoxic cancer treatment impacting on long-term quality of life. Symptoms include numbness, tingling, and pain, affecting the distal extremities. However, patients often report symptoms discrepant from the expected symmetrical distribution and the degree of concurrence with objective assessment remains ill-defined. This study aimed to investigate severity and symmetry of neuropathy symptoms to enable comparison of objective measures and patient report.

METHODS

Forty-five taxane-treated patients (F = 43, 66 ± 1.5 years, 19 months post-treatment) completed bilateral neuropathy assessments via clinical examination, sensory nerve conduction studies (NCS), and patient questionnaires. The laterality index (LI) was calculated as a ratio of smaller to larger side-to-side differences.

RESULTS

Neuropathy was reported by 89% of the cohort. On clinical examination, 83% had ≥ 2 abnormalities, with 38-35% having upper or lower limb sensory amplitudes below normative range. Thirty-five percent indicated side-to-side symptom asymmetry; however, there was no significant asymmetry evident on clinical examination (LI Asym = .60 ± .10, Sym = .76 ± .05, NS) and no difference in side-to-side NCS (median LI:Asym = .69 ± .06, Sym = .81 ± .04, NS; Sural LI:Asym = .80 ± .04, Sym = .81 ± .04, NS). Accordingly, there was no statistical association between patient-reported and objective assessment of side-to-side asymmetry, suggesting discordance between patient experience and objective assessment. Similarly, discrepancies in symptom severity between hands and feet were reported by 32% of the cohort. However, patients reporting differences in symptom severity between the hands and feet were just as likely to present with comparable assessments as to demonstrate objective discrepancies.

CONCLUSIONS

Discrepancies may exist between the patient experience of CIPN and objective assessments. Understanding these discrepancies may help to elucidate underlying mechanisms and better inform treatment strategies.

Pathogenesis of platinum-induced peripheral neurotoxicity: Insights from preclinical studies

One of the most relevant dose-limiting adverse effects of platinum drugs is the development of a sensory peripheral neuropathy that highly impairs the patients' quality of life. Nowadays there are no available efficacy strategies for the treatment of platinum-induced peripheral neurotoxicity (PIPN), and the only way to prevent its development and progression is by reducing the dose of the cytostatic drug or even withdrawing the chemotherapy regimen. This clinical issue has been the main focus of hundreds of preclinical research works during recent decades. As a consequence, dozens of in vitro and in vivo models of PIPN have been developed to elucidate the molecular mechanisms involved in its development and to find neuroprotective targets. The apoptosis of peripheral neurons has been identified as the main mechanism involved in PIPN pathogenesis. This mechanism of DRG sensory neurons cell death is triggered by the nuclear and mitochondrial DNA platination together with the increase of the oxidative cellular status induced by the depletion of cytoplasmic antioxidant mechanisms. However, since there has been no successful transfer of preclinical results to clinical practise in terms of therapeutic approaches, some mechanisms of PIPN pathogenesis still remain to be elucidated. This review is focused on the pathogenic mechanisms underlying PIPN described up to now, provided by the critical analysis of in vitro and in vivo models.