A Systematic Review of the Diagnostic Methods of Small Fiber Neuropathies in Rehabilitation

Patient Outcomes After Peripheral Nerve Injury Depend on Bimanual Dexterity and Preserved Use of the Affected Hand

BACKGROUND

Little is known about how peripheral nerve injury affects human performance, behavior, and life. Hand use choices are important for rehabilitation after unilateral impairment, but rarely measured, and are not changed by the normal course of rehabilitation and daily life.

OBJECTIVE

To identify the relationship between hand use (L/R choices), motor performance, and patient-centered outcomes.

METHODS

Participants (n = 48) with unilateral peripheral nerve injury were assessed for hand use via Block Building Task, Motor Activity Log, and Edinburgh Handedness Inventory; dexterity (separately for each hand) via Nine-Hole Peg Test, Jebsen Taylor Hand Function Test, and a precision drawing task; patient-centered outcomes via surveys of disability, activity participation, and health-related quality of life; and injury-related factors including injury cause and affected nerve. Factor Analysis of Mixed Data was used to explore relationships between these variables. The data were analyzed under 2 approaches: comparing dominant hand (DH) versus non-dominant hand (NH), or affected versus unaffected hand.

RESULTS

The data were best explained by 5 dimensions. Good patient outcomes were associated with NH performance, DH performance (separately and secondarily to NH performance), and preserved function and use of the affected hand; whereas poor patient outcomes were associated with preserved but unused function of the affected hand.

CONCLUSION

After unilateral peripheral nerve injury, hand function, hand usage, and patient life arise from a complex interaction of many factors. To optimize rehabilitation after unilateral impairment, new rehabilitation methods are needed to promote performance and use with the NH, as well as the injured hand.

Exercise intervention for the management of chemotherapy-induced peripheral neuropathy: a systematic review and network meta-analysis

Purpose

Although exercise is recommended for cancer survivors with chemotherapy-induced peripheral neuropathy (CIPN), the effective types of exercise for preventing and treating CIPN remain unclear. This systematic review and network meta-analysis (NMA) aimed to evaluate the comparative effects of exercise on CIPN.

Methods

We included relevant randomized controlled trials (RCTs) identified in a 2019 systematic review that evaluated the effects of exercise on CIPN and conducted an additional search for RCTs published until 2023. We evaluated the risk of bias for each RCT; the comparative effectiveness of exercise on patient-reported quality of life (QOL) through an NMA; and the effectiveness of exercise on QOL scores, patient-reported CIPN symptoms, and pain through additional meta-analyses.

Results

Twelve studies (exercise, n = 540; control, n = 527) comparing 8 exercise interventions were included in the analysis. All studies were determined to have a high risk of bias. The meta-analyses showed significantly improved QOL [standard mean differences (SMD) 0.45; 95% confidence interval (CI) = 0.12 to 0.78] and CIPN symptoms (SMD 0.46; 95% CI = 0.11 to 0.82). No severe adverse events were reported. Pain tended to improve with exercise (SMD 0.84; 95% CI = -0.11 to 1.80). An NMA suggested that the interventions of a combination of balance and strength training showed a significant improvement in QOL scores compared to the control.

Conclusion

Exercise interventions may be beneficial for improving QOL and CIPN symptoms. High-quality large clinical trials and data are needed to conclude that exercise is beneficial and safe.

Netazepide, an Antagonist of Cholecystokinin Type 2 Receptor, Prevents Vincristine-Induced Sensory Neuropathy in Mice

Among the vinca-alkaloid class, vincristine is a potent chemotherapeutic agent with significant neurotoxic effects and is employed to address a wide spectrum of cancer types. Recently, the therapeutic potential of the cholecystokinin type 2 receptor (CCK2R) as a target for vincristine-induced peripheral neuropathy (VIPN) was demonstrated. In this study, the impact of preventive CCK2R blockade using netazepide (Trio Medicines Ltd., London, UK) was investigated in a mouse model of vincristine-induced peripheral neuropathy. Netazepide is a highly selective CCK2R antagonist under development for the treatment of patients with gastric neuroendocrine tumors caused by hypergastrinemia secondary to chronic autoimmune atrophic gastritis. Vincristine-induced peripheral neuropathy was induced by intraperitoneal injections of vincristine at 100 µg/kg/d for 7 days (D0 to D7). Netazepide (2 mg/kg/d or 5 mg/kg/d, per os) was administered one day before vincristine treatment until D7. Vincristine induced a high tactile allodynia from D1 to D7. VIPN was characterized by dorsal root ganglion neuron (DRG) and intraepidermal nerve fiber (IENF) loss, and enlargement and loss of myelinated axons in the sciatic nerve. Netazepide completely prevented the painful symptoms and nerve injuries induced by vincristine. In conclusion, the fact that netazepide protected against vincristine-induced peripheral neuropathy in a mouse model strongly supports the assessment of its therapeutic potential in patients receiving such chemotherapy.

Sudomotor dysfunction in diabetic peripheral neuropathy (DPN) and its testing modalities: A literature review

Long term consequences of diabetes mellitus (DM) may include multi-organ complications such as retinopathy, cardiovascular disease, neuronal, and kidney damage. One of the most prevalent complication is diabetic peripheral neuropathy (DPN), occurring in half of all diabetics, and is the main cause of disability globally with profound impact on a patient's quality of life. Small fiber neuropathy (SFN) can develop in the pre-diabetes stage preceding large fiber damage in DPN. Asymptomatic SFN is difficult to diagnose in early stages, with sudomotor dysfunction considered one of the earliest manifestations of autonomic neuropathy. Early detection is crucial as it can prevent potential cardiovascular events. Although punch skin biopsy is the gold-standard method for SFN diagnosis, implementation as routine screening is hindered due to its invasive, impractical, and time-consuming nature. Other sudomotor testing modalities, most of which evaluate the postganglionic cholinergic sympathetic nervous system, have been developed with varying sensitivity and specificity for SFN diagnosis. Here, we provide an overview on the general mechanism of DPN, the importance of sudomotor assessment for early detection of autonomic dysfunction in DPN, the benefits and disadvantages of current testing modalities, factors that may affect testing, and the importance of future discoveries on sudomotor testing for successful DPN diagnosis.

Assessment of intraepidermal nerve fiber density and neurophysiological studies in patients with idiopathic polyneuropathy

Background

Idiopathic polyneuropathy is an asymmetrical, length-dependent neuropathy in which neurophysiology demonstrates axonal damage involving large fibers, along with insidious onset and slow progression over 6 months, with no identified etiology in spite of thorough investigations. This study aimed to evaluate the diagnostic role of clinical, electrophysiological, and histopathological studies in patients with idiopathic polyneuropathy.

Methods

Case–control study included 20 patients with clinical and neurophysiological evidence of sensory or sensory–motor neuropathy with no apparent etiology after laboratory investigation were recruited from 127 patients with sensory–motor neuropathy of unknown etiology (the patients group). Twenty apparently healthy individuals, age- and sex-matched, with no neuropathy symptoms (the control group), were recruited from the Neurology Clinic of Al-Azhar University, Assuit.

Results

Age of onset of patients with idiopathic polyneuropathy (44–70) years, duration of illness (1–6) years, 60% had painful neuropathy, diagnostic neuropathic pain questioner (DN4 score) (5–7), abnormal pin brick (80%), abnormal vibration (90%), abnormal fine touch (75%), distal weakness (70%), and lost ankle reflex (90%). In the control group, there were substantial differences with respect to prolonged latency, diminished sympathetic skin response amplitude, and significant intraepidermal nerve fiber density reduction in skin biopsy cases. In diagnosing idiopathic polyneuropathy, the specificity and sensitivity of sympathetic skin response were (80–86)% and (81–89.5)%, respectively, whereas those of diminished intraepidermal nerve fiber density were (92.5%) and (97.5%), respectively.

Conclusion

The assessment of intraepidermal nerve fiber density had an important good diagnostic role in cases presented with polyneuropathy.

DTI and MTR Measures of Nerve Fiber Integrity in Pediatric Patients With Ankle Injury

Acute peripheral nerve injury can lead to chronic neuropathic pain. Having a standardized, non-invasive method to evaluate pathological changes in a nerve following nerve injury would help with diagnostic and therapeutic assessments or interventions. The accurate evaluation of nerve fiber integrity after injury may provide insight into the extent of pathology and a patient's level of self-reported pain. The aim of this investigation was to evaluate the extent to which peripheral nerve integrity could be evaluated in an acute ankle injury cohort and how markers of nerve fiber integrity correlate with self-reported pain levels in afferent nerves. We recruited 39 pediatric participants with clinically defined neuropathic pain within 3 months of an ankle injury and 16 healthy controls. Participants underwent peripheral nerve MRI using diffusion tensor (DTI) and magnetization transfer imaging (MTI) of their injured and non-injured ankles. The imaging window was focused on the branching point of the sciatic nerve into the tibial and fibular division. Each participant completed the Pain Detection Questionnaire (PDQ). Findings demonstrated group differences in DTI and MTI in the sciatic, tibial and fibular nerve in the injured ankle relative to healthy control and contralateral non-injured nerve fibers. Only AD and RD from the injured fibular nerve correlated with PDQ scores which coincides with the inversion-dominant nature of this particular ankle injuruy cohort. Exploratory analyses highlight the potential remodeling stages of nerve injury from neuropathic pain. Future research should emphasize sub-acute time frames of injury to capture post-injury inflammation and nerve fiber recovery.

Intraepidermal Nerve Fiber Density as Measured by Skin Punch Biopsy as a Marker for Small Fiber Neuropathy: Application in Patients with Fibromyalgia

Small fiber neuropathy (SFN) is a type of peripheral neuropathy that occurs from damage to the small A-delta and C nerve fibers that results in the clinical condition known as SFN. This pathology may be the result of metabolic, toxic, immune-mediated, and/or genetic factors. Small fiber symptoms can be variable and inconsistent and therefore require an objective biomarker confirmation. Small fiber dysfunction is not typically captured by diagnostic tests for large-fiber neuropathy (nerve conduction and electromyographic study). Therefore, skin biopsies stained with PGP 9.5 are the universally recommended objective test for SFN, with quantitative sensory tests, autonomic function testing, and corneal confocal imaging as secondary or adjunctive choices. Fibromyalgia (FM) is a heterogenous syndrome that has many symptoms that overlap with those found in SFN. A growing body of research has shown approximately 40-60% of patients carrying a diagnosis of FM have evidence of SFN on skin punch biopsy. There is currently no clearly defined phenotype in FM at this time to suggest whom may or may not have SFN, though research suggests it may correlate with severe cases. The skin punch biopsy provides an objective tool for use in quantifying small fiber pathology in FM. Skin punch biopsy may also be repeated for surveillance of the disease as well as measuring response to treatments. Evaluation of SFN in FM allows for better classification of FM and guidance for patient care as well as validation for their symptoms, leading to better use of resources and outcomes.

Peripheral Neuropathy under Oncologic Therapies: A Literature Review on Pathogenetic Mechanisms

Peripheral neurologic complications are frequent adverse events during oncologic treatments and often lead to dose reduction, administration delays with time elongation of the therapeutic plan and, not least, worsening of patients’ quality of life. Experience skills are required to recognize symptoms and clinical evidences and the collaboration between different health professionals, in particular oncologists and hospital pharmacists, grants a correct management of this undesirable occurrence. Some classes of drugs (platinates, vinca alkaloids, taxanes) typically develop this kind of side effect, but the genesis of chemotherapy-induced peripheral neuropathy is not linked to a single mechanism. This paper aims from one side at summarizing and explaining all the scattering mechanisms of chemotherapy-induced peripheral neuropathy through a detailed literature revision, on the other side at finding new approaches to possible treatments, in order to facilitate the collaboration between oncologists, hematologists and hospital pharmacists.

Contribution of Skin Biopsy in Peripheral Neuropathies

In the last three decades the study of cutaneous innervation through 3 mm-punch-biopsy has provided an important contribution to the knowledge of small fiber somatic and autonomic neuropathies but also of large fiber neuropathies. Skin biopsy is a minimally invasive technique with the advantage, compared to sural nerve biopsy, of being suitable to be applied to any site in our body, of being repeatable over time, of allowing the identification of each population of nerve fiber through its target. In patients with symptoms and signs of small fiber neuropathy the assessment of IntraEpidermal Nerve Fiber density is the gold standard to confirm the diagnosis while the quantification of sudomotor, pilomotor, and vasomotor nerve fibers allows to evaluate and characterize the autonomic involvement. All these parameters can be re-evaluated over time to monitor the disease process and to evaluate the effectiveness of the treatments. Myelinated fibers and their receptors can also be evaluated to detect a “dying back” neuropathy early when nerve conduction study is still normal. Furthermore, the morphometry of dermal myelinated fibers has provided new insight into pathophysiological mechanisms of different types of inherited and acquired large fibers neuropathies. In genetic neuropathies skin biopsy has become a surrogate for sural nerve biopsy, no longer necessary in the diagnostic process, to study genotype–phenotype correlations.

A Systematic Review of Pharmacologic and Rehabilitative Treatment of Small Fiber Neuropathies

The aim of this systematic review is to guide the physician in defining the pharmacologic and rehabilitative therapeutic approaches for adopting the best strategies described in the current literature. The search was conducted in PubMed, EMBASE, Cochrane Library and Web of Science to identify the treatment of small fiber neuropathies. Two reviewers independently reviewed and came to a consensus on which articles met inclusion/exclusion criteria. The authors excluded the duplicates, animal studies and included the English articles in which the treatment of patients with small fiber neuropathies was described. The search identified a total of 975 articles with the keywords “small fiber neuropathy” AND “rehabilitation” OR “therapy” OR “treatment”. Seventy-eight selected full-text were analyzed by the reviewers. Forty-two publications met the inclusion criteria and were included in the systematic review to describe the rehabilitative and pharmacologic treatment of small fiber neuropathies. Despite the range of different protocols of treatment for small fiber neuropathy, other robust trials are needed. In addition, always different therapeutic approaches are used; a unique protocol could be important for the clinicians. More research is needed to build evidence for the best strategy and to delineate a definitive therapeutic protocol.