Quantitative assessment of diabetic amyotrophy using magnetic resonance neurography-a case-control analysis

Focal inflammatory neuropathies

This chapter focuses on neuropathies that present with focal involvement of nerve roots, plexus, and/or peripheral nerves associated with autoimmune and inflammatory mechanisms that present with focal involvement of nerve roots, plexus and/or peripheral nerves. The clinical presentation, diagnosis, and treatment of focal autoimmune demyelinating neuropathies, focal nonsystemic vasculitic disorders (diabetic and nondiabetic radiculoplexus neuropathies, postsurgical inflammatory neuropathy, and neuralgic amyotrophy), and focal neuropathies associated with sarcoidosis and bacterial and viral infections are reviewed.

The role of imaging in focal neuropathies

Electrodiagnostic testing (EDX) has been the diagnostic tool of choice in peripheral nerve disease for many years, but in recent years, peripheral nerve imaging has been used ever more frequently in daily clinical practice. Nerve ultrasound and magnetic resonance (MR) neurography are able to visualize nerve structures reliably. These techniques can aid in localizing nerve pathology and can reveal significant anatomical abnormalities underlying nerve pathology that may have been otherwise undetected by EDX. As such, nerve ultrasound and MR neurography can significantly improve diagnostic accuracy and can have a significant effect on treatment strategy. In this chapter, the basic principles and recent developments of these techniques will be discussed, as well as their potential application in several types of peripheral nerve disease, such as carpal tunnel syndrome (CTS), ulnar neuropathy at the elbow (UNE), radial neuropathy, brachial and lumbosacral plexopathy, neuralgic amyotrophy (NA), fibular, tibial, sciatic, femoral neuropathy, meralgia paresthetica, peripheral nerve trauma, tumors, and inflammatory neuropathies.

Diabetic Neuropathies

OBJECTIVE

This article provides an up-to-date review of the diagnosis and management of the most common neuropathies that occur in patients with diabetes.

LATEST DEVELOPMENTS

The prevalence of diabetes continues to grow worldwide and, as a result, the burden of diabetic neuropathies is also increasing. Most diabetic neuropathies are caused by hyperglycemic effects on small and large fiber nerves, and glycemic control in individuals with type 1 diabetes reduces neuropathy prevalence. However, among people with type 2 diabetes, additional factors, particularly metabolic syndrome components, play a role and should be addressed. Although length-dependent distal symmetric polyneuropathy is the most common form of neuropathy, autonomic syndromes, particularly cardiovascular autonomic neuropathy, are associated with increased mortality, whereas lumbosacral radiculoplexus neuropathy and treatment-induced neuropathy cause substantial morbidity. Recent evidence-based guidelines have updated the recommended treatment options to manage pain associated with distal symmetric polyneuropathy of diabetes.

ESSENTIAL POINTS

Identifying and appropriately diagnosing the neuropathies of diabetes is key to preventing progression. Until better disease-modifying therapies are identified, management remains focused on diabetes and metabolic risk factor control and pain management.

Characterizing conventional ankle MRI findings of nerve and muscle changes in diabetic patients: a case-control study

BACKGROUND

Foot and ankle amputation is a feared complication of diabetic neuropathy and diabetes mellitus (DM) accounts for 80% of all in-hospital amputations. Magnetic resonance neurography is an effective tool in characterizing neuromuscular sequelae of the disease. However, conventional ankle MRI is more commonly performed and has not been studied to assess neuromuscular changes of DM.

OBJECTIVE

The objective is to characterize neuromuscular changes of diabetic patients in a case-control study using conventional ankle MRI.

METHODS

Between November 2019 and July 2021, 110 consecutive ankle MRI scans (n = 102 patients) at our county hospital were reviewed and met the inclusion criteria. Patients were divided into two cohorts, diabetic (N = 63) and non-diabetic (N = 39). Demographics, HgbA1c, and reason for MRI study were collected via retrospective chart review. The presence of intramuscular edema-like signal, pattern of the edema, muscle fatty infiltration, and measurements of the cross-sectional area of the posterior, medial, and lateral tibial nerves (PTN, MPN, and LPN) was recorded blinded to the clinical findings by two readers.

RESULTS

Muscle edema-like signal was much more likely to be found in DM (odds ratio 19.5, 95% CI 7.0-54.6, p < 0.001). DM also showed increase of 0.87 in the mean grade of muscle fatty infiltration (p < 0.001). There were higher rates of nerve T2 hyperintensity (odds ratio 14.0, 95% CI 3.1-62.7, p < 0.001) and the measured areas of the PTN, MPN, and LPN were also larger in DM compared to their non-diabetic counterparts (PTN: 0.16 cm² vs. 0.10 cm², p < 0.01; MPN: 0.09 cm² vs. 0.05 cm², p < 0.01; LPN: 0.07 cm² vs. 0.04 cm², p < 0.05).

CONCLUSION

Conventional ankle MRIs can be used to detect DM-related neuromuscular changes.

Autoimmune polyneuropathies

The autoimmune peripheral neuropathies with prominent motor manifestations are a diverse collection of unusual peripheral neuropathies that are appreciated in vast clinical settings. This chapter highlights the most common immune-mediated, motor predominant neuropathies excluding acute, and chronic inflammatory demyelinating polyradiculoneuropathy (AIDP and CIDP, respectively). Other acquired demyelinating neuropathies such as distal CIDP and multifocal motor neuropathy will be covered. Additionally, the radiculoplexus neuropathies, resulting from microvasculitis-induced injury to nerve roots, plexuses, and nerves, including diabetic and nondiabetic lumbosacral radiculoplexus neuropathy and neuralgic amyotrophy (i.e., Parsonage-Turner syndrome), will be included. Finally, the motor predominant peripheral neuropathies encountered in association with rheumatological disease, particularly Sjögren's syndrome and rheumatoid arthritis, are covered. Early recognition of these distinct motor predominant autoimmune neuropathies and initiation of immunomodulatory and immunosuppressant treatment likely result in improved outcomes.

Magnetic resonance neurography: is it so complicated that it needs a touch of genius?

KEY POINTS

• Neuropathy imaging is not that complicated or illusive that it needs a touch of genius.• By gaining MR imaging expertise of peripheral nerve lesions and using knowledge of common clinical patterns and diseases, general radiology practitioners can prudently participate in the multidisciplinary care for appropriate and timely management of peripheral neuropathy patients.

Rare diabetic neuropathies: It is not only distal symmetrical polyneuropathy

The prevalence of diabetes mellitus is increasing at an epidemic level, leading to a consequent increase of its chronic complications, including neuropathy. Diabetic neuropathy constitutes a heterogeneous group of disorders with distinct clinical presentations and pathophysiological mechanisms. These distinct forms may be categorised according to their clinical presentation as symmetrical (distal symmetrical polyneuropathy, autonomic and acute sensory neuropathy) and focal or multifocal (radiculoplexus neuropathies, entrapment syndromes, cranial palsies and other mononeuropathies). Additionally, people with diabetes may have neuropathies due to causes other than diabetes. The commonest forms of diabetic neuropathy are distal symmetrical polyneuropathy and autonomic neuropathy. However, clinicians should be aware that people with diabetes may suffer from less common forms of neuropathy and should be able to recognise their symptoms and signs. The recognition of the rare diabetic neuropathies is crucial, as they often lead to different clinical outcomes and require different management. The aim of the present narrative, non-systematic review is to outline the rare types of diabetic neuropathies.

Lumbosacral Radiculoplexus Neuropathy: Neurologic Outcomes and Survival in a Population-Based Study

OBJECTIVE

To determine whether patients in the community with lumbosacral radiculoplexus neuropathy (LRPN) have milder neuropathy than referral patients, we characterized the outcomes and survival of population-based compared to referral-based LRPN cohorts.

BACKGROUND

Previously, we found that the incidence of LRPN is 4.16/100,000/y, a frequency greater than other inflammatory neuropathies. The survival of patients with LRPN is uncharacterized.

METHODS

Sixty-two episodes in 59 patients with LRPN were identified over 16 years (2000-2015). Clinical findings were compared to previous referral-based LRPN cohorts. Survival data were compared to those of age- and sex-matched controls.

RESULTS

At LRPN diagnosis, median age was 70 years, median Neuropathy Impairment Score (NIS) 22 points, 92% had pain, 95% had weakness, 23% were wheelchair-bound, and median modified Rankin Scale score (mRS) was 3 (range 1-4). At last follow-up, median NIS improved to 17 points (p < 0.001) with 56% having ≥4 points improvement, 16% were wheelchair-bound, and median mRS was 2. Compared to referral-based LRPN cohorts, community patients with LRPN had less impairment, less bilateral disease (37% vs 92%), and less wheelchair usage (23% vs 49%). LRPN survival was 86% at 5 years and 55% at 10 years. Compared to age- and sex-matched controls, patients with LRPN had 76% increased risk of death (p = 0.016). In multivariate analysis, diabetes, age, stroke, chronic kidney disease, peripheral artery disease, and coronary artery disease were significant mortality risk factors but LRPN was not.

CONCLUSION

LRPN is a painful, paralytic, asymmetric, monophasic, sometimes bilateral pan-plexopathy that improves over time but leaves patients with impairment. Although having LRPN increases mortality, this increase is probably due to comorbidities (diabetes) rather than LRPN itself.

Application of High-Resolution Ultrasound on Diagnosing Diabetic Peripheral Neuropathy

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes mellitus (DM). The typical manifestation is a length-dependent "glove and sock" sensation. At present, diagnosis is mainly dependent on clinical manifestations. Since the pathogenesis is not clear, there are no effective treatment measures. Management consists mainly of glucose control, peripheral nerve nutrition, and other measures to delay the progress of the disease; early diagnosis is therefore crucial to improving prognosis and quality of life for patients with DPN. Due to the lack of obvious symptoms in 50% of patients and the low sensitivity of neuro-electrophysiology to small fibers, the missed diagnosis rate is high. High-resolution ultrasound (HRU), as a convenient noninvasive tool, has been proven by many studies to have excellent clinical value in diagnosing DPN. With the development of related new technology, HRU shows promise for the screening, diagnosing, and follow-up of DPN, which could serve as a biomarker and provide new diagnostic insights. In this paper, we review the ability of HRU to detect nerve cross-sectional area and blood flow, and echo and other image changes, and in showing the characteristics of peripheral nerve morphological changes in patients with DPN. We also explore the application of two other recent technological developments-shear wave elastography (SWE) and ultrasound scoring systems-in improving the diagnostic efficiency of HRU in peripheral neuropathy.

Diabetic Lumbosacral Radiculoplexus Neuropathy (Diabetic Amyotrophy)

Diabetic lumbosacral radiculoplexus neuropathy, also known as diabetic amyotrophy, has a characteristic course of sudden onset of unilateral pain in the thigh and hip, which may spread to the other side in weeks to months and proceeds with progressive lower extremity weakness, often resulting in the inability to walk unassisted. The syndrome is typically monophasic, and most patients will recover at least to some degree. Less typical features include lack of pain, distal predominant weakness, absence of diabetes, and upper extremity involvement. This article provides a series of interesting cases to highlight the diagnostic challenges and discusses management decision making.

Update on classification, epidemiology, clinical phenotype and imaging of the nonsystemic vasculitic neuropathies

PURPOSE OF REVIEW

Single-organ vasculitis of the peripheral nervous system (PNS) is often designated nonsystemic vasculitic neuropathy (NSVN). Several variants or subtypes have been distinguished, including migratory sensory neuropathy, postsurgical inflammatory neuropathy, diabetic radiculoplexus neuropathies, skin-nerve vasculitides, and, arguably, neuralgic amyotrophy. NSVN often presents as nondiabetic lumbosacral radiculoplexus neuropathy (LRPN). This review updates classification, clinical features, epidemiology, and imaging of these disorders.

RECENT FINDINGS

A recent study showed the annual incidence of LRPN in Olmstead County, Minnesota to be 4.16/100 000:2.79/100 000 diabetic and 1.27/100 000 nondiabetic. This study was the first to determine the incidence or prevalence of any vasculitic neuropathy. In NSVN, ultrasonography shows multifocal enlargement of proximal and distal nerves. In neuralgic amyotrophy, MRI and ultrasound reveal multifocal enlargements and focal constrictions in nerves derived from the brachial plexus. Histopathology of these chronic lesions shows inflammation and rare vasculitis. Diffusion tensor imaging of tibial nerves in NSVN revealed decreased fractional anisotropy in one study.

SUMMARY

Single-organ PNS vasculitides are the most common inflammatory neuropathies. Neuralgic amyotrophy might result from PNS vasculitis, but further study is necessary. The usefulness of focal nerve enlargements or constrictions in understanding pathological mechanisms, directing biopsies, and monitoring disease activity in NSVN should be further investigated.

[Polyneuropathies in vasculitis and connective tissue diseases : Clinical manifestations and diagnostic recommendations]

Vasculitic neuropathies result from inflammation of the vasa nervorum followed by ischemia and destruction of the peripheral nerve. The inflammation can be systemic or localized, i.e. non-systemic. Systemic vasculitis can be divided into primary and secondary forms. The latter is associated with, e.g. connective tissue diseases, infections, cancer or induced by certain drugs. Around two thirds of patients with systemic vasculitis develop vasculitic neuropathy presenting as characteristic painful, multifocal mononeuropathy of acute onset. The group of non-systemic neuropathies has grown in recent years with the addition of diabetic and non-diabetic lumbosacral radiculoplexus neuropathies, among others. Within the group of connective tissue diseases, other non-vasculitic neuropathies can occur as nerve-entrapment syndromes and sensory ataxic neuropathy. The aim of this article is to present a condensed overview of neuropathies associated with vasculitis and connective tissue diseases and to communicate characteristic clinical symptoms supporting rapid diagnostic and therapeutic procedures.