Sonographic and electrodiagnostic features of hereditary neuropathy with liability to pressure palsies

Neuromuscular Ultrasound in Polyneuropathies

Neuromuscular ultrasound is a painless, radiation-free, high-resolution imaging technique for assessing the peripheral nervous system. It can accurately depict changes in the nerves and muscles of individuals with neuromuscular conditions, and it is therefore a robust diagnostic tool for the assessment of individuals with polyneuropathies. This review will outline the typical ultrasonographic changes found in a wide variety of polyneuropathies. In general, demyelinating conditions result in greater nerve enlargement than axonal conditions, and acquired conditions result in more patchy nerve enlargement compared to diffuse nerve enlargement in hereditary conditions. This review is data-driven, but more nuanced anecdotal findings are also described. The overall goal of this paper is to provide clinicians with an accessible review of the ultrasonographic approaches and findings in a wide variety of polyneuropathies.

Hereditary neuropathy associated with liability to pressure palsies: a 24-year experience with carpal and cubital tunnel surgery

The aim of this single-centre retrospective study was to evaluate the outcomes of carpal tunnel release surgery in patients with hereditary neuropathy with pressure palsies (HNPP). The secondary aims were to identify prognostic factors for the outcome of carpal tunnel release and to assess the outcome of cubital tunnel release. Our primary hypothesis was postoperative improvement. In total, 18 patients (26 carpal tunnel releases) with at least one symptomatic carpal tunnel syndrome were included. At a median follow-up of 8.5 years, more than 73% of the patients were satisfied with the results. The visual analogue scale (0 to 10) for discomfort decreased by 2.2 points (p < 0.001). The Boston Carpal Tunnel Questionnaire symptom severity scale decreased by 1.3 points (p < 0.001). The decrease in the Functional Status Scale was not significant. No significant prognostic factor for outcome was identified. A total of 12 patients also underwent cubital tunnel release, and three patients underwent just this procedure (23 procedures). Despite the lack of preoperative data, cubital tunnel release provided encouraging results. Level of evidence: III.

Application and Research Progress of High Frequency Ultrasound in the Diagnosis of Chronic Inflammatory Neuropathies

In recent years, clinicians have gradually improved their understanding of multiple neuropathy and have done some studies about chronic inflammatory neuropathies, for example, chronic inflammatory demyelinating polyneuropathy, multifocal motor neuropathy, and Lewis-Sumne syndrome. The early diagnosis is very important for the next step treatment and long-term prognosis. At present, the disease mainly depends on clinical and neural electrophysiological examination, but imaging studies are few. In recent years, with the rapid development of high frequency ultrasound, it could clearly show the morphology of the nerve, and it has been an emerging diagnosis tool of polyneuropathies. This article mainly reviews the application and the latest research progress of high frequency ultrasound in these diseases.

Review Article "Spotlight on Ultrasonography in the Diagnosis of Peripheral Nerve Disease: The Evidence to Date"

Neuromuscular ultrasound is rapidly becoming incorporated into clinical practice as a standard tool in the assessment of peripheral nerve diseases. Ultrasound complements clinical phenotyping and electrodiagnostic evaluation, providing critical structural anatomical information to enhance diagnosis and identify structural pathology. This review article examines the evidence supporting neuromuscular ultrasound in the diagnosis of compressive mononeuropathies, traumatic nerve injury, generalised peripheral neuropathy and motor neuron disease. Extending the sonographic evaluation of nerves beyond simple morphological measurements has the potential to improve diagnostics in peripheral neuropathy, as well as advancing the understanding of pathological mechanisms, which in turn will promote precise therapies and improve therapeutic outcomes.

Nerve Ultrasound as Helpful Tool in Polyneuropathies

Background: Polyneuropathies (PNP) are a broad field of diseases affecting millions of people. While the symptoms presented are mostly similar, underlying causes are abundant. Thus, early identification of treatable causes is often difficult. Besides clinical data and basic laboratory findings, nerve conduction studies are crucial for etiological classification, yet limited. Besides Magnetic Resonance Imaging (MRI), high-resolution nerve ultrasound (HRUS) has become a noninvasive, fast, economic and available tool to help distinguish different types of nerve alterations in neuropathies. Methods: We aim to describe typical ultrasound findings in PNP and patterns of morphological changes in hereditary, immune-mediated, diabetic, metabolic and neurodegenerative PNP. Literature research was performed in PubMed using the terms ‘nerve ultrasound’, neuromuscular ultrasound, high-resolution nerve ultrasound, peripheral nerves, nerve enlargement, demyelinating, hereditary, polyneuropathies, hypertrophy’. Results: Plenty of studies over the past 20 years investigated the value of nerve ultrasound in different neuropathies. Next to nerve enlargement, patterns of nerve enlargement, echointensity, vascularization and elastography have been evaluated for diagnostic terms. Furthermore, different scores have been developed to distinguish different etiologies of PNP. Conclusions: Where morphological alterations of the nerves reflect underlying pathologies, early nerve ultrasound might enable a timely start of available treatment and also facilitate follow up of therapy success.

New evidence for secondary axonal degeneration in demyelinating neuropathies

Development of peripheral nervous system (PNS) myelin involves a coordinated series of events between growing axons and the Schwann cell (SC) progenitors that will eventually ensheath them. Myelin sheaths have evolved out of necessity to maintain rapid impulse propagation while accounting for body space constraints. However, myelinating SCs perform additional critical functions that are required to preserve axonal integrity including mitigating energy consumption by establishing the nodal architecture, regulating axon caliber by organizing axonal cytoskeleton networks, providing trophic and potentially metabolic support, possibly supplying genetic translation materials and protecting axons from toxic insults. The intermediate steps between the loss of these functions and the initiation of axon degeneration are unknown but the importance of these processes provides insightful clues. Prevalent demyelinating diseases of the PNS include the inherited neuropathies Charcot-Marie-Tooth Disease, Type 1 (CMT1) and Hereditary Neuropathy with Liability to Pressure Palsies (HNPP) and the inflammatory diseases Acute Inflammatory Demyelinating Polyneuropathy (AIDP) and Chronic Inflammatory Demyelinating Polyneuropathy (CIDP). Secondary axon degeneration is a common feature of demyelinating neuropathies and this process is often correlated with clinical deficits and long-lasting disability in patients. There is abundant electrophysiological and histological evidence for secondary axon degeneration in patients and rodent models of PNS demyelinating diseases. Fully understanding the involvement of secondary axon degeneration in these diseases is essential for expanding our knowledge of disease pathogenesis and prognosis, which will be essential for developing novel therapeutic strategies.

Nerve ultrasound in hereditary transthyretin amyloidosis: red flags and possible progression biomarkers

Background

Diagnostic delay of hereditary transthyretin amyloidosis (ATTRv, v for variant) prevents timely treatment and, therefore, concurs to the mortality of the disease. The aim of the present study was to explore with nerve ultrasound (US) possible red flags for early diagnosis in ATTRv patients with carpal tunnel syndrome (CTS) and/or polyneuropathy and in pre-symptomatic carriers.

Methods

Patients and pre-symptomatic carriers with a TTR gene mutation were enrolled from seven Italian centers. Severity of CTS was assessed with neurophysiology and clinical evaluation. Median nerve cross-section area (CSA) was measured with US in ATTRv carriers with CTS (TTR-CTS). One thousand one hundred ninety-six idiopathic CTS were used as controls. Nerve US was also performed in several nerve trunks (median, ulnar, radial, brachial plexi, tibial, peroneal, sciatic, sural) in ATTRv patients with polyneuropathy and in pre-symptomatic carriers.

Results

Sixty-two subjects (34 men, 28 women, mean age 59.8 years ± 12) with TTR gene mutation were recruited. With regard to CTS, while in idiopathic CTS there was a direct correlation between CTS severity and median nerve CSA (r = 0.55, p < 0.01), in the subgroup of TTR-CTS subjects (16 subjects, 5 with bilateral CTS) CSA did not significantly correlate with CTS severity (r = − 0.473). ATTRv patients with polyneuropathy showed larger CSA than pre-symptomatic carriers in several nerve sites, more pronounced at brachial plexi (p < 0.001).

Conclusions

The present study identifies nerve morphological US patterns that may help in the early diagnosis (morpho-functional dissociation of median nerve in CTS) and monitoring of pre-symptomatic TTR carriers (larger nerve CSA at proximal nerve sites, especially at brachial plexi).

Current and future applications of ultrasound imaging in peripheral nerve disorders

Neuromuscular ultrasound (NMUS) is a rapidly evolving technique used in neuromuscular medicine to provide complimentary information to standard electrodiagnostic studies. NMUS provides a dynamic, real time assessment of anatomy which can alter both diagnostic and management pathways in peripheral nerve disorders. This review describes the current and future techniques used in NMUS and details the applications and developments in the diagnosis and monitoring of compressive, hereditary, immune-mediated and axonal peripheral nerve disorders, and motor neuron diseases. Technological advances have allowed the increased utilisation of ultrasound for management of peripheral nerve disorders; however, several practical considerations need to be taken into account to facilitate the widespread uptake of this technique.

Hereditary neuropathy with liability to pressure palsies

Hereditary neuropathy with liability to pressure palsies (HNPP) is characterized by recurrent sensory and motor neuropathy in individual nerves starting in adolescence or young adulthood, focal conduction abnormalities at entrapment sites on nerve conduction studies, and sausage-like swellings (tomacula) of the myelin sheaths by nerve biopsy. It is characterized genetically by the deletion of the chromosome 17p11.2-p12 region including the peripheral myelin protein-22 gene in the overwhelming majority of cases. HNPP may be frequently underdiagnosed or misdiagnosed owing to the heterogeneity of clinical and electrophysiological appearance. The main objective of this review is to describe clinical manifestations, paraclinical features such as electrodiagnostic, pathological, radiological and genetics findings, and possible treatments.

Nerve ultrasound in polyneuropathies

Ultrasound can be used to visualize pathology in the peripheral nerves of patients with polyneuropathy. Nerve enlargement is the most frequent pathology, but other abnormalities, including abnormal nerve echogenicity and vascularity, are also encountered. This monograph presents an overview of the role of nerve ultrasound in the evaluation and management of both inherited and acquired polyneuropathies. A description of the sonographic techniques and common abnormalities is provided, followed by a presentation of typical findings in different neuropathies. Scoring systems for characterizing the presence and pattern of nerve abnormalities as they relate to different polyneuropathies are presented. Muscle Nerve 57: 716-728, 2018.

Different nerve ultrasound patterns in charcot-marie-tooth types and hereditary neuropathy with liability to pressure palsies

INTRODUCTION

Nerve ultrasound in Charcot-Marie-Tooth (CMT) disease has focused mostly on the upper limbs. We performed an evaluation of a large cohort of CMT patients in which we sonographically characterized nerve abnormalities in different disease types, ages, and nerves.

METHODS

Seventy patients affected by different CMT types and hereditary neuropathy with liability to pressure palsies (HNPP) were evaluated, assessing median, ulnar, fibular, tibial, and sural nerves bilaterally. Data were correlated with age.

RESULTS

Nerve dimensions were correlated with CMT type, age, and nerve site. Nerves were larger in demyelinating than in axonal neuropathies. Nerve involvement was symmetric.

DISCUSSION

CMT1 patients had larger nerves than did patients with other CMT types. Patients with HNPP showed enlargement at entrapment sites. Our study confirms the general symmetry of ultrasound nerve patterns in CMT. When compared with ultrasound studies of nerves of the upper limbs, evaluation of the lower limbs did not provide additional information. Muscle Nerve 57: E18-E23, 2018.

Ultrasound in the diagnosis of peripheral neuropathy: structure meets function in the neuromuscular clinic

Peripheral nerve ultrasound (US) has emerged as a promising technique for the diagnosis of peripheral nerve disorders. While most experience with US has been reported in the context of nerve entrapment syndromes, the role of US in the diagnosis of peripheral neuropathy (PN) has recently been explored. Distinctive US findings have been reported in patients with hereditary, immune-mediated, infectious and axonal PN; US may add complementary information to neurophysiological studies in the diagnostic work-up of PN. This review describes the characteristic US findings in PN reported to date and a classification of abnormal nerve US patterns in PN is proposed. Closer scrutiny of nerve abnormalities beyond assessment of nerve calibre may allow for more accurate diagnostic classification of PN, as well as contribute to the understanding of the intersection of structure and function in PN.

Distinctive patterns of sonographic nerve enlargement in Charcot-Marie-Tooth type 1A and hereditary neuropathy with pressure palsies

OBJECTIVE

The extent of sonomorphologic differences of peripheral nerves between CMT and HNPP is unknown.

METHODS

We recruited 9 patients with CMT-1A and 9 with HNPP. Patients underwent a standardized sonographic protocol, which evaluated nerve size and vascularization. We quantitatively assessed fascicle size and echogenicity.

RESULTS

All 18 patients demonstrated nerve enlargement, but no increased vascularization. HNPP demonstrated larger nerves at sites of entrapment (median nerve at the carpal tunnel p=0.049, ulnar nerve at the sulcus p<0.001), greater swelling ratios of median (p<0.001), ulnar (p=0.017) and fibular nerve (p=0.005) than CMT-1A. CMT-1A revealed larger nerves proximal to sites of entrapment (median and fibular nerve, brachial plexus p<0.001). Nerve fascicles where larger (p<0.001) and more hypo-echogenic in CMT-1A. Nerve, fascicle size nor echogenicity correlated with age, gender or MRC sum-score.

CONCLUSIONS

Ultrasonography of nerves reveals specific phenotypes differentiating CMT-1A from HNPP. In CMT-1A enlargement of nerves and fascicles is multifocal among multiple nerves, whereas in HNPP nerve enlargement is restricted to sites of entrapment.

SIGNIFICANCE

Our findings of specific sonomorphological phenotypes, differentiating CMT-1A from HNPP, may help to improve our pathophysiological insights in CMT and HNPP.

Ultrasonographic findings in hereditary neuropathy with liability to pressure palsies

OBJECTIVES

The aims of this study were to evaluate the sonographic findings of patients with hereditary neuropathy with liability to pressure palsies (HNPP) and to examine the correlation between sonographic and electrophysiological findings.

METHODS

Nine patients whose electrophysiological findings indicated HNPP and whose diagnosis was confirmed by genetic analysis were enrolled in the study. The median, ulnar, peroneal, and tibial nerves were evaluated by ultrasonography.

RESULTS

We ultrasonographically evaluated 18 median, ulnar, peroneal, and tibial nerves. Nerve enlargement was identified in the median, ulnar, and peroneal nerves at the typical sites of compression. None of the patients had nerve enlargement at a site of noncompression. None of the tibial nerves had increased cross-sectional area (CSA) values. There were no significant differences in median, ulnar, and peroneal nerve distal motor latencies (DMLs) between the patients with an increased CSA and those with a normal CSA. In most cases, there was no correlation between electrophysiological abnormalities and clinical or sonographic findings.

DISCUSSION

Although multiple nerve enlargements at typical entrapment sites on sonographic evaluation can suggest HNPP, ultrasonography cannot be used as a diagnostic tool for HNPP. Ultrasonography may contribute to the differential diagnosis of HNPP and other demyelinating polyneuropathies or compression neuropathies; however, further studies are required.

PMP22 related neuropathies: Charcot-Marie-Tooth disease type 1A and Hereditary Neuropathy with liability to Pressure Palsies

PMP22 related neuropathies comprise (1) PMP22 duplications leading to Charcot-Marie-Tooth disease type 1A (CMT1A), (2) PMP22 deletions, leading to Hereditary Neuropathy with liability to Pressure Palsies (HNPP), and (3) PMP22 point mutations, causing both phenotypes. Overall prevalence of CMT is usually reported as 1:2,500, epidemiological studies show that 20-64% of CMT patients carry the PMP22 duplication. The prevalence of HNPP is not well known. CMT1A usually presents in the first two decades with difficulty walking or running. Distal symmetrical muscle weakness and wasting and sensory loss is present, legs more frequently and more severely affected than arms. HNPP typically leads to episodic, painless, recurrent, focal motor and sensory peripheral neuropathy, preceded by minor compression on the affected nerve. Electrophysiological evaluation is needed to determine whether the polyneuropathy is demyelinating. Sonography of the nerves can be useful. Diagnosis is confirmed by finding respectively a PMP22 duplication, deletion or point mutation. Differential diagnosis includes other inherited neuropathies, and acquired polyneuropathies. The mode of inheritance is autosomal dominant and de novo mutations occur. Offspring of patients have a chance of 50% to inherit the mutation from their affected parent. Prenatal testing is possible; requests for prenatal testing are not common. Treatment is currently symptomatic and may include management by a rehabilitation physician, physiotherapist, occupational therapist and orthopaedic surgeon. Adult CMT1A patients show slow clinical progression of disease, which seems to reflect a process of normal ageing. Life expectancy is normal.

Entrapment syndrome of multiple nerves in graft-versus-host disease

INTRODUCTION

Peripheral nerve entrapment syndromes are associated with hereditary neuropathy with liability to pressure palsies and a variety of rheumatic and endocrinological diseases.

METHODS

We report a patient with entrapment syndromes of multiple nerves associated with chronic graft-versus-host-disease (GVHD) after allogeneic hematopoietic stem cell transplantation. Nerve ultrasound, histology, and ultrastructural changes were assessed.

RESULTS

The 51-year-old man had developed severe deep dermal sclerosis due to chronic GVHD with a progressive polyneuropathy and entrapment syndromes of multiple nerves. Pre-stenotic enlargement was shown by nerve ultrasound. Histology demonstrated fibrosis of the epineurium with scarce infiltration of macrophages. Electron microscopy demonstrated alterations of the myelin sheaths and marked depletion of normal-sized myelinated nerve fibers.

CONCLUSIONS

In addition to polyneuropathy, chronic GVHD can be associated with peripheral nerve entrapment syndromes and should be added to the differential diagnosis of compressive neuropathies.