The role of neuromuscular ultrasound in diagnostics of peripheral neuropathies induced by cytostatic agents or immunotherapies

A relevant number of cancer patients who receive potentially neurotoxic cytostatic agents develop a chemotherapy-induced peripheral neuropathy over time. Moreover, the increasing use of immunotherapies and targeted agents leads to a raising awareness of treatment-associated peripheral neurotoxicity, e.g., axonal and demyelinating neuropathies such as Guillain-Barré-like syndromes. To date, the differentiation of these phenomena from concurrent neurological co-morbidities or (para-)neoplastic nerve affection as well as their longitudinal monitoring remain challenging. Neuromuscular ultrasound (NMUS) is an established diagnostic tool for peripheral neuropathies. Performed by specialized neurologists, it completes clinical and neurophysiological diagnostics especially in differentiation of axonal and demyelinating neuropathies. No generally approved biomarkers of treatment-induced peripheral neurotoxicity have been established so far. NMUS might significantly extend the repertoire of diagnostic and neuromonitoring methods in this growing patient group in short term. In this article, we present enlargements of the dorsal roots both in cytostatic and in immunotherapy-induced neurotoxicity for the first time. We discuss related literature regarding new integrative applications of NMUS for cancer patients by reference to two representative case studies. Moreover, we demonstrate the integration of NMUS in a diagnostic algorithm for suspected peripheral neurotoxicity independently of a certain cancer treatment regimen emphasizing the emerging potential of NMUS for clinical routine in this interdisciplinary field and prospective clinical trials.

Hoffmann's syndrome in the differential work-up of myopathic complaints: a case report

BACKGROUND

Hoffmann's syndrome is a rare form of hypothyroid myopathy in adults, which is mainly characterized by muscular weakness and muscular pseudohypertrophy.

CASE PRESENTATION

We report about a 61-year-old Western European man with myalgia, myxedema and pseudohypertrophy of the calf muscles. Laboratory tests revealed significantly elevated thyroid stimulating hormone (TSH) and creatine kinase (CK). Muscle MRI showed muscular hypertrophy of the lower limbs, but no signs of myositis or myopathy (no gadolinium enhancement, no edema, no fatty degeneration). In addition, electromyography (EMG) detected spontaneous activity. After the beginning of thyroxin-therapy it took six months until the muscle weakness improved and the myalgia regressed.

CONCLUSIONS

Here, we focus on diagnostic routines and typical findings to differentiate Hoffmann's syndrome from other myopathies. Clinical hallmarks of Hoffmann's syndrome are pseudohypertrophy and weakness of the calf muscles in combination with elevated CK and elevated TSH. EMG is well suited to detect the involvement of the muscles and muscle MRI helps to differentiate it from other myopathies. Hoffmann's syndrome is a rare myopathy due to hypothyroidism and plays a role in the differential diagnosis of myopathic complaints even if hypothyroidism has not been detected before.

Evaluating Diagnostic Ultrasound of the Vagus Nerve as a Surrogate Marker for Autonomic Neuropathy in Diabetic Patients

Background and Objectives: Diagnostic ultrasound of the vagus nerve has been used to examine different polyneuropathies, and it has been suggested to be useful as a marker of autonomic dysfunction in diabetic patients. Materials and Methods: We analyzed the cross-sectional area (CSA) of the right vagus nerve of 111 patients with type 2 diabetes in comparison to 104 healthy adults and 41 patients with CIDP (chronic inflammatory demyelinating polyneuropathy). In the diabetes group, sympathetic skin response (SSR) was measured as an indicator for autonomic neuropathy. Carotid intima-media thickness (CIMT) was measured as a surrogate for atherosclerosis. Clinical symptoms of polyneuropathy were assessed using the Neuropathy Symptom Score and the Neuropathy Disability Score. Results: In total, 61.3% of the diabetes patients had clinical signs of polyneuropathy; 23.4% had no SSR at the feet as an indicator of autonomic neuropathy. Mean vagus nerve CSA did not differ in patients with and without diabetic polyneuropathy or in diabetic patients with and without SSR at the feet. No significant correlation was found between vagus nerve CSA and CIMT or SSR parameters in diabetic patients. Mean CSA of the right vagus nerve was slightly larger in diabetic patients (p = 0.028) and in patients with CIDP (p = 0.015) than in healthy controls. Conclusions: Effect sizes and mean differences were rather small so that a reliable diagnosis cannot be performed based on the vagus nerve measurement of a single person alone. Vagus nerve CSA seems not suitable as an indicator of autonomic dysfunction or cardiovascular risk in diabetic patients.

Electrodiagnostic Testing and Nerve Ultrasound of the Carpal Tunnel in Patients with Type 2 Diabetes

In diabetic patients, controversies still exist about the validity of electrodiagnostic and nerve ultrasound diagnosis for carpal tunnel syndrome (CTS). We analyzed 69 patients with type 2 diabetes. Nerve conduction studies and peripheral nerve ultrasound of the median nerve over the carpal tunnel were performed. CTS symptoms were assessed using the Boston Carpal Tunnel Questionnaire. Polyneuropathy was assessed using the Neuropathy Symptom Score and the Neuropathy Disability Score. Although 19 patients reported predominantly mild CTS symptoms, 37 patients met the electrophysiological diagnosis criteria for CTS, and six patients were classified as severe or extremely severe. The sonographic cross-sectional area (CSA) of the median nerve at the wrist was larger than 12 mm² in 45 patients (65.2%), and the wrist-to-forearm-ratio was larger than 1.4 in 61 patients (88.4%). Receiver operating characteristic analysis showed that neither the distal motor latency, the median nerve CSA, nor the wrist-to-forearm-ratio could distinguish between patients with and without CTS symptoms. Diagnosis of CTS in diabetic patients should primarily be based upon typical clinical symptoms and signs. Results of electrodiagnostic testing and nerve ultrasound have to be interpreted with caution and additional factors have to be considered especially polyneuropathy, but also body mass index and hyperglycemia.

Nerve Ultrasound Predicts Treatment Response in Chronic Inflammatory Demyelinating Polyradiculoneuropathy-a Prospective Follow-Up

As reliable biomarkers of disease activity are lacking, monitoring of therapeutic response in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) remains a challenge. We sought to determine whether nerve ultrasound and electrophysiology scoring could close this gap. In CIDP patients (fulfilling EFNS/PNS criteria), we performed high-resolution nerve ultrasound to determine ultrasound pattern sum scores (UPSS) and predominant echotexture nerve conduction study scores (NCSS) as well as Medical Research Council sum scores (MRCSS) and inflammatory neuropathy cause and treatment disability scores (INCAT) at baseline and after 12 months of standard treatment. We retrospectively correlated ultrasound morphology with nerve histology when available. 72/80 CIDP patients featured multifocal nerve enlargement, and 35/80 were therapy-naïve. At baseline, clinical scores correlated with NCSS (r2 = 0.397 and r2 = 0.443, p < 0.01), but not or hardly with UPSS (Medical Research Council sum scores MRCSS r2 = 0.013, p = 0.332; inflammatory neuropathy cause and treatment disability scores INCAT r2 = 0.053, p = 0.048). Longitudinal changes in clinical scores, however, correlated significantly with changes in both UPSS and NCSS (r2 = 0.272-0.414, p < 0.0001). Combining nerve/fascicle size with echointensity and histology at baseline, we noted 3 distinct classes: 1) hypoechoic enlargement, reflecting active inflammation and onion bulbs; 2) nerve enlargement with additional hyperechogenic fascicles/perifascicular tissue in > 50% of measured segments, possibly reflecting axonal degeneration; and 3) almost no enlargement, reflecting "burned-out" or "cured" disease without active inflammation. Clinical improvement after 12 months was best in patients with pattern 1 (up to 75% vs up to 43% in pattern 2/3, Fisher's exact test p < 0.05). Nerve ultrasound has additional value not only for diagnosis, but also for classification of disease state and may predict treatment response.

Neurofilament markers for ALS correlate with extent of upper and lower motor neuron disease

OBJECTIVE

To determine the diagnostic performance and prognostic value of phosphorylated neurofilament heavy chain (pNfH) and neurofilament light chain (NfL) in CSF as possible biomarkers for amyotrophic lateral sclerosis (ALS) at the diagnostic phase.

METHODS

We measured CSF pNfH and NfL concentrations in 220 patients with ALS, 316 neurologic disease controls (DC), and 50 genuine disease mimics (DM) to determine and assess the accuracy of the diagnostic cutoff value for pNfH and NfL and to correlate with other clinical parameters.

RESULTS

pNfH was most specific for motor neuron disease (specificity 88.2% [confidence interval (CI) 83.0%-92.3%]). pNfH had the best performance to differentially diagnose patients with ALS from DM with a sensitivity of 90.7% (CI 84.9%-94.8%), a specificity of 88.0% (CI 75.7%-95.5%) and a likelihood ratio of 7.6 (CI 3.6-16.0) at a cutoff of 768 pg/mL. CSF pNfH and NfL levels were significantly lower in slow disease progressors, however, with a poor prognostic performance with respect to the disease progression rate. CSF pNfH and NfL levels increased significantly as function of the number of regions with both upper and lower motor involvement.

CONCLUSIONS

In particular, CSF pNfH concentrations show an added value as diagnostic biomarkers for ALS, whereas the prognostic value of pNfH and NfL warrants further investigation. Both pNfH and NfL correlated with the extent of motor neuron degeneration.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that elevated concentrations of CSF pNfH and NfL can accurately identify patients with ALS.

Ultrasound pattern sum score, homogeneity score and regional nerve enlargement index for differentiation of demyelinating inflammatory and hereditary neuropathies

OBJECTIVE

To investigate the use of nerve ultrasound in the differentiation between Charcot-Marie Tooth hereditary neuropathy (CMT1) and chronic inflammatory demyelinating polyradiculoneuropathies (CIDP), multifocal motor neuropathy (MMN) and multifocal acquired demyelinating sensory and motor neuropathies (MADSAM).

METHODS

Ultrasound/electrophysiology of predefined nerves was performed in CMT1a/b, immunoneuropathies, and healthy controls. Ultrasound pattern sum score (UPSS, sum of the amount of 12 predefined measurement points), homogeneity score (HS) and regional nerve enlargement index (RNEI) in ulnar, median, and tibial nerve were used for evaluation of morphology.

RESULTS

13 CMT1, 27 CIDP, 10 MADSAM, 12 MMN, and 23 controls were included. Significant enlargement was shown in all neuropathies compared to the controls, (p<0.001), however the amount of enlargement as evaluated by the UPSS was most prominent in CMT compared to the others (median UPSS 18 vs. 11/8.5/5 in CIDP/MADSAM/MMN, p<0.001). Homogeneous enlargement was significantly more often seen in CMT (67%, HS 6 vs. 2-3 in immune-mediated PNP, p<0.001), while in CIDP the enlargement was regional, homogeneous or inhomogeneous with equal contribution. In MMN and MADSAM regional enlargement (48%/40%) next to normal segments (∼20%) predominated (RNEI in MMN=2, in MADSAM=1 vs. 0 in the others). CSAs were inversely correlated with motor conduction velocity.

CONCLUSION

Ultrasound, quantified by UPSS, HS, and RNEI facilitates a reliable and reproducible differentiation of immunoneuropathies and hereditary neuropathies by the use of boundary values.

SIGNIFICANCE

By the use of quantitative scores, ultrasound differentiation of demyelinating neuropathies is operationalized and ameliorated compared to CSA measurements only.

Ultrasound differentiation of axonal and demyelinating neuropathies

INTRODUCTION

Ultrasound can be used to visualize peripheral nerve abnormality. Our objective in this study was to prove whether nerve ultrasound can differentiate between axonal and demyelinating polyneuropathies (PNPs).

METHODS

Systematic ultrasound measurements of peripheral nerves were performed in 53 patients (25 with demyelinating, 20 with axonal, 8 with mixed neuropathy) and 8 healthy controls. Nerve conduction studies of corresponding nerves were undertaken.

RESULTS

Analysis of variance revealed significant differences between the groups with regard to motor conduction velocity, compound muscle action potential amplitude, and cross-sectional area (CSA) of different nerves at different locations. Receiver operating characteristic curve analysis revealed CSA measurements to be well suited for detection of demyelinating neuropathies, and boundary values of peripheral nerve CSA could be defined.

CONCLUSIONS

Systematic ultrasound CSA measurement in different nerves helped detect demyelination, which is an additional cue in the etiological diagnosis of PNP, along with nerve conduction studies and nerve biopsy.