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Objective To assess axonal function prior to subcutaneous immunoglobulin (SCIG) therapy or placebo in relation to relapse in chronic inflammatory demyelinating polyneuropathy (CIDP) to determine whether axonal damage can predict therapy response. Methods Relapse rates in patients from the Polyneuropathy and Treatment with Hizentra (PATH) study, where patients were treated with placebo or SCIG (IgPro20), were analyzed by baseline (post-intravenous immunoglobulin stabilization) axonal damage (≤1 mV peroneal compound muscle action potential) status. Results In patients with non-axonal damage, relapses were significantly higher with placebo (73.0%) than IgPro20 (0.2 g/kg: 39.1%, 0.4 g/kg: 19.2%). In patients with axonal damage, IgPro20 had no effect on relapse (placebo: 25.0%, IgPro20: 0.2 g/kg: 30.0%, 0.4 g/kg: 19.4%). Patients with axonal damage relapsed significantly less on placebo versus non-axonal damage, but they also demonstrated higher baseline disability. Conclusion Axonal damage may correspond to relapse upon treatment withdrawal; patients with axonal damage relapse less, possibly reflecting poor response to immunoglobulin therapy, while non-axonal damage patients may experience more relapse, perhaps indicating better treatment response. Significance In CIDP patients with axonal loss, immunoglobulin therapy may not be as effective. Assessing axonal damage could help guide therapy, with immunoglobulins ideally used before substantial axonal damage arises.

Objective To explore the diagnostic accuracy of the split-hand index (SHI) for amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA) using sonographic assessment of muscle thickness. Methods We performed a prospective sonographic assessment of hand muscle thickness in 59 controls, 87 patients with ALS, and 33 patients with SMA. We determined the diagnostic accuracy of SHI for differentiating patients with ALS and SMA from controls. Results Patients with ALS and SMA had significantly lower muscle thickness and SHI values compared with controls. SHI showed excellent diagnostic accuracy for differentiating ALS from controls, and good diagnostic accuracy for differentiating SMA from controls. Conclusions SHI determined by sonographic measurement of hand muscle thickness seems to be a promising tool for the diagnosis of ALS and may be added easily when performing neuromuscular ultrasound. Significance SHI determined by sonographic measurement of hand muscle thickness can differentiate between healthy subjects and patients with ALS and SMA.

Objective To compare the correlations of relaxed and contracted limb muscle thickness with clinical scales in patients with amyotrophic lateral sclerosis (ALS) and spinal muscular atrophy (SMA). Methods Patients with ALS and SMA were prospectively recruited from December 2018 to November 2019. All patients underwent clinical assessment and sonographic muscle thickness measurement of eight relaxed muscles (biceps brachii, abductor pollicis brevis (APB), first dorsal interosseous, abductor digiti minimi, quadriceps, tibialis anterior, extensor digitorum brevis, and abductor hallucis brevis), and four contracted muscles (biceps brachii, APB, quadriceps, and tibialis anterior). Results 91 patients with ALS and 31 patients with SMA were recruited. Contracted muscle thickness compared to relaxed muscle showed higher reliability and similar or better correlations with muscle strength and clinical scales, especially in ALS patients with hyperreflexia. Strong to very strong correlations with clinical scales were observed with multivariate analysis of relaxed and contracted muscle thickness (0.64–0.87). Conclusions Sonographic evaluation of contracted muscle thickness is an objective measure that correlates with disease burden. It is feasible, quick, valid and reliable, and may be superior to evaluation of relaxed muscles. Significance Sonographic evaluation of contracted muscle thickness is superior to evaluation of relaxed muscles.

Objectives To explore the correlations between different muscle cramp characteristics including cramp frequency and severity and clinical and large and small nerve fiber measures in patients with diabetes type 1 (DM 1) and 2 (DM 2). Methods Prospective cross sectional study of healthy controls and patients with DM 1 and DM 2 recruited between April 2009 and November 2012. Participants underwent clinical evaluation and large and small nerve fiber studies, and the frequency and correlations of muscle cramps were explored. Results 37 controls, 51 patients with DM 1, and 69 patients with DM 2 were studied. Muscle cramps were the most frequent symptom captured by the Toronto Clinical Neuropathy Score (TCNS) in all groups, up to 78% in patients with DM 2. In patients with DM 1, but not DM 2, muscle cramp frequency and severity were correlated with clinical (TCNS) and both large (electrophysiology and vibration perception thresholds) and small nerve fiber measures. Conclusions Muscle cramps are frequent in diabetes and are correlated with clinical and both small and large nerve fiber measures in DM 1, suggesting that their origin and propagation might extend beyond the motor nerve. Significance Muscle cramps correlate with nerve fiber measures in DM 1.

Objectives To explore the increased diagnostic yield of repetitive nerve stimulation (RNS) following activation for myasthenia gravis (MG) diagnosis, and compare with testing an additional muscle at rest only. Methods We performed a retrospective chart review of patients diagnosed with MG attending the neuromuscular clinic from 2013 to 2015 and extracted data on electrophysiological studies, including frequency of decrement of 10% or above, with facial RNS at rest, and following activation. Results The total cohort included 102 patients with MG, 65 with generalized, and 37 with ocular MG. Facial RNS sensitivities for diagnosing MG were 32–46% and 14–19% respectively. The increase in RNS sensitivity following muscle activation was 6–8% for frontalis muscle recordings, and 0–2% for nasalis muscle recordings. Recording from both muscles at rest only, increased the sensitivity by 9–15%. Conclusion RNS is a valid method for confirming a clinical diagnosis of MG. The increased diagnostic yield of RNS following activation is controversial. Our study shows that the increased diagnostic yield of facial RNS following activation is modest, and is less than performing facial RNS in a second muscle. Significance Performing facial RNS in an additional muscle at rest appears to be more sensitive than facial RNS in a single muscle after activation.

Diabetic sensorimotor polyneuropathy (DSP) is the most common complication of diabetes. In order to manage DSP effectively, it is necessary to formulate an accurate diagnosis and monitor subjects regularly. This review of important aspects of the diagnosis of DSP starts with a conceptual framework that includes elements of DSP epidemiology, pathophysiology, and therapy. The emphasis of the review is to present our current understanding of diagnostic methods for DSP including their utility and limitations. Screening for DSP in the diabetes clinic can be achieved successfully using simple clinical tests. Clinical neurophysiological methods are necessary to exclude other diagnoses, stage severity, and monitor the course of DSP. Novel investigative techniques are highly promising, but their usefulness in the clinic setting remains limited at this time. This article presents an overview of diagnostic methods for DSP.