Nerve size correlates with clinical severity in Charcot-Marie-Tooth disease 1A.

INTRODUCTION: Nerve cross-sectional area (CSA) is larger than normal in Charcot-Marie-Tooth disease 1A (CMT1A), although to a variable extent. We explored whether CSA is correlated with CMT clinical severity measured with neuropathy score version 2 (CMTNS2) and its examination subscore (CMTES2) in CMT1A. METHODS: We assessed 56 patients with CMT1A (42 families). They underwent nerve conduction study (NCS) and nerve high-resolution ultrasound (HRUS) of the left median, ulnar, and fibular nerves. RESULTS: Univariate analysis showed NCS and HRUS variables to be significantly correlated with CMTNS2 and CMTES2 and with each other. Multivariate analysis showed that ulnar motor nerve conduction velocity (ß: -0.19) and fibular compound muscle action potential amplitude (-1.50) significantly influenced CMTNS2 and that median forearm CSA significantly influenced CMTNS2 (ß: 5.29) and CMTES2 (4.28). DISCUSSION: Nerve size is significantly associated with clinical scores in CMT1A, which suggests that it might represent a potential biomarker of CMT damage and progression.

Nerve ultrasound findings differentiate Charcot-Marie-Tooth disease (CMT) 1A from other demyelinating CMTs.

OBJECTIVE: Ulnar/median motor nerve conduction velocity (MNCV) is ≤38 m/s in demyelinating Charcot-Marie-Tooth disease (CMT). Previous nerve high resolution ultrasound (HRUS) studies explored demyelinating CMT assuming it as a homogeneous genetic/pathological entity or focused on CMT1A. METHODS: To explore the spectrum of nerve HRUS findings in demyelinating CMTs, we recruited patients with CMT1A (N = 44), CMT1B (N = 9), CMTX (N = 8) and CMT4C (N = 4). They underwent nerve conduction study (NCS) and HRUS of the median, ulnar, peroneal nerve, and the brachial plexus. RESULTS: Median, ulnar and peroneal MNCV significantly differed across CMT subtypes. Cross sectional area (CSA) was markedly and diffusely enlarged at all sites, except entrapment ones, in CMT1A, while it was slightly enlarged or within normal range in the other CMTs. No significant right-to-left difference was found. Age had limited effect on CSA. CSAs of some CMT1A patients largely overlapped with those of other demyelinating CMTs. A combination of three median CSA measures could separate CMT1A from other demyelinating CMTs. CONCLUSIONS: Nerve HRUS findings are heterogeneous in demyelinating CMTs. SIGNIFICANCE: Nerve HRUS may separate CMT1A from other demyelinating CMTs. The large demyelinating CMTs HRUS spectrum may be related to its pathophysiological variability.

The Association between Serum Cytokines and Damage to Large and Small Nerve Fibers in Diabetic Peripheral Neuropathy.

Diabetic peripheral neuropathy (DPN) is a frequent complication of type 2 diabetes mellitus (DM) and may involve small and large peripheral nerve fibers. Recent evidence suggests a role of cytokines in DPN. The paper is aimed at exploring whether the serum concentration of cytokines is associated with small and large nerve fiber function and with neuropathic pain (NP). We recruited a group of 32 type 2 DM patients who underwent serum cytokines (TNF-α, IL-2, IL-4, IL-6, and IL-10) dosage as well as electrodiagnostic and quantitative sensory testing (QST) assessment to explore damage to large and small nerve fibers. Raised serum levels of IL-6 and IL-10 correlated with markers of large nerve fiber sensory and motor axonal damage. Raised IL-10 serum level was associated with signs of motor nerve demyelination. No differences were found in pain characteristics and electrodiagnostic and QST markers of small nerve fiber function in relation to cytokines serum levels. IL-6 and IL-10 serum levels were associated with large nerve fiber damage but not to small fibers function or NP. IL-6 and IL-10 cytokines might play a role in the pathogenesis of nerve fiber damage or represent a compensatory or neuroprotective mechanism.

An electrodiagnostic technique for assessing palmar proper digital nerves of the hand: Normative data and clinical application.

INTRODUCTION: There is no standard electrodiagnostic technique for palmar proper digital nerves (PaPDNs). In this study we investigated sensory nerve action potentials (SNAPs) to PaPDN stimulation in normal subjects and patients. METHODS: SNAPs of PaPDNs were recorded in response to selective antidromic stimulation at the web space and mixed nerve stimulation at the wrist in 14 controls. The selectivity of PaPDN stimulation and the effect of recording electrode position on SNAP amplitude were studied. The technique was tested in 2 patients with PaPDN lesions. RESULTS: The technique yielded selective PaPDN stimulation at the web space. SNAP amplitude to PaPDN stimulation was influenced by age and was larger than SNAP amplitude to wrist stimulation. The recording electrode positions influenced SNAP amplitude. In patients, we documented PaPDN lesions, which were confirmed at surgery, whereas conventional wrist mixed nerve stimulation yielded negative findings. CONCLUSIONS: Selective PaPDN stimulation at the web space is feasible and may be helpful for electrodiagnosis of PaPDN lesions.