Ultrasound of peripheral nerves distinguishes inherited sensory neuronopathy of cerebellar ataxia with neuropathy and vestibular areflexia syndrome from inherited axonopathy

Abstract

Introduction/AimsRecent studies have shown that ultrasound of peripheral nerves can distinguish inherited sensory neuronopathy from acquired axonopathy with a high degree of accuracy. In this study we aimed to determine whether ultrasound can also distinguish inherited sensory neuronopathy from inherited axonopathy. MethodsWe compared the ultrasound cross‐sectional areas (CSAs) of the median, ulnar, sural, and tibial nerves of retrospectively recruited patients with cerebellar ataxia with neuropathy and vestibular areflexia syndrome (CANVAS), in whom sensory neuronopathy is a cardinal feature, with Charcot‐Marie‐Tooth type 2 (CMT2) disease patients, who have an inherited axonopathy, using the Kruskal‐Wallis test and receiver‐operating characteristic curves. ResultsThere were 17 patients with CANVAS and 18 with CMT2. The upper limb nerve CSAs were significantly smaller in CANVAS than in CMT2 (P < .001), with the CSAs of the median nerve at mid‐forearm and ulnar nerve at mid‐arm being a third or less the size of those of the CMT2 patients. Nerve ultrasound reliably distinguished CANVAS from CMT2 with ROC areas under the curve between 0.97 and 0.99. The lower limb CSAs of the two patient groups were not significantly different. DiscussionUltrasound of the upper limb nerves distinguishes CANVAS sensory neuronopathy from inherited axonopathy with high accuracy and can therefore be proposed as a reliable additional tool in the investigation of these diseases.

Neuromuscular ultrasound as a marker for inherited sensory neuronopathy

“…The receiver operating characteristic (ROC) curves were derived for comparison of the sensory neuronopathy patients with healthy control subjects in one study, 6 ALS in another, 8 and CMT2 in a third study. 13 All three studies showed a high discriminatory power for ultrasound, with areas under the curve (AUCs) of 0.92 to 1, sensitivity 0.82 to 1, and specificity 0.89 to 1 (Table 3).…”

“…Eight papers that used ultrasound in various inherited diseases with sensory neuronopathies were identified. [2][3][4]6,8,9,12,13 On further selection, a study of nerve ultrasound in Friedreich ataxia was excluded. 12 We also excluded a preliminary report on seven patients with CANVAS, 2 who were subsequently included in a larger study conducted by the same authors.…”

“…3,4,6,8,9,13 In total, 49 patients with sensory neuronopathy participated in these studies. The clinical diagnosis of the sensory neuronopathy was CANVAS in two studies (17 patients overall, of whom 14 participated in both studies), 3,13 SCA2 in two (14 patients overall, 7 of whom were included in both studies), 4,6 and SBMA in two studies (18 patients). 8,9 In four of the six studies, patients were recruited prospectively.…”

“…3,4,8,9 In the remaining two studies, group comparisons were made using previously recorded ultrasound data. 6,13 The CSAs of multiple mixed nerves of the upper limbs were assessed in all those studies. The ultrasonographer was blinded to the clinical and electrophysiological findings of the CANVAS and SCA2 patients.…”

“…Eight papers that used ultrasound in various inherited diseases with sensory neuronopathies were identified 2–4,6,8,9,12,13 . On further selection, a study of nerve ultrasound in Friedreich ataxia was excluded 12 .…”