Department of Neurology and Clinical Neurophysiology, Bay of Plenty District Health Board, Tauranga.
Auckland District Health Board, Auckland.
Eur J Neurol. 2018 Apr;25(4):659-665. doi: 10.1111/ene.13563. Epub 2018 Feb 26.
Sensory neuronopathy is a cardinal feature of cerebellar ataxia neuropathy vestibular areflexia syndrome (CANVAS). Having observed that two patients with CANVAS had small median and ulnar nerves on ultrasound, we set out to examine this finding systematically in a cohort of patients with CANVAS, and compare them with both healthy controls and a cohort of patients with axonal neuropathy. We have previously reported preliminary findings in seven of these patients with CANVAS and seven healthy controls.
We compared the ultrasound cross-sectional area of median, ulnar, sural and tibial nerves of 14 patients with CANVAS with 14 healthy controls and 14 age- and gender-matched patients with acquired primarily axonal neuropathy. We also compared the individual nerve cross-sectional areas of patients with CANVAS and neuropathy with the reference values of our laboratory control population.
The nerve cross-sectional area of patients with CANVAS was smaller than that of both the healthy controls and the neuropathy controls, with highly significant differences at most sites (P < 0.001). Conversely, the nerve cross-sectional areas in the upper limb were larger in neuropathy controls than healthy controls (P < 0.05). On individual analysis, the ultrasound abnormality was sufficiently characteristic to be detected in all but one patient with CANVAS.
Small nerves in CANVAS probably reflect nerve thinning from loss of axons due to ganglion cell loss. This is distinct from the ultrasound findings in axonal neuropathy, in which nerve size was either normal or enlarged. Our findings indicate a diagnostic role for ultrasound in CANVAS sensory neuronopathy and in differentiating neuronopathy from neuropathy.
感觉神经元病是小脑共济失调神经病前庭反射消失综合征（CANVAS）的主要特征。我们观察到两名 CANVAS 患者的正中神经和尺神经在超声检查中较小，因此我们着手系统地检查了一组 CANVAS 患者的这一发现，并将其与健康对照组和一组轴索性神经病患者进行了比较。我们之前曾在七名 CANVAS 患者和七名健康对照者中报告了初步发现。
我们比较了 14 名 CANVAS 患者、14 名健康对照者和 14 名年龄和性别匹配的获得性主要轴索性神经病患者的正中神经、尺神经、腓肠神经和胫神经的超声横截面积。我们还比较了 CANVAS 患者和神经病患者的各个神经横截面积与我们实验室对照组人群的参考值。
CANVAS 患者的神经横截面积小于健康对照组和神经病对照组，大多数部位差异具有高度显著性（P<0.001）。相反，神经病对照组上肢的神经横截面积大于健康对照组（P<0.05）。在个别分析中，除了一名 CANVAS 患者外，所有患者均存在超声异常。
CANVAS 中的小神经可能反映了由于节细胞丢失导致轴突丢失引起的神经变薄。这与轴索性神经病的超声表现不同，后者的神经大小正常或增大。我们的发现表明，超声在 CANVAS 感觉神经元病以及区分神经元病与神经病方面具有诊断作用。
