Reduced Phrenic CMAP Amplitudes in Obesity Despite Preserved Diaphragm Ultrasound Measures.

IF 2.9 3区医学 Q2 CLINICAL NEUROLOGY

Muscle & Nerve Pub Date : 2026-11-01 Epub Date: 2026-09-20 DOI:10.1002/mus.70414

Andrea J Boon, Elie Naddaf, Grayson Beecher

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引用次数: 0

Abstract

Introduction/aims: Phrenic nerve conduction studies (NCS) are regularly used in the evaluation of neuromuscular respiratory dysfunction; however, the impact of body mass index (BMI) on phrenic compound muscle action potential (CMAP) amplitudes remains poorly characterized. We evaluated the relationship between BMI and phrenic CMAP amplitudes in patients without evidence of neuromuscular diaphragmatic dysfunction.

Methods: We performed a retrospective secondary analysis of patients derived from two previously published cohorts from Mayo Clinic (Rochester, Minnesota) and the University of Alberta (Edmonton, Alberta) evaluating diaphragm ultrasound in suspected neuromuscular respiratory insufficiency. Patients without evidence of neuromuscular disease affecting the diaphragm who underwent bilateral phrenic NCS and diaphragm ultrasound were included.

Results: Seventy-nine patients met inclusion criteria, including 36 with BMI ≥ 30 kg/m². Median phrenic CMAP amplitudes were significantly lower in patients with BMI ≥ 30 kg/m² compared to BMI < 30 kg/m² (0.25 mV [IQR 0.10-0.38] vs. 0.50 mV [0.30-0.65], p < 0.001). Low phrenic CMAP amplitudes (< 0.3 mV) were more common in patients with obesity (58% vs. 21%, p < 0.001). BMI demonstrated a moderate negative correlation with phrenic CMAP amplitude (ρ = -0.50, p < 0.001). Diaphragm thickness at functional residual capacity did not differ significantly between BMI groups, while diaphragm thickening ratio was modestly lower in obesity.

Discussion: Elevated BMI is associated with lower phrenic CMAP amplitudes in patients without evidence of neuromuscular diaphragmatic dysfunction. Reduced phrenic CMAP amplitudes in obesity may reflect technical recording limitations rather than clinically meaningful diaphragmatic dysfunction. Low-amplitude phrenic responses in patients with obesity should be interpreted cautiously and alongside adjunctive assessments such as diaphragm ultrasound.

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尽管保留膈超声测量，肥胖患者膈CMAP振幅降低。

简介/目的：膈神经传导研究（NCS）经常用于评估神经肌肉呼吸功能障碍；然而，身体质量指数（BMI）对膈复合肌动作电位（CMAP）振幅的影响仍然缺乏表征。我们评估了没有神经肌肉膈肌功能障碍的患者BMI和膈肌CMAP振幅之间的关系。方法：我们对来自梅奥诊所（罗切斯特，明尼苏达州）和阿尔伯塔大学（埃德蒙顿，阿尔伯塔）的两个先前发表的队列患者进行了回顾性的二次分析，评估膈超声在疑似神经肌肉呼吸功能不全中的作用。没有神经肌肉疾病影响膈肌的证据的患者接受了双侧膈NCS和膈超声检查。结果：79例患者符合纳入标准，其中BMI≥30 kg/m2 36例。BMI≥30 kg/m2的患者膈肌CMAP中位振幅明显低于BMI为2的患者(0.25 mV [IQR 0.10-0.38] vs. 0.50 mV [0.30-0.65]， p讨论：BMI升高与无神经肌肉膈肌功能障碍的患者膈肌CMAP中位振幅降低相关。肥胖患者膈肌CMAP振幅的降低可能反映了技术记录的局限性，而不是临床意义上的膈肌功能障碍。肥胖患者的低幅度膈反应应谨慎解释，并与膈超声等辅助评估一起进行。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Muscle & Nerve 医学-临床神经学

CiteScore

6.40

自引率

5.90%

发文量

287

审稿时长

3-6 weeks

期刊介绍： Muscle & Nerve is an international and interdisciplinary publication of original contributions, in both health and disease, concerning studies of the muscle, the neuromuscular junction, the peripheral motor, sensory and autonomic neurons, and the central nervous system where the behavior of the peripheral nervous system is clarified. Appearing monthly, Muscle & Nerve publishes clinical studies and clinically relevant research reports in the fields of anatomy, biochemistry, cell biology, electrophysiology and electrodiagnosis, epidemiology, genetics, immunology, pathology, pharmacology, physiology, toxicology, and virology. The Journal welcomes articles and reports on basic clinical electrophysiology and electrodiagnosis. We expedite some papers dealing with timely topics to keep up with the fast-moving pace of science, based on the referees'' recommendation.