Percutaneous magnetic coil stimulation of the phrenic nerve roots and trunk

doi:10.1016/0924-980X(95)00159-I

Electroencephalography and Clinical Neurophysiology/Electromyography and Motor Control

Volume 97, Issue 6, December 1995, Pages 369-374

Electroencephalograp...

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Abstract

We describe a technique of percutaneous magnetic coil NO stimulation of the phrenic nerve trunk on one side of the neck and phrenic roots over the upper cervical vertebral column in 10 normal subjects and 2 patients. We were able to obtain compound muscle action potentials (CMAPs) from the diaphragm at two sites (xiphoid process and 7th intercostal space) after stimulation of the phrenic nerve trunk and roots. We noted that the onset latencies after phrenic root stimulation remained fixed despite increasing the stimulus intensity from 50% to 100% and on moving the MC vertically or laterally, suggesting that stimulation of the fastest conducting fibers was occurring at a fixed site, most likely at the intervertebral foramina. Absent responses unilaterally in one and prolonged latencies to diaphragmatic CMAPs in another patient confirmed phrenic neuropathy in these patients.

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Cited by (20)

Reliability of the diaphragmatic compound muscle action potential evoked by cervical magnetic stimulation and recorded via chest wall surface EMG
2017, Respiratory Physiology and Neurobiology
Citation Excerpt :
We cannot exclude the possibility our signals were contaminated; however, pragmatic design and experimentation has led to an approach that may reduce the chance of crosstalk from non-diaphragmatic muscles. Electrodes were positioned close together and situated near the costochondral junction in compliance with recommendations by Verin et al. (2002) Additionally, patients with phrenic nerve palsy do not demonstrate any electrical activity using chest wall electrodes in response to phrenic nerve stimulation, suggesting that the signal was not contaminated due to the unavoidable stimulation of non-diaphragmatic muscles (Chokroverty et al., 1995). Where possible, it may be of benefit to place multiple electrode pairs along the anterior chest wall in order to determine the most suitable electrode configuration on a subject-by-subject basis.
Stimulation of the phrenic nerve via cervical magnetic stimulation (CMS) elicits a compound muscle action potential (CMAP) that allows for assessment of diaphragm activation. The reliability of CMS to evoke the CMAP recorded by chest wall surface EMG has yet to be comprehensively examined.
CMS was performed on healthy young males (n = 10) and females (n = 10). Surface EMG electrodes were placed on the right and left hemi-diaphragm between the 6–8th intercostal spaces. CMAPs were analysed for: latency, duration, peak-to-peak amplitude, and area. Reliability within and between experimental sessions was assessed using intraclass correlation coefficients (ICC). Bilateral (right-left) and sex-based (male-female) comparisons were also made (independent samples t-test).
All CMAP characteristics demonstrated high reproducibility within (ICCs > 0.96) and between (ICCs > 0.89) experimental sessions. No statistically significant bilateral or sex-based differences were found (p > 0.05).
CMS is a reliable and non-invasive method to evaluate phrenic nerve conduction.
The cortico-diaphragmatic pathway involvement in amyotrophic lateral sclerosis: Neurophysiological, respiratory and clinical considerations
2006, Journal of the Neurological Sciences
Cortico-diaphragmatic pathway was investigated by means of transcranial magnetic stimulation (TMS), in 14 patients affected by definite amyotrophic lateral sclerosis (ALS) without clinical signs of respiratory impairment. Spirometry, gas analysis, and measurement of static inspiratory and expiratory pressures were performed in all patients.
Forced vital capacity, forced expiratory volume at the first and second peak expiratory flow, sniff effort from FRC level (SNIP), maximal inspiratory and expiratory pressure at mouth (MIP/MEP), maximal transdiaphragmatic pressure (Pdimx) were considered. TMS was performed, recording by surface electrodes from hemidiaphragm, bilaterally. Latency of cortical and spinal motor-evoked potentials (Cx-MEP/Sp-MEP) and central motor conduction time (CMCT) were measured.
None of the patients showed altered spirometry and gas levels. Seven patients showed decreased Pdimx and eight of MEP values. Four patients showed a delayed Sp-MEP. In one patient the Cx-MEP was abolished while the mean values of both Cx-MEP and CMCT were significantly increased (19.2 ± 4.1 ms, P < 0.0001; 10.8 ± 4.8 ms, P < 0.0001). Cx-MEP and CMCT did not show significant correlations with any of the respiratory measures. The patients with prolonged Sp-MEP, showed longer disease duration, lower Norris score, lower Pdimx and MEP values. In conclusion, cortico-diaphragmatic study is a sensitive measure to reveal subclinical diaphragmatic impairment although not correlated to respiratory measures.
Electrodiagnostic assessment of respiratory dysfunction in motor neuron disease
2004, Handbook of Clinical Neurophysiology
This chapter reviews the role of electrodiagnostic and other means of assessing respiratory dysfunction in motor neuron diseases (MND), particularly amyotrophic lateral sclerosis (ALS). The chapter emphasizes phrenic nerve studies, electromyography (EMG) of the diaphragm and other respiratory muscles, and sleep studies. Destruction of the anterior horn cells in the spinal cord or neuronal loss within the respiratory center is responsible for ventilatory failure in ALS and other MNDs. By the time the clinical indicators of respiratory failure are evident (weak cough, restless sleep, daytime drowsiness, morning headache, and paradoxical respiration), respiratory failure is often advanced. EMGs of the chest wall and diaphragm are performed and reveal the presence of fibrillation or positive sharp waves recorded from the external oblique, intercostals, and diaphragm. The predominant neural drive to the respiratory muscles during sleep is through the phrenic nerves, and patients with diaphragm muscle weakness are prone to nocturnal hypoventilation. The duration of rapid eye movement (REM) sleep is reduced in ALS patients. Inspiratory ventilatory failure responds to noninvasive positive pressure ventilation (NPPV), whereas expiratory ventilatory failure results in poor cough and is better treated with a cough-assist device.
Are the neurophysiological techniques useful for the diagnosis of diaphragmatic impairment in multiple sclerosis (MS)?
2003, Clinical Neurophysiology
Objective: To characterize cortico-diaphragmatic pathway involvement in multiple sclerosis (MS) by means of transcranial magnetic stimulation (TMS), and verify its clinical impact.
Methods: TMS from diaphragm (Dia), and abductor digiti minimi (AbdV°) was performed in 26 MS patients. Phrenic nerve (PN) conduction study was also performed. Expanded disability status scale (EDSS) and fatigue descriptive scale (FDS) were measured. Forced vital capacity (FVC), forced expiratory volume at the first second (FEV1), peak expiratory flow (PEF) were tested: the predicted percentage value (% pred) was considered.
Results: Cortical motor evoked potential (Cx-MEP) latency and central motor conduction time (CMCT) were prolonged, respectively, in 31 and 23% of patients from Dia, in 76 and 79% from AbdV°. PN-compound motor action potential (CMAP) was normal. EDSS correlated to Cx-MEP from AbdV° (P<0.01), and PN-CMAP amplitude (P<0.05), FEV1 % pred (P<0.01), PEF % pred (P<0.01). PN-CMAP amplitude correlated to FVC % pred P=0.05, FEV1 % pred P<0.01, PEF % pred P<0.01. Fatigue was related to AbdV° Cx-MEP and CMCT (P<0.05 and P<0.01).
Conclusions: Cortico-diaphragmatic pathway is impaired only in a minority of MS patients. Lack of correlation between TMS findings from Dia and respiratory tests argues against its routinary use to detect subclinical respiratory alterations. Fatigue seems to be related to the motor impairment rather than to respiratory distress.
Diaphragm compound muscle action potential measured with magnetic stimulation and chest wall surface electrodes
2002, Respiratory Physiology and Neurobiology
To seek a method to reliably measure phrenic nerve conduction time (PNCT) with magnetic stimulation we investigated two stimulus sites, placing the magnetic coil at the cricoid cartilage (high position) or close to the clavicle (low position). We also compared compound muscle action potential (CMAP) recorded from three different sites: in the sixth to eighth intercostal spaces in the anterior axillary line (Ant-a); in the 8th intercostal space close to the midclavicular line; and with one electrode at the lower sternum and the other at the costal margin. Fourteen normal subjects were studied. The PNCT measured by magnetic stimulation in the high position recorded from (Ant-a) was 7.6±0.6 on the left side and 8.4±0.7 on the right. The PNCT recorded from all three sites become much shorter when the magnetic coil was moved from the high to the low position. Our results show that PNCT can be accurately measured with magnetic stimulation when care is taken to avoid coactivation of the brachial plexus.
Position effect of trans-spinal magnetic stimulation on diaphragmatic motor evoked potential in healthy humans
2022, Journal of Applied Physiology

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Main articlePercutaneous magnetic coil stimulation of the phrenic nerve roots and trunk

Abstract

Electroenceph. clin. Neurophysiol.

Electroenceph. clin. Neurophysiol.

Magnetic stimulation of the human brain and peripheral nervous system: an introduction and the results of an initial clinical evaluation

Neurosurgery

Phrenic nerve conduction study in normal subjects

Muscle Nerve

Clinical applications of magnetic stimulation in radiculopathy and plexopathy

Magnetic stimulation of the human peripheral nervous system

Phrenic nerve conduction studies in respiratory insufficiency

Neurology

Recurrent isolated altemating phrenic nerve palsies: a variant of brachial neuritis

Thorax

Main article
Percutaneous magnetic coil stimulation of the phrenic nerve roots and trunk