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European Journal of Cardio-thoracic... Apr 2016The importance of phrenic nerve preservation during pneumonectomy remains controversial. We previously demonstrated that preservation of the phrenic nerve in the...
OBJECTIVES
The importance of phrenic nerve preservation during pneumonectomy remains controversial. We previously demonstrated that preservation of the phrenic nerve in the immediate postoperative period preserved lung function by 3-5% but little is known about its long-term effects. We, therefore, decided to investigate the effect of temporary ipsilateral cervical phrenic nerve block on dynamic lung volumes in mid- to long-term pneumonectomy patients.
METHODS
We investigated 14 patients after a median of 9 years post pneumonectomy (range: 1-15 years). Lung function testing (spirometry) and fluoroscopic and/or sonographic assessment of diaphragmatic motion on the pneumonectomy side were performed before and after ultrasonographic-guided ipsilateral cervical phrenic nerve block by infiltration with lidocaine.
RESULTS
Ipsilateral phrenic nerve block was successfully achieved in 12 patients (86%). In the remaining 2 patients, diaphragmatic motion was already paradoxical before the nerve block. We found no significant difference on dynamic lung function values (FEV1 'before' 1.39 ± 0.44 vs FEV1 'after' 1.38 ± 0.40; P = 0.81).
CONCLUSIONS
Induction of a temporary diaphragmatic palsy did not significantly influence dynamic lung volumes in mid- to long-term pneumonectomy patients, suggesting that preservation of the phrenic nerve is of greater importance in the immediate postoperative period after pneumonectomy.
Topics: Adult; Aged; Female; Humans; Lung; Male; Middle Aged; Nerve Block; Organ Sparing Treatments; Phrenic Nerve; Pneumonectomy; Postoperative Complications
PubMed: 26405235
DOI: 10.1093/ejcts/ezv334 -
Biomedical Physics & Engineering Express Jul 2023Peripheral magnetic stimulation is a promising assistive technique for rehabilitation. Today's magnetic stimulation devices, designed for transcranial stimulation,...
Peripheral magnetic stimulation is a promising assistive technique for rehabilitation. Today's magnetic stimulation devices, designed for transcranial stimulation, operate at currents of 6 kA and higher. This makes them expensive and bulky. Many motor neurons in peripheral nerves are more accessible, have large diameters, and require significantly lower field strengths for stimulation. In this work, we present a simulation environment to determine the threshold current required to trigger an action potential in phrenic nerve motor neurons for different coil geometries. An anatomical model was used for coil placement and realistic field calculations. The field distribution was calculated using the finite integration technique and then applied to a neuronal model to simulate the axon membrane dynamics. For general applicability, the coil-nerve distance and the axon diameter were varied. We show that the required current was approximately 1.3 kA for a nerve-coil distance of 35 mm, which corresponds to 20% of the available power of a commercial TMS device. By including the nearby vagus nerve in the simulations, we showed that accidental stimulation of this nerve is highly unlikely. Our results pave the way for the development of smaller, less complex, and more affordable stimulators and promise to increase the use of peripheral magnetic stimulators in clinical settings.
Topics: Phrenic Nerve; Neurons; Axons; Computer Simulation; Magnetic Phenomena
PubMed: 37459838
DOI: 10.1088/2057-1976/ace7d7 -
Scientific Reports Aug 2018Communicating fibres between the phrenic nerve and sympathetic nervous system may exist, but have not been characterized histologically and immunohistochemically, even...
Communicating fibres between the phrenic nerve and sympathetic nervous system may exist, but have not been characterized histologically and immunohistochemically, even though increased sympathetic activity due to phrenic nerve stimulation for central sleep apnoea may entail morbidity and mortality. We, therefore, conducted a histological study of the phrenic nerve to establish the presence of catecholaminergic fibres throughout their course. The entire phrenic nerves of 35 formalin-fixed human cadavers were analysed morphometrically and immunohistochemically. Furthermore, the right abdominal phrenic nerve was serially sectioned and reconstructed. The phrenic nerve contained 3 ± 2 fascicles in the neck that merged to form a single fascicle in the thorax and split again into 3 ± 3 fascicles above the diaphragm. All phrenic nerves contained catecholaminergic fibres, which were distributed homogenously or present as distinct areas within a fascicle or as separate fascicles. The phrenicoabdominal branch of the right phrenic nerve is a branch of the celiac plexus and, therefore, better termed the "phrenic branch of the celiac plexus". The wall of the inferior caval vein in the diaphragm contained longitudinal strands of myocardium and atrial natriuretic peptide-positive paraganglia ("caval bodies") that where innervated by the right phrenic nerve.
Topics: Abdomen; Autonomic Pathways; Diaphragm; Female; Humans; Male; Neck; Phrenic Nerve; Thorax
PubMed: 30076368
DOI: 10.1038/s41598-018-30145-x -
Experimental Neurology Oct 2023Moderate acute intermittent hypoxia (mAIH) elicits plasticity in both respiratory (phrenic long-term facilitation; pLTF) and sympathetic nerve activity (sympLTF) in...
HYPOTHESES
Moderate acute intermittent hypoxia (mAIH) elicits plasticity in both respiratory (phrenic long-term facilitation; pLTF) and sympathetic nerve activity (sympLTF) in rats. Although mAIH produces pLTF in normal rats, inconsistent results are reported after cervical spinal cord injury (cSCI), possibly due to greater spinal tissue hypoxia below the injury site. There are no reports concerning cSCI effects on sympLTF. Since mAIH is being explored as a therapeutic modality to restore respiratory and non-respiratory movements in humans with chronic SCI, both effects are important. To understand cSCI effects on mAIH-induced pLTF and sympLTF, partial or complete C2 spinal hemisections (C2Hx) were performed and, 2 weeks later, we assessed: 1) ipsilateral cervical spinal tissue oxygen tension; 2) ipsilateral & contralateral pLTF; and 3) ipsilateral sympLTF in splanchnic and renal sympathetic nerves.
METHODS
Male Sprague-Dawley rats were studied intact, or after partial (single slice) or complete C2Hx (slice with ∼1 mm aspiration). Two weeks post-C2Hx, rats were anesthetized and prepared for recordings of bilateral phrenic nerve activity and spinal tissue oxygen pressure (PtO). Splanchnic and renal sympathetic nerve activity was recorded in intact and complete C2Hx rats.
RESULTS
Spinal PtO near phrenic motor neurons was decreased after C2Hx, an effect most prominent with complete vs. partial injuries; baseline PtO was positively correlated with mean arterial pressure. Complete C2Hx impaired ipsilateral but not contralateral pLTF; with partial C2Hx, ipsilateral pLTF was unaffected. In intact rats, mAIH elicited splanchnic and renal sympLTF. Complete C2Hx had minimal impact on baseline ipsilateral splanchnic or renal sympathetic nerve activity and renal, but not splanchnic, sympLTF remained intact.
CONCLUSION
Greater tissue hypoxia likely impairs pLTF and splanchnic sympLTF post-C2Hx, although renal sympLTF remains intact. Increased sympathetic nerve activity post-mAIH may have therapeutic benefits in individuals living with chronic SCI since anticipated elevations in systemic blood pressure may mitigate hypotension characteristic of people living with SCI.
Topics: Humans; Rats; Male; Animals; Rats, Sprague-Dawley; Motor Neurons; Spinal Cord Injuries; Hypoxia; Oxygen; Phrenic Nerve
PubMed: 37451584
DOI: 10.1016/j.expneurol.2023.114478 -
Thorax Aug 2022This study characterised the hemidiaphragm elevation on 3-month interval chest X-rays (CXRs) of patients post COVID-19 pneumonia. 467 CXRs were screened; 19 (4.1%) had...
This study characterised the hemidiaphragm elevation on 3-month interval chest X-rays (CXRs) of patients post COVID-19 pneumonia. 467 CXRs were screened; 19 (4.1%) had an elevated hemidiaphragm. There were 15 (3.2%) patients of interest with new hemidiaphragm elevation, persisting on average 7 months post COVID-19 diagnosis. Symptomatic patients underwent diaphragm ultrasound (n=12), pulmonary function test (n=10), muscle function test (n=6) and neurophysiology (n=5), investigating phrenic nerve function. Ultrasound demonstrated reduced/paradoxical diaphragmatic movements in eight; four of eight had reduced thickening fraction. Neurophysiology peripheral limb studies did not support the differential diagnoses of critical illness neuropathy/myopathy. We propose that, in selected patients, COVID-19 may cause phrenic nerve mononeuritis.
Topics: COVID-19; COVID-19 Testing; Diaphragm; Humans; Mononeuropathies; Phrenic Nerve
PubMed: 35459747
DOI: 10.1136/thoraxjnl-2021-218257 -
Regional Anesthesia and Pain Medicine Jan 2021The costoclavicular brachial plexus block is performed deep and posterior to the midpoint of the clavicle. There are limited data evaluating the spread of the...
BACKGROUND AND OBJECTIVES
The costoclavicular brachial plexus block is performed deep and posterior to the midpoint of the clavicle. There are limited data evaluating the spread of the costoclavicular brachial plexus block. We performed a cadaveric study to evaluate the spread of injectate after a costoclavicular brachial plexus block.
METHODS
Five ultrasound-guided costoclavicular block injections were performed with 20 mL of 0.1% methylene blue. The brachial plexus and its branches were dissected from the level of C4 to the lower axilla. The extent of dye spread was recorded including spread to the phrenic nerve, suprascapular nerve, roots, trunks, divisions, cords and terminal branches of the brachial plexus.
RESULTS
The dye extended cephalad to the level of the cricoid cartilage in two of the five injections; three injections had dye extending 0.75 cm, 1.5 cm and 2 cm caudad to the level of the cricoid cartilage, respectively. The C7, C8 and T1 nerve roots were stained in all injections. The dye did not extend cephalad to the C5 and C6 nerve roots. All trunks, cords and divisions of the brachial plexus were stained, as was the suprascapular nerve. There was no spread of dye to the phrenic nerve in any of the specimens.
CONCLUSIONS
This cadaveric study demonstrates that ultrasound-guided injection in the costoclavicular space spreads cephalad to the brachial plexus in the supraclavicular space, consistently reaching the suprascapular nerve and all trunks and cords of the brachial plexus, while sparing the phrenic nerve.
Topics: Brachial Plexus; Brachial Plexus Block; Cadaver; Humans; Phrenic Nerve; Ultrasonography, Interventional
PubMed: 33024005
DOI: 10.1136/rapm-2020-101585 -
Journal of Plastic, Reconstructive &... Sep 2018The widely used nerve transfer sources for elbow flexion in patients with upper brachial plexus avulsion (UBPA) include partial ulnar nerve, phrenic nerve, and... (Comparative Study)
Comparative Study
The widely used nerve transfer sources for elbow flexion in patients with upper brachial plexus avulsion (UBPA) include partial ulnar nerve, phrenic nerve, and intercostal nerves. A retrospective review of 21 patients treated with phrenic and partial ulnar nerve transfers for elbow flexion after UBPA was carried out. In the phrenic nerve transfer group, the phrenic nerve was transferred to the anterolateral bundle of the anterior division of the upper trunk; in the partial ulnar nerve transfer group, one fascicle of the ulnar nerve was transferred to the biceps branch. The British Medical Research Council (MRC) grading system, angle of elbow flexion, electromyography (EMG), and the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire scoring were used to evaluate the recovery of elbow flexion at least 3 years postoperatively. The efficiency of motor function in phrenic nerve transfer group was 82%, whereas it was 80% in partial ulnar nerve transfer group. The outstanding rates of angle of elbow flexion were 64% and 70% in phrenic and partial ulnar nerve transfer groups, respectively. The DASH scores after surgery were significantly lower than those before surgery in the two groups. There was no statistical difference between the two groups in the changes of DASH scores before and after surgery. Both of phrenic and partial ulnar nerve transfers had good prognosis for elbow flexion in patients with UBPA.
Topics: Adolescent; Adult; Brachial Plexus; Brachial Plexus Neuropathies; Elbow Joint; Electromyography; Female; Follow-Up Studies; Humans; Male; Middle Aged; Nerve Transfer; Phrenic Nerve; Recovery of Function; Retrospective Studies; Time Factors; Ulnar Nerve; Young Adult
PubMed: 29980455
DOI: 10.1016/j.bjps.2018.05.024 -
Annals of Anatomy = Anatomischer... Jan 2022Diaphragm pacing allows certain ventilator-dependent patients to achieve weaning from mechanical ventilation. The reference method consists in implanting intrathoracic... (Observational Study)
Observational Study
BACKGROUND
Diaphragm pacing allows certain ventilator-dependent patients to achieve weaning from mechanical ventilation. The reference method consists in implanting intrathoracic contact electrodes around the phrenic nerve during video-assisted thoracic surgery, which involves time-consuming phrenic nerve dissection with a risk of nerve damage. Identifying a phrenic segment suitable for dissection-free implantation of electrodes would constitute progress.
STUDY DESIGN
This study characterizes a free terminal phrenic segment never fully described before. We conducted a cadaver study (n = 14) and a clinical observational study during thoracic procedures (n = 54).
RESULTS
A free terminal phrenic segment was observed on both sides in 100% of cases, "jumping" from the pericardium to the diaphragm and measuring 60 mm [95% confidence interval; 48-63] and 72.5 mm [65-82] (right left, respectively; p = 0.0038; cadaver study). This segment rolled up on itself at end-expiration and became unravelled and elongated with diaphragm descent (clinical study). Three categories of fat pads were defined (type 1: pericardiophrenic bundle free of surrounding fat; type 2: single fatty fringe leaving the phrenic nerve visible until diaphragmatic entry; type 3: multiple fatty fringes masking the site of penetration of the phrenic nerve) that depended on body mass index (p = 0.001, clinical study). Hematoxylin-eosin and toluidine blue staining (cadaver study) showed that all of the phrenic fibers in the distal, pre-branching part of the terminal segment were contained within a single epineurium containing a variable number of fascicles (right: 1 [95%CI 0.65-4.01]; left 5 [3.37-7.63]; p = 0.03).
CONCLUSION
Diaphragm pacing through periphrenic electrodes positioned on the terminal phrenic segment should be tested.
Topics: Cadaver; Diaphragm; Electrodes, Implanted; Humans; Pericardium; Phrenic Nerve
PubMed: 34562604
DOI: 10.1016/j.aanat.2021.151835 -
Clinical Neurophysiology : Official... Jan 2016To evaluate the correlation between diaphragm thickness assessed by ultrasound (US) with respiratory function tests and the diaphragm motor responses, in patients with...
OBJECTIVE
To evaluate the correlation between diaphragm thickness assessed by ultrasound (US) with respiratory function tests and the diaphragm motor responses, in patients with amyotrophic lateral sclerosis (ALS).
METHODS
42 consecutive ALS patients were studied (11 with bulbar-onset), excluding patients with marked orofacial paresis. Investigation included: revised ALS functional rating scale (ALSFRS-R), forced vital capacity (FVC), maximal voluntary ventilation (MVV), maximal inspiratory (MIP) and expiratory (MEP) pressures, nasal inspiratory pressure during sniff (SNIP); peak-to-peak amplitude of the diaphragmatic motor response to phrenic nerve stimulation (Diaphragm-CMAP), diaphragmatic thickness measured by ultrasound during maximal inspiration and during maximal expiration. Patients were analysed in bulbar or spinal subgroups. Correlations and multiple linear regression models were studied.
RESULTS
The mean age at disease onset was 58.4 ± 11.1 years and with a mean disease duration of 17.8 ± 13.6 months. Ultrasound studies of diaphragm thickness in full inspiration correlated with diaphragm CMAP in the whole population and in spinal-onset patients; and were similar in the two groups. Multiple linear modelling showed that FVC, SNIP and MVV were dependent on the change of thickness (p=0.001, 0.001 and 0.020, respectively) and that MIP and MEP were related to diaphragm CMAP p=0.003 and p=0.025, respectively).
CONCLUSION
Diaphragm thickness correlates with Diaphragm-CMAP, except in bulbar-onset patients. Respiratory tests are dependent on both diaphragm thickness and Diaphragm-CMAP.
SIGNIFICANCE
US thickness of the diaphragm correlates with the number of functional motor units as assessed by the phrenic nerve motor amplitude.
Topics: Adult; Aged; Amyotrophic Lateral Sclerosis; Diaphragm; Female; Humans; Male; Middle Aged; Phrenic Nerve; Respiratory Function Tests; Ultrasonography
PubMed: 25971723
DOI: 10.1016/j.clinph.2015.03.024 -
ELife Jan 2020The precise pattern of motor neuron (MN) activation is essential for the execution of motor actions; however, the molecular mechanisms that give rise to specific...
The precise pattern of motor neuron (MN) activation is essential for the execution of motor actions; however, the molecular mechanisms that give rise to specific patterns of MN activity are largely unknown. Phrenic MNs integrate multiple inputs to mediate inspiratory activity during breathing and are constrained to fire in a pattern that drives efficient diaphragm contraction. We show that Hox5 transcription factors shape phrenic MN output by connecting phrenic MNs to inhibitory premotor neurons. genes establish phrenic MN organization and dendritic topography through the regulation of phrenic-specific cell adhesion programs. In the absence of genes, phrenic MN firing becomes asynchronous and erratic due to loss of phrenic MN inhibition. Strikingly, mice lacking genes in MNs exhibit abnormal respiratory behavior throughout their lifetime. Our findings support a model where MN-intrinsic transcriptional programs shape the pattern of motor output by orchestrating distinct aspects of MN connectivity.
Topics: Animals; Genes, Homeobox; Mice; Motor Neurons; Phrenic Nerve; Respiration; Transcription, Genetic
PubMed: 31944180
DOI: 10.7554/eLife.52859