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Forensic Pathophysiology of Asphyxial Death
Published in Sudhir K. Gupta, Forensic Pathology of Asphyxial Deaths, 2022
It supports the muscles of inspiration and expiration. Respiration is regulated by two different neural mechanisms: the first one is for voluntary control and the second for autonomic control. The cerebral cortex is the seat controlling the voluntary respiratory movements via transmission of regulating impulses through the corticospinal tracts to the respiratory motor neurons. The autonomic control system is orchestrated by a group of pacemaker cells in the medulla oblongata, which activate the motor neurons in cervical and thoracic spinal cord controlling the inspiratory muscles. Phrenic nerve originates from the cervical roots C2–C4 and controls the diaphragm, while external intercostal muscles are controlled by the thoracic nerves of the spinal cord.
Anatomy, Physiology, and Dysfunction of the Diaphragm
Published in Massimo Zambon, Ultrasound of the Diaphragm and the Respiratory Muscles, 2022
Partial or complete healing of phrenic nerve damage occurs often but commonly requires a long time (up to 3 years) (43,44). Idiopathic or more clearly defined (e.g., chronic inflammatory demyelinating polyneuropathy and Charcot–Marie–Tooth disease) peripheral neuropathies follow their clinical course.
Complications of upper extremity bypass grafting for occlusive and aneurysmal disease
Published in Sachinder Singh Hans, Mark F. Conrad, Vascular and Endovascular Complications, 2021
Dissection of the subclavian artery can lead to injury of the vagus and phrenic nerves. If the vagus nerve is injured near the common carotid artery, the patient will experience paralysis of the ipsilateral vocal cord from the recurrent laryngeal nerve. This can cause life-threatening airway issues, and any persistent hoarseness after surgery should prompt an evaluation of the cords. Injury to the phrenic nerve will lead to paralysis of the diaphragm. Unilateral diaphragmatic paralysis results in loss of lung volume on chest x-ray. Many patients are asymptomatic at rest but will experience shortness of breath with exertion. For traction injuries, this may be transient, but in some cases, the patient's condition never improves.
Unilateral diaphragmatic dysfunction following thoracic outlet surgery diagnosed by point-of-care ultrasound
Published in Journal of Community Hospital Internal Medicine Perspectives, 2021
Wesley Cain, Sunny S. Cai, Christian Salcedo, Steven Embry, Melissa Scalise
Unilateral diaphragmatic paralysis or weakness following injury to the phrenic nerve results can be a rare complication after thoracic outlet surgery [2,3]. Patients with unilateral diaphragmatic dysfunction are usually asymptomatic at rest but may have exertional dyspnea and decreased exercise performance [4]. Patients may also note a worsening in supine position [5]. Workup of patients with diaphragm dysfunction may consist of chest radiographs, computed tomography, fluoroscopy, pulmonary function testing, phrenic nerve conduction studies, and transdiaphragmatic pressure measurements. These diagnostic tests have variable sensitivity and specificity, and some are invasive or uncomfortable examinations as well as expose patients to radiation [4]. Point-of-care ultrasound is non-invasive and has been shown to have similar accuracy to most other modalities to evaluate for diaphragm dysfunction [5–7]. For example, a prospective study of 82 patients with dyspnea referred to the EMG laboratory for evaluation of neuromuscular respiratory failure found ultrasound to be 93% sensitive and 100% specific for the diagnosis of neuromuscular diaphragmatic dysfunction [7].
Thoracoscopic intercostal to phrenic nerve transfer for diaphragmatic reanimation in a child with tetraplegia
Published in The Journal of Spinal Cord Medicine, 2021
Jacob Latreille, Erika B. Lindholm, Dan A. Zlotolow, Harsh Grewal
The phrenic nerve receives input from the ventral rami of C3, C4, and C5 and descends superficially to the anterior scalene towards the diaphragm where it separates into three branches to provide innervation inferiorly.2,13 It is the only nerve to supply motor innervation to the diaphragm. Dysfunction of the phrenic nerve therefore leads to pneumonia, sleep disorders, pulmonary effusion, atelectasis, and ventilator dependency.9 These injuries can often be assessed by NCS and needle electromyography in conjunction with M-mode ultrasound.14,15 If spinal cord levels C3, C4, or C5 are all within the zone of injury to the spinal cord, pacing the phrenic nerve is impossible due to Wallerian degeneration of the nerve distally and inability to propagate electrical signals.13 To overcome the loss of axons in the phrenic nerve, multiple nerve transfers have been recommended. The goal is to achieve ventilator independency; an outcome associated with increased mobility, speech, quality of life, and reduced health care costs.9
Stimulation of abdominal and upper thoracic muscles with surface electrodes for respiration and cough: Acute studies in adult canines
Published in The Journal of Spinal Cord Medicine, 2018
James S. Walter, Joseph Posluszny, Raymond Dieter, Robert S. Dieter, Scott Sayers, Kiratipath Iamsakul, Christine Staunton, Donald Thomas, Mark Rabbat, Sanjay Singh
There is a continuing need to develop improved methods to assist with ventilation and cough following SCI, particularly in individuals with tetraplegia.27 Current results with surface electrodes and the 12-Channel Neuroprosthetic Platform extends our prior findings toward this goal.11,25–31 Further study is needed, because some of the current studies were limited to only two or three animals and other limitations cited above. Clinical testing of some of the current methods, however, is warranted because surface electrode stimulation is widely used in patients with SCI.19–23 Such testing depend on the level of spinal cord injury because the stimulation has to be applied in non-sensate areas. For SCI at low spinal cord levels, surface stimulation is limited to lower thoracic and abdominal muscles. For individuals with cervical level SCI, surface stimulation could be applied to both extradiaphragmatic muscles for expiration. For individuals receiving phrenic nerve stimulation for diaphragmatic inspiration, stimulation of the extradiaphragmatic muscles could be coordinated with the diaphragm. Monitoring during upper thorax stimulation should include EKG recording to assess the occurrence of heart arrhythmia, which, if observed, would mandate stopping stimulation.