Developmental regulation of membrane traffic organization during synaptogenesis in mouse diaphragm muscle

In innervated adult skeletal muscles, the Golgi apparatus (GA) displays a set of remarkable features in comparison with embryonic myotubes. We have previously shown by immunocytochemical techniques, that in adult innervated fibers, the GA is no longer associated with all the nuclei, but appears to be concentrated mostly in the subneural domain under the nerve endings in chick (Jasmin, B. J., J. Cartaud, M. Bornens, and J.-P. Changeux. 1989. Proc. Natl. Acad. Sci. USA. 86:7218-7222) and rat (Jasmin, B. J., C. Antony, J.-P. Changeux, and J. Cartaud. 1995. Eur. J. Neurosci. 7:470-479). In addition to such compartmentalization, biochemical modifications take place that suggest a functional specialization of the subsynaptic GA. Here, we focused on the developmental regulation of the membrane traffic organization during the early steps of synaptogenesis in mouse diaphragm muscle. We investigated by immunofluorescence microscopy on cryosections, the distribution of selected subcompartments of the exocytic pathway, and also of a representative endocytic subcompartment with respect to the junctional or extrajunctional domains of developing myofibers. We show that throughout development the RER, the intermediate compartment, and the prelysosomal compartment (mannose 6-phosphate receptor-rich compartment) are homogeneously distributed along the fibers, irrespective of the subneural or extrajunctional domains. In contrast, at embryonic day E17, thus 2-3 d after the onset of innervation, most GA markers become restricted to the subneural domain. Interestingly, some Golgi markers (e.g., alpha-mannosidase II, TGN 38, present in the embryonic myotubes) are no longer detected in the innervated fiber even in the subsynaptic GA. These data show that in innervated muscle fibers, the distal part of the biosynthetic pathway, i.e., the GA, is remodeled selectively shortly after the onset of innervation. As a consequence, in the innervated fiber, the GA exists both as an evenly distributed organelle with basic functions, and as a highly differentiated subsynaptic organelle ensuring maturation and targeting of synaptic proteins. Finally, in the adult, denervation of a hemidiaphragm causes a burst of reexpression of all Golgi markers in extrasynaptic domains of the fibers, hence showing that the particular organization of the secretory pathway is placed under nerve control.

Simplified technique of heart-lung transplantation

Well-known complications of heart-lung transplantation include mediastinal bleeding and phrenic nerve injury. Conventional technique places the hila behind the phrenic nerves. We have placed the hila in front of the phrenic nerve in our last 10 patients, using direct caval anastomoses when feasible. This minimizes traction on and dissection around the phrenic nerves, and allows anterior rotation of the heart-lung block for easier hemostasis of the posterior mediastinum after implantation.

[Effect of halothane on ventilation and arterial blood gases in rats with and without diaphragmatic paralysis]

Some patients with diaphragmatic paralysis or dysfunction maintain ventilation by use of other muscles. Anaesthesia, in modifying the performance of these muscles, presents a potential risk to such patients. To evaluate this risk, the effects of halothane on ventilation and arterial blood gases were studied on a model of bilateral diaphragmatic paralysis, the phrenectomized rat. The study was performed on 43 rats. Success of phrenectomy was confirmed at laparotomy, which did not result in blood gas changes. Laparotomy was performed in 23 rats and a carotid artery was catheterized. In 11 control rats, phrenic nerves were exposed but not sectioned, and in 12 other rats, the phrenic nerves were sectioned. Ventilation was measured by plethysmography in awake rats before and after surgery and in the same rats anaesthetized with halothane 1.1%. In the 23 rats, a decrease in weight and core temperature was observed after operation and this was more marked in phrenectomized than in control rats. In the 11 control rats, ventilation increased postoperatively without change in blood gases. In these rats, halothane caused a decrease in minute ventilation and PaO2 and an increase in PaCO2. Phrenectomy in awake rats led to an increase in minute ventilation, hypoxaemia and hypercapnia. In these rats, halothane led to death in three and a decrease in minute ventilation, with hypercapnia and hypoxaemia in the nine other rats. Blood gas changes were greater than in anaesthetized controls. In the intact rat, halothane leads to blood gas changes comparable to those observed in other species and humans. The present study confirms the effects of halothane on respiratory muscles other than the diaphragm and demonstrates the severe respiratory risk of anaesthesia in patients whose ventilation is maintained by these muscles.

Diaphragmatic flutter presenting as inspiratory stridor

Diaphragmatic flutter is a rarely reported disorder in which the diaphragm involuntarily contracts at a rapid rate. We report a unique case in which diaphragmatic flutter was associated with inspiratory stridor and was severely disabling. A new approach to the treatment of this condition, phrenic nerve crush, provided an optimal outcome, with resolution of symptoms and the return of normal diaphragmatic function. Pathophysiology and treatment of this condition are discussed.

Electrophrenic respiration after intercostal to phrenic nerve anastomosis in a patient with anterior spinal artery syndrome: technical case report

Long-term positive pressure mechanical ventilation has been the standard of care for patients with respiratory insufficiency caused by high cervical spine injury. Stimulation of the phrenic nerves, and thus the diaphragm, with an implanted phrenic nerve pacemaker has provided adequate ventilation and an alternative to the standard. Diaphragmatic pacing, also known as electrophrenic respiration, requires an intact phrenic nerve to act as a conduit for the applied stimulus. Propagation of the stimulus is impossible if the injury sustained has led to axonal loss in the phrenic nerve. This may be expected if the damage to the spinal cord is at the C3-C5 level. If the cell bodies of the motor neurons in this region have been damaged, or direct injury to the phrenic nerve has occurred, then diaphragmatic pacing is not feasible by the traditional method. Microsurgical repair of peripheral nerves and nerve grafting have provided the impetus for research into anastomosis of a viable intercostal nerve to a nonfunctional phrenic nerve, with subsequent reinnervation of the diaphragm. Once successful axonal regeneration and diaphragmatic reinnervation have occurred, the distal phrenic nerve may then be paced. This case documents the first successful institution of electrophrenic respiration after intercostal to phrenic nerve anastomosis.

Brachial plexus injury with cough attack: case report

Cough attacks elicited by movement of the neck and right arm are reported in a patient who had sustained several shoulder injuries and who had an anterior scalenectomy. The coughing was accompanied by weakness in the right upper limb. At exploration, the phrenic nerve was found adhered to the brachial plexus. The cough attacks disappeared, and the weakness of the right upper limb improved somewhat after lysis of the adhesions between the phrenic nerve and the plexus and after external neurolysis of the upper, middle, and lower trunks. Postoperatively, the patient could elevate his right arm without coughing.

Phrenic nerve reinnervation of the cat's larynx: a new technique with proven success

Reinnervation of the posterior cricoarytenoid muscle (PCA) should provide vocal cord abduction on inspiration, and passive adduction to enable phonation. Previous investigators have shown that reinnervation is possible, but results have not been clinically encouraging. When reinnervation was successful, the question remained whether it was provided by the transplanted nerve or by the ingrowth of adjacent nerves. In this study the phrenic nerve was transplanted directly into the PCA in a series of 12 cats. Fibrin glue was used to overcome nerve trauma and to prevent retraction of the nerve from the PCA. Laryngoscopy, electromyography, and retrograde labeling of the phrenic motoneurons provided evidence of functional reinnervation in 9 cats. Partial or complete failure in the remaining 3 was due to retraction of the nerve from the muscle. These results appear to justify trials of the procedure in humans.

Selective laryngeal abductor reinnervation in cats using a phrenic nerve transfer and ORG 2766

Reinnervation of the recurrent laryngeal nerve following nerve injury often leads to laryngeal synkinesis. Selective reinnervation of adductor and abductor muscles might be able to avoid synkinesis. This study presents the results of selective abductor reinnervation in cats, using a phrenic nerve transfer to the recurrent laryngeal nerve and directing all reinnervating axons toward the abductor muscle. Simultaneously, a blind, placebo-controlled, pilot study was performed to evaluate the capacity of ORG 2766, administered subcutaneously (25 micrograms/kg per 48 hours), to facilitate reinnervation by stimulation of axon sprouting. Reinnervation surgery was performed in 10 cats. Postoperative evaluation included videolaryngoscopy, electromyography, histological examination, and quantification of reinnervating axons. Nine cats could be evaluated, of which eight demonstrated electromyographic and laryngoscopic activity as soon as 6 weeks following surgery. The one cat showing no abduction was found to have an inadequate nerve anastomosis and was marked as a surgical failure. After 10 weeks, near-normal or more than normal abduction was seen in the eight cats, and histological proof of reinnervation was obtained in seven of them; one cat could not be evaluated histologically owing to unsuccessful fixation. Although no conclusive evidence was obtained concerning the effect of ORG 2766, the tendencies found warrant further experiments with this compound on laryngeal reinnervation.

Respiration after phrenicotomy and hydrocortisone treatment in anaesthetized rats

The study was designed to determine the extent to which respiratory muscle wasting, resulting from corticosteroid-induced atrophy, may affect respiration in normal rats and in rats with denervated diaphragm. Twenty four male Wistar rats were divided into four groups: 1) controls with sham operation (SX) and vehicle injections: 2) SX with eight hydrocortisone (HC) injections (60 mg.kg-1.day-1 i.m.); 3) phrenicotomized (PX), injected with vehicle; 4) PX and HC-treated. HC treatment was started on the thirteenth day after surgery. Under urethane anaesthesia, tidal volume, respiratory rate, arterial carbon dioxide tension (PaCO2) and occlusion pressure were measured at rest and after 5 min of stimulated-breathing induced by added dead space 22nd day after surgery. All HC-treated animals decreased body weight by 32% compared to untreated rats. The diaphragm weight was reduced in PX rats by 29%, and after HC by 44%, while in PX rats with HC treatment diaphragm weight decreased by only 21%. PX rats (HC-untreated) had the lowest minute ventilation and occlusion pressure. There was no difference in ventilation between control and both HC-treated groups at rest. However, ventilation in PX and HC-treated rats did not increase upon stimulation, and the occlusion pressure increased significantly only in the HC-untreated animals. We conclude that in the rat, HC treatment did not affect resting ventilation, but it impaired ventilation performance, during increased demand, in animals handicapped by diaphragm denervation.

Endoscopic laser medial arytenoidectomy for airway management in bilateral laryngeal paralysis

A review of our recent experience in patients with bilateral laryngeal paralysis is described. While we continue to use phrenic nerve transfers in patients with mobile arytenoids, patients with fixed arytenoids generally require some sort of vocal cord lateralization, either by arytenoidectomy and arytenoidopexy or by partial vocal cord resection. The endoscopic laser medial arytenoidectomy is a convenient and effective method for opening the posterior glottic airway. One arytenoid is reduced medially with the carbon dioxide laser. After about 3 months the opposite arytenoid can be treated similarly, if necessary. The procedure does not appear to affect arytenoid mobility, as the posterior commissure mucosa and underlying interarytenoid muscle are protected and hence unaffected by the procedure. Those patients with at least one mobile arytenoid cartilage are candidates for posterior cricoarytenoid muscle reinnervation. Although ansa cervicalis and phrenic nerve techniques have been described, the author has concentrated efforts on the phrenic nerve. This report describes the endoscopic laser medial arytenoidectomy procedure, while the phrenic nerve patients will be reported in a subsequent manuscript.

Effects of in utero phrenic nerve section on the development of collagen and elastin in lamb lungs

Interference with fetal breathing movements is known to retard morphologic development of the lung and to reduce compliance. We hypothesized that the lower compliance might be in part due to effects on lung structural proteins. We studied the effects of phrenic nerve section in utero on lung compliance and on the lung contents of collagen, elastin, and DNA. At 110 to 112 days of gestation, one fetal lamb in each of 12 twin pregnancies had either both phrenic nerves cut (PX) or a sham operation (S). The other twin was left unoperated (Upx, Us) as a control. They were killed 14 to 22 days later, and the concentrations in lung parenchyma of collagen (as hydroxyproline HPro), elastin, and DNA were measured, together with lung compliance and dry and wet weight. Paired comparisons were made (PX versus Upx and S versus Us). Both operated groups (PX, S) had smaller lungs with lower water content than did their unoperated twins. Absolute static compliance in PX was reduced, but compliance relative to lung weight was unchanged, and there was no significant difference between S and Us. There were no significant effects of PX on the concentrations of HPro, elastin, and DNA, or on the elastin/collagen ratio. Compliance was not correlated with either HPro or elastin content. HPro content increased significantly with gestational age in all groups. It is concluded that phrenic nerve section retards the increase of lung compliance and possibly air space, but it does not affect the overall rate of lung cell proliferation or of deposition of elastin or collagen.(ABSTRACT TRUNCATED AT 250 WORDS)

Phrenic nerve pacing in two young quadriplegic ventilator-dependent patients

Patients who survive high cervical injury are usually dependent on mechanical ventilation and tracheostomy if the lesion above C3 is complete. We report our experience with phrenic nerve pacing (PNP) to achieve ventilator-independence in two young quadriplegic patients. A diaphragm conditioning programme, and combination of low frequency electrophrenic stimulation within each inspiratory burst and low breathing frequency enabled both patients initially to achieve continuous 24 hour ventilation independent of mechanical ventilation. One patient reverted to overnight mechanical ventilation (six hours) after three years. PNP should be considered in ventilator dependent patients with high cervical injury to achieve independence and improve quality of life.

Phrenicotomy in the rat: acute changes in blood gases, pH and body temperature

Adult male rats were used to compare blood gases, pH and body temperature (Tb) before and after acute bilateral phrenicotomy. Under anaesthesia a femoral artery was catheterised and ties were placed round the phrenic nerves of seven rats (PNX group), while in five rats the ties were placed in the vicinity of the phrenic nerves (SHAM group). Twenty-four hours after surgery arterial blood samples were collected during quiet wakefulness (QW) and grooming (G), before and 1 h after the ties were pulled, and analysed for PO2, PCO2 and pH. No changes were detected in the SHAM samples taken before and after the ties were pulled. In the PNX group a significant decrease in Tb occurred (QW, 0.6 degrees C; G, 1.5 degrees C). Following PNX PaO2 decreased by 11.2 mmHg (QW) and 10.0 mmHg (G); PaCO2 increased by 2.6 mmHg (QW) and 2.4 mmHg (G) and pH fell by 0.04 (QW) and 0.03 (G). All changes except in PaCO2 (QW) were significant. It is concluded that the changes in Tb, blood gases and pH which follow phrenicotomy in the rat are due to an increase in dead space ventilation (VD) and a small reduction in alveolar ventilation (VA) associated with a faster, shallower pattern of breathing.

Innervation of the paralyzed laryngeal muscles by phrenic motoneurons. A quantitative study by light and electron microscopy

In the cat, inspiratory opening of the paralyzed glottis recovered after unilateral or bilateral reinnervation of the posterior cricoarytenoid (PCA) muscles by phrenic axons. The morphometric analysis of the regenerated recurrent laryngeal nerves (RLNs), showed that proliferation was abundant; 4 months after the nerve anastomosis, more than 500 myelinated axonal branches repopulated the RLNs. The mean diameter of motor axons (3.5 to 5.0 microns) was lower than in normal phrenic and RLN (8 to 10 microns), and the mean internode length was about half that of the normal RLN. Histochemical examination of the PCA muscle revealed that muscle fiber composition (44% type I and 56% type II muscle fiber) was fairly similar to that of normal PCA. The contraction time of the reinnervated muscles was as long as 60 msec at the time of movement recovery, but it shortened to 25 to 30 msec when the reinnervation time increased. These anatomical and functional results support the choice of the phrenic nerve for laryngeal reinnervation.

Facial reanimation after facial nerve injury

Patients with facial paralysis are often seen in neurosurgical practice. Obtaining full facial symmetry and function after facial nerve damage presents the neurosurgeon with a difficult challenge. Various surgical techniques have been developed to deal with this problem. These include primary nerve repair, nerve to nerve anastomosis, nerve grafting, neurovascular pedicle grafts, regional muscle transposition, microvascular muscle transfers, and nerve transfers. Patient selection, timing of surgery, and details of surgical technique are discussed. The results of hypoglossal-facial anastomosis in 24 patients are described.

Muscle transfer for laryngeal paralysis. Restoration of inspiratory vocal cord abduction by phrenic-omohyoid transfer

Omohyoid muscle transfer to the denervated posterior cricoarytenoid muscle (PCA) was performed in three monkeys. The transposed omohyoid muscle was reinnervated by the phrenic nerve by performing nerve anastomosis prior to muscle transfer. The muscles were sutured over the denervated ipsilateral PCA muscle to allow for neurotization of the denervated PCA muscle in such a way as to reproduce the directional vector of PCA contraction, eg, to mimic the directional pull of the PCA muscle. The muscle flaps were found to be long enough to reach the contralateral PCA muscle, confirming that the technique might be used ultimately for bilateral simultaneous PCA reinnervation. Each animal achieved reinnervation. The superiorly based omohyoid muscle flap was found to more closely emulate the size and orientation of the underlying PCA muscle. Electromyography, videolaryngoscopy, and histologic examination were used to confirm the results. The procedure has the potential for PCA muscle replacement in long-standing cases of paralysis with PCA denervation atrophy as well as for reinnervating a denervated PCA muscle.

Alteration in breathing of the awake rat after laryngeal and diaphragmatic muscle paralysis

The respiratory rate (f), tidal volume (VT) and ventilation (V) were measured in 3 groups of rats: 10 rats before and after cutting both recurrent laryngeal nerves (RLNX), 10 rats before and after bilateral phrenicotomy (PNX) and 5 sham transected (SHAMX) rats. All rats were exposed to air and gas mixtures, deficient in O2 and/or enriched with CO2. The barometric method was used to measure ventilatory parameters. The sham operation did not affect breathing pattern or ventilation. In RLNX rats, breathing the various gas mixtures exhibited no changes in V because f uniformly increased as VT declined. Therefore, loss of the neural control of the respiratory functions of the larynx in awake rats exposed to selected gas mixtures has no untoward effects on alveolar ventilation. Changes in ventilation of PNX rats, compared with SHAMX rats, depends on the gas composition breathed. With increasing severity of hypoxia and/or hypercapnia, PNX rats show a marked reduction in alveolar ventilation over that of the SHAMX rats. Thus, when the diaphragm is no longer able to participate in ventilatory responses, gas exchange is likely to become deficient.

After phrenicotomy the rat alters the output of the remaining respiratory muscles without changing its sleep-waking pattern

The respiratory activity of selected rib cage and abdominal wall muscles was studied in intact and bilaterally phrenicotomized (PNX) rats during non-rapid eye movement sleep (nREMS) and REMS. The polygraphic method was used to identify the animal's sleep-waking states before and after PNX. Electromyographic (EMG) recordings were made from the following muscles: the parasternals of the 1st, 3rd, and 5th interspaces; the external and internal intercostals of the 1st, 6th and 10th interspaces; the levator costae attaching to the 10th rib; the scalenus medius; and, the abdominal wall muscles, the external and internal obliques and rectus abdominis. After PNX, all rib cage muscles contracted exclusively during inspiration and all but one increased their activity. The exception was the internal intercostal muscle of the 10th interspace; its activity decreased. The external and internal oblique muscles, both of which were active during expiration in nREMS, also increased their output after PNX: rectus abdominis became an inspiratory muscle. The persistence of phasic activity of respiratory muscles during REMS varied not only from muscle to muscle but from one REMS epoch to another. The sleep-waking pattern of the PNX rat differed in only a minor way from that of the intact rat. Therefore, we conclude that the rat with total paralysis of its diaphragm uses mainly its neurometabolic mechanisms to achieve an adequate level of alveolar ventilation and not neurobehavioral mechanisms.

Root avulsion of brachial plexus in infants and children

Twenty-one patients, under 6 years of age, with root avulsion of the brachial plexus were treated from 1975 to 1987. Among them, 9 had root avulsion of the upper trunk, 2 root avulsion of the lower trunk with middle trunk broken, and 10 root avulsion of the whole brachial plexus. Follow-up of 16 patients showed excellent results in 2 patients, good in 11, fair in 1 and poor in 2. It is suggested that good results can be obtained if multi-paired nerve transfer is adopted in treatment. We conclude that owing to anatomical and physiological characteristics of the respiratory system in children, it is harmful to perform phrenic nerve transfer concomitantly with intercostal nerve transfer. Advisably, two-stage operation is required, otherwise dyspnea and pneumonia are liable to occur. In addition, the time of the operation could be extended to 4-5 years after injury in children, but best results are obtained if the operation is performed within 1 year.

Aminophylline enhances ventilation in phrenicotomized rats

The aim was to test the effects of aminophylline (AP) on breathing of phrenicotomized rats. Fifty seven male rats of the Wistar strain were anaesthetized with 1.3 g.kg-1 urethane i.p. They were phrenicotomized, divided into 6 groups and given 5, 10, 20, 40 and 80 mg.kg-1 AP i.v. or a corresponding volume of saline. Ventilation, tracheal occlusion pressure and arterial blood gases were measured. In all animals phrenicotomy resulted in hypoventilation with corresponding hypoxaemia (from control 11.9 +/- 1.0 to 10.4 +/- 0.8 kPa) and hypercapnia (from control 4.6 +/- 0.5 to 5.5 +/- 0.6 kPa). In the control group (with saline) 4 h later the PaO2 was 8.6 +/- 1.1 kPa and PaCO2 7.2 +/- 0.6 kPa. After AP 1 h after phrenicotomy the minute ventilation increased in a dose-dependent manner by 1-66%. 4 h after phrenicotomy the minute ventilation of rats with 20 and 40 mg.kg-1 of AP was significantly higher than that of the control group. AP prevented hypoventilation when injected into phrenicotomized rats. The results give no unequivocal basis from which to decide the proportion of central and peripheral effects of AP.

Effect of denervation of the phrenic nerve on the action of calcitonin gene-related peptide in rat diaphragm

The effect of denervation on Calcitonin gene-related peptide (CGRP)-induced enhancement of the twitch contraction of skeletal muscle was studied. In rat diaphragm denervated 2 weeks previously, the basal twitch contraction induced by transmural stimulation was about twice that in control muscle, and the basal adenylate cyclase activity and cyclic AMP (cAMP) contents of the tissue were increased. This denervation did not affect the dose-dependent beta -adrenergic stimulation of twitch contraction, but abolished the CGRP-induced enhancement of twitch contraction. The latter phenomenon seems to be caused in part by decrease in CGRP-induced accumulation of cAMP over the basal level, because of increase in the basal cAMP level after denervation. The involvement of another inhibitory second messenger system coupled with CGRP receptors is discussed.

[Adenocarcinoma of the cardia: results of distal esophagectomy and total enlarged gastrectomy using left thoracophrenolaparotomy]

An analysis was made of the results obtained in terms of postoperative complications, mortality and the 5-year survival rate in a series of 23 patients diagnosed as adenocarcinoma of the cardias who underwent total gastrectomy with distal esophagectomy via left thoracophrenolaparotomy, with esophagojejunostomy on a Roux-en-Y loop. We consider the results as favorable and conclude that this procedure has an application in adequately selected patients.

Recovery of inspiratory abduction of the paralyzed vocal cords after bilateral reinnervation of the cricoarytenoid muscles by one single branch of the phrenic nerve

The aim of this study was to provide the bilateral reinnervation of the posterior cricoarytenoid (PCA) muscles by the superior root of the right phrenic nerve. In six adult cats, the right phrenic root was anastomosed to the distal stump of the transected recurrent laryngeal nerve (RLN) on the same side. The RLN adductor branch was then cut and anastomosed to a nerve graft whose end was carried contralaterally and sutured to the left RLN or to the left PCA muscle. The phrenic fibers regrowing along the RLN abductor branch reinnervated the right PCA muscle and restored the inspiratory abduction of the right vocal cord in all the animals. In five of the six cats, the fibers regenerated through the RLN adductor branch and the graft reached the left PCA muscle and also restored the inspiratory opening of the larynx on the left side. Histological nerve examination revealed a fairly symmetrical distribution of the regenerated phrenic axons to the right and left PCA muscles.

Bilateral phrenic nerve palsy associated with benign thyroid goiter

Phrenic nerve palsy secondary to benign thyroid enlargement is a previously unreported complication. Large goiters, particularly substernal, may impinge upon adjacent structures, often leading to significant symptoms such as dysphagia or dyspnea due to airway compression. The phrenic nerve may be stretched by a large goiter along its course in the neck, but the more likely site of injury is the point at which it enters the thoracic cavity adjacent to the first rib. Such an injury, caused by compression, may go unrecognized if unilateral, as symptoms would be uncommon. However, bilateral phrenic nerve palsy can cause significant dyspnea due to pulmonary insufficiency, particularly in an elderly patient with cardio-pulmonary disease. Early operative treatment of the goiter may prevent this complication or limit its severity, thus avoiding permanent nerve injury.

Selective reinnervation of the abductor and adductor muscles of the canine larynx after recurrent nerve paralysis

Functional rehabilitation of the larynx after unilateral vocal cord paralysis was attempted in the dog by selective reinnervation of the laryngeal muscles. The intralaryngeal branches of the right recurrent nerve were dissected. The adductor branch was anastomosed with the ansa cervicalis; the abductor branch was anastomosed with the trunk of the phrenic nerve either within the larynx or through the recurrent nerve, the adductor branch of which was sectioned. Results could be analyzed in seven dogs: mobility of the vocal cord was checked, and electromyography, stimulation of the nerves, and histologic studies were performed. Functional reinnervation of both the adductor and abductor muscles was obtained in only one case, with good abduction. Adduction was recorded in five cases. False-positive results emphasize the necessity of collecting several types of data before concluding that functional reinnervation has been accomplished. The reliability of the procedure can and must be improved.

Mechanism of rib cage inspiratory muscle recruitment in diaphragmatic paralysis

Paralysis of the diaphragm promotes an increase in the activation of the rib cage inspiratory muscles, and previous studies have suggested that this compensation is primarily due to vagal mechanisms (6). To test this hypothesis, we have assessed the effect of diaphragmatic paralysis on the electrical response of 19 parasternal intercostal muscles in eight anesthetized, vagotomized, spontaneously breathing dogs in the supine posture. Complete diaphragmatic paralysis was induced by section of the C5, C6, and C7 phrenic nerve roots in the neck. With the animals breathing room air, diaphragmatic paralysis resulted in a mean 94% increase in the peak height of integrated parasternal activity (p less than 0.001) associated with a 14 mm Hg decrease in arterial PO2 (p less than 0.05) and an 8 mm Hg increase in arterial PCO2 (p less than 0.001). The augmented parasternal activity was unrelated to the duration of inspiration and persisted when the animals were given a hyperoxic gas mixture. Thus the rib cage inspiratory muscles still compensate for diaphragmatic paralysis in the absence of vagal signals and of hypoxemia. This compensation probably results from the considerably augmented CO2 load placed on the extradiaphragmatic muscles.

[Reinnervation of the larynx in an experiment]

In an experiment on five dogs the authors investigated the topographic anatomical relations of the laryngeal recurrent nerve, the vagus, the phrenic nerve and ansa cervicalis. They elaborated a surgical approach to the above nerves. In nine dogs the authors dissected the n. laryngeus recurrens and made anastomoses: an end-to-end anastomosis in three dogs, a bypass anastomosis of the distal stump of the recurrent laryngeal nerve with a separated portion of the trunk of the vagus in two dogs, an end-to-end anastomosis of the distal stump of the recurrent laryngeal nerve with the dissected central portion of the phrenic nerve in four dogs (in one also interposition of the nerve trunk from a small branch of the ansa cervicalis was made). Reaxonization was investigated by histological examination. Satisfactory functional results were achieved after anastomosis of the recurrent laryngeal nerve and the phrenic nerve. Less satisfactory results were obtained when a portion of the vagus was used and subsequent anastomosis of the distal stump of the recurrent laryngeal nerve nad finally after end-to-end anastomosis of the previously dissected recurrent laryngeal nerve.

The effect of chronic biphrenectomy on lung growth and maturation in fetal lambs. Morphologic and morphometric studies

Three fetal lambs underwent phrenic nerve section between Days 99 and 104 of gestation, and 2 twins of the experimental animals underwent sham operation at the same time. When they were killed at 135 to 137 days of gestation, the experimental animals had lower specific lung weights (g/kg) and lung volumes (ml/kg) and had delayed lung development by subjective microscopy. Light microscopic morphometry showed significantly less volume proportion of potential gas-exchanging air spaces, less parenchyma, and more gas-exchanging wall. Scanning electron microscopy confirmed these findings and also showed that the transition zone between conducting and gas-exchanging areas was less sharp in the experimental animals, attributed to diminished alveolarization of distal conducting airways. Transmission electron microscopy, together with morphometry, showed a diminished maturation of alveolar Type II cells, with fewer osmiophilic lamellar bodies and more glycogen. The number of mesenchymal-Type II cell interconnections was not altered. Maturation of bronchiolar epithelium was not affected, and mesenchymal-epithelial connections were not observed. We conclude that bilateral phrenic nerve section not only diminishes lung growth, but also diminishes intrauterine maturation of the alveolar well. Maturation of bronchiolar epithelium may not be affected by fetal respiration.

Experimental laryngeal reinnervation by phrenic nerve implantation into the posterior cricoarytenoid muscle

Under general anaesthesia, 5 dogs underwent sectioning of the right recurrent nerve followed by implantation of the phrenic nerve into the posterior cricoarytenoid (PCA) muscle. Some 6-7 months later the dogs were sacrificed after registration of vocal cord motility. Still photographs and movie film of the larynx were taken during quiet and forced respiration and at electrical stimulation of the implanted phrenic nerve. The PCA and vocal muscles were removed for histochemical studies. We found practically no abductory movement of the vocal cord on the reinnervated side, either during quiet or forced respiration. During forced inspiration there was, however, a slight medial bowing of the right vocal cord. At electrical stimulation there was a sphincteric movement of the entire larynx. Histochemistry showed a reinnervation picture of both the PCA and the vocal muscles on the experimental side. The conclusion drawn from this study is that axonal escape, probably from the implantation site, results in an unwanted reinnervation of laryngeal adductor muscles, which neutralize the abducting effect of the PCA muscle during inspiration. This method therefore does not seem to be suitable as a treatment alternative for bilateral recurrent nerve paralysis.

Technique for implantation of phrenic nerve electrodes

Permanent ventilatory support is necessary in patients with upper motor neuron respiratory muscle paralysis and central alveolar hypoventilation. Weaning these patients from chronic ventilation is extremely advantageous. Diaphragm pacing accomplishes this goal. In the past implantation of phrenic nerve electrodes has been undesirable either because the procedure is too extensive or because of the high failure rates. This report describes a simple, expeditious, and uniformly successful technique for bilateral phrenic nerve electrode placement.

Restoring abduction of paralyzed vocal cords in the cat using selective laryngeal reinnervation by phrenic motoneurons

The aim of this work was to reestablish the respiratory function of the paralyzed larynx through reinnervation of the posterior cricoarytenoid (PCA) muscle by phrenic motoneurons. In nine adult cats the adductor branch of the recurrent laryngeal nerve (RLN) of one side was cut and ligated, while the abductor branch was left intact. The whole RLN was then transected lower in the neck and its distal stump anastomosed to the upper branch of the phrenic nerve. Periodical laryngoscopies under ketamine anesthesia assessed that the inspiratory abduction of the paralyzed vocal cord recovered within 45 days to 60 days in all cats. Abduction was caused by reinnervation of the PCA muscle from phrenic motoneurons, as demonstrated by electrophysiological and anatomical (retrograde transport of horseradish peroxidase) testings.

The human posterior cricoarytenoid (PCA) muscle and diaphragm. A histochemical comparison as a basis for reinnervation attempts

PCA (posterior cricoarytenoid) muscles and biopsies from the SCM (sterno-cleidomastoid) muscles as well as the diaphragm were serially sectioned and incubated for myofibrillar ATPase and selected metabolic enzymes. The three main fibre types were present in all muscles, although some PCA muscles seemed to lack IIB fibres. The mean fibre type pattern of the PCA muscle was 57% type I, 36% type IIA and 7% type IIB, as compared with 42% type I, 42% type IIA and 16% type IIB in the diaphragm. All fibre types of the PCA muscle and the diaphragm were significantly more oxidative and less glycolytic than the corresponding SCM muscle fibres. Most striking was the finding of high 3-HBDH activity in the PCA and diaphragm muscle fibres, especially in type I.

Functional results after experimental reinnervation of the posterior cricoarytenoid muscle in dogs

The purpose of the present investigation was to test and compare three different types of experimental posterior cricoarytenoid (PCA) muscle reinnervation. Dogs were subjected to reinnervation by the recurrent nerve itself (self-reinnervation) (n = 6), by the ansa cervicalis nerve (n = 5) or by the phrenic nerve (n = 5). In all but three of the self-reinnervation cases the adductor branch of the nerve was cut and ligated. Three to seven months postoperatively--depending upon the experimental approach--the animals were anesthetized and the function of the vocal cords was tested, visually evaluated and photographed. In the self--reinnervated larynges there were no observable movements on the reinnervated side during quiet inspiration, while during forced inspiration there were small but inconsistent movements. In the larynges reinnervated by the ansa cervicalis nerve no movements could be observed on the reinnervated side during either quiet or forced respiration. In four out of five larynges reinnervated by the phrenic nerve there were larger excursions on the reinnervated side as compared to the normal side during quiet respiration. During forced inspiration the excursions increased on both sides, but relatively more on the normal side. In all experiments indirect electrical stimulation gave large excursions on the experimental side indicating successful reinnervation. It is concluded that the phrenic nerve appears to be the best alternative if reinnervation of the PCA muscle in paralyzed larynges is attempted.

A histochemical evaluation of experimentally reinnervated canine laryngeal muscles

Sixteen dogs underwent different types of experimental reinnervation procedures of the posterior cricoarytenoid (PCA) muscle - reinnervation by the recurrent nerve itself (self-reinnervation) (n = 6), by the ansa cervicalis nerve (n = 5) or by the phrenic nerve (n = 5). After functional evaluation the normal left and the reinnervated right PCA muscles were removed for histochemical analysis. Cryostat sections were incubated for actomyosin ATPase, NADH-TR and alpha-GPDH. All muscles showed microscopical evidence of successful reinnervation. There was a slight change in the muscle fiber type composition in the reinnervated muscle as compared to the normal side. Incubations for the NADH-TR and alpha-GPDH showed less staining intensity in the reinnervated muscles. The histochemical differences between normal and reinnervated muscles were small, however, and probably of minor importance with regard to the function of the muscles.

Successful reinnervation of the diaphragm after phrenic nerve transection

A 16-month-old infant presented with bilateral diaphragmatic paralysis and respiratory failure after removal of a thoracic teratoma. Right diaphragmatic function recovered after end-to-end anastomosis of a transected phrenic nerve. We conclude that phrenic nerve repair can restore diaphragmatic function and should be attempted in selected cases of diaphragmatic paralysis due to phrenic nerve injury.

Successful repair of a transected phrenic nerve with restoration of diaphragmatic function

This report describes the feasibility of restoring motor function of the diaphragm by early repair of a transected phrenic nerve, and discusses causes and consequences of phrenic nerve damage.

Electrophrenic respiration following anastomosis of phrenic with branchial nerve in the cat

Patients with high spinal cord injuries may be totally dependent on artificial ventilation. Prolonged use of mechanical devices requires intensive care, which restricts the mobility of these patients. Electrophrenic respiration has been used with success to overcome this difficulty. However, a prerequisite for electrophrenic respiration is a viable phrenic nerve. Patients with spinal cord injuries at the C-3 to C-5 levels do not have a viable phrenic nerve due to gradual degeneration of axons in these nerves. In the present study on cats, the authors caused degeneration in one of the phrenic nerves by sectioning it low in the neck. Then the distal end of the phrenic nerve was anastomosed to the proximal segment of a sectioned brachial nerve. Sixteen to 32 weeks were allowed for the growth of brachial axons into the anastomosed phrenic nerve. Each cat served as its own control because one of the phrenic nerves was left intact. It was observed that pacing of the anastomosed phrenic nerve produced respiration comparable to spontaneous respiration or to respiration induced by pacing the intact phrenic nerve. Lack of rhythmic bursts of electrical activity in the anastomosed phrenic nerve and electromyographic activity in the ipsilateral hemidiaphragm confirmed that the anastomosed phrenic nerve remained disconnected from the respiratory motoneurons. Abundance of collagen matrix in the electron micrographs of the anastomosed phrenic nerve indicated that degeneration of the axons of phrenic motoneurons had occurred and the brachial nerve had grown into the phrenic nerve stump. These results indicate that electrophrenic respiration may be possible in patients with spinal cord injuries at the C-3 to C-5 vertebral levels if the phrenic nerve is kept viable by anastomosing it to a branch of the brachial nerve.

[Facial nerve reconstruction--after the operation of C-P angle tumor]

Nineteen patients who undergo facial nerve reconstruction after the operation of cerebellopontine angle tumor from 1964 to 1981 were investigated. Eighteen cases were of acoustic neurinoma, and one was of low grade astrocytoma. Spinal accessory-facial nerve anastomosis was performed in thirteen cases. Cross facial nerve graft was done in three cases. Hypoglossal-facial nerve anastomosis, phrenico-facial nerve anastomosis, and intracranial direct anastomosis were done in one case each. In spinal accessory-facial nerve anastomosis cases, good result was obtained only in 30%, but using microsurgical technique since 1972, its rate went up to 50%. In cross facial nerve anastomosis cases in which two sural nerve grafts were used and the zygomatic and the buccal branches of the right and left connected each other, only one of three revealed good result. The cases of hypoglossal and intracranial direct facial anstomosis resulted in good recovery. As our conclusion, it is difficult to obtain the powerful reinnervation by means of the spinal accessory facial nerve anatomosis and the cross facial nerve graft. Therefore, the best method to be chosen in facial nerve reconstruction seems intracranial direct anastomosis. If the method is impossible, hypoglossal-facial nerve anastomosis should be chosen as the second best. The cross facial nerve graft seems to be leaving much room for technical improvement.

Respiratory function after paralysis of the right hemidiaphragm

We studied a 45-yr-old man with normal lung function before and 7 wk after right phrenic nerve crush. Total lung capacity, functional residual capacity, and forced vital capacity decreased with residual volume remaining unchanged. Static compliance was also unchanged. Ventilatory response to CO2 (delta Ve/delta PaCO2) was preserved, but P0.1 response to CO2 (delta P0.1/delta PaCO2) increased. Analysis of raw mouth pressure suggested that these responses were the result of a new rapid pattern of inspiratory pressure development. Regional washout was slowed on the side with paralysis, but the normal apex-to-base gradient of regional volumes was preserved. Inhaled 133Xe boluses were distributed away from the side of paralysis, and bolus distribution changed relatively little with increased flow. These results suggested that in compensation for paralysis of a hemidiaphragm, a new pattern of inspiratory muscle recruitment developed, involving more rapid contraction of the remaining muscles of inspiration.

[Surgery of the recurrent nerve. Studies on the problem of functional rehabilitation after recurrent nerve injuries]

One of the most important problems involved in rehabilitation surgery of the recurrent nerve arises from the fact that this nerve carries fibers displaying antagonistic activities which is an accordance with the different functions of the larynx as an organ of phonation, respiration and swallowing. As a consequence of random reinnervation of the internal laryngeal musculature taking place after reconstruction of the N. recurrens, the complicated sequence of vocal cord movements, varying with the different functions of the larynx, cannot be restituted in its proper order. To avoid such functional failures, a method for selective reinnervation of the M. posticus as the most important glottis opener on the one hand, and of the glottis-closing musculature on the other, was tested in animal experiments. Two different anastomoses are forming the basis of the experimental model. 1. Phrenicus-ramus posterior anastomosis for reinnervation of the M. posticus. 2. Recurrens-ramus anterior anastomosis for reinnervation of the adductors. The results show that successful reinnervation of the abductor by means of the phrenic nerve, and of the adductors by means of the recurrence nerve separated from the vagus, can be achieved, and that this reinnervation also permits satisfactory phase-synchronous regulation.