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.