Minimally invasive diaphragm plication in an infant

We report the use of video-assisted thoracic surgery to plicate the diaphragm after phrenic nerve injury associated with an operation for congenital heart disease. Right diaphragm paresis developed in a cyanotic newborn girl with pulmonary atresia and intact ventricular septum after a right modified Blalock-Taussig shunt. Diaphragm plication was performed endoscopically and the patient recovered. Refinement of technique and instrumentation may allow wider application of video-assisted thoracoscopic plication of the diaphragm in neonatal and pediatric patients.     

Randomized study of chemotherapy and surgery versus radiotherapy for stage IIIA non-small-cell lung cancer: a National Cancer Institute of Canada Clinical Trials Group Study

We treated two children with the unusual complication of ulnar nerve palsy after closed both-bone forearm fractures. Both patients developed an ulnar claw-hand deformity within 7 weeks of injury that resolved spontaneously by 20 weeks postinjury with nonoperative treatment. No patient showed any signs or symptoms of an ischemic compartment syndrome. Both nerve injuries were identified immediately at the time of fracture by a careful neurologic examination. This avoids confusion with a postreduction nerve entrapment injury or ischemic injury after a localized compartment syndrome, which may have considerably different treatments and outcomes. We recommend that a careful neurologic examination be recorded before any manipulative reduction of forearm fractures in children. If an ulnar nerve palsy is detected, it is probably a result of nerve contusion and should resolve without the need for surgical exploration.     

A new strategy of muscle transposition for treatment of shoulder deformity caused by obstetric brachial plexus palsy

Cross-innervation (caused by misdirection of regenerated axons), muscular imbalance (caused by muscle paresis or earlier recovery), and growth are the three main causes of shoulder deformity due to obstetric brachial plexus palsy. If perioperative studies demonstrate the existence of muscle recovery by cross-innervation, a new strategy of muscle transposition to minimize the influence of cross-innervation is used. Release of antagonistic muscles (pectoralis major and teres major muscles) and augmentation of paretic muscles (transferring teres major to the infraspinatus muscle, reinserting both ends of the clavicular part of the pectoralis major muscle laterally) are performed for reconstruction. Since 1993, 29 patients having shoulder deformity caused by obstetric brachial plexus palsy underwent reconstruction utilizing this strategy of muscle transposition. The timing for the reconstruction was at an average of 8.5 years (range, 4 to 21 years). The average shoulder abduction following the muscle transposition was 151 degrees (i.e., average gain 104 percent, or 77 degrees) and that of external rotation was 72 degrees (average gain 200 percent, or 48 degrees). Compared with the patients who had no surgery for shoulder deformity caused by obstetric brachial plexus palsy and early nerve surgery for the infant obstetric brachial plexus palsy, the results of the strategy seem to be significantly impressive.     

Unilateral phrenic nerve paralysis from cutting down a Christmas tree

Stretch injury to the phrenic nerve is an unusual cause of unilateral diaphragmatic paralysis. In this case the injury occurred while the patient was lying on the ground and cutting down a Christmas tree with a hand saw.     

Effects of intraphrenic injection of potassium on diaphragm activation

The purpose of the present study was to determine whether potassium, injected into the arterial supply of the diaphragm, would reflexly alter efferent diaphragmatic motor outflow and systemic arterial pressure. Studies were performed using in situ canine diaphragm muscle strips in which the inferior phrenic artery and vein were cannulated and all other sources of strip blood flow were ligated. Injection of potassium (0.1 meq) into the inferior phrenic artery elicited a small transient (1-2 breaths) decrease in the peak strip tension developed during spontaneous muscle contractions, in peak integrated strip electromyographic (EMG) activity, and in the peak integrated EMG activity of the contralateral hemidiaphragm. This was followed by a more pronounced and more sustained increase in each of these parameters as well as an increase in systemic arterial pressure. This latter excitatory response was qualitatively similar to that induced by the injection of capsaicin (5 and 25 micrograms) into the phrenic artery. Section of the left phrenic nerve abolished the effects of intra-arterial potassium and capsaicin on systemic arterial pressure and right hemidiaphragm EMG activity. These data support the existence of a potent excitatory phrenic-to-phrenic reflex that can be activated by potassium injection into the diaphragm. Activation of this pathway increases diaphragm motor activation and augments systemic arterial pressure.     

Intensity of MR contrast enhancement does not correspond to clinical and electroneurographic findings in acute inflammatory facial nerve palsy

PURPOSE: To determine the value of MR contrast enhancement in predicting the course of acute inflammatory facial nerve palsy and in selecting patients for surgical decompression. METHODS: Six patients with an acute inflammatory incomplete or complete peripheral facial nerve palsy (five idiopathic and one herpetic in origin) had repeated MR imaging studies with and without contrast enhancement, electroneurography, and clinical examinations to establish a connection between the intensity of contrast enhancement on MR images, the clinical condition, and the electrophysiological data. The examinations were performed every second day starting on the first day of admission until clinical recovery was proved by clinical deblockage (spontaneous clinical improvement). The last examination was performed 3 months after the onset of the facial nerve palsy. RESULTS: An abnormal, very intense contrast enhancement of the facial nerve was always present in the distal intrameatal and proximal tympanic segments and in the geniculate ganglion. The labyrinthine segment exhibited a mild to moderate enhancement, and the distal tympanic and mastoid segments showed a moderate to intense enhancement. The intensity of contrast enhancement did not correspond to the severity, duration, or course of the facial nerve palsy, and the electroneurographic data had no predictive value in indicating the severity of the inflammatory process. Three months after clinical recovery, a persistent and more or less unchanged or even slightly more intense contrast enhancement was observed. CONCLUSION: The long-lasting intense contrast enhancement seen in the facial nerve segments of patients who have acute peripheral inflammatory facial nerve palsy is explained by a two-phase breakdown of the blood-nerve barrier.     

Diaphragm activation with intramuscular stimulation in dogs

We studied in 10 supine anesthetized dogs diaphragm contraction produced by electrical activation with intramuscular electrodes surgically implanted in the ventral surface of the diaphragm and compared this with activation of the ipsilateral phrenic nerve (C5, 6, and 7) before it entered the thorax. Repetitive 40-Hz pulse trains with supramaximal current stimulus were used after hyperventilation of the animals to apnea. A single intramuscular electrode within 1 to 2 cm of the site of phrenic nerve entry into the diaphragm produced a mean transdiaphragmatic pressure of 12.0 cm H2O +/- 0.97 SE and mean tidal volume of 0.27 L +/- 0.04 SE. Mean values observed with phrenic nerve stimulation were not statistically different, and both electrode systems produced equivalent outward abdominal motion and upper rib cage paradox, as monitored by inductive plethysmography. There was no difference in gas exchange during stimulation with a single hemidiaphragm electrode and mechanical ventilation compared at the same tidal volume and respiratory rate. Blockade of neuromuscular transmission with curare eliminated intramuscular and phrenic nerve stimulation proportionately, suggesting that activation of the diaphragm is dependent in both cases on the phrenic nerve. This technique does not entail manipulation of the phrenic nerve and may have clinical application as an alternative technique for diaphragm pacing.     

Facial palsy in Kawasaki syndrome

Facial nerve palsy, a very rare complication of Kawasaki syndrome, has been reported in only 25 patients. We treated a 12-week-old boy with bilateral coronary artery aneurysms due to Kawasaki syndrome who developed marked unilateral peripheral facial nerve palsy on day 36 of illness. None of the 25 previously reported patients with this complication were treated with immunoglobulin; they required 7 to 90 days to recover. In our patient, treatment with this agent was associated with complete resolution of facial nerve palsy within 36 hours. Review of prior cases demonstrates that children with Kawasaki-associated facial nerve palsy have more than twice the risk for coronary artery aneurysm (52% vs <25%) as that of children who do not develop this neurological complication. Unexplained facial nerve paralysis in young children with a prolonged febrile illness should provoke consideration of Kawasaki syndrome and of echocardiography to exclude coronary artery aneurysms. Although facial palsy appears likely to resolve in all patients that survive the acute phase of Kawasaki syndrome, treatment with intravenous immunoglobulin appears to considerably shorten the time to full recovery and provides an important clue to the mechanisms of neurological injury in this illness.     

Origin of tonic electrical activity patterns in the diaphragm of the fetal lamb

The respiratory pattern generator in fetal and postnatal life activates the phrenic nucleus and diaphragm muscle with phasic bursts of activity. In the fetus, diaphragmatic activity is also characterized by tonic activity patterns of unknown origin. We have examined whether such activity is diaphragmatic, or radiated from nearby ribcage muscles, by placing two sets of electrodes side-by-side in the costal portion of the diaphragm in five fetuses. The rationale for this approach is that if tonic activity, radiates to the diaphragm it should be recorded by both sets of electrodes and there should be no delay between the action potentials from each set of electrodes. Of 24 single tonic units identified, 15 were recorded from only one of the two sets of electrodes in the diaphragm. In the 9 tonic units recorded from both sets of electrodes, there was a time delay between the appearance of the action potentials in the two recordings (mean +/- S.E.M. 1.6 +/- 0.2 ms). This is the expected conduction delay along the muscle fibres separating the two electrodes. Since tonic diaphragmatic activity persisted in fetuses with the spinal cord transected rostral or caudal to the phrenic nucleus, we conclude that the spinal cord alone is sufficient to produce the tonic activity recorded from the fetal diaphragm but that the brain may also generate such activity.     

Preconceptional education

Although studies have examined the susceptibility and pattern of injury induced by infusion of free radical-generating solutions into a number of vital organs, no such investigation has been performed for the diaphragm. The purpose of the present study was to examine the susceptibility of the diaphragm to damage by a free radical-generating solution (iron-ADP complexes). Studies were performed using an in situ canine diaphragmatic strip preparation in which the phrenic artery supplying the strip was cannulated and perfused with blood from the ipsilateral femoral artery. Four groups of studies were performed: (1) a group in which saline was infused into the arterial supply of the diaphragm for 15 min; (2) a group in which a solution of iron-ADP was infused; (3) a group in which both iron-ADP and superoxide dismutase (SOD), a free radical scavenger, were infused; and (4) a group given iron-ADP and denatured SOD. Strip tension and blood flow were monitored during electrically induced diaphragmatic contractions for 15 min before intraphrenic infusions, during the period of infusions, and for 90 min after cessation of infusions. We found that diaphragm tension did not change over time in saline-treated control animals but fell significantly in animals in which iron-ADP was infused. The effects of iron-ADP were largely prevented by concomitant administration of active SOD, but not by denatured SOD. On average, at 90 min after cessation of infusions, tension had fallen to 82 +/- 6, 41 +/- 8, 63 +/- 4, and 28 +/- 9% of its initial value in saline, iron-ADP, iron-ADP/SOD, and iron-ADP/denatured SOD groups, respectively (p < 0.001 for comparison of the four groups, with saline and iron-ADP/SOD groups different from the other two groups). Diaphragm blood flow did not change significantly in any group. These data suggest that free radical-mediated diaphragmatic injury can result in a marked reduction in diaphragm contractility.     

Release of thiamine and formation of a methylthiamine-like substance in the phrenic nerve-diaphragm preparation of the rat

An increased formation of a radioactive methylthiamine-like substance (MTLS) in the end plate region of the rat diaphragm muscle and a release of radioactivity chromatographed as thiamine into the bath medium after a subcutaneous injection of 35S-thiamine were found after stimulation of the phrenic nerve. There was also an increased formation of the radioactive methylthiamine-like substance in the denervated diaphragm preparation incubated with radioactive acetylcholine (ACh) in comparison with the innervated diaphragm.     

Ultrasound evaluation of piglet diaphragm function before and after fatigue

Clinically, a noninvasive measure of diaphragm function is needed. The purpose of this study is to determine whether ultrasonography can be used to 1) quantify diaphragm function and 2) identify fatigue in a piglet model. Five piglets were anesthetized with pentobarbital sodium and halothane and studied during the following conditions: 1) baseline (spontaneous breathing); 2) baseline + CO2 [inhaled CO2 to increase arterial PCO2 to 50-60 Torr (6.6-8 kPa)]; 3) fatigue + CO2 (fatigue induced with 30 min of phrenic nerve pacing); and 4) recovery + CO2 (recovery after 1 h of mechanical ventilation). Ultrasound measurements of the posterior diaphragm were made (inspiratory mean velocity) in the transverse plane. Images were obtained from the midline, just inferior to the xiphoid process, and perpendicular to the abdomen. M-mode measures were made of the right posterior hemidiaphragm in the plane just lateral to the inferior vena cava. Abdominal and esophageal pressures were measured and transdiaphragmatic pressure (Pdi) was calculated during spontaneous (Sp) and paced (Pace) breaths. Arterial blood gases were also measured. Pdi(Sp) and Pdi(Pace) during baseline + CO2 were 8 +/- 0.7 and 49 +/- 11 cmH2O, respectively, and decreased to 6 +/- 1.0 and 27 +/- 7 cmH2O, respectively, during fatigue + CO2. Mean inspiratory velocity also decreased from 13 +/- 2 to 8 +/- 1 cm/s during these conditions. All variables returned to baseline during recovery + CO2. Ultrasonography can be used to quantify diaphragm function and identify piglet diaphragm fatigue.     

Neonatal sciatic palsy: etiology and outcome of 21 cases

INTRODUCTION: Sciatic nerve paralysis is a rare entity in the newborn. Few reference in specialized tests indicate that in the majority of cases the sciatic palsy has been observed after misplaced injections into the buttocks. The prognosis is variable and appears to be better after umbilical vessel catheterization for injection of medications than after misplaced muscular injections. In case of recovery it takes place within 3 to 12 months. OBJECTIVE: The objective of the present study is to know the evolution of neonatal sciatic palsy and to determine their injury noxe in regard to perinatal factors, and their relationship with long-time outcome, and to look for prognostic clues of clinical utility. MATERIAL AND METHODS: We evaluated perinatal factors of newborn children with sciatic nerve paralysis, followed for more than 18 months of clinical evolution, in a neuropediatric centre. RESULTS: Twenty one newborn with such criteria were evaluated. Gestational age was within 32 and 42 weeks (median 38.2). The birth weight was between 2,100 and 4,100 g (median 2,973). The majority of cases obtained total recovery (16 of 21). The time of recovery was 4 to 14 months (median 8.8). Free ambulation was obtained by all cases (at 10 to 24 months). No apparent cause was observed in the majority of cases. Cesarean delivery was more frequent specially in cases with permanent consequences. CONCLUSION: Long-time prognostic of neonatal sciatic palsy is generally good. In our series all the cases with consequences were associated to cesarean delivery. The duration of cesarean intervention and the anesthesic hypotony of the newborn could be implicated in the sciatic nerve injury of poor outcome.     

Blunt traumatic rupture of the diaphragm: sonographic diagnosis

Ultrasonographic features of seven patients with diaphragmatic rupture due to blunt trauma were analyzed. The ruptures occurred at the left hemidiaphragm in four patients and at the right in three. Direct ultrasonographic findings were as follows: disrupted diaphragm in four patients; nonvisualized diaphragm in three patients; floating diaphragm in two patients; and herniation of the liver or bowel loops through the diaphragmatic defect in three patients. Indirect sonographic findings included pleural effusion or subphrenic fluid collection in five patients and splenic laceration in one. Although the number of patients was limited, ultrasonography was very useful for the diagnosis of diaphragmatic rupture.     

Respiratory activity of the rat posterior cricoarytenoid muscle

An anatomic and electrophysiological study of the rat posterior cricoarytenoid (PCA) muscle is described. The intramuscular nerve distribution of the PCA branch of the recurrent laryngeal nerve was demonstrated by a modified Sihler's stain. The nerve to the PCA was found to terminate in superior and inferior branches with a distribution that appeared to be confined to the PCA muscle. Electromyography (EMG) recordings of PCA muscle activity in anesthetized rats were obtained under stereotaxic control together with measurement of phrenic nerve discharge. A total of 151 recordings were made in 7 PCA muscles from 4 rats. Phasic inspiratory activity with a waveform similar to that of phrenic nerve discharge was found in 134 recordings, while a biphasic pattern with both inspiratory and post-inspiratory peaks was recorded from random sites within the PCA muscle on 17 occasions. The PCA EMG activity commenced 24.6 +/- 2.2 milliseconds (p < .0001) before phrenic nerve discharge. The results are in accord with findings of earlier studies that show that PCA muscle activity commences prior to inspiratory airflow and diaphragmatic muscle activity. The data suggest that PCA and diaphragm motoneurons share common or similar medullary pre-motoneurons. The earlier onset of PCA muscle activity may indicate a role for medullary pre-inspiratory neurons in initiating PCA activity.     

Early assessment of diaphragmatic dysfunction in children in the ITU: chest radiology and phrenic nerve stimulation

Diaphragmatic dysfunction is a common postoperative complication of cardiac surgery in children, with important effects on respiratory morbidity. Its early diagnosis, followed by prompt surgical intervention, has been shown to reduce morbidity. However, the commonest method of diagnosis, based on hemi-diaphragmatic elevation on the chest radiograph, may be less accurate than direct techniques for assessing phrenic nerve function. We have compared electrophysiological and radiological diagnoses of diaphragmatic abnormality in 100 children (aged 3 days to 17.5 yrs) undergoing cardiac surgery, looking at respiratory morbidity as assessed by the duration of ventilation, the time spent on the cardiac intensive care unit (CICU), and the requirement for reintubation. Despite showing good reproducibility, radiological diagnosis was neither sensitive nor specific in identifying patients with electrophysiological phrenic nerve damage. Analysis of the measures of outcome supported the electrophysiological technique. Patients with electrophysiological evidence of damage had a longer duration of ventilation, spent longer on the CICU, and had a greater incidence of reintubation than either radiologically abnormal or "normal" patients. Chest X-rays are not a good method for diagnosing phrenic nerve damage in the early postoperative period in children. If early diagnosis is needed, then direct assessment of phrenic nerve function, such as the measurement of phrenic latency, may be a better technique.     

Neuromuscular disorders associated with failure to wean from the ventilator

OBJECTIVE: To determine, by retrospective chart analysis, the frequency, type and significance of neuromuscular disorders in patients whose clinical features suggested a neuromuscular cause of failure to wean. BACKGROUND: Failure to wean is a common and difficult problem in critical care units. While a neuromuscular cause may be suspected in some patients, the frequency and type has not been determined utilizing comprehensive electrophysiological studies of limbs and the respiratory system. Such knowledge may aid in patient management and prognosis. METHODS: The clinical setting was a critical care/trauma centre that admits 1500 patients per year, approximately 500 being on ventilators for longer than five days. We analyzed the hospital charts of 40 patients admitted to the unit during three years, whose respiratory assessment suggested a neuromuscular cause for failure to wean from the ventilator. To investigate this possibility, we performed electrophysiological studies of the limbs and also of the respiratory system by phrenic nerve conduction and needle electromyography of the chest wall and diaphragm. The results were compared to 25 healthy controls. RESULTS: 38 of 40 patients (95%) had a neuromuscular disorder: 25--critical illness polyneuropathy, 2--Guillain-Barré syndrome, 4--diabetic and critical illness polyneuropathy, 2--uremic and critical illness polyneuropathy, 10--an abnormality of central drive, 5--unilateral phrenic nerve palsy, 3--a neuromuscular transmission defect, and 5--a primary myopathy. Fifteen (38%) had a combination of disorders. Patients with more severe polyneuropathy took longer to wean, a mean of 136 versus 52 days (p = 0.007). The severity of the polyneuropathy had no effect on mortality. CONCLUSIONS: Electrophysiological studies of limbs and the respiratory system are together valuable in confirming the presence, and identifying the specific type of neuromuscular cause for difficulty in weaning from the ventilator. This information is important in patient management and prognosis.     

Plication of paralyzed hemidiaphragm after right sleeve pneumonectomy

Right diaphragmatic plication was performed in a 62-year-old man who underwent right sleeve pneumonectomy and then required prolonged mechanical ventilation owing to right diaphragmatic paralysis. The plication was very effective in allowing him to be weaned from the ventilator. The transdiaphragmatic pressure, the ratio of gastric to esophageal pressure swing, and the work of breathing per liter of ventilation improved remarkably after plication. Our experience indicates the beneficial effect of such a plication on contralateral lung function from the standpoint of clinical and respiratory mechanics.     

Incidentally detected mitral valve anomaly?

Four children, who developed ulnar nerve palsy following percutaneous fixation of supracondylar fracture of the humerus by Kirschner wires (K-wires) are reported. In one the K-wire was removed within 48 h and the neuropraxia recovered immediately. In the other three patients recovery took an average of 6 weeks after removal of the wires and only after exploration of the ulnar nerve. The nerve was found to be trapped behind the medial epicondyle of the humerus. Release and subsequent transposition of the nerve resulted in recovery. Certain measures are suggested to prevent this avoidable complication in the treatment of supracondylar fractures of the humerus in children.     

Neuroma-in-continuity resection: early outcome in obstetrical brachial plexus palsy

The short-term effect of neuroma-in-continuity resection in obstetrical brachial plexus palsy was evaluated to test the hypothesis that the neuroma does not contribute to useful limb function. Twenty-six patients with obstetrical brachial plexus palsy underwent resection of the neuroma-in-continuity and interpositional nerve grafting, and 17 patients underwent neurolysis only. The preoperative and postoperative active movement scores were recorded using an eight-point scale for 15 joint motions in each patient. Data analysis examined the change in total limb motion scores over time within patients undergoing neuroma-in-continuity resection and a comparison with those patients undergoing neurolysis. Compared with preoperative assessment, limb motion scores after neuroma resection were significantly decreased at 6 weeks, not significantly different by 3 months, and significantly improved at 12 months postoperatively. In comparison to patients undergoing neurolysis only, limb motion scores after neuroma resection were not significantly different at 3, 6, and 12 months postoperatively. These findings are unlikely to be accounted for by axonal regeneration across interpositional nerve grafts. Nerve regeneration or recovery in the nongrafted segment of the plexus must be sufficient to reproduce preoperative motion. Resection of the neuromas-in-continuity in obstetrical brachial plexus palsy does not significantly diminish motor activity.