Bilateral isolated phrenic neuropathy causing painless bilateral diaphragmatic paralysis:

The authors report four patients with a syndrome of painless bilateral isolated phrenic neuropathy. Electrophysiologic testing demonstrated active denervation restricted to the diaphragm. Long-term recovery was poor. The authors conclude that bilateral isolated phrenic neuropathy is a cause of painless diaphragmatic paralysis distinguishable from immune brachial plexus neuropathy and other neuromuscular disorders with similar clinical presentation.

[A case of bilateral diaphragmatic paralysis clinically suggestive of brachial neuritis]

A 55-year-old man complained of acute onset of shoulder pain and dyspnea in the supine position. A diagnosis of bilateral diaphragmatic paralysis was made based on clinical inspection of his breathing pattern, radiographic appearance, and pulmonary function tests. He had had no traumatic or thoracic surgery or inflammatory episode. He did not suffer from diabetes, other central neural diseases, or any neoplastic disease. From the clinical feature and electromyographic findings, phrenic nerve involvement of brachial neuritis without any other muscle involvement was considered as a causative disease. When he received non-invasive intermittent positive-pressure ventilation by nasal mask in a supine position, his dyspnea was substantially attenuated and Carbon dioxide retention was lessened. After 1 year, his shoulder pain is still persisting and radiographic findings are not remarkably improved.

Chest radiography cannot predict diaphragm function

The finding of hemidiaphragm elevation on a chest radiograph, in absence of an ipsilateral lung disease, is assumed to indicate severe hemidiaphragm dysfunction. To test this hypothesis we retrospectively reviewed chest radiograph findings and corresponding twitch transdiaphragmatic pressure (T(W)P(DI)) results from 42 (17 female, age range 22-79 years) consecutive patients who underwent phrenic nerve stimulation studies. Chest radiographs were independently reviewed in a blind manner by two radiologists. The interobserver agreement was moderate, the kappa value ranging from 0.48 (left hemidiaphragm) to 0.59 (lung parenchyma). Hemidiaphragm dysfunction was diagnosed if T(W)P(DI) of corresponding hemidiaphragm was less than 3.5 cm H2O. The prevalence of patients with an elevated unilateral hemidiaphragm on chest radiograph was 64% and of patients with unilateral paralysis judged by T(W)P(DI) was 24%. Sensitivity, specificity, positive and negative predictive values for chest radiograph, as a diagnostic test for unilateral diaphragm dysfunction were 0.90, 0.44, 0.33 and 0.93, respectively. We conclude that the isolated elevation of hemidiaphragm on chest radiograph is of little value in the diagnosis of unilateral hemidiaphragm paralysis, though the condition is unlikely if diaphragm elevation is absent.

Thoracic gas volume measurements in paralyzed mice

We have previously measured thoracic gas volume (VTG) in spontaneously breathing mice using a whole body plethysmograph and have now extended our technique to allow for V(TG) measurements during paralysis. BALB/c mice were anesthetized and placed in a body-box and ventilated via a tracheostomy cannula through the box wall. Box pressure (Pb) and tracheal pressure (Pao) were measured during spontaneous breathing, and again after paralysis while mechanically compressing the chest. V(TG) was much larger after paralysis (0.49+/-0.06 ml, positive end-expiratory pressure = 2 cmH2O) when compared with spontaneous breathing (0.31+/-0.01 ml). External chest compression produced looping in the plots of Pb versus Pao that was attributable to gradual changes in Pb upon release of the mechanical chest compression and had the character of thermal transients. Under the assumption that the rate of heating of the air in the chamber was proportional to the pressure applied to the animal's chest, and that any increase in air temperature was dissipated by heat absorption by the chamber walls, we developed an algorithm that corrected for the thermal events. This yielded similar results for V(TG) (0.30+/-0.02 ml) as obtained during spontaneous efforts. Our method may prove particularly useful when paralysis is required for the precise measurement of lung mechanics.

Respiratory arrest in systemic lupus erythematosus due to phrenic nerve neuropathy

Diaphragmatic weakness in patients with systemic lupus erythematosus (SLE) is a controversial issue and is claimed to have a neuropathic, myopathic or unknown pathogenesis. In this patient a predominantly motor neuropathy with diaphragmatic paralysis due to axonal involvement of the phrenic nerve was discovered and successfully treated with immunosuppressive drugs.

Incidence and treatment of diaphragmatic paralysis after cardiac surgery in children

OBJECTIVE

Diaphragmatic paralysis (DP) caused by phrenic nerve injury is potentially life-threatening in infants. Phrenic nerve injury due to thoracic surgery is the most common cause of DP in children. We retrospectively analyzed incidence, surgical details, management and follow-up of our patients with DP after cardiac surgery to develop an algorithm for the management and follow-up.

METHODS

Retrospective analysis of 43 patients with DP after cardiac surgery performed between 1996 and 2000.

RESULTS

Median age at cardiac surgery was 1 month (range 3 days to 9 years). Incidence of DP was 5.4%. A trend towards higher incidences of DP were observed after arterial switch operation (10.8%, P=0.18), Fontan procedure (17.6%, P=0.056) and Blalock-Taussig Shunt (12.8%, P=0.10). Median time from cardiac surgery to surgical plication was 21 days (range 7-210 days). Transthoracic diaphragmatic plication was performed in 29/43 patients, no plication was done in 14/43 patients. Patients in whom diaphragmatic plication was required were younger (median age 2 months, range 21 days to 53 months versus 17.5 months, range 4 days to 110 months; P<0.001). Indications for plication were failure to wean from ventilator (n=22), respiratory distress (n=4), cavopulmonary anastomosis (n=2), and failure to thrive (n=1). All these symptoms resolved after diaphragmatic plication, however, 8/29 patients with plication and 2/14 without plication died. Cause of death was not related to diaphragmatic plication in any patient. Position of plicated diaphragm was normal in 18/21 surviving patients 1 month after plication. In 2/12 surviving patients without plication hemidiaphragm showed a normal position 1 year after surgery. The rate of pulmonary infections was not significantly different during 12-60 months follow-up.

CONCLUSIONS

DP is an occasional complication of cardiac surgery. High incidences of DP were seen after arterial switch operation, Fontan procedure and Blalock-Taussig shunt (BT). Respiratory insufficiency requires diaphragmatic plication in most infants with DP whereas older children may tolerate DP. Transthoracic diaphragmatic plication is an effective treatment of DP and achieves relief of respiratory insufficiency in most patients. Spontaneous recovery from postsurgical DP is rare.

Dyspnea as the predominant manifestation of bilateral phrenic neuropathy

Phrenic neuropathy associated with brachial neuritis has been well described; however, bilateral phrenic neuropathy with minimal or no involvement of the brachial plexus has not. We review the clinical features, as well as the results of radiographic studies, pulmonary function tests, and electrodiagnostic studies, of 3 patients in whom dyspnea was the presenting manifestation of bilateral phrenic neuropathy. All 3 patients had acute-onset dyspnea, which led to consideration of a pulmonary or cardiac etiology. Phrenic nerve conduction studies showed bilateral axonal degeneration of the phrenic nerves. Diaphragmatic paralysis should be considered in the differential diagnosis of acute-onset dyspnea. Dyspnea increases typically when the patient lies down, and paradoxical respiration may be present. Neck, shoulder, or upper limb pain may occur at onset. Inspiratory pressures may be reduced, but a comparison of the forced vital capacity when the patient is standing and supine is more specific for diaphragmatic weakness. Phrenic nerve conduction studies and diaphragmatic electromyography may provide evidence of bilateral involvement. Subclinical evidence of brachial plexus involvement may be present. The prognosis for patients with bilateral phrenic neuropathy may be more favorable than reported previously.

Spontaneous bilateral diaphragmatic paralysis: a rare cause of respiratory failure

Bilateral diaphragmatic paralysis (BDP) can occur in the course of motor neuron disease, myopathy, or from mechanical damage or the use of "ice slush" during cardiac surgery. BDP has been observed during and after infections, associated with systemic lupus erythematosus and mediastinal tumors, or may have idiopathic etiology. It is a serious and life-threatening condition. A 62-yr-old man presented with slowly progressive dyspnoea that worsened in the supine position and on bending forward. Chest X-rays, fluoroscopy, lung-function parameters and blood-gas analysis revealed respiratory failure. BDP was confirmed from a phrenic nerve stimulation test and measurement of transdiaphragmatic pressure (Pdi). Since there was no evidence of an obvious etiology, BDP was considered idiopathic. Other muscles were not involved. The pathological basis was probably focal demyelination in segments of the phrenic nerve. Because of increasing diaphragmatic muscle fatigue, the patient was treated with a nasal mask providing bi-level positive airway pressure (BiPAP) ventilation during the night. Clinical suspicion of BDP should always be raised in patients suffering slowly progressive dyspnoea without any obvious cardiac, metabolic or traumatic predisposing factors, and orthopnoea and dyspnoea on bending forward. Electromyographic tests and measurement of Pdi can reveal the correct diagnosis.

Influence of immersion in water on muscle function and breathing pattern in patients with severe diaphragm weakness

STUDY OBJECTIVE

Dyspnea is a common symptom in patients with diaphragm weakness or paralysis. In particular, dyspnea may be aggravated by immersion. We hypothesized that immersion to the neck in water would decrease vital capacity and consequently increase the demand/capacity ratio of the respiratory muscles.

DESIGN

Case series study.

SUBJECTS

Seven patients with profound diaphragm weakness or paralysis proven by phrenic nerve stimulation, and seven normal control subjects.

INTERVENTION AND MEASUREMENTS

We measured land-based and water-based spirometry, breathing pattern, and mouth occlusion pressures.

RESULTS

We found that the patients could preserve minute ventilation despite a fall in vital capacity from a mean of 2.3 to 1.3 L, but this required an increased respiratory rate (RR) [21.4 to 26.7 breaths/min, p = 0.018]. We used mouth occlusion pressure 100 ms after the start of inspiration (P(0.1)) as an estimation of the drive to breath; P(0.1) increased from 1.4 to 3.9 cm H(2)O (p = 0.018) without significant change in tidal volume.

CONCLUSIONS

Relative to control subjects, patients with diaphragm weakness have augmented drive to breathe in order to attempt to defend gas exchange. This conclusion is implied by the presevered minute ventilation with immersion, the augmented RR, and elevated P(0.1) relative to maximum static inspiratory pressure.

Respiratory inductance plethysmography used to diagnose bilateral diaphragmatic paralysis: a case report

OBJECTIVE

To report the use of respiratory inductance plethysmography in the diagnosis and management for a case of bilateral diaphragmatic paralysis after repeated sternotomies in a 23-month-old child.

DESIGN

Case report.

SETTING

A 15-bed pediatric cardiothoracic intensive care unit in an academic children's hospital.

INTERVENTIONS

The patient could not be weaned from the ventilator after a repeat sternotomy for pulmonary artery reconstruction. Pulmonary function test results were within normal limits, and plain film radiography, ultrasonography, and fluoroscopy were unable to establish a definitive diagnosis. Evaluation of thoracoabdominal synchrony was undertaken using respiratory inductance plethysmography (RespiTrace). The work of breathing was assessed using esophageal manometry to obtain the pressure-rate product.

RESULTS

During spontaneous breathing, complete thoracoabdominal asynchrony was noted, with clockwise Konno-Mead loops and associated phase angles of nearly 180 degrees. The pressure-rate product was 120 cm H(2)O/min, indicating elevated work of breathing. The pressure-rate product decreased dramatically, as indicated by measurement and observation, in response to increased levels of continuous positive airway pressure.

CONCLUSIONS

The diagnosis of bilateral diaphragmatic paralysis can be confirmed by measurement of thoracoabdominal synchrony. Therapeutic and diagnostic application of continuous positive airway pressure may predict response to diaphragmatic plication. Controlled trials comparing measurement of thoracoabdominal synchrony with standard methods for the early diagnosis of diaphragmatic paralysis are needed.

A pattern recognition method to distinguish gradual unilateral diaphragm paralysis in the cat

This work deals with the application of a pattern recognition method to distinguish the degree of diaphragm paralysis after gradual unilateral sections of phrenic nerve rootlets in anesthetized, spontaneously breathing cats. The data set consisted of the features that characterize breathing pattern and of phrenic nerve amplitude. The method called for stratification of 6-dimensional vectors into three classes: intact, partial, and complete unilateral phrenicotomy, which offers the possibility to construe the classification rule on the basis of the information contained in a set of feature vectors with the known class-membership. This method deals with the use of a distance function as a measure of similarity between two feature points. The results show that the degree of diaphragm paralysis could be recognized with the probability higher than 90%. Distinguishing the severity of diaphragmatic dysfunction and the compensatory strategies of the respiratory system, knowing only a handful of basic values describing breathing pattern, might have a practical meaning in respiratory emergencies.

Central hypoventilation and diaphragmatic eventration: diagnosis and management

Congenital central alveolar hypoventilation syndrome (CCAHS) is a disorder of ventilatory control that occurs without neuromuscular blockade or pulmonary disease. It is characterized by a lack of response to habitual respiratory stimulants, especially hypercapnia. In this article, the management of this syndrome by diaphragmatic pacing is discussed. Paralysis of the phrenic nerve in small children usually results from injury during birth or during a cardiothoracic operation and results in eventration of the hemidiaphragm. Alternatively, eventration of the diaphragm may be a congenital condition. In both cases it may lead to respiratory distress in the newborn. In this article, we review the diagnosis of these conditions and their management, focusing on the surgical indications. We also discuss outcome.

Functional Electrical Stimulation (FES) for spinal cord injury

Restoration of respiratory motion by stimulation of the phrenic nerve was investigated. Respiratory motion was restored successfully by introducing a breathing pacemaker to a patient with respiratory disturbance due to upper cervical spinal cord injury. Breathing pacemakers are considered to be more similar to physiological conditions compared to mechanical ventilators. Although the system is very expensive, its cost effectiveness may be excellent, provided that it can be used for long hours each day over an extended period. The system is effective in improving patient QOL because it dramatically increases patient mobility. From these findings, it is concluded that breathing pacemakers should be used more frequently in Japan, and that various forms of support are necessary to cope with economic and other concerns.

[A case report of hemidiaphragmatic paresis caused by interscalene brachial plexus block]

A 76-yr-old woman was scheduled for left upper extremity orthopedic procedure. Preoperative examinations were within normal limits except forced vital capacity. Interscalene brachial plexus block with 0.25% bupivacaine 15 ml, was performed under general anesthesia. Her intraoperative course was uneventful. She, however, complained of the dyspnea after removal of a tracheal tube, and Spo2 dropped to 89%. A chest X-ray demonstrated the elevation of hemidiaphragm. She was diagnosed as ipsilateral hemidiaphragmatic paresis, treated with oxygen inhalation under deep breathing for approximately one hour, and then transferred to the common ward. We conclude that respiratory movement should be carefully observed following interscalene brachial plexus block especially in geriatric patients.

Transient post-traumatic hemidiaphragmatic paralysis in two cats

A diagnosis of post-traumatic hemidiaphragmatic paralysis was made in two cats. Both cats had a history of trauma and paradoxical inward movement of the abdominal wall at inspiration. Thoracic radiographs were taken at inspiration and expiration. Although the images were suggestive of hemidiaphragmatic paralysis, definitive diagnosis was reached by fluoroscopy in one cat and by ultrasonography in the second. Both cases resolved spontaneously and diaphragmatic function was normal at follow-up.