Unilateral diaphragmatic paresis following supracostal post-percutaneous nephrolithotomyA Bhat, JE Katz, NA Smith, HN Shah
Department of Urology, University of Miami Miller School of Medicine, Miami, Florida, USA
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/jpgm.JPGM_13_21
Source of Support: None, Conflict of Interest: None
Keywords: Complications, percutaneous nephrolithotomy, phrenic nerve injury, supracostal access
A 43-year-old man presented with symptomatic left complete staghorn calculus causing left flank pain. Intravenous urogram confirmed good renal function with staghorn calculus. He was otherwise in perfect physical health. He was counseled and consented for left percutaneous nephrolithotomy (PCNL). Pre-operative chest X-ray (CXR) was normal [Figure 1]a. He underwent upper-pole access prone PCNL. The access was supracostal (10th intercostal space) and fluoroscopically made. The initial puncture needle access traversed the pleural space in expiration to prevent lung trauma. The duration of surgery was 75 min and estimated blood loss was 100 ml. Complete stone clearance was confirmed endoscopically and fluoroscopically. The procedure was tubeless with placement of ureteral stent and no nephrostomy tube. Postprocedure, fluoroscopy revealed left costophrenic angle blunting.
The patient had postoperative flank pain which is usually encountered in a patient after supracostal PCNL. Although he did not report breathing difficulty, examination revealed reduced air entry on auscultation on the left lower chest with no crepitations. As a protocol, all patients undergoing PCNL with supracostal access undergo routine chest X-ray postoperatively in our unit, even if they lack any respiratory symptoms to look for possibility of any hydrothorax, hemothorax or pneumothorax which are known chest complications of supracostal access for PCNL. Postoperative CXR in the patient showed elevation of left dome of diaphragm [Figure 1]b. He did not show any symptoms of breathlessness or drop in oxygen saturation.
Owing to the suspicion of loculated pleural effusion along with distortion of the cardiac silhouette on routine postoperative CXR, a chest computerized tomography (CT) scan was performed for further evaluation. It revealed left hemidiaphragmatic elevation with complete stone clearance [Figure 2]a, [Figure 2]b [Figure 2]c, [Figure 2]d. A diagnosis of left hemidiaphragmatic paresis was made and a multi-disciplinary team of experts was consulted which included a pulmonologist, internal medicine physician, and anesthesiologist. As the patient was absolutely stable and had no signs or symptoms of respiratory failure, the recommendation from the team was to initiate chest physical therapy and incentive spirometry. The patient was observed overnight and there were no other complications during his hospital stay. A decision was therefore made to discharge the patient with instructions to contact us immediately if he developed any respiratory difficulty or increase in pain. He was also advised intensive spirometry multiple times in a day at home as recommended per the pulmonologist. Regular telephone checks were performed to ensure his progress. He remained remarkably stable throughout his stay at home and follow-up CXR at one month was normal. The complication was therefore classified as Clavien Dindo Grade 1. He underwent office cystoscopy with stent removal at one month.
Diseases that interfere with diaphragmatic innervation can produce dysfunction by impeding the mechanical movements of breathing. Common causes of unilateral diaphragmatic elevation include trauma, inflammatory causes like herpes zoster, thoracic malignancies like lung cancers, neurological causes like demyelinating disorders and diaphragmatic paresis either due to phrenic nerve or diaphragmatic involvement. Although multiple mechanisms can result in phrenic nerve injury including blunt/penetrating trauma, the most common cause remains iatrogenic, primarily from thoracic and cardiac surgery. These injuries have not been reported with abdominal surgeries, especially with endourological procedures.
PCNL is the preferred endourological procedure for large-volume renal calculi. The supracostal approach with upper-pole calyceal puncture provides the most straightforward access to stones in upper calyx, renal pelvis and lower calyces. However, it is associated with significantly higher risk of pulmonary complications. The posterior portion of the diaphragm originates from the tip of the 10th-12th rib posteriorly and the lower part of the lung lies at the level of the tenth vertebra posteriorly. Therefore, the supra-costal puncture always pierces the diaphragm and there are increased chances of injuring the lung or pleura. The motor, sensory and sympathetic innervation of the diaphragm and the central tendon of the diaphragm is by the phrenic nerve on either side. The majority of phrenic nerve branching occurs on the inferior surface of the diaphragm, and during open surgery involving diaphragm, care must be taken to place all diaphragmatic incisions circumferentially if possible, to avoid injury to phrenic nerve branches.
The theoretical possibility of phrenic nerve injury in supracostal PCNL originates due to the extensive arborization of the nerve below the diaphragm, where it can get damaged during supracostal renal access and dilatation. Another mechanism that may result in phrenic nerve injury is utilization of cold irrigant solution during the procedure. This analogy was described by Canbaz et al. who identified that the icy slush used for myocardial protection is a major factor causing phrenic nerve injury during cardiac surgery. Although our patient had a supracostal access as a possible etiology of phrenic nerve injury, warm isotonic saline irrigant was used during the entire procedure, thereby excluding the possibility of hypothermia associated injury to the nerve. The corresponding author had experience of performing a total of 2079 PCNL's between April 2003 to March 2017. Of these 998 patients required a supra-costal approach, out of which 209 needed 10th intercostal space approach due to the location of the stones and the anatomy. Hence lack of expertise of operating surgeon cannot be cited as a possible cause of complication. We believe the origin of complication was due to neuropraxia of terminal branches of phrenic nerve on diaphragm that resulted during supracostal access for PCNL. In this procedure, the renal puncture tract travelled thoracic cage between 10th and 11th rib entering the pleural space and then going through diaphragm to enter upper pole of renal parenchyma.
It is now established that in a case of unilateral diaphragmatic paralysis as well, patients tend to have unexplained dyspnea and reduction in inspiratory capacity which is due to reduced pressure produced by the contralateral hemidiaphragm. Phrenic nerve injury may present as diaphragmatic dysfunction and its diagnosis requires a high index of suspicion due to nonspecific signs and symptoms. In UADP, the patient is often asymptomatic at rest and has dyspnea only during exertion. This unilateral diaphragmatic paresis is typically found incidentally on chest radiograph as was seen in our patient. The diagnosis of UADP is established by chest CXR that shows unilateral hemidiaphragmatic elevation due to the paralyzed phrenic nerve. One of the ways to diagnose UADP is by the Sniff test which can be performed during fluoroscopy to evaluate diaphragm function. The sniffing maneuver activates the diaphragm and exaggerates its movement, and this can be observed in real time on fluoroscopy. CT scan with thin slices outlines the diaphragm and administration of oral contrast can delineate the abdominal organs displaced into the thoracic cavity thereby conclusively establishing the diagnosis.
Management is dependent on the severity of symptoms. Most cases of unilateral diaphragmatic dysfunction in asymptomatic patients can be safely managed by mere observation and complete recovery is usually expected in most cases. However, patients with respiratory symptoms can be treated with supplemental oxygen, nebulization, and chest physical therapy with good outcomes. Severe cases may require surgical plication either by open or minimally invasive techniques. Close communication with the thoracic surgical team is essential for optimal outcomes. Our patient had no respiratory symptoms and was managed conservatively with respiratory therapy in the form of incentive spirometry. He improved without any residual sequelae.
The aim of our case report was to highlight the fact to the urological community, that a rare complication of paresis of the hemidiaphragm is indeed possible while carrying out a commonly performed surgery––PCNL for kidney stones, especially when the puncture for initial access is supracostal. To the best of our knowledge, there is no report of diaphragmatic paresis after PCNL reported in the literature.
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[Figure 1], [Figure 2]