Plication of the Diaphragm

Plication of the diaphragm is a surgical procedure that has been performed since the 1920s for the treatment of diaphragmatic paralysis.[1] Diaphragmatic paralysis is a serious problem for individuals suffering from the respiratory abnormalities, reduced energy levels, and sleep disturbances that are commonly associated with the disorder. The inability of the lung to expand fully in patients with diaphragmatic paralysis also makes these individuals more susceptible to pleural effusions, pneumonia, and atelectasis.

The goal of diaphragm plication is to flatten the dome of the diaphragm, providing the lung with greater volume for expansion. Since its original description, diaphragm plication has been performed with numerous modifications, including the minimally invasive video-assisted thoracic surgery (VATS) approach.[2, 3] Laparoscopic robot-assisted diaphragm plication has also been reported.[4] Diaphragm plication surgery using both transabdominal and transthoracic approaches has been performed in both children and adults.

Alternatives to diaphragm plication for the successful treatment of diaphragmatic paralysis include diaphragm pacing and phrenic nerve grafting.[5] Recently, there has been progress in the area of phrenic nerve surgery, which repairs injuries to the phrenic nerve using nerve grafts or nerve transfers.[6, 7] Alternatively, patients with bilateral diaphragmatic paralysis from spinal cord injury may be better served with a diaphragm pacemaker to restore function to the diaphragm. Patients with diaphragmatic paralysis now have options for treatment, including both phrenic nerve grafting and diaphragm plication.

Diaphragm plication is appropriate for pediatric and adult patients with symptomatic diaphragmatic paralysis who have failed conservative management and have not exhibited spontaneous signs of improvement. There are instances when diaphragmatic paralysis is temporary; over the course of weeks to months, the injury may reverse itself, ultimately resulting in a return of normal diaphragm function. However, if there are no signs of spontaneous improvement over a 6- to 12-month period, then the injury is likely permanent.

A proper assessment of the muscle paralysis will determine if diaphragm plication is the most appropriate treatment option. Typically, this applies to patients with severe neuromuscular injuries who demonstrate complete loss of diaphragm motor units, making reinnervation difficult or impossible. Furthermore, complete loss of diaphragmatic innervation from the phrenic nerve will prevent successful diaphragm pacing. A comprehensive electrodiagnostic assessment of the phrenic nerve and diaphragm will usually provide the necessary information.

Patients with diaphragmatic paralysis are not candidates for diaphragm plication surgery if the injury is thought to be temporary or they are exhibiting signs of spontaneous improvement. Furthermore, diaphragm plication is contraindicated if the individual has significant comorbidities that would increase risk. Active or recurrent pulmonary infections, chronic lung disorders, and severe heart disease could be associated also be associated with unacceptable risks if diaphragm plication surgery was attempted.

Relevant Anatomy

The relevant anatomy consists of the right and left phrenic nerve and respective hemidiaphragm on both sides of the body. Each phrenic nerve leaves the spinal cord at the cervical level in the neck (C3-5), runs down the neck on the scalene muscle, and dives under the clavicle into the chest cavity.

In the chest cavity, each nerve runs between the heart and lung, entering the diaphragm towards the medial aspect of the muscle and dividing into several branches to provide nerve impulses to the various parts of the muscle. The intramuscular phrenic nerve has some variability; however, it is generally described as having several large branches that innervate segments of the diaphragm with an overlapping “net” of smaller nerve fibers.

The diaphragm is a broad flat muscle that effectively acts as both the barrier between the thoracic and abdominal cavities, and the primary muscle of inspiration. When the diaphragm muscle contracts, it descends, permitting the lungs to expand passively.

The vital role of the diaphragm in respiration is obvious, though its contribution varies based on position and sleep. The diaphragm is responsible for 56% of the tidal volume in the awake, supine patient and up to 81% during periods of deep sleep.

Outcomes are generally favorable with good long-term prognosis. In a study of 17 patients, Graham et al demonstrated that transthoracic plication resulted in improvement in symptoms and pulmonary function tests.[8] Specifically, the forced vital capacity improved up to 18%. In a study of 15 patients with an average follow-up of 10 years, Higgs et al also demonstrated durable improvements in dyspnea scores, patient satisfaction, and pulmonary function tests.[9] Specifically, forced expiratory volume improved 15.4%. In a study of 41 patients using thoracoscopic techniques, Freeman et al demonstrated improvement in forced vital capacity of 17% and forced expiratory volume of 21%.[10]

Patients with diaphragmatic paralysis are typically referred to a pulmonologist for complete workup and evaluation. All patients suspected of having diaphragmatic paralysis should undergo a chest radiograph and a Sniff test (a fluoroscopic chest radiograph taken during both inspiration and expiration). The Sniff test can assess whether or not the diaphragm is moving appropriately.

Computed tomography or magnetic resonance imaging is necessary to look for abnormalities in the cervical spinal cord, neck, and/or chest cavity, especially to eliminate the possibility of a neoplasm in proximity to the nerve in any of these anatomical locations.

Pulmonary function testing or lung spirometry should be performed when considering diaphragmatic plication. Diaphragmatic paralysis is usually associated with a mild-to-moderate restrictive deficit on spirometry testing, with a reduction in forced expiratory volume, forced vital capacity, and maximum voluntary ventilation.

Electrical studies of the phrenic nerve and diaphragm muscle function are helpful to determine the severity of the injury and likelihood of spontaneous recovery. A phrenic nerve conduction study and diaphragm electromyography assess both nerve and muscle function, respectively. Unfortunately, because of the rarity of the condition, there are few physicians that perform these tests regularly, so it may be difficult to get accurate results.

After diaphragm plication, patients remain in the hospital for wound and chest tube management. Postoperative chest radiographs are performed to confirm reexpansion of the lung and to evaluate the repositioned diaphragm. Patients are discharged from the hospital when their pain can be managed comfortably with oral narcotics and usually after the chest tubes have been removed.

Patients are followed on a regular basis for the first 6-8 weeks, or until full healing has occurred. Regular chest radiographs are obtained as needed. Most patients will follow up with their pulmonologist in the first 3-6 months postoperatively for repeat pulmonary function testing to assess for improvements in lung function.

For a long time, diaphragm plication surgery was the only definitive treatment for symptomatic diaphragm paralysis. Because the paralyzed diaphragm muscle remains in an elevated position and prevents normal expansion of the lung with inspiration, the plication procedure flattens the dome of the muscle in an attempt to recreate its normal inspiratory position.[11] In doing so, the lung may be able to expand more readily, thereby improving ventilatory capabilities and alleviating some or all of the respiratory symptoms. Although this procedure does not result in physiological movement of the diaphragm and is instead a "static" repair leading to functional benefits, a successful plication does reverse paradoxical motion that is associated with the most severe cases of paralysis.

Patients receive general anesthesia and are then positioned for the procedure depending on the approach (ie, transsternal, transthoracic, transabdominal). The video-assisted thoracoscopic approach is less invasive, using small incisions placed in specific locations to visualize the diaphragm with a camera. The most common approach is a muscle-sparing minithoracotomy through the 6th or 7th intercostal space on the side of the paralyzed diaphragm. Video-assisted mini-thoracotomy has been reported to decrease recovery time, shorten hospital stays and significantly improve forced expiratory volume.[12] A plication may also be performed using a laparoscopic approach from a subdiaphragmatic orientation.

Thoracoscopic surgery usually requires three or more port wounds to complete the procedure. Some institutions, however, perform most thoracic surgical procedures with a two-port or single-port technique. Single-port thoracoscopic approach has been shown to be feasible and safe.[13] Uniportal thoracoscopic procedures seem to offer substantial benefit in terms of postoperative pain and cosmesis with similar outcomes as other surgical techniques.[14, 15]

The critical components of the procedure are as follows:

• The redundant diaphragm is manipulated in order to eliminate billowing and pulmonary crowding.
• The pleated portion of the diaphragm is folded and may be anchored to the diaphragm anteriorly for sturdy fixation.
• The plicated diaphragm is anchored to the costal arch of the 6th rib to prevent loosening.
• The diaphragm is accessed through one of the planned techniques and several (4-6) nonabsorbable monofilament sutures are woven or pleated in the sagittal plane to effectively reduce redundancy and flatten the diaphragm.
• Excess in the center can be folded back and sutured to the costal margin if necessary. A technique using a stapler has also been described for this plication. The pleated diaphragm becomes taut and fixed.
• A chest tube is placed and the incision is closed.

Complications are rare but can occur as with any thoracic procedure. Care must be taken not to injure the intraabdominal organs while placing the plication sutures through the diaphragm.[13] Any injury thus incurred may manifest immediately with bleeding (spleen, liver) or by delayed presentation of peritonitis due to injury to the stomach or bowel. Wound infection is rare.

Complications specific to plication surgery in the chest include the following:

• Injury to the pericardium/heart
• Bleeding
• Injury to intraabdominal organs, including stomach, spleen, and liver
• Injury to the pulmonary parenchyma

General complications to thoracic incision and thoracotomy may include chronic thoracotomy pain, atelectasis, pneumonia, pulmonary embolism, pleural effusion, empyema, chest wall infection, deep venous thrombosis, urinary tract infection, myocardial infarction, and any complication of general anesthesia (eg, mental status changes, stroke, myocardial infarction).

Another potential long term complication is relapse of the elevated diaphragm and/or paradoxical movement due to loosening of the sutures. When this occurs, patients will report a recurrence of the exertional dyspnea and difficulties with physical functioning that were associated with the original onset of the paralysis.