BASICS
DESCRIPTION
Often an incidental finding with chest radiograph é á
- It may not cause resting pulmonary symptoms unless there is underlying comorbidity such as COPD, cardiac disease, muscular weakness, obesity; but with exertion, symptoms may occur.
- Infection in the affected lung may be slow to clear.
EPIDEMIOLOGY
Incidence
Uncommon é á
Prevalence
Some literature indicate increased rate of right-sided paralysis. é á
ETIOLOGY AND PATHOPHYSIOLOGY
Interruption in the phrenic nerve conduction to the diaphragm leaflets é á
- On radiographic studies, the paralyzed hemidiaphragm will be elevated and accentuated dome on both PA and lateral films.
- Paralysis may be complete or incomplete.
- Paralysis may be either flaccid or spastic.
- Flaccid weakness may become spastic with improvement of underlying conditions.
- Paradoxical movement of diaphragm with respiration may cause hypoxia, as excess CO2 (hypercapnia) will move to the unaffected lung during inspiration.
RISK FACTORS
Neck injury, cardiothoracic surgery, blunt force trauma to chest, chemotherapy é á
- Metabolic or inflammatory disorders creating pressure on the phrenic nerve
- Metabolic disturbances: hypokalemia; hypomagnesemia; hypocalcemia; hypophosphatemia; low folate and vitamins B6 and B12, low thyroid studies
- Substernal thyroid, hypothyroidism, mediastinal diseases
- Aortic aneurysm
- Neoplasm
- Pneumonia, viruses such as herpes zoster
- Spinal cord disorders (syringomyelia, poliomyelitis, motor neuron disease) (1)
- Trauma or surgery disrupting neural pathway (transection, stretching, crushing, or hypothermic injury, interscalene nerve blocks)
- Blunt and penetrating trauma from motor vehicle accidents, gunshot wounds, stab wounds
- Open heart surgery, pulmonary vein ablation, atrial fibrillation cryosurgery
- Cervical spine manipulations, spinal cord injuries particularly to C3 " ôC5 spine (1)
- Radiation therapy to brain, cervical, or mediastinal areas
- Tumor compression/mediastinal masses compression due to bronchogenic or mediastinal tumors
- Lung cancer (most common is metastatic lung cancer ~30%)
- Thyroid goiter
- Myopathies or neuropathies: There may be a 3- to 4-decade delay until diaphragmatic weakness develops.
- Demyelinating diseases: Guillain-Barre syndrome, multiple sclerosis, ALS, myasthenia gravis
- Neuritis from muscular dystrophy, Charcot-Marie-Tooth, diabetes, alcoholism
- Postinfective neuritis such as diphtheria, tetanus, typhoid, measles, botulism type A, zoster, and Lyme disease
- Mechanical ventilation diffuse atrophy can occur even after brief periods of mechanical ventilation (2).
- Drug cause: aminoglycosides, etoposide, vincristine, cyclophosphamide, doxorubicin, rituximab (3)
COMMONLY ASSOCIATED CONDITIONS
In many cases, the cause is never identified. é á
DIAGNOSIS
HISTORY
Patients may be asymptomatic. é á
- Dyspnea on exertion/decreased exercise tolerance may be mild to severe unless patient has other underlying pulmonary disease (asthma, COPD, bronchiectasis, TB, bronchitis; this UPD may cause dyspnea at rest).
- Chest wall pain, pleurisy
- Muscle fatigue (limited ability to exercise)
- Dyspnea while laying with paralyzed side down
- Occasional hypoventilation during sleep, especially REM sleep
PHYSICAL EXAM
- Decreased to absent breath sound on affected side
- Reduced excursion on affected side
- Dullness or absence of tone on percussion
- Paradoxical movement of abdomen when breathing in recumbent position
- Auscultation of bowel sounds in thorax
- Palpation under the costal margin for descended hemidiaphragm during inspiration
DIFFERENTIAL DIAGNOSIS
All causes of dyspnea é á
DIAGNOSTIC TESTS & INTERPRETATION
Initial Tests (lab, imaging)
- Blood work: CBC " öchecking for polycythemia or anemia
- CMP " öchecking for glucose, renal, and liver studies
- ESR " öchecking for inflammatory diseases
- Thyroid studies " öTSH and T4 studies
- Additional studies if indicated " öfolate, vitamin B12, heavy metal screen, blood lead level, ANA, ANCA, hepatitis panels, Lyme titer, rheumatoid factor, acetylcholine receptor antibodies
- ABG " ömay demonstrate hypoxemia and/or hypercapnia
- Imaging
- CXR " öelevated hemidiaphragm with elevated and accentuated dome on both PA and lateral films showing possible subsegmental atelectasis (~90% diagnostic in unilateral diaphragmatic paralysis)
- There may be mediastinal shift on inspiration.
- Traumatic rupture shows abdominal contents in the thorax on the affected side.
- Fluoroscopy " öthe "SNIFF TEST " Ł is used to assess the motion of the diaphragm through sharp inspiratory effort through the nostrils. With UPD, there will be a paradoxical movement of the diaphragms. False positives may occur in up to 6% of patients (2)[C].
- CT " öCT chest is indicated to determine the potential cause, if mediastinal pathology is suspected. Abdominal CT may be needed if there is no mediastinal involvement.
Follow-Up Tests & Special Considerations
- MRI of the neck if injury or pathologic conditions involving the spinal column or nerve roots is suspected.
- Pulmonary function testing (PFT) (1,4)[C]: upright and supine vital capacity. The restrictive dysfunction becomes more severe when patient is in a supine position. Breathlessness does not always correlate to the severity of dysfunction noted. PFTs have high negative value if no change in FVC and TLC; FEV1 with change in position is a good indication that there is no diaphragmatic weakness or paralysis.
- NIP " öless than ó ł ĺ60 cwp for women and ó ł ĺ70 cwp for men
- FVC " öwill show a decrease of 10 " ô30% in supine test from upright test
- TLC " ömay be mildly restricted (70 " ô79% of predicted) to severely restricted (30 " ô50% of predicted)
- Residual capacity " öis usually normal
- ABG: PCO2 45 mm Hg or greater during daytime
- Oxygen saturation of <88% for 5 consecutive minutes during night warrants further workup with diagnostic sleep studies or UPD noted on other studies.
- Sleep studies are warranted when hypoxia is noted during sleep or when patient reports excessive daytime sleepiness, fatigue, malaise, morning headaches, insomnia, prominent REM sleep (1,4)[C].
- Special considerations:
- Transdiaphragmatic pressures is the criterion standard for diagnosis measuring changes of intra-abdominal pressure and pleural pressure. This testing is generally not available through most medical institutions. This will require referral to expert to perform and interpret the results (2)[C].
- Phrenic nerve conduction studies are of limited use due to "cross-talk " Ł between adjacent muscle fibers. This will be needed only if diaphragmatic pacing is being considered. Interpretation will be completed by the specialist (2)[C].
- Ultrasonography " öM-mode ultrasonography may lead to prompt identification showing no movement of muscle.
- B-mode ultrasonography " ö<20% thickening of diaphragm is diagnostic of paralysis.
TREATMENT
GENERAL MEASURES
Depends on the underlying cause and in the presence of nocturnal hypoventilation é á
- Metabolic disturbances: Correct electrolyte and/or hormonal imbalances.
- Nocturnal hypoventilation: Noninvasive positive pressure is preferred because it can improve both symptoms and physiologic derangements if hypoventilation is noted during sleep, which occurs especially during REM sleep (1)[C].
MEDICATION
First Line
Medications are limited to the cause, such as hormonal replacement therapies. é á
- If there is neurologic involvement, the patient should be referred to neurologist for appropriate medication management.
ISSUES FOR REFERRAL
- When patient is suspected to have neurologic involvement
- When surgical intervention is considered
- Transdiaphragmatic pressure measurements for consideration for diaphragmatic pacing therapy
ADDITIONAL THERAPIES
Treat sleep-disordered breathing when suspected and documented. é á
SURGERY/OTHER PROCEDURES
- Plication of the diaphragm for patients with unilateral diaphragmatic paralysis who have severe dyspnea, cough, chest pain, or are ventilator-dependent. Surgery may be helpful in flaccid paralysis. Morbid obesity or progressive neuromuscular diseases are contraindications to plication surgery (5,6)[C].
- Resection of tumor encasing the phrenic nerve usually yields good results (5,6)[C].
- Phrenic nerve pacemaker is only possible if the phrenic nerve is fully intact; possible treatment in high cervical quadriplegics (5,6)[C].
COMPLEMENTARY & ALTERNATIVE MEDICINE
Support sleep with noninvasive positive pressure (BiPAP) if orthopnea or sleep-disordered breathing is present (1,4)[C]. é á
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Patient Monitoring
- Patient monitoring up to 3 years for possible recovery
- Periodic/serial chest films
- Monitor for stability of lung function with serial pulmonary function studies.
- Close follow-up if dysfunction is secondary to tumor with assessment for possible recurrence
PATIENT EDUCATION
- Cold phrenic nerve injury generally resolves; however, recovery may take up to 3 years.
- Recovery following chemotherapy has been noted, but is highly variable.
PROGNOSIS
- Long-term prognosis is good with limited activity reduction.
- Spontaneous recovery is minimal after 2 to 3 years.
- Generally, patients will lead relatively normal lives, usually developing compensatory mechanisms.
- Prognosis of unilateral disease is usually good unless patient has significant underlying pulmonary or neurologic disease.
- Phrenic function may improve with time in patients with UPD after cardiac surgery or other surgical procedures that involve the cervical or mediastinal regions.
- Patients with high cervical spine injuries, advanced lung disease, or progressive chronic demyelinating disease fare worse.
COMPLICATIONS
- Hypoventilation during sleep with hypoxia and/or hypercapnia
- Atelectasis
- Slowly resolving infection in the affected lung
REFERENCES
11 Benditt é áJO, Boitano é áLJ. Pulmonary issues in patients with chronic neuromuscular disease. Am J Respir Crit Care Med. 2013;187(10): 1046 " ô1055.22 Doorduin é áJ, van Hees é áHW, van der Hoeven é áJG, et al. Monitoring of the respiratory muscles in the critically ill. Am J Respir Crit Care Med. 2013;187(1):20 " ô27.33 Stevens é áWW, Sporn é áPH. Bilateral diaphragm weakness after chemotherapy for lymphoma. Am J Respir Crit Care Med. 2014;189(7):e12.44 Qureshi é áA. Diaphragm paralysis. Semin Respir Crit Care Med. 2009;30(3):315 " ô320.55 Versteegh é áMI, Jouk Tjien é áAT. Diaphragm plication in adult patients with diaphragm paralysis. Multimed Man Cardiothorac Surg. 2007;2007(1217):mmcts.2006.002568.66 Elefteriades é áJ, Singh é áM, Tang é áP, et al. Unilateral diaphragm paralysis: etiology, impact, and natural history. J Cardiovasc Surg (Torino). 2008;49(2):289 " ô295.
ADDITIONAL READING
McCool é áFD, Tzelepis é áGE. Dysfunction of the diaphragm. N Engl J Med. 2012;366(10):932 " ô942. é á
CODES
ICD10
J98.6 Disorders of diaphragm é á
ICD9
519.4 Disorders of diaphragm é á
SNOMED
paralysis of diaphragm (disorder) é á
CLINICAL PEARLS
- Often an incidental finding with chest radiograph
- Dyspnea on exertion/decreased exercise tolerance may be mild to severe unless patient has other underlying pulmonary disease (asthma, COPD, bronchiectasis, TB, bronchitis; thus UPD may cause dyspnea at rest).
- In the presence of nocturnal hypoventilation, noninvasive positive pressure is preferred because it can improve both symptoms and physiologic derangements if hypoventilation is noted during sleep, which occurs especially during REM sleep.