Ultrasound Imaging of the Diaphragm

The diaphragm is the major muscle of respiration and its dysfunction is associated with problems ranging from orthopnea to prolonged recovery from surgery or ventilator management. Common causes of diaphragm dysfunction include phrenic neuropathy, motor neuron disease, neuromuscular junction disorders, and myopathy. This article reviews sonographic findings of normal diaphragm, including key quantitative ultrasound measurements that are helpful in the evaluation of diaphragm. It also discusses various clinical application of this technique in diagnosis of neuromuscular diseases.

Bilateral Isolated Phrenic Neuropathy: a Rare Cause of Dyspnoea

Bilateral diaphragm paralysis due to bilateral isolated phrenic neuropathy (BIPN) is a very rare cause of unexplained respiratory failure. We present a 65-year-old patient with no relevant previous medical history who presented in the Pulmonology Clinic with mMRC1 dyspnoea and orthopnoea. After the medical work-up, diaphragmatic paresis was diagnosed. Inspiratory muscle training resulted in mild symptomatic improvement and treatment with noninvasive mechanical ventilation (NIV) was initiated. This condition is generally chronic and has a poorer prognosis, compared to other cases of phrenic nerve involvement. In this case, NIV restored near-normal daily function.

Phrenic neuropathy water immersion dyspnea

ObjectiveTo investigate the following among patients with phrenic neuropathy: (1) occurrences of water immersion activity‐induced dyspnea; (2) clinical, electrophysiologic, sonographic, and pulmonary function test abnormalities; and (3) frequency of documented counseling regarding the risks of water immersion activities.MethodsWe identified all patients with test-confirmed phrenic neuropathy seen from January 1, 2000, to December 31, 2018, at Mayo Clinic.ResultsOf 535 patients with phrenic neuropathy, documentation of dyspnea with water activities was identified in 4% (22/535). The risks of water immersion were only documented in patients having experienced this problem. The majority had isolated phrenic neuritis or neuralgic amyotrophy syndrome (77.3%), mean age was 55 years (range 31–79), and most patients were men (81.9%). Patients had right-sided (45.5%) or bilateral (54.5%) phrenic neuropathy. None had isolated left phrenic involvement. Near-fatal drowning occurred in 18.2% (4/22), with persons needing assistance to be rescued from the water, following diving into water. Dyspnea with water immersion was the only symptom in 4.5% (1/22) and the presenting respiratory symptom in 36.4% (8/22). A range of electrophysiologic, sonographic, and pulmonary function test abnormalities including mild abnormalities were seen and not found to be significantly different from those in patients in whom water-induced dyspnea was not recorded.ConclusionRespiratory distress with water immersion activities is a serious complication of phrenic neuropathies. Physician-documented counseling is lacking. Isolated phrenic neuritis, neuralgic amyotrophy, and right-sided and bilateral phrenic involvement are most commonly implicated, but the range of severity and testing abnormalities suggest that all patients with neuralgic amyotrophy or phrenic neuropathy should be warned especially about diving into water.

Bilateral phrenic neuropathy responsive to intravenous immunoglobulin treatment

The aetiology of phrenic neuropathy is often unknown, but immune mechanisms may play a role. In a typical case of bilateral phrenic neuropathy with paradoxical breathing (video), an inflammatory pathogenesis was suggested by prolonged distal latency of phrenic nerve compound muscle action potentials in nerve conduction studies and a clear-cut albumin-cytologic dissociation. This encouraged us to treat the patient with a standard dose of intravenous immunoglobulin. After obtaining a strong improvement at spirometry, we repeated the second cycle of intravenous immunoglobulin and observed normalization of symptoms within few weeks and no relapse after 3 years. This case suggests that lumbar puncture should be performed in the acute phase of phrenic neuropathies to detect potential responders to immunomodulatory treatment.

Fontan Failure Secondary to Charcot-Marie-Tooth–Induced Phrenic Neuropathy

Charcot-Marie-Tooth disease comprises a vast array of defects in myelin integrity that causes progressive peripheral sensorimotor neuropathy. It is the most prevalent inherited peripheral neuropathy, and it can affect the management of coexisting medical conditions. We report the case of a 25-year-old woman who had undergone successful Fontan surgery during childhood, but her Fontan circulation failed as a result of diaphragmatic paresis caused by Charcot-Marie-Tooth disease type 1A. This diagnosis precluded cardiac transplantation.