Diaphragmatic Dysfunction in Neuralgic Amyotrophy: An Electrophysiologic Evaluation of 16 Patients Presenting with Dyspnea

Abstract

We report 16 adult men (age, 41 to 75 yr) with neuralgic amyotrophy (NA) who presented with dyspnea due to involvement of the diaphragm. All patients developed breathlessness after a prodrome of acute severe neck and shoulder pain. Bilateral diaphragm paralysis (BDP) was confirmed in 12 patients and unilateral diaphragm paralysis (UDP) in four by the absence of electrical and mechanical responses to percutaneous phrenic nerve stimulation. Global expiratory muscle strength was well preserved in all patients, but inspiratory muscle strength was reduced in proportion to the extent of diaphragmatic involvement. Lung function showed low lung volumes with preservation of carbon monoxide transfer coefficient in all patients. Two BDP patients were hypoxic (PaO2 = 67 and 54 mm Hg, respectively) on daytime arterial blood gas analysis; the latter patient with pre-existing chronic obstructive pulmonary disease and marked obesity also had borderline hypercapnia (PaO2 = 49 mm Hg). Overnight sleep studies in three BDP and two UDP patients showed frequent intermittent arterial oxygen desaturations apparently caused by obstructive sleep apneas, but there was no evidence of alveolar hypoventilation. Follow-up muscle studies in five BDP and four UDP patients between 2 and 4 yr after initial referral showed complete recovery of diaphragmatic function in only two UDP patients, one of whom relapsed a year later. We postulate that NA may be an important but underrecognized cause of diaphragmatic paralysis in otherwise normal patients. Diaphragmatic strength returns very slowly, if at all.

Diaphragmatic paralysis due to Lyme disease

“…He did not demonstrate evidence of respiratory failure (even when supine), he did not complain of orthopnoea, and he denied any reduction in exercise tolerance. Perhaps it is not surprising that there was no evidence of respiratory failure in this case since, in the absence of underlying lung disease, unilateral diaphragmatic paralysis is a rare cause of respiratory failure and its symptoms can be mild [12,13].…”

A 54-Year-Old Man with Acute Onset Orthopnea and Sleep-Related Hypoxia

“…1,2 The differential diagnoses for this patient's subacutely evolving bilateral diaphragmatic weakness included bilateral isolated phrenic neuropathy (BIPN), [3][4] neuralgic amyotrophy ([NA] also known as Parsonage-Turner Syndrome), [5][6][7] and amyotrophic lateral sclerosis. There was no evidence for other conditions which may rarely cause bilateral phrenic neuropathies, such as diabetes, 8 multifocal motor neuropathy with conduction block, 9 POEMS syndrome, 10 sarcoidosis, 11 arsenic poisoning, 12 prior irradiation, 13 or acid maltase deficiency.…”

Bilateral Phrenic Nerve Paralysis Manifested by Orthopnea for 6 Months in a Patient with Neuralgic Amyotrophy

“…The male to female ratio in patients with NA has been reported to be 2.4 : 1 (11). In a report by Mulvey et al,all 12 patients with NA complicated by BPP were men (13), while 4 of 5 such patients were men in a report by Tsao et al (14). In other reports, NA was more frequently complicated by BPP in men than in women (15,16).…”

“…In the case of respiratory failure due to BPP, use of non-invasive positive pressure ventilation (NPPV) assists ventilation (1,12). Regarding the prognosis of NA complicated by BPP, one report noted slight bilateral improvement in diaphragmatic function during the observation period of 1 to 4 years (14), but other reports stated that few cases showed improvement (13,15 …”