Share:


Work-Up for Diaphragmatic Dysfunction in Neuromuscular Disorders Requires Standardized Diagnostic Criteria

    Josef Finsterer Affiliation

Abstract

In a recent article, Türk et al. reported about a retrospective study of 30 patients with respiratory insufficiency due to diaphragmatic dysfunction having undergone nerve conduction studies of the phrenic nerve or needle electromyography (EMG) of the diaphragm [1]. We have the following comments/concerns.
Inclusion criteria are contradictory. Since the study had a retrospective design, the authors knew the diagnosis of all patients, except those with unknown cause, (n=8) in advance. According to the inclusion criteria, those with a known cause of phrenic nerve lesion (n=22) should have been excluded.

How to Cite
1.
Finsterer J. Work-Up for Diaphragmatic Dysfunction in Neuromuscular Disorders Requires Standardized Diagnostic Criteria. ijmhs [Internet]. 29Oct.2018 [cited 15Nov.2018];8(10):174-5. Available from: http://innovativejournal.in/index.php/ijmhs/article/view/2328
Online First
Oct 29, 2018
Abstract Views
42
PDF Downloads
13
XML Downloads
0
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.

Commentary:

In a recent article, Türk et al. reported about a retrospective study of 30 patients with respiratory insufficiency due to diaphragmatic dysfunction having undergone nerve conduction studies of the phrenic nerve or needle electromyography (EMG) of the diaphragm [ 1 ]. We have the following comments/concerns.

Inclusion criteria are contradictory. Since the study had a retrospective design, the authors knew the diagnosis of all patients, except those with unknown cause, (n=8) in advance. According to the inclusion criteria, those with a known cause of phrenic nerve lesion (n=22) should have been excluded.

It is not comprehensible why the reference limit for distal latency of the phrenic nerve was 8.5ms for all patients, regardless of age, sex, and height [ 2 ]. It is easily comprehensible that tall probands will have a longer distal latency than short probands. Since men are usually taller than females, it is also comprehensible that the distal latency of the phrenic nerve will be longer in males as compared to females. Furthermore, it is comprehensible that the phrenic nerve distal latency will increase and that nerve conduction will decrease with age. Inspiration/expiration and affection of the upper motoneuron may additionally influence phrenic nerve conduction [ 3 ].

According to table 1 , four patients had undergone needle-EMG of the diaphragm, but only in one patient the results of this investigation were provided [ 1 ]. Which were the needle-EMG findings in the other three patients? Since 28/30 patients had neuropathy of the phrenic nerve, it is quite likely that these three patients had a neurogenic pattern with enlarged motor unit action potentials and a thinned interference pattern.

Pompe disease may not only manifest with myopathy but also with neuropathy [ 4 ]. In the one patient with Pompe disease and a myogenic EMG, were nerve conduction studies of the phrenic nerve or other nerves normal?

Isolated neuropathy of the phrenic nerve is rather rare [ 5 ]. Did the 28 patients with neuropathy of the phrenic nerve also present with neuropathy of the peripheral nerves supplying the limb muscles or the facial muscles?

Five patients were reported to have experienced complete recovery of diaphragmatic dysfunction [ 1 ]. Two of these patients had a neuropathy of the phrenic nerve of unknown cause [ 1 ]. How do the authors explain that two patients recovered without receiving any specific diagnosis or treatment for diaphragmatic dysfunction? The three others that fully recovered responded favorably to treatment for myasthenia, borelliosis, or CIDP [ 1 ].

Concerning those with idiopathic phrenic nerve neuropathy, was the family history taken and positive for neuropathy and did relatives of these patients undergo clinical exam, nerve conduction studies, and if indicated, needle EMG?

In conclusion, this retrospective study could be more meaningful if inclusion / exclusion criteria would be more strict, if age-, sex-, and height dependent reference limits would have been applied, if EMG results of all patients would have been reported, if nerve conduction studies of nerves other than the phrenic nerve would have been provided, and if full recovery of idiopathic phrenic nerve neuropathy would have been discussed.

References:

  1. Diaphragmatic dysfunction as the presenting symptom in neuromuscular disorders: A retrospective longitudinal study of etiology and outcome in 30 German patients TĂźrk Matthias, Weber Irina, Vogt-Ladner Gernot, SchrĂśder Rolf, Winterholler Martin. Neuromuscular Disorders.2018-jun;:484-490. [ CrossRef ] [Google Scholar]
  2. Effect of age on changes in motor units functional connectivity Arjunan SridharP, Kumar Dinesh. 2015 37th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC).2015. [ CrossRef ] [Google Scholar]
  3. The impact of spasticity on diaphragm contraction: Electrophysiological assessment Miranda Bruno, Pinto Susana, Carvalho Mamedede. Clinical Neurophysiology.2018-aug;:1544-1550. [ CrossRef ] [Google Scholar]
  4. Causally treatable, hereditary neuropathies in Fabry\textquotesingles disease, transthyretin-related familial amyloidosis, and Pompe\textquotesingles disease Finsterer J, Wanschitz J, Quasthoff S, Iglseder S, LĂśscher W, Grisold W. Acta Neurologica Scandinavica.2017-mar;:558-569. [ CrossRef ] [Google Scholar]
  5. Ventilation/Perfusion scan aids in the diagnosis of diabetes mellitus induced trepopnea due to isolated right phrenic nerve palsy Subramanyam Padma, Palaniswamy ShanmugaSundaram. Indian Journal of Nuclear Medicine.2013. [ CrossRef ] [Google Scholar]

Latest Article