American Society of Regional Anesthesia and Pain Medicine May 2015 - (Page 11)
Phrenic Nerve Injury and Interscalene Nerve Block
Have We Learned Anything From the Surgical
Treatment of Over 150 Cases of Diaphragmatic
Paralysis From Multiple Etiologies?
D
iaphragmatic paralysis tends to be a problematic diagnosis
for both the afflicted individual and the treating physician
alike. Most patients undergo an extensive cardiac and
pulmonary workup as a response to the presenting symptoms,
including dyspnea with exertion, orthopnea, chest discomfort, and
lethargy.1 Even when there is a possible preceding event or series
of events that could be considered likely causes of the paralysis,
physicians are often hesitant in their presumptive diagnosis.
Compounding the delay and adding to patients' frustration is that
many are ultimately told this will be a chronic condition they must
learn to live with.
Since 2007, we have been treating patients with diaphragmatic
paralysis by using a peripheral nerve surgery algorithm. The
rationale for this approach is based on the notion that most cases
of diaphragmatic paralysis are the result of a phrenic nerve injury.
Peripheral nerve injuries throughout the body are readily amenable
to repair by using methods originally developed in the 1930s.2
With the advent of microsurgical techniques, the subspecialty of
peripheral nerve surgery blossomed owing to the effectiveness of
meticulous and delicate repair of nerve injuries.3 Until recently, the
primary areas in which these techniques have been applied were
limited to nerves of the upper and lower extremities, and facial
nerve.4,5
To date, at our tertiary bicoastal referral centers, we have evaluated
more than 300 individuals with diaphragmatic paralysis, including
over 150 patients who have undergone phrenic nerve surgery.
Approximately 30% of those
treated have interscalene nerve
block (ISB) as their underlying
etiology, comprising the most
common cause of diaphragmatic
paralysis in our patient
population.6
include electromyography/nerve
conduction studies (EMG/NCS), sniff
testing, magnetic resonance imaging
(MRI), and pulmonary function
testing. Although the sniff test usually
confirms the diagnosis, the EMG/
NCS provides quantitative information
regarding the phrenic neuropathy.
Thus, it is often possible to
characterize the severity of the nerve
injury by analyzing nerve conduction
velocities and motor amplitudes.
Matthew R. Kaufman, MD, FACS
Intraoperative findings often suggest
Codirector, Center for the
sequelae of an inflammatory event(s)
Treatment of Paralysis and
such as compressive adhesions
Reconstructive Nerve Surgery,
from adjacent vascular or fibrous
Jersey Shore University Medical
structures and nerve torsion or
Center, Neptune, New Jersey
displacement from extensive fibrosis
Voluntary Clinical Assistant
(Figure 1). Alternatively, microscopic
Professor of Surgery
visualization of segmental atrophy
David Geffen UCLA Medical
and nerve sheath hyperemia, when
Center, Los Angeles, California
present as the most significant
discernible abnormality, may
Section Editor:
be indicative of nerve anoxia
Steven Orebaugh, MD
from other causes (ie, adverse
pharmacologic effect) (Figure 2).
Another common finding is diffuse
(nonsegmental) atrophy that is exemplified by a visible reduction in
the diameter of the phrenic nerve throughout its course in the neck,
a finding that could suggest an underlying cervical radiculopathy. A
combination of microscopic visualization and intraoperative nerve
threshold testing provides the most comprehensive manner in
which to assess nerve pathology, and we are often able to ascertain
whether there is one process
or a combination of factors
contributing to the absence of
diaphragmatic activity.
"Perhaps there should be equivalent
emphasis placed on patient
screening to determine those who
may be more susceptible to ISBrelated complications"
Presurgical evaluation and
operative intervention provide us
with a possibility to reverse the
paralysis and an opportunity to
investigate the pathologic process. Initially, we ask for a detailed
history in an attempt to identify possible etiologies, especially
the temporal relationship between antecedent event(s) and onset
of respiratory symptoms. Review of our extensive database of
patients with diaphragmatic paralysis has allowed us to assess
whether certain preexisting conditions may be associated with a
susceptibility to phrenic nerve injury. Our preoperative evaluations
The analysis of our subset of
patients with diaphragmatic
paralysis after ISB raises
several considerations regarding
predisposing conditions,
the pathologic process, and
prospects for treatment. Our
prior report (Anesthesiology, August 2013) was a case series of
patients with diaphragmatic paralysis after ISB and suggested
an inadvertent mechanical or pharmacologic insult to the phrenic
nerve.7 Subsequent to this report, we have had the opportunity to
exponentially increase our experience with this patient population
and intend on updating the original series once outcome data are
collected.
American Society of Regional Anesthesia and Pain Medicine
2015
11
3
Table of Contents for the Digital Edition of American Society of Regional Anesthesia and Pain Medicine May 2015
President’s Message
Editorial
Pharmacogenetics in Monitoring of Chronic Pain Patients: Are We There Yet?
Phrenic Nerve Injury and Interscalene Nerve Block: Have We Learned Anything From the Surgical Treatment of Over 150 Cases of Diaphragmatic Paralysis From Multiple Etiologies?
An Exercise in Negotiation: The Success of the Pain Medicine Fellowship Match
Regional Analgesia for Patients with Acute Rib Fractures
Application of Regional Anesthetic Techniques for Cancer Pain
American Society of Regional Anesthesia and Pain Medicine May 2015
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