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wileyonlinelibrary.com/journal/ane Acta Neurol Scand. 2018;138:4–11.
© 2018 John Wiley & Sons A/S.
Published by John Wiley & Sons Ltd
1 | INTRODUCTION
Neuromyelitis optica spectrum disorders (NMOSDs) associ-
ated with aquaporin- 4 antibody (AQP4- Ab) are severe idiopathic
immune- mediated inflammatory diseases, which are character-
ized by frequent relapses and progressive irreversible disability.
1
The 2015 International Panel for NMO Diagnosis (IPND) criteria
is a significant change for the earlier diagnosis and management
of NMOSDs. A recent research reported that application of
the 2015 criteria led to a rise in diagnosis of NMOSDs by 76%.
2
Hyponatremia is a potentially serious complication of neurological
disorders. However, only several reports have focused on the asso-
ciation between hyponatremia and NMOSDs. Previously, the asso-
ciation between NMOSDs and hyponatremia, especially that due to
syndrome of inappropriate antidiuretic hormone secretion (SIADH),
was considered rare. In fact, the actual prevalence of hyponatremia
in NMOSDs patients is not low, and it sometimes manifests as an
initial presenting symptom. Importantly, concurrent hyponatremia
may increase the severity of neurological symptoms. In neurosurgi-
cal patients, the potential causes of hyponatremia include inappro-
priate intravenous infusion, SIADH, adrenocorticotropic hormone
(ACTH) deficiency disease, and cerebral salt- wasting syndrome
(CSWS). In particular, distinguishing between SIADH and CSWS
is the greatest challenge because of similarities in clinical findings
and laboratory abnormalities. Accurate and early differentiation
between the two conditions will have important implications for
the selection of appropriate therapy. In contrast to CSWS, SIADH
should be treated with strict fluid restriction. Inappropriate fluid
management will lead to worsened hyponatremia, with potentially
fatal outcomes.
Here, we describe two patients with AQP4 antibody- positive
NMOSDs who developed hyponatremia. Patient #1 was the first
NMOSDs patient reported to develop hyponatremia caused by
CSWS. In Patient #2, hyponatremia, attributed to SIADH, presented
as an initial symptom. In addition to these two cases, we present a
review of the literature on this topic.
Accepted: 14 March 2018
DOI: 10.1111/ane.12938
REVIEW ARTICLE
Hyponatremia in neuromyelitis optica spectrum disorders:
Literature review
S. Jin | Z. Long | W. Wang | B. Jiang
Department of Neurology, The Second
Xiangya Hospital, Central South University,
Changsha, China
Correspondence
Wei Wang and Bo Jiang, Department of
Neurology, The Second Xiangya Hospital,
Central South University, Changsha, Hunan,
China.
Emails: wangweidoctor@csu.edu.cn;
jiangbo3173@csu.edu.cn
Funding information
National Natural Science Foundation of
China, Grant/Award Number: 81601083
Hyponatremia is a potentially serious electrolyte abnormality observed in neuromy-
elitis optica spectrum disorders (NMOSDs), and its most common cause is syndrome
of inappropriate antidiuretic hormone secretion (SIADH). Another potential cause of
hyponatremia is cerebral salt- wasting syndrome (CSWS), although CSWS has not
previously been reported in NMOSDs. Accurate and early differentiation between
SIADH and CSWS is difficult. However, the two conditions have important implica-
tions for the selection of therapy. Here, we describe two patients with aquaporin- 4
antibody (AQP4- Ab)- positive NMOSDs who developed hyponatremia as a result of
CSWS and SIADH, respectively. Additionally, we review all previously reported stud-
ies of hyponatremia in patients with NMOSDs and propose several potential patho-
physiological mechanisms of hyponatremia. In conclusion, NMOSDs accompanied by
hyponatremia are not actually rare, but have previously been given little attention.
Furthermore, SIADH should not be the only consideration, before the exclusion of
rare but significant CSWS.
KEYWORDS
aquaporin-4 antibody, cerebral salt-wasting syndrome, hyponatremia, neuromyelitis optica
spectrum disorders, syndrome of inappropriate antidiuretic hormone
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