Syndrome of inappropriate antidiuresis may herald or accompany neuromyelitis optica

Abstract

HERALD OR ACCOMPANY NEUROMYELITIS OPTICAAquaporin-4 (AQP4) is the target autoantigen of an immunoglobulin G (IgG) autoantibody that distinguishes a spectrum of inflammatory demyelinating CNS disorders (the neuromyelitis optica [NMO] spectrum) from multiple sclerosis (MS) and other CNS demyelinating disorders. 1 Compelling evidence supports this IgG having a central role in the pathogenesis of NMO. AQP4 is concentrated in astrocytic foot processes at interfaces between CNS parenchyma and fluid compartments, both CSF and blood, 1 and in areas involved in osmosensitivity and osmoregulation, including supraoptic and paraventricular nuclei of the hypothalamus and sensory circumventricular organs, the subfornical organ, the organum vasculosum of the lamina terminalis, and the area postrema. 2 A single case of the syndrome of inappropriate antidiuresis (SIAD) has been described in NMO. 3 Here we report the frequency of SIAD in NMO.Methods. Standard protocol approvals, registrations, and patient consents. The study was approved by the Institutional Review Board. The study involved retrospective chart review of 160 AQP4-IgG seropositive Mayo Clinic patients identified though the Neuroimmunology Laboratory's NMO database who provided consent to have their records reviewed.Our inclusion criterion, hyponatremic patients fulfilling modified Bartter and Schwartz criteria for SIAD, 4 required that data be available for both serum sodium concentration and blood/urine osmolality, at the onset of NMO or during a relapse of the disease. We excluded patients whose hyponatremia was attributable to carbamazepine or diuretic therapy (3), lymphoma (1), or thyroid dysfunction (1). No patient had signs of cerebral salt wasting syndrome.Results. Among 160 patients with NMO or NMO spectrum disorder, 43 had sufficient data for the study. Seven patients (16%) met diagnostic criteria for SIAD (table). The median age at disease onset was 55 years (range 15-72). The median follow-up interval was 67 months (range 24 -150). SIAD was the initial symptom of the attack in 5 of the 43 patients (12%). Hyponatremia was mild (130 mmol/L) in 1 patient, moderate (120 -130 mmol/L) in 4, and severe (Ͻ120 mmol/L) in 2. Only 1 patient experienced confusion and decreased consciousness attributable to hyponatremia. No information about sodium urinary concentration and plasma vasopressin levels was available. No patient was on any diuretic therapy or had adrenal insufficiency. Creatinine and BUN were unremarkable in all patients. Two patients experienced intractable vomiting, 2 had nausea, and 1 patient developed a syndrome of posterior reversible encephalopathy at the time of documented hyponatremia. Hyponatremia resolved in all patients after fluid intake was restricted to 1 L per day. No patient experienced a recurrence of hyponatremia.MRI revealed brain abnormalities in 4 patients; 1 had fluid-attenuated inversion recovery and T2weighted signal abnormalities extending from the brainstem into the area postrema region. Five patients had radiologic signs compa...

Paraneoplastic neuromyelitis optica spectrum disorders: three new cases and a review of the literature

“…Disease in CNS could start with the movement of AQP4-IgG from the periphery into the circumventricular organs, where blood-brain barriers might lack, such as the area postrema [20] and the posterior hypothalamus [24], …”

Anorexia Heralding the Onset of Neuromyelitis Optica

“…Brain lesions are now a well-recognized feature of NMO (3), and the presence of "cloud-like" enhancement has been described as being specific for the disease (6). In particular, pathological (7), radiological (3) and clinical (8,9) studies have shown that brain sensory CVOs (the area postrema, organum vasculosum lamina terminalis and subfornical organ) are preferentially involved in NMO.…”

“…Both anorexia (4,5) and an increased appetite (11) associated with inflammatory lesions involving the area postrema or the hypothalamus have been described in NMO patients. Pathologic studies have revealed that inflammatory lesions of the area postrema are present in up to 40% of NMO patients (9). However, the subfornical organ and the organum vasculosum of the lamina terminalis have not yet been studied in patients with NMO.…”

Neuromyelitis optica spectrum disorder associated with osmotic demyelination syndrome

“…Hypothalamic lesions have been associated with disturbance of water and salt equilibrium [2]. Herein, we report a case of NMOSD associated with hyponatremia and osmotic demyelination syndrome (ODS).…”