Brain and spinal cord atrophy in NMOSD and MOGAD: Current evidence and future perspectives

Neuromyelitis optica spectrum disorder (NMOSD) is a severe form of inflammation of the central nervous system (CNS) including acute myelitis, optic neuritis and brain syndrome. Currently, the classification of NMOSD relies on serologic testing, distinguishing between seropositive or seronegative anti-aquaporin-4 antibody (AQP4) status. However, the situation has recently grown more intricate with the identification of patients exhibiting the NMOSD phenotype and myelin oligodendrocyte glycoprotein antibodies (MOGAD). NMOSD is primarily recognized as a relapsing disorder; MOGAD can manifest with either a monophasic or relapsing course. Significant symptomatic inflammatory CNS injuries with stability in clinical findings outside the acute phase are reported in both diseases. Nevertheless, recent studies have proposed the existence of a subclinical pathological process, revealing longitudinal changes in brain and spinal cord atrophy. Within this context, we summarise key studies investigating brain and spinal cord measurements in adult NMOSD and MOGAD. We also explore their relationship with clinical aspects, highlight differences from multiple sclerosis (MS), and address future challenges. This exploration is crucial for determining the presence of chronic damage processes, enabling the customization of therapeutic interventions irrespective of the acute phase of the disease.

Anti-glial fibrillary acidic protein antibody and anti-aquaporin-4 antibody double-positive neuromyelitis optica spectrum disorder: A case report

BACKGROUND

A case of neuromyelitis optica spectrum disorder (NMOSD) with positive cerebrospinal fluid (CSF) anti-aquaporin-4 antibody (AQP4-IgG) and anti-glial fibrillary acidic protein IgG (GFAP-IgG) at the time of relapse was reported. The exact roles of GFAP-IgG in NMOSD are not fully understood and are the subject of ongoing research. This study revealed the possible connection between GFAP-IgG and the occurrence or development of diseases.

CASE SUMMARY

A 19-year-old woman was admitted to the hospital due to a constellation of symptoms, including dizziness, nausea, and vomiting that commenced 1 year prior, reoccurred 2 mo ago, and were accompanied by visual blurring that also began 2 mo ago. Additionally, she presented with slurred speech and ptosis, both of which emerged 1 mo ago. Notably, her symptoms deteriorated 10 d prior to admission, leading to the onset of arm and leg weakness. During hospitalization, magnetic resonance imaging showed high T2-fluid attenuated inversion recovery signals, and slightly high and equal diffusion-weighted imaging signals. The serum antibody of AQP4-IgG tested positive at a dilution of 1:100. CSF antibody testing showed positive results for GFAP-IgG at a dilution of 1:10 and AQP4-IgG at a dilution of 1:32. Based on these findings, the patient was diagnosed with NMOSD. She received intravenous methylprednisolone at a daily dose of 500 mg for 5 d, followed by a tapering-off period. Afterward, the rate of reduction was gradually slowed down and the timely use of immunosuppressants was implemented.

CONCLUSION

The CFS was slightly GFAP-IgG-positive during the relapse period, which can aid in the diagnosis and treatment of the disease.

Utility of the tibial nerve somatosensory evoked potentials in differentiating between neuromyelitis optica spectrum disorders and multiple sclerosis

BACKGROUND

Somatosensory evoked potentials (SEPs) are widely used for the diagnosis and evaluation of neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS). However, whether the parameters of tibial nerve SEPs can help to distinguish NMOSD from MS remains unclear. Thus, the aim of this study was to investigate the utility of tibial nerve SEP parameters in differentiating patients with NMOSD and MS.

METHODS

The clinical data of patients with NMOSD or MS treated in our institution between 2005 and 2021 were retrospectively extracted from our electronic database. Additional inclusion criteria were presentation with sensory symptoms in the lower extremities with corresponding lesions in the magnetic resonance images as well as available data on anti-aquaporin-4 antibodies and tibial nerve SEPs. The Z-scores of the N21-P38 interval (central sensory conduction time), P38 latency, and P38 amplitude were compared between the patients with NMOSD and MS. The relationship of disease severity with the parameters of the tibial nerve SEPs was also evaluated.

RESULTS

Twenty patients with NMOSD and 13 patients with MS were enrolled. The Z-scores of the N21-P38 interval and P38 latency were significantly higher in the MS group than in the NMOSD group (p < 0.05 and p < 0.01, respectively), whereas there was no difference in the Z-scores of the P38 amplitude between the two groups. In the MS group, only the N21-P38 interval and P38 latency were significantly correlated with disease severity (p < 0.05 and p < 0.01, respectively). In contrast, none of the tibial nerve SEP parameters were significantly correlated with disease severity in the NMOSD group.

CONCLUSION

Evaluation of the N21-P38 interval and P38 latency in tibial nerve SEPs potentially helps in differentiating between NMOSD and MS.

Treatment response, risk of relapse and clinical characteristics of Taiwanese patients with neuromyelitis optica spectrum disorder

BACKGROUND/PURPOSE

The long-term disease course and efficacy of maintenance therapies have rarely been investigated in Asian patients with neuromyelitis optica spectrum disorder (NMOSD).

METHODS

Medical records of patients fulfilling the 2015 International Consensus Diagnostic Criteria for NMOSD at three medical centers in Taiwan were systematically analyzed. Linear regression analysis was performed to investigate factors related to annualized relapse rate (ARR); survival analysis was used to estimate the relapse-free intervals among therapies.

RESULTS

A total of 557 relapses affecting 648 regions (202 optic neuritis, 352 acute myelitis, and 94 brain syndromes) in 204 patients were analyzed during a follow-up period of 69.5 months (range, 1-420). Up to 36.1% of myelitis-onset patients and 24.0% of optic neuritis-onset patients exhibited a limited form disease, defined as having one or more relapses confined to the same region. The median ARR was significantly lower in patients with limited form disease than those with relapses involving multiple regions (0.30 vs. 0.47, respectively). An older age at disease onset was associated with a lower ARR (p = 0.023). Kaplan-Meier analysis showed that the estimated time (months) to next relapse was longest in rituximab-treatment group (58.0 ± 13.2), followed by immunosuppressant (48.5 ± 4.8) or prednisone (29.6 ± 4.6) groups, and shortest in those without maintenance therapy (27.6 ± 4.2) (p = 8.1 × 10^-7).

CONCLUSION

Limited form disease and older age at disease onset are associated with a lower relapse rate in NMOSD. Compared to no maintenance therapy, rituximab and immunosuppressant significantly reduce the relapse risks.

Five-year visual outcomes after optic neuritis in anti-MOG antibody-associated disease

INTRODUCTION

Optic neuritis (ON) is a major phenotype of clinical attack related to demyelinating neurological diseases of the central nervous system, including multiple sclerosis (MS), anti-aquaporin-4 (AQP4) antibody-positive neuromyelitis optica spectrum disorder (NMOSD), and anti-myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). As the concept of MOGAD is relatively new, the long-term visual outcomes after ON in MOGAD remains unclear.

METHODS

To elucidate the long-term visual prognosis after ON in MOGAD, patients with MOGAD whose visual acuity were regularly followed for more than 5 years from the onset of ON were enrolled. Best-corrected visual acuity (BCVA) at nadir in the acute phase and at 1 and 5 years from onset was evaluated. The data from patients with MOGAD were compared with those from patients with MS or anti-AQP4-positive NMOSD.

RESULTS

Twenty-three patients (31 ON-involved eyes) with MOGAD, 20 patients (24 ON-involved eyes) with MS, and 22 patients (24 ON-involved eyes) with anti-AQP4-positive NMOSD were evaluated. All BCVA at nadir, 1 year, and 5 years from the onset of ON were much worse in anti-AQP4-positive NMOSD than in MS (p = 0.0024) and MOGAD (p = 0.0014) patients. In MOGAD and anti-AQP4-positive NMOSD, the serum disease-specific antibody titer was not associated with the subsequent visual prognosis. Visual acuity had almost fully recovered spontaneously or shortly after initiating acute treatment in 22 of the 23 patients with MOGAD-ON. The administration of high-dose intravenous steroid therapy further facilitated early recovery of visual acuity. Meanwhile, a small fraction of patients with extensive optic nerve lesions involving the chiasma irreversibly experienced severe visual impairment despite appropriate acute treatment.

CONCLUSION

Although a small fraction of patients with MOGAD who presented with extensive optic nerve lesions experienced irreversible severe visual impairment, the long-term visual outcomes after 5 years from ON in patients with MOGAD were generally as good as that in patients with MS and much better than that in patients with anti-AQP4-positive NMOSD.

Visual outcome of aquaporin-4 antibody-positive optic neuritis with maintenance therapy

PURPOSE

To assess the effect of maintenance therapy on visual outcomes in preventing recurrences one year after first onset in patients with aquaporin-4 antibody (AQP4Ab)-positive optic neuritis.

STUDY DESIGN

Retrospective study.

METHODS

The medical charts of 56 patients with optic neuritis (22 with AQP4Ab-positive and 34 with AQP4Ab-negative) at Niigata University Medical and Dental Hospital were retrospectively analyzed. Clinical characteristics, including visual acuity and number of recurrences one year after first onset, were compared among patients who were AQP4Ab-positivie with and those without maintenance therapy such as oral prednisolone and azathioprine, as well as those who were AQP4Ab-negative.

RESULTS

The mean ages were 49.3 and 45.2 years in the AQP4Ab-positive and the AQP4Ab-negative groups. The female to male ratio was 21:1 and 18:16 in the two groups, respectively. Multiple between-group comparison showed a statistically significant difference in visual acuity one year after first onset between the AQP4Ab-positive without maintenance therapy group and the AQP4Ab-negative group (0.05 (median, same applies below) vs. 1.0, p < 0.01). There was also a statistically significant difference in the number of recurrences in the year after first onset between the AQP4Ab-positive with and without maintenance therapy groups (1 vs. 0, p < 0.01).

CONCLUSION

This study demonstrates that patients with AQP4Ab-positive optic neuritis without maintenance therapy had the poorest visual acuity and the most recurrences one year after first onset. These results indicate that reducing the number of recurrences with maintenance therapy could improve the visual outcomes in patients with AQP4Ab-positive optic neuritis.

Differential patterns of interhemispheric functional connectivity between AQP4-optic neuritis and MOG-optic neuritis: a resting-state functional MRI study

BACKGROUND

Several neuroimaging studies demonstrated that optic neuritis (ON) leads to functional and anatomical architecture changes in the brain. The alterations of interhemispheric functional connectivity (IFC) in patients with AQP4-ON and myelin oligodendrocyte glycoprotein (MOG)-ON are not well understood.

PURPOSE

To investigate the differential patterns of VMHC in patients with AQP4-ON and MOG-ON.

MATERIAL AND METHODS

Twenty-one patients with AQP4-ON, 11 patients with MOG-ON, and 34 healthy controls underwent resting-state MRI scans. One-way ANOVA was used to identify regions in which the zVMHC differed among the three groups. Post hoc two-sample t-tests were then conducted to compare zVMHC values between pairs of groups. Pearson correlation analysis was conducted to reveal relationships between mean zVMHC values and clinical variables in the AQP4-ON and MOG-ON groups.

RESULTS

The results revealed significant differences in zVMHC values in the PreCG among the three groups. Compared to the control group: the AQP4-ON group showed significantly lower VMHC values in the superior temporal gyrus, inferior frontal gyrus, and PreCG; and the MOG-ON group showed significantly higher zVMHC values in the PostCG. Compared to the AQP4-ON group, the MOG-ON group showed significantly lower zVMHC values in the PreCG/PostCG (voxel-level P<0.01, GRF correction, cluster-level P<0.05).

CONCLUSION

Patients with AQP4-ON and those with MOG-ON showed abnormal VMHC in the motor cortices, sensorimotor cortices, and frontal lobe, possibly indicating impaired sensorimotor function in patients with ON. Moreover, differential patterns of VMHC in patients with AQP4-ON, compared to patients with MOG-ON, might serve as a clinical indicator for classification of ON.

Very-Late-Onset Neuromyelitis Optica Spectrum Disorder in a Patient with Breast Cancer and Parkinson Disease

Anti-aquaporin-4 (anti-AQP-4) antibody-positive neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune disorder resulting in severe, recurrent optic neuritis, transverse myelitis, brain stem syndrome, and other types of neurological involvement. Its median age of onset has been reported to be around 40 years. We report herein a case of very-late-onset NMOSD (76 years of age) and try to promote its awareness as a type of neurological deterioration in elder patients. A 76-year-old woman suffering from Parkinson disease was admitted to our hospital because of consciousness disturbance. Cranial magnetic resonance imaging revealed the presence of fluid-attenuated inversion recovery high-signal-intensity lesions in the right peri- and intralateral ventricle. Part of this lesion and the meninges showed gadolinium enhancement. Physical examination revealed the presence of a tumor in the right breast, which was later diagnosed as invasive ductal carcinoma. In addition, laboratory examinations led to the detection of anti-AQP-4 antibodies in her serum; consequently, the patient was diagnosed as having NMOSD. She received initial pulsed steroid therapy, followed by right mastectomy. Although the patient's consciousness improved significantly, she developed abrupt-onset bilateral leg weakness and multiple longitudinal spinal cord lesions. Additional steroid therapy ameliorated the patient's leg weakness and reduced the swelling of the spinal cord.

Intravenous immunoglobulin treatment for steroid-resistant optic neuritis: a multicenter, double-blind, randomized, controlled phase III study

PURPOSE

To evaluate the efficacy and safety of intravenous "freeze-dried sulfonated human normal immunoglobulin (GGS)" in patients with steroid-resistant optic neuritis (ON).

STUDY DESIGN

Multicenter, prospective, double-blind, parallel-group, randomized controlled trial.

METHODS

Patients with steroid-resistant acute ON were randomly assigned to receive either intravenous GGS (GGS group) or intravenous methylprednisolone (steroid pulse [SP] group). Visual acuity (logarithm of the minimum angle of resolution [logMAR]), mean deviation (MD) value of the Humphrey Field Analyzer, and critical flicker fusion frequency were measured as efficacy endpoints; adverse events (AEs) were assessed as the safety endpoint.

RESULTS

Thirty-two patients (16 patients/group) received the study drugs. The primary endpoint, change in logMAR at week 2 compared to baseline, showed no statistically significant intergroup difference. However, compared with the SP group, change in the GGS group was increasingly indicative of visual improvement, with least squares mean difference of > 0.3 logMAR. On post-hoc analyses, the percentage of patients in the GGS and SP groups with improvement by ≥ 0.3 logMAR at week 2 were 75.0% and 31.3%, respectively. Changes in MD values at week 2 compared to baseline were 9.258  ±  8.296 (mean ± standard deviation) dB and 3.175  ±  6.167 dB in the GGS and SP groups, respectively. These results showed statistically significant intergroup differences (visual acuity improvement, P = 0.032; change in MD values, P = 0.030). No clinically significant AEs were observed.

CONCLUSION

Our results suggest that intravenous immunoglobulin could be a safe and efficacious therapeutic option for prompt treatment of steroid-resistant acute ON.

TRIAL REGISTRATION

JapicCTI-132080.

Evaluation of emotional intelligence (EI) in neuromyelitis optica spectrum disorder (NMOSD) patients compared to healthy individuals

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is known as an autoimmune astrocytopathic disorder involving central nervous system (CNS). The aim of this study was to compare Emotional Intelligence (EI) score between NMOSD patients and healthy individuals, and to find out the possible effect of this disease on EI.

METHODS

A total of 45 NMOSD participants and 48 healthy individuals were enrolled in this study. Demographic information (e.g., gender and age) of all participants as well as their level of education, and data on the patients' duration of disease were collected. EI of each participant was assessed using Persian version of Emotional Quotient inventory (EQ-i) questionnaire.

RESULTS

The mean total EI score was significantly different between the participants and controls (322±36.7 vs 338±31.5, p value<0.03). Compared to controls, patients had a poor performance in 4 of 15 EI subscales including emotional self-awareness (21.29±3.6 vs 22.85±3, p value<0.03), optimism (22.4±4 vs 24.1±3.1, p value<0.03), self-regard (22.7±4.6 vs 24.5±3.4, p value<0.04), and impulse control (16.9±6.5 vs 19.5±5.5, p value<0.05). No difference was found between anti-aquaporin-4 antibody (AQP4-IgG) positive and AQP4-IgG negative patients regarding EI score or its subscale scores, except for self-actualization (p value<0.05).

CONCLUSION

Our study showed that EI could be regarded as a tool for understanding emotions, thoughts, and behavior of NMOSD patients. It was implied that taking therapeutic steps could improve the performance of NMOSD patients with EI impairment in social life.

Two Cases of Very-Late-Onset Neuromyelitis Optica Spectrum Disorder (NMOSD) in Patients over the Age of 80

We report two cases of very-late-onset neuromyelitis optica spectrum disorder (NMOSD) in patients over the age of 80 with transverse myelopathy as the initial manifestation. In both cases, the patients presented with paraplegia and sensory, bladder, and rectal disturbances. Thoracic magnetic resonance imaging showed longitudinal high-intensity signals on a T2-weighted image. The patients received high-dose methylprednisolone. Their serum was positive for anti-AQP4 antibody (cell-based assay) during the clinical course. They were diagnosed with NMOSD and treated with immunoadsorption, plasmapheresis, and followed up with daily prednisolone. Very-late-onset NMOSD in patients over the age of 80 has only rarely been reported. The present cases suggest that NMOSD should be considered for elderly patients presenting with transverse myelitis. Early diagnosis and treatment are important.

Acute intractable vomiting: Do I belong somewhere else?

Patients suffering from acute intractable vomiting are usually treated in the Gastroenterology department. The causes of acute intractable vomiting range from acute pancreatitis and acute intestinal obstruction to cardiac causes like acute myocardial infarction and neurological causes like posterior circulation stroke. However, most of the underlying causes of acute intractable vomiting also produce other telltale signs/symptoms. Rarely, isolated acute intractable vomiting may be the initial symptom of a recurrent neurological syndrome of neuromyelitis optica spectrum disorder (NMOSD). Not only can it be promptly treated if diagnosed correctly, but also a timely diagnosis may help in prevention of recurrent neurological deficits, which can sometimes be life threatening. We present three cases of NMOSD that presented with intractable vomiting and were treated in a Gastroenterology facility prior to their diagnosis.

Refractory neuromyelitis optica spectrum disorder in systemic lupus erythematosus successfully treated with rituximab

We present a case of a woman with systemic lupus erythematosus (SLE) who had refractory episodes of neuromyelitis optica spectrum disorder (NMOSD) and was successfully treated with rituximab. She was positive for anti-aquaporin-4 (AQP4) antibody and had typical cranial and longitudinally extended spinal lesions but no optic nerve involvement. There is no established treatment for NMOSD/SLE overlap cases. Our experience suggests that rituximab may be effective for patients with combined SLE and anti-AQP4 antibody-positive NMOSD.

Neuromyelitis Optica Spectrum Disorder Coinciding with Spinocerebellar Ataxia Type 31

We report the unusual case of a 63-year-old man with spinocerebellar ataxia (SCA) type 31 who developed neuromyelitis optica spectrum disorder (NMOSD) 14 years after the onset of cerebellar symptoms. In addition to cerebellar atrophy, magnetic resonance imaging showed multiple high-intensity areas in the brain and a long thoracic cord lesion from Th1/2 to Th11. The combination of NMOSD and SCA31 is accidental. However, our case suggests that inflammatory processes could be involved in the pathogenesis of NMOSD and SCA31.

Neuromyelitis Optica Spectrum Disorders

Neuromyelitis optica (NMO) is clinically characterized by severe optic neuritis and transverse myelitis, but recent studies with anti-aquaporin-4-antibody specific to NMO have revealed that the clinical spectrum is wider than previously thought. International consensus diagnostic criteria propose NMO spectrum disorders (NMOSD) as the term to define the entire spectrum including typical NMO, optic neuritis, acute myelitis, brain syndrome, and their combinations. NMOSD is now divided into anti-aquaporin-4-antibody-seropositive NMOSD and -seronegative NMOSD (or unknown serostatus). MR imaging and optical coherence tomography are indispensable in the diagnosis and evaluation of NMOSD. This article reviews the clinical and MR imaging findings of anti-aquaporin-4-antibody-seropositive and anti-myelin oligodendrocyte glycoprotein-antibody-seropositive NMOSD.

Pregnancy-related relapse risk factors in women with anti-AQP4 antibody positivity and neuromyelitis optica spectrum disorder

BACKGROUND

Few reports describe the influence pregnancy has on the annualized relapse rate (ARR) in neuromyelitis optica spectrum disorder (NMOSD).

OBJECTIVE

To examine pregnancy-related attacks (attacks during pregnancy or within 1 year postpartum) and identify the risk factors for an attack in Japanese NMOSD patients.

METHODS

We retrospectively reviewed 139 Japanese women whom had aquaporin-4 (AQP4) antibody-positive NMOSD. Among the 114 patients with information, 47 women had 56 pregnancies. We compared the ARR before, during and after pregnancy.

RESULTS

Of the 47 NMOSD patients with pregnancy, 22 women (46.8%) had a pregnancy-related attack of the disease (either an onset event or a relapse). The ARR was significantly higher in the first 3 months postpartum (1.80 ± 2.04), than before the pregnancy (0.57 ± 1.16; p = 0.0043) and did not significantly decrease during pregnancy. The ARR before hospitalization and treatment was analyzable in 55 patients without pregnancy and was 1.09 ± 1.17. Among the 11 patients with onset before pregnancy, nine patients had a pregnancy-related attack with a relapse in the previous year, and their immunosuppression was discontinued or made to be at low doses; while the two patients on higher-dose therapies were relapse-free.

CONCLUSION

In the present study, pregnancy-related attack was common in NMOSD, and unlike in multiple sclerosis, the ARR was not reduced during pregnancy. Discontinued or insufficient immunosuppression appeared to increase the risk of pregnancy-related attack.

Nanovesicle-based platform for the electrophysiological monitoring of aquaporin-4 and the real-time detection of its antibody. Biosens Bioelectron. 2014;61:140-146. [PMID: 24874657 DOI: 10.1016/j.bios.2014.05.003]

Aquaporin-4 (AQP4) water channel protein transports water molecules across cell membranes bidirectionally and involves in a neurological disorder, neuromyelitis optica (NMO) caused by anti-AQP4 antibodies. Here, we developed a platform based on nanovesicle-carbon nanotube hybrid nanostructures for the real-time detection of anti-AQP4 antibodies and the electrophysiological monitoring of AQP4 activities. Using the hybrid device, we could detect anti-AQP4 antibodies with a high sensitivity and estimate the binding constants under different osmotic conditions. The results show AQP4 had a better affinity to anti-AQP4 antibodies under hyper-osmotic conditions than normal conditions. Furthermore, our device can be utilized to study the real-time cellular responses related with AQP4 such as those to different osmotic stresses. This nanovesicle-based platform can be a simple but versatile tool for basic research about AQP4 and related biomedical applications such as disease diagnostics.

Antibodies against interferon-beta in neuromyelitis optica patients

Neuromyelitis optica (NMO) is an antibody-mediated autoimmune inflammatory disease of the CNS. A poor response to treatment with recombinant interferon beta (IFN-ß) in NMO patients has been suggested, although the precise mechanisms remain uncertain. We analyzed occurrence and clinical consequences of IFN-neutralizing antibodies (NAbs) in 15 IFN-ß treated NMO-patients from a population-based retrospective case series cohort. NMO patients not treated with IFN-ß acted as a reference group. IFN-ß antibody determinations included binding antibodies (BAbs) measured by immunoassay and NAbs measured by a neutralization bioassay. Antibodies were determined 6-36 months after initiation of IFN-β therapy and NAbs additionally 5-10 years post-therapy. BAbs were detected in 14/15 NMO patients; 6/15 were NAbs-positive (3 at 5-10 years post-therapy) two of those anti-AQP4 antibody-positive; seven of the nine NAbs-negative patients were anti-AQP4 antibody-positive. Eleven patients (three NAbs-positive, eight NAbs-negative) developed cerebral lesions and 12 patients (four NAbs-positive, eight NAbs-negative) spinal cord lesions on magnetic resonance imaging as gadolinium positive lesions or T2-weighted lesions, at significantly higher frequencies than NMO reference group (p<0.009). Exacerbation occurred within 90 days in four and 6-36 months in eight patients. Progression of disease activity in NMO patients occurred during IFN-β treatment, irrespective of IFN-neutralizing antibody status.

Anti-aquaporin-4 antibody-positive neuromyelitis optica presenting with syndrome of inappropriate antidiuretic hormone secretion as an initial manifestation

The distribution of neuromyelitis optica (NMO)-characteristic brain lesions corresponds to sites of high aquaporin-4 (AQP4) expression, and the brainstem and hypothalamus lesions that express high levels of AQP4 protein are relatively characteristic of NMO. The syndrome of inappropriate antidiuretic hormone secretion (SIADH) is one of the important causes of hyponatremia and results from an abnormal production or sustained secretion of antidiuretic hormone (ADH). SIADH has been associated with many clinical states or syndromes, and the hypothalamic-neurohypophyseal system regulates the feedback control system for ADH secretion. We report the case of a 63-year-old man with NMO, whose initial manifestation was hyponatremia caused by SIADH. Retrospective analysis revealed that the serum anti-AQP4 antibody was positive, and an MRI scan showed a unilateral lesion in the hypothalamus. SIADH recovered completely with regression of the hypothalamic lesion. As such, NMO should even be considered in patients who develop SIADH and have no optic nerve or spinal cord lesions but have MRI-documented hypothalamic lesions.