Intractable Nausea Due to the Area Postrema Syndrome of Neuromyelitis Optica: An Uncommon Cause of a Common Symptom

Area postrema syndrome in neuromyelitis optica spectrum disorder: diagnostic challenges and descriptive patterns

Background

Although area postrema syndrome (APS) is one of the core clinical features of neuromyelitis optic spectrum disorder (NMOSD), it is frequently misdiagnosed as gastrointestinal or systemic disorders. In this study, we describe the diagnostic challenges in NMOSD patients with APS and their characteristic clinical and radiological features. All patients who attended our university hospitals during the period from March 2019 to August 2020 with a diagnosis of NMOSD according to the latest diagnostic criteria were admitted and evaluated clinically, radiologically with gadolinium-enhanced brain and spinal MRI, measures of serum Anti-Aquaporin 4 (Anti-AQP4) and clinical status using the Expanded Disability Status Scale (EDSS) scores. APS was diagnosed if there was a history of intractable nausea, vomiting, or hiccups (INVH) that had lasted longer than 1 week with the exclusion of other etiologies, or less than 48 h if associated with a lesion in the dorsal medulla on MRI scan.

Results

Twenty out of 90 (22.2%) identified patients with a diagnosis of NMOSD had a history of unexplained intractable nausea, vomiting or hiccoughs lasting an average of 20 days. Seventeen patients were anti-Aquaporin 4 seropositive. Seven patients (35%) presented initially with isolated clinical features of APS and were diagnosed only after subsequent relapse. Patients with APS preceding other core clinical presentations (13 cases, 65%) were diagnosed after development of motor manifestations. All patients developed acute myelitis during the course of illness. Brain and spinal MRI scans showed that 13 had a linear lesion in the dorsal tegmentum of the medulla oblongata adjacent to the fourth ventricle. Otherwise, longitudinally extensive transverse myelitis was found in 80%, while 35% showed extension of the cord lesion to the AP.

Conclusions

APS as a core clinical characteristic of NMOSD is not a rare presentation as was previously thought and can occur in both AQP4-seropositive and seronegative NMOSD.

MRI to detect and localize the area postrema in multiple sclerosis: The role of 3D-DIR and 3D-FLAIR

BACKGROUND AND PURPOSE

Area postrema (AP) is a highly vascularized paired 2 mm-long anatomical structure, localized on the dorsal inferior surface of the medulla oblongata, at the caudal end of the fourth-ventricle. AP is principally affected in AP syndrome, which is commonly associated with autoimmune inflammatory diseases, including essentially neuromyelitis optica spectrum disorder (NMOSD). The aim of this study is to assess the best cerebral MRI sequences and planes for AP detection in order to assist or aid in the diagnosis of difficult NMOSD cases.

METHODS

3DT1, 2DT2, 3D-fluid-attenuated inversion recovery (3DFLAIR), and 3D-double inversion recuperation (3DDIR), routinely used in inflammatory diseases, were analyzed and scored based on quality (0-2), and ability to detect AP in each plane (0 = no detection, 1 = probable detection, 2 = obvious detection). Based on image availability, subjects were divided into three groups: Group-1, including 100 randomly selected subjects with 3DT1 and 3DFLAIR, Group-2, including 30 multiple sclerosis (MS) patients from the "Observatoire Français de la Sclérose En Plaques" (OFSEP) with 3DT1, 3DFLAIR, and 3DDIR, and Group-3, including 164 OFSEP MS patients with 3DFLAIR and 2DT2.

RESULTS

AP was undetectable on 3DT1 and 2DT2. AP was detected in 87% of 3DFLAIR in Group-1, 90% in Group-2, and 90% in Group-3. AP was also detected in 100% of 3DDIR images in the axial plane.

CONCLUSIONS

As evidenced, AP was easily assessed on 3DDIR and 3DFLAIR emphasizing the importance of adding these sequences to NMOSD MRI-protocols. Moreover, the most effective imaging plane in identifying AP was the axial plane.

Vomiting in Neuromyelitis Optica: An Atypical Presentation

Neuromyelitis Optica (NMO), also known as Devic's disease, is a demyelinating disorder of the central nervous system (CNS) that majorly involves the optic nerves and the spinal cord. It is an idiopathic and an autoimmune disorder. The patient typically presents with symptoms pertaining to the eye or spinal cord, such as a decrease in visual acuity, visual field defects, pain in the eyes, loss of vision, numbness, and weakness of the limbs with or without bladder dysfunction. Vomiting, however, is an atypical presentation of this disorder. We report here a case of an 18-year-old female who presented to our tertiary care set-up with a one-month history of intractable non-bilious vomiting and dull epigastric pain. After going through several initial investigations and being discharged home, she returned after five days with complaints of intractable vomiting, double vision and inability to stand or walk. Later, the presence of anti-NMO antibodies led to the diagnosis of Neuromyelitis Optica Spectrum Disorder (NMOSD). Through this case, we highlight the importance of considering NMO in a patient presenting with intractable vomiting to enable prompt diagnosis and treatment of the disease, thus preventing further disability.

Area Postrema: Fetal Maturation, Tumors, Vomiting Center, Growth, Role in Neuromyelitis Optica

INTRODUCTION

The area postrema in the caudal fourth ventricular floor is highly vascular without blood-brain or blood-cerebrospinal fluid barrier. In addition to its function as vomiting center, several others are part of the circumventricular organs for vasomotor/angiotensin II regulation, role in neuromyelitis optica related to aquaporin-4, and somatic growth and appetite regulation. Functions are immature at birth. The purpose was to demonstrate neuronal, synaptic, glial, or ependymal maturation in the area postrema of normal fetuses. We describe three area postrema tumors.

METHODS

Sections of caudal fourth ventricle of 12 normal human fetal brains at autopsy aged six to 40 weeks and three infants aged three to 18 months were examined. Immunocytochemical neuronal and glial markers were applied to paraffin sections. Two infants with area postrema tumors and another with neurocutaneous melanocytosis and pernicious vomiting also studied.

RESULTS

Area postrema neurons exhibited cytologic maturity and synaptic circuitry by 14 weeks'. Astrocytes coexpressed vimentin, glial fibrillary acidic protein, and S-100β protein. The ependyma is thin over area postrema, with fetal ependymocytic basal processes. A glial layer separates area postrema from medullary tegmentum. Melanocytes infiltrated area postrema in the toddler with pernicious vomiting; two children had primary area postrema pilocytic astrocytomas.

CONCLUSIONS

Although area postrema is cytologically mature by 14 weeks, growth increases and functions mature during postnatal months. We recommend neuroimaging for patients with unexplained vomiting and that area postrema neuropathology includes synaptophysin and microtubule-associated protein-2 in patients with suspected dysfunction.