Pediatric Multiple Sclerosis Presenting as Area Postrema Syndrome

Nausea and Vomiting as Initial Manifestations of Pediatric NMOSD

Intractable nausea and vomiting are commonly attributed to gastrointestinal (GI) conditions but can sometimes be a symptom of an underlying central nervous system disease. One potentially overlooked neurologic cause of intractable nausea and vomiting that is refractory to antiemetics is area postrema syndrome (APS). APS is a condition characterized by lesions of the dorsal caudal medulla and is considered a core clinical feature of neuromyelitis optica spectrum disorder (NMOSD). APS is present in up to 30% of patients ultimately diagnosed with NMOSD and can be the first presenting symptom of NMOSD in 12% of patients, as our case illustrates. Importantly, APS is highly responsive to immunotherapy. We present the case of a 14-year-old female with a history of migraines who presented to the emergency department multiple times for persistent nausea, vomiting, and hiccups. Multiple GI diagnoses were considered until she developed additional neurologic symptoms that prompted further workup and revealed the final diagnosis of NMOSD-APS. We posit that NMOSD-APS should be considered in the differential diagnosis for patients with intractable nausea and vomiting, especially in patients with a negative GI workup result and poor response to antiemetics.

The Etiology and Outcome of Area Postrema Syndrome in Childhood: Two Cases and a Literature Review

BACKGROUND

Area postrema syndrome (APS), a rare childhood condition, manifests as intractable nausea and hiccups. APS has high diagnostic significance in neuromyelitis optica syndrome spectrum disorders (NMOSD) and can be the initial presentation of other critical diseases, including brainstem glioma.

METHODS

We described two representative cases of unrelated Japanese patients with APS. An etiologic evaluation, including a detailed intracranial neuroradiological examination and autoantibodies assessment, was performed. We also reviewed the literature focusing on the prognosis of pediatric APS symptoms.

RESULTS

A 14-year-old girl with aquaporin-4 antibody-positive NMOSD showed a good prognosis with immunotherapy, whereas another nine-year-old girl with irresectable medullary low-grade glioma had persistent symptoms for more than 10 years. All reported children aged >12 years were diagnosed with NMOSD, and patients aged <13 years showed heterogeneous etiologies.

CONCLUSIONS

Distinctive time courses and neuroimaging features were key clinical findings for the diagnostic and therapeutic processes in these patients. This literature review highlights the wide spectrum and prognosis of pediatric-onset APS.

Neurological Etiologies and Pathophysiology of Cyclic Vomiting Syndrome

Cyclic vomiting syndrome is an idiopathic chronic periodic disorder of childhood which may persist into the adult years. Although cyclic vomiting syndrome is considered a central nervous system disorder, it is often managed by a pediatric gastroenterologist. The practitioner should not assume a gastrointestinal or non-neurological cause of symptoms especially if there are coexisting neurological symptoms and signs or if vomiting does not bring relief; this suggests a possible central nervous system cause, which may necessitate a pediatric neurology consultation. Examples of central nervous system causes of cyclic vomiting syndrome that can have subjective and objective neurological findings include abdominal migraine, certain types of epilepsy, structural lesions (tumors, Chiari malformation, demyelinating disease), mitochondrial disease, autonomic disorders, fatty acid/organic acid disorders, urea cycle defects, and cannabinoid hyperemesis syndrome. Improved familiarity with cyclic vomiting syndrome and its mimics may improve the time to appropriate diagnosis and may reduce morbidity related to cyclic vomiting syndrome.

Pediatric NMOSD: A Review and Position Statement on Approach to Work-Up and Diagnosis

Neuromyelitis Optica Spectrum Disorder (NMOSD) is an inflammatory demyelinating disease of the central nervous system (CNS) primarily affecting the optic nerves and spinal cord, but also involving other regions of the CNS including the area postrema, periaqueductal gray matter, and hypothalamus. Knowledge related to pediatric manifestations of NMOSD has grown in recent years, particularly in light of newer information regarding the importance of not only antibodies to aquaporin 4 (AQP4-IgG) but also myelin oligodendrocyte glycoprotein (MOG-IgG) in children manifesting clinically with this syndrome. In this review, we describe the current state of the knowledge related to clinical manifestations, diagnosis, and chronic therapies for children with NMOSD, with emphasis on literature that has been published in the last 5 years. Following the review, we propose recommendations for the assessment/follow up clinical care, and treatment of this population.

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.

Area postrema syndrome as frequent feature of Bickerstaff brainstem encephalitis

Objective

Area postrema (AP) syndrome (defined as: nausea and/or emesis and/or singultus at onset of brainstem dysfunction) comprises complex pathophysiologic mechanisms triggered by different entities. The first objective was to assess the frequency of AP syndrome as a clinical feature in brainstem encephalitis (BE). Finding an especially high prevalence of AP syndrome in Bickerstaff brainstem encephalitis (BBE), we also analyzed the frequency of AP syndrome in other autoimmune diseases with anti-ganglioside antibodies (Guillain-Barré syndrome (GBS) and its variants).

Methods

We systematically evaluated the prevalence of AP syndrome in BE in all patients treated at our university hospital during a 15-year period. In a second step, BBE patients were compared to GBS and Miller Fisher syndrome (MFS) patients as clinical subtypes of a disease continuum without brainstem dysfunction.

Results

We found AP syndrome in 8 of 21 BE patients, including 3 of 7 BBE and in 4 of 112 GBS/MFS patients. AP syndrome was as a frequent but under-recognized feature of BE with a significant impact on patients' well being.

Interpretation

Manifestation of AP syndrome in BBE but also in GBS and its subtypes point toward a role of autoimmune antibodies that should be investigated in future studies. Considerable misdiagnosis or nonrecognition complicates diagnostic and therapeutic management. Therefore, AP syndrome should be considered in any episode of otherwise unexplained nausea, emesis, or singultus.