Area postrema syndrome (APS) in neuromyelitis optica spectrum disorder (NMOSD) is not as rare as initially thought, according to a new study published in The Egyptian Journal of Neurology, Psychiatry and Neurosurgery.
Researchers found that 20 out of 90 patients with NMOSD (22.2%) were diagnosed with APS after a history of intractable nausea, vomiting, or hiccups. APS was not limited to only patients who were anti-aquaporin-4 seropositive, as 3 of the patients were seronegative but tested positive for anti-myeline oligodendrocyte glycoprotein antibodies.
The researchers associated this finding with the possibility that a lack of the blood-brain barrier at the area postrema may allow other pathogenic autoantibodies to also enter that could lead to APS. The study found that 12 patients had APS from the outset of NMOSD while the other 8 patients developed it on subsequent relapses.
“Identification and diagnosis of APS has both diagnostic and prognostic implications. APS might herald a more severe motor, visual or brainstem lesion. Thus, it is necessary to recognize APS early and to commence therapy as soon as possible to prevent NMOSD recurrence with more devastating neurologic deficits,” the authors emphasized.
Read more about the NMOSD etiology
Patients experienced APS for an average of 20 days (interquartile range, 7 days to 3 months) and all patients experienced nausea and vomiting, but only 30% experienced hiccups. All of the patients initially consulted a gastroenterologist or an internist and were misdiagnosed with gastrointestinal disorders. Six of the patients even went through thorough and repeated gastrointestinal evaluations.
“Unfortunately, when APS occurs at the onset of NMOSD especially in the absence of additional neurological deficits, it is commonly misdiagnosed by gastroenterologists or internists as a digestive system disease or other systemic illness with consequent delay in initiating treatment and risk of exacerbating NMOSD,” the authors said.
The average age of disease onset was 30 years (range, 11-50 years) and was similar to patients without APS (average, 31.1 years; range, 6-56 years). There were a total of 16 females in the NMOSD-APS group giving a slightly higher ratio of female to male patients than the patients with NMOSD without APS (4:1 vs 2.8:1).
All patients eventually developed acute myelitis. Thirteen patients (65%) displayed a linear lesion in the dorsal tegmentum of the medulla oblongata adjacent to the fourth ventricle, 80% showed longitudinally extensive transverse myelitis, and 35% presented with an extension of a spinal cord lesion to the area postrema on the brain and spinal magnetic resonance imaging scans.
Khedr EM, Farweez HM, Abo Elfetoh N, et al. Area postrema syndrome in neuromyelitis optica spectrum disorder: diagnostic challenges and descriptive patterns. Egypt J Neurol Psychiatr Neurosurg. 2021;57(1). doi:10.1186/s41983-021-00390-5