In medicine, you cannot treat what you do not diagnose. An undiagnosed/misdiagnosed condition can lead to unnecessary tests and ineffective treatment: an unworkable set of circumstances that leads to nowhere. 

How common is it for diseases to be misdiagnosed? When I was a medical student, I was informed about the case of a patient with acromegaly who was initially misdiagnosed. Because the initial signs of this condition are so subtle, the patient’s physician did not suspect anything amiss and therefore did not pursue any investigations that might have led to a correct diagnosis. As a result, the acromegaly was allowed to develop unchecked for years, resulting in permanent disfigurement. 

The harsh reality of medical practice is that all physicians, no matter how well-versed in their craft, will at some point in their careers miss out on an important diagnosis. This inevitability is amplified in general practice, in which physicians often see dozens of patients a day. In addition, physicians are encouraged to have the most likely medical diagnoses in mind before contemplating the possibility of a rare disease. 

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Some missed diagnoses are naturally more consequential than others. If a disease can result in the loss of life or limb, a misdiagnosis is considered a “never” event — something that should not happen under any circumstances. Some diseases, such as neuromyelitis optica spectrum disorder (NMOSD), may not result in immediate irreversible harm, but the cumulative impact of relapses over time can cause disability and depress quality of life. 

Read more about NMOSD etiology 

“Between 80-100% of NMOSD patients report chronic pain, including: neuropathic pain, pain attacks, or headache,” Holroyd and colleagues wrote in Current Opinion in Ophthalmology. “Other symptoms shown to negatively impact quality of life in NMOSD include reduced mobility, anxiety, depression, bowel/bladder dysfunction, visual impairment, and sexual dysfunction.” 

How Physicians Approach NMOSD Globally

In Neurology and Therapy, Min and colleagues conducted a study to understand how treatment practices around NMOSD compare worldwide. 

NMOSD is most commonly confounded with multiple sclerosis; both diseases were considered 1 and the same only a few years ago. However, the discovery of the role of aquaporin-4 immunoglobulin G (AQP4-IgG) in the pathogenesis of NMOSD allowed clinicians to distinguish between the 2 autoimmune conditions. 

The great challenge of NMOSD is that relapses can be devastating, often requiring the patient to be hospitalized. In addition, severe relapses can be fatal. Therefore, it is imperative that physicians are able to identify a NMOSD relapse when they see 1; a misdiagnosis would eat away at precious time and may leave behind irreversible damage. 

The good news is that significant advancements in NMOSD therapeutics have given patients a lifeline; for example, intravenous methylprednisolone has emerged as a treatment option of choice for acute flare-ups. In addition, plasma exchanges have shown notable efficacy in dulling the effects of NMOSD relapses. There is also new evidence that suggests that the use of both therapies simultaneously improves disability outcomes. 

How are physicians globally approaching the diagnosis and treatment of NMOSD? In their study on this subject, Min and colleagues recruited neurologists from across the globe, including countries such as the United States, Germany, Italy, Brazil, South Korea, and China (n=389), who were asked to participate in a 30 to 60 minute online survey and contribute a minimum of 2 to 4 clinical records of patients with AQP4-IgG-seropositive NMOSD. 

In addition, the research team recruited patients with NMOSD (n=34) to participate in telephone interviews that lasted around 30 minutes. The purpose of these interviews was to understand their perspectives on the impact of the disease on their quality of life and their overall satisfaction with their treatment. 

Read more about NMOSD treatment 

The findings of this study revealed that misdiagnosis among patients with NMOSD is fairly common; approximately 25% of patients with NMOSD were initially misdiagnosed (most commonly in China, where awareness of the condition is low). Among the most common misdiagnoses were optic neuritis (8%), idiopathic myelitis (10%), multiple sclerosis (44%), and stroke (7%). A mere 32% of misdiagnosed patients were correctly diagnosed with NMOSD within 2 months. 

The research team also discovered that patients who were misdiagnosed underwent more relapses (mean total until survey initiation: 3.3) compared to patients who were correctly diagnosed from the beginning (mean total until survey initiation: 2.8). Around 23% of patients who were misdiagnosed experienced a severe relapse compared to 10% who were correctly diagnosed.

The impact of a misdiagnosis on a patient’s psychological well-being is considerable. Most patients who were misdiagnosed were simply told that they had alternative conditions, such as fatigue or stress, or gastric/ophthalmological issues. This means that patients have no recourse when experiencing relapses that they were told should not be happening. 

A patient who was initially misdiagnosed but later received a diagnosis of NMOSD recounts: 

“I was scared and angry because I had only just accepted my [wrong] diagnosis and was then diagnosed with something else. I was aware of what NMO was and was terrified of going blind.” 

When counting the costs of a misdiagnosis, a few things become clear: it can lead to delayed treatment, irreversible harm/death, and confusion/frustration on the part of the patient. Physicians can reduce the risk of a misdiagnosis by being thoroughly familiar with NMOSD signs and symptoms and diagnostic protocol. In doing so, physicians will be positioning themselves to serve the community of patients with this rare disorder with excellence, preserving quality of life and securing better outcomes. 


Holroyd KB, Manzano GS, Levy M. Update on neuromyelitis optica spectrum disorderCurr Opin Ophthalmol. Published online November 3, 2020. doi:10.1097/ICU.0000000000000703

Min JH, Capobianco M, Welsh C, et al. Understanding treatment decisions in neuromyelitis optica spectrum disorder: a global clinical record review with patient interviewsNeurol Ther. Published online February 24, 2023. doi:10.1007/s40120-022-00431-y