Nicole, a Sydney woman using a pseudonym to protect her privacy, spent nine years believing she had multiple sclerosis. The period was marked by specialist appointments, tests, intensive medication and grief. "It was horrible. I don't have a partner, so I always thought, 'who's going to look after me? Am I going to end up in a wheelchair?' ... I did research on end-of-life in Switzerland," she said.
Her main symptom was dizziness. Brain scans showed demyelination, the deterioration of the fatty coating around nerve fibres that is common in MS, and she had weakness in her limbs. Multiple neurologists diagnosed the condition. Then in 2023, when the now 63-year-old underwent a stapedectomy to treat hearing loss, her ear, nose and throat surgeon suggested her severe dizziness came from untreated crystals in her ear. A new neurologist ran tests, treatment for vertigo resolved the dizziness, and she was cleared of MS. The demyelination was determined to be benign. She says she has been fine ever since.
Her account has been brought into the spotlight alongside news this week that actor Christina Applegate, 54, was wrongly diagnosed. On the MeSsy podcast, which she co-hosts with Jamie-Lynn Sigler, Applegate said her doctor told her she does not have MS. "She came into my room, and she said, 'Congratulations, you don't have MS'. I was not happy at all, everybody else was so happy, crying." Applegate, diagnosed in 2021, made clear that a corrected diagnosis has not restored her health. "You don't get misdiagnosed and suddenly, I'm better. I haven't gotten better, Jamie, if anything I have gotten worse, so I'm back at square one," she said.
Professor Todd Hardy, a neurologist at the University of Sydney, said MS is challenging to diagnose because no single test definitively establishes it. "We bring together the patient's history, neurological examination, MRI findings and, where appropriate, tests of cerebrospinal fluid and other investigations," he said. Symptoms vary and overlap with other conditions, and MRI scans can show abnormalities that resemble MS but are actually due to migraine, ageing or small-vessel disease.
A small 2019 study found 18 per cent of new MS patients at two US clinics were misdiagnosed, and a 2024 systematic review put the frequency of misdiagnosis between 5 and 41 per cent, with underdiagnosis ranging from 3 to 58 per cent. In September last year, updated diagnostic guidelines, the revised McDonald criteria, were introduced in countries including Australia to allow earlier and more accurate diagnosis.
The path to a correct diagnosis can be slow in the other direction too. Justine Martin, a 55-year-old Geelong author and keynote speaker, has lived with MS for 16 years, but it took eight months to be diagnosed. Her blurry vision, fatigue and impaired cognition were initially dismissed as migraine, even though her mother had MS and Martin asked about it. "They put me on migraine pills, and I was still getting worse," she said. For Martin, a label, however harrowing, brought clarity: "That's where your mind goes to a very dark place" when there is no diagnosis.
Hardy said the vast majority of patients diagnosed by experienced clinicians following a thorough assessment should have confidence in that diagnosis. Applegate's experience highlights the importance of getting the diagnosis right, he said, but it does not mean other people's diagnoses are necessarily wrong. Anyone with genuine concerns should discuss them with their treating neurologist.
The issue extends beyond MS. In Australia, around 140,000 cases of diagnostic error occur each year, or one in seven. Associate professor Julia Harrison, head of medicine at Monash University, said a good diagnosis is accurate, timely, made as early as possible, and communicated with the patient. Conditions that are rare, have no test, progress very quickly or slowly, or are mimicked by other diseases are harder to diagnose, with cancer, infectious disease, vascular conditions and autoimmune disease among the most difficult. Research also points to gender bias: a University of Cambridge study of 6,600 patients found women with autoimmune diseases are more likely than men to be diagnosed instead with a psychiatric or psychosomatic condition.