Many of us with slow progression ALS encounter problems of diagnosis and/or re-diagnosis. For some, a definitive diagnosis of ALS can take years because we don’t present with typical ALS progression. Delayed diagnosis is a major complaint among pALS. For others of us, the original diagnosis may be quick, but then our lack of typical disease progression, along with other symptoms that don’t line up with ALS, can lead to a rethink of the original diagnosis. According to the ALS Association website, 10-15% of all ALS diagnoses end up being re-diagnosed as some other disease, typically an “ALS mimic,” of which there are many. This is an excellent reason to get a second opinion if your case isn’t clear-cut.
In my case, I had a speedy initial diagnosis in March 2018. This was despite the fact that my father has had a similar pattern of slow, asymmetric leg muscle weakness for the past 20 years (but not ALS), which raised the possibility that I might have some other nonfatal, inherited neurological condition. When I changed ALS clinics in September 2020, the new team of neurologists were intrigued by the parallel symptoms with my father, and noted enough anomalies in my case – including the very slow and limited disease progression, as well as other symptoms – to propose exploring a re-diagnosis. After running additional tests, the results were inconclusive, so for now, and possibly well into the foreseeable future, I remain diagnosed with “atypical” ALS, with the proviso that the diagnosis will be periodically revisited as more evidence accumulates.
As you can imagine, the possibility of being re-diagnosed with a non-fatal ALS mimic was head-spinning, and then learning that the test results were too inconclusive to warrant a re-diagnosis was a let-down. But the fact that the door to a possible re-diagnosis is still open gives me hope. I keep coming back to that figure of 10-15% of all ALS diagnoses being false positives. That’s a lot of people each year (600 to 900 in the US alone) who were told they have ALS but who later learn they have some other neurological disease or condition (This works both ways — a much larger number of people are originally misdiagnosed with some other condition and then later learn they have ALS). And there must be many people like me, who have an ALS diagnosis but whose symptoms are “atypical” and who live for years with some uncertainty about the diagnosis. This is unavoidable for a disease diagnosed by process of elimination.
Living with uncertainty can be very hard, especially when it involves a diagnosis of a terminal illness. But for now, at least, I feel comfortable with the ambiguity. The uncertainty is a source of hope. Each month without changes in my condition is another small piece of evidence that just maybe I have some other rare but non-fatal neurological disease. Time will tell.