The 6.7% study - eyeballed

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The 6.7% study - eyeballed

Postby dwl on November 27th, 2002, 11:39 am

Hi everyone,

I apologise if anyone else has actually eyeballed this paper & posted about it. I eventually tracked it down in our local hospital's medical library & have taken a copy (Annals of Neurology Vol 35 No 3 March 1994 pp375-376).

It appears that the 6.7% of ALS patients who had fasciculation as their presenting symptom did NOT have EMG's when they presented. One assumes that if they had been tested, then the EMG would have been abnormal. This opinion is also expressed in a reply by the authors of the Mayo clinic study (see below).

Note also that this is NOT the same as saying that 6.7% of twitchers develop ALS.

The authors of the original Mayo clinic study posted a very comprehensive reply which makes for comforting reading for all those who have had clean EMG's.

If anyone's interested, I'll have a go at scanning it & posting it on the site.

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Postby Arron on November 27th, 2002, 1:49 pm

Thanks for the confirmation David. It just goes to show even more that twitching alone has NOTHING to do with ALS, especially if the person has a clean EMG. It's everyone's inoput like this that really makes all of this come together and combined information is very powerful.
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Postby Guest on November 27th, 2002, 6:26 pm

Dwl

I would be very interested to see the report. I was planning to pick up a copy at our local University. would prefer not to... I might get sidetrack in a maze of concerning medical literature
... you know
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Postby dwl on November 30th, 2002, 6:51 am

This is the 6.7% study as published in the Annals of Neurology. As you can see, it is actually a letter with a reply from the authors of the original Mayo Clinic study. The paper they refer to is in the Canadian Journal of Neurological Science which I don't have access to, but their summary looks pretty concise. I guess the take-home message is - if you want to be absolutely certain you don't have MND/ALS, have an EMG.

I scanned it in so don't be surprised if the OCR software has thrown in a few glitches!

-------------------------------------------------------------------------------------

Not-So-Benign Fasciculation
Andrew Eisen, MD, FRCP(C), and Heather Stewart, BSc

We commend Blexrud and colleagues [1} for tackling the always worrying problem of benign fasciculation. The case against "benign fasciculation," heralding amyotrophic lateral sclerosis (ALS) in their retrospective study has been convincingly documented.
The reader, however, is left with the impression that fasciculation in the absence of other neurological deficit should never be of concern. This is not so. Twenty-one of 312 (6.7%) consecutive patients seen in our ALS clinic, who fulfilled the criteria of typical ALS, had fasciculation as the first and, at the time, only manifestation of their disease. The mean time interval between developing fasciculation and other deficits was 7.2 months (range, 2.4-13.6 mo) [2]. The majority of patients were men (n = 17). The mean age of patients who had fasciculation as their initial manifestation was not different from other patients with ALS (55.7 ± 12.4 yr compared with 57.3 ± 13.6 yr). Patients were only considered if they or their spouse sought medical help for the particular problem of fasciculation. Careful inquiry into the history of patients with ALS reveals that many notice fasciculations (usually with muscle cramps) for weeks, months, and rarely years before the onset of neurological deficit. Thus, fasciculation as an early feature of ALS may be commoner than we suspect.
Blexrud and colleagues [1] do not tell us whether there are electromyographic features of benign versus nonbenign fasciculations. We would argue that benign fasciculation is not a good term since it is possible to distinguish it from fasciculation of more concern on electromyographic grounds. Most fasciculation associated with ALS is of long duration and high amplitude. Narrowing the recording band pass (500
or even 1000 Hz to 10 or 20 kHz) reveals that such fasciculation is often complex and composed of many muscle fibers. The potential is frequently unstable and its components may demonstrate increased electromyographic jitter or blocking. In contrast, fasciculation recorded from patients who do not go on to develop serious disease (up to the last time of follow-up) is invariably simple and stable and the potentials resemble those of normal voluntary recruited motor units.
As pointed out by Blexrud and colleagues [1}, a large number of their patients were medically educated, thus prompting their seeking medical attention. In contrast, it is rare for patients who subsequently develop ALS to seek medical aid at a time when the only manifestation of their disease is fasciculation. However, we are presently following "unaffected" members of two families with familial ALS, several of whom have complex fasciculations as described above. It remains to be seen if any develop other evidence of the disease.
There is no doubt that many normal people who never develop serious neurological disease have lifelong fasciculation (and cramps). Most if not all become aware of the problem at a young age. On the other hand, we firmly believe that caution is required when fasciculation starts for the first time after the age of 45 years. Some will clearly go on to develop ALS.

Neuromuscular Diseases Unit (EMG) Vancouver General Hospital 855 West 12th Avenue Vancouver, BC, V5Z IM9, Canada


References
1. Blexrud MD, Windebank AJ, Daube JR. Long-term follow-up of 121 patients with benign fasciculations. Ann Neurol 1993;34: 622-625
2. Eisen A, Pant B, MacNeil M, Stewart H. Fasciculations as an initial feature of amyotrophic lateral sclerosis. Can J Neurol Sci 1992;19:280


Reply

Marceil D. Blexrud, Anthony J. Windebank, MD, and Jasper R. Daube, MD
The comments by Drs Eisen and Stewart are very appropriate and do match our experience. There is no doubt that in retrospect many patients observe fasciculation as their first symptom of amyotrophic lateral sclerosis (ALS). As implied by Dr Eisen, it is very rare for patients to present at this stage. They tend to present when weakness or incoordination has developed. It is our experience, however, that patients who have fasciculation alone as the first symptom of ALS always have electromyographic (EMG) abnormalities when they present with fasciculation. This does provide the opportunity to stress again that the subjects in this study had both a normal complete neurological examination and normal EMG, performed by experienced observers. When these criteria are met, we believe that one can strongly reassure the patient.
Eisen and Stewart also raised the question about the EMG features of benign versus nonbenign fasciculations. The study was not designed to evaluate that question; however, the fasciculation potentials typically had the characteristics of normal motor unit potentials.
Finally, we would agree that caution is important, in the absence of satisfactory EMG studies and for the "unaffected" members of families with familial ALS.

Department of Neurology Mayo Clinic
1501 Guggenheim Building 200 First Street. SW Rochester. MN 55905
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Postby Asterix on December 2nd, 2002, 5:41 am

dwl,
thank you very much for taking the time to provide that interesting article !

It is always good to see factual/scientific first-hand information instead of speculations :)
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Postby jblack on December 2nd, 2002, 1:20 pm

The posting of this freaked me out, briefly, to be honest. But after a more rational reading, I've taken some comfort from it.

I know that not everyone here is under 40, but it seems from the survey and "age" topic that many are. For those of us who are, please note that even amongst the 6.7% of ALS sufferers here who presented with fascics only, NONE were under 40 (The age range 43-67). Even the authors of that letter, who were urging caution, were urging it specifically for either people over 45 or people with ALS in their families.
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Postby tlotoxl on December 2nd, 2002, 2:38 pm

...which isn't very reassuring for those of us who do have als in our families :?
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Postby jblack on December 2nd, 2002, 3:09 pm

But of course a clean EMG will be. Have you had yours? Sorry, I should probably remember that. But if you've had one and it's clean, rest easy! Alternatively if you've had your fascics for a significant amount of time (6 months+), every passing day without clinical weakness decreases your chances significantly. Soon ALS will be ruled out, and you can stop worrying!
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