"Bibrachial amyotrophy" by definition is disease in only the two arms, at the moment. It's like saying "only the arms are wasting right now." "Man in the barrel," an older label, is for the thin (atrophied) arms, as if they had been squished by a narrow barrel. You may also hear "brachial diplegia." These are all the same thing. Problem is, it may not stay an accurate description.
These terms are used sometimes when there are no UMN signs and so the doc hesitates to say ALS definitively, mindful of the formal criteria. However, the EMG will show the acute and chronic denervation and discharges characteristic of ALS. On the other hand, some patients stay at BBA, and this is more likely if all the regions apart from the arms were normal on the EMG. You can look at the report, Bronx, to see if this is the case.
So it might not progress to ALS -- but if a new region is affected, "BBA" becomes the "flail arm subtype" of ALS, which is what Larry had. In his case, he had no UMN signs but was diagnosed w/ ALS anyway (and I should note, he did have EMG signs of ALS in his legs as well as arms).
The FA subtype, in turn, may not affect other regions in the sequence or timing that is more common in "regular" ALS, and survival tends to be a little longer (median 59 months in one study), but it is still invariably fatal like all ALS.
RN, you may be confused about the Trilogy -- most PALS do not require nor benefit from supplemental oxygen. But your dad's machine is almost certainly being used as a BiPAP, not a CPAP (check the settings and see that IPAP > EPAP). If not, you should have those settings changed or do it yourself.
Bronx, I'm sorry for your news. As with any MND, I would seek a second opinion. But don't be surprised or discouraged if you hear "ALS" from the second doc, esp. if the EMG shows signs beyond the arms, because at some clinics, they want patients to be eligible for SSDI, services and such sooner rather than later. I'd assume for the moment that ALS is a real possibility and plan life accordingly. And we'll support you however we can, either way.
--Laurie
