temp heaviness or weakness shoulders

I have had several episodes of temporary weakness or heaviness in both arms.  The episode doesn't last very long - perhaps a minute or so.  It's happened three times in the past 6 weeks and I remember it happening a couple of other times more than a year ago.  When these episodes ocurred I hadn't been doing any physical exertion.  The weakness and heaviness is in both arms from the shoulders to the hands and is fairly overwhelming when it happens.  It's as if I can't lift my arms or use them.  There isn't really any pain or other symptoms.  Does anyone know whether these symptoms are signifcant - should I see a doctor?  Do you know what causes this to happen?

[beta_girl]

Yes.  That has happened to me.  Intermittant weakness, with a strange sort of dizziness that leaves my upper body limp.  It happens rarely, but when it happens is as you say, overwhelming.  I am a healthy, physically active 58 year old woman.