Could it be ALS?

  I just saw a spot on the news about ALS.  I am a 41 y.o. male.  I have noticed the onset of slurring in my speech.  I have no other neurological symptoms, but am concerrned aobut the speech.  I have had aan MRI and it shows nothing.  What are the symptomsof ALS?  Could there be a clear MRI with early onset of this illness?  I am looking for an explanation for this problem.  The only solution offered by my doc is stress?  I have not heard of speech difficultioes related to stress?  You input would be helpful.
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I think a few facts should put your mind at rest.
The there are no specific findings on MRI in ALS, an abnormal MRI would
tend to exclude the diagnosis.
While slurred speech is a sign of ALS it is part of a much larger picture
and would not present alone, slurred speech in ALS is due to damage to nerve
cells of the vagus nerve in the brainstem, the vagus nerve also controls
swallowing so the speech problems are accompanied by swallowing problems.
In the absence of swallowing problwems, severe muscle weakness, twitching
of muscle fibers, wasting of the tongue, cramps and limb muscle wasting,
I would consider the likelhood that you have ALS to be very remote.
Obviously I cannot make a definite diagnosis of what exactly is causing your
problems via the internet, but nothing you say gives me a strong
suspicion that you have ALS.
If you have already been cleared from this point of view by a doctor
who has had the opportunity to examine you and who has excluded things
like brain tumor and MS by means of an MRI scan I would suggest you no
longer need to worry about this possibility.