Unilateral/Bilateral - MND/ALS has, characteristically, unilateral initial presentation, involving most of the time limb distal regions, where roots C8-T1 and L5-S1 are the most commonly affected, with ipsilateral or contralateral progression to the other roots, in a progressive and cumulative manner.

Does ALS start on one side?

Although ALS affects both sides of the body, atrophy may start on one side, becoming symmetrical as the disease progresses.

Does ALS start in one limb or both?

The first sign of ALS usually appears in the hand or arm and can show as difficulty with simple tasks such as buttoning a shirt, writing, or turning a key in a lock. In other cases, symptoms initially affect one leg.