The most severe effects are at the furthest distances from the spinal cord. The hands and forearms are therefore affected more than the upper arms and shoulders and the feet and ankles more than the thighs and hips. Parts at the ends of limbs are called distal, those near the trunk are called proximal, so peripheral neuropathies affect distal structures and functions more than proximal ones. In the lower limbs, weakness of ankle movements often causes foot drop, so that the affected person may have to adopt a high stepping walk in order that his toes will clear the ground. Also, weakness of muscles between the knee and the ankle, and of muscles below the ankle, often leads to imbalance of muscle power.
Persistent imbalance leads in turn to deformity, determined by the action of the stronger muscle.
In the upper limbs there is weakness of grip and of wrist movements and sometime a characteristic appearance of the hand due to muscle imbalance. Generally, proximal weakness is more serious. The big, proximal muscles are the ones that we use to stand and walk. Some people with no muscle function at all below the knees can still stand and walk. Disease of comparable severity is often less gravely disabling, therefore, if it is distal than if it is proximal.