Focal Limb Weakness

Abstract

Focal weakness of the limbs can be organized by affected body region. Shoulder weakness is most commonly due to C5–6 radiculopathy or brachial plexopathy. Scapular winging is usually secondary to long thoracic or accessory neuropathy. Hand weakness is most commonly the result of ulnar neuropathy, C8–T1 radiculopathy, motor neuron disease, or cerebral processes. Wrist drop is a special kind of hand weakness. The two most common sources of wrist drop are radial neuropathy and stroke, and can be differentiated from each other with focused examination. Proximal leg weakness is usually the result of upper lumbar radiculopathy or lumbar plexopathy. Postpartum leg weakness has multiple potential causes that can be distinguished by careful examination. Foot drop may be due to lesions of the peroneal nerve, sciatic nerve, L5 nerve root, or central nervous system. Multifocal weakness is due to multifocal central or peripheral nervous system disease. Relevant peripheral nervous system causes of multifocal weakness include mononeuropathy multiplex, multifocal motor neuropathy with conduction block, and hereditary neuropathy with liability to pressure palsies.