Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 24-06: Weakness & Paralysis + Key Features Download Section PDF Listen +++ ++ Loss of muscle power may result from Central disease involving the upper or lower motor neurons Peripheral disease involving the roots, plexus, or peripheral nerves Disorders of neuromuscular transmission Primary disorders of muscle + Clinical Findings Download Section PDF Listen +++ ++ Weakness resulting from upper motor neuron lesions Characterized by selective involvement of certain muscle groups Associated with spasticity, increased tendon reflexes, and extensor plantar responses Lower motor neuron lesions Lead to muscle wasting as well as weakness, with flaccidity and loss of tendon reflexes However, no change in the plantar responses unless the neurons subserving them are directly involved Fasciculations may be evident over affected muscles In distinguishing between a root, plexus, or peripheral nerve lesion, the distribution of the motor deficit and of any sensory changes is of particular importance In disturbances of neuromuscular transmission, weakness is Patchy in distribution Often fluctuates over short periods of time Not associated with sensory changes In myopathic disorders, weakness is Usually most marked proximally in the limbs Not associated with sensory loss or sphincter disturbance Not accompanied by muscle wasting or loss of tendon reflexes, at least not until an advanced stage + Diagnosis Download Section PDF Listen +++ ++ See individual disorders + Treatment Download Section PDF Listen +++ ++ See individual disorders