paralysis

absence of voluntary movement that is due to destruction or impairment of the motor centers of the spinal cord or brain or of tracts of the central or peripheral nervous system. A distinction is made between paralysis and paresis, the latter being a condition in which motor functions are weakened but present. Both conditions may be caused by disturbances of the blood circulation, inflammation, traumata, or tumors of the nervous system. An unusual kind of paralysis occurs in hysteria. Paralyses must be distinguished from motor disorders associated with inflammation of muscles and lesions of bones and joints, which restrict the range of movement mechanically. Paralysis may affect one muscle, one extremity (monoplegia), the arm and leg on one side (hemiplegia), both arms or both legs (paraplegia), or other combinations of muscles.

Peripheral paralysis is a flaccid paralysis that involves the motor cells of the spinal cord and its anterior roots, peripheral nerves, plexuses, or nuclei of the cranial nerves. Central paralysis is a spastic paralysis that involves the brain’s central motor neurons or their outgrowths in the spinal cord.

Peripheral paralysis is characterized by the complete absence of movement, decrease in muscle tone, loss of reflexes, and muscular atrophy. Sensory disorders occur when a peripheral nerve or plexus containing both motor and sensory fibers is affected.

Central paralysis is characterized not by the complete loss of motor functions but by their dissociation—the loss of some functions and intensification of others. While voluntary movement is absent, muscle tone and tendon and periosteal reflexes increase and pathological Babinski’s, Rossolimo’s, and other reflexes appear. Associated movements (synkinesis) are observed. These are involuntary movements that occur in paralyzed extremities during voluntary movements of healthy extremities. Sensory disturbances are also observed.

Extrapyrimidal paralysis arises when the subcortical structures of the brain are affected. Associated, reflex, and voluntary movements are absent (akinesia). Muscle tone is plastic, and the extremity can move only passively.

Electromyography and other special methods of examination are important for differential diagnosis.

The prognosis and treatment are determined by the disease that caused the paralysis. Among the special methods used to restore the functions of the extremity are massage and remedial gymnastics.