Paresias

Paresias, commonly referred to as paresis in English, denotes partial paralysis or weakness of voluntary muscles. It results from reduced motor strength due to impairment of motor pathways in the central nervous system or abnormalities of peripheral nerves or neuromuscular junctions. The term can appear in plural as paresias in some contexts, but in standard English medical usage the singular paresis is more common.

Paresias are categorized by the body regions affected: monoparesis (one limb), hemiparesis (one side of the body), paraparesis (both legs), and tetraparesis or quadriparesis (all four limbs). The pattern helps localize lesions along the motor pathways, such as the brain, brainstem, spinal cord, nerve roots, peripheral nerves, or neuromuscular junctions.

Common causes include acute events like stroke and traumatic brain or spinal injuries; demyelinating or inflammatory diseases such as multiple sclerosis; spinal cord compression or injury; peripheral neuropathies; motor neuron diseases; Guillain-Barré syndrome; and various myopathies or metabolic disorders. The underlying condition often determines the distribution, progression, and associated symptoms such as spasticity, flaccidity, sensory changes, or fatigue.

Evaluation typically involves a neurologic examination to assess strength, reflexes, and tone, followed by imaging (MRI or CT) to identify central lesions and, when appropriate, spinal imaging. Electrodiagnostic tests (EMG/NCS) help distinguish neuropathic from myopathic causes. Laboratory studies and lumbar puncture may support inflammatory or infectious etiologies.

Management focuses on treating the underlying cause and restoring function through rehabilitation, physical and occupational therapy, and assistive devices. Pharmacologic treatments may address spasticity, pain, or neuropathic symptoms. Prognosis varies widely and depends on the etiology, location, and timeliness of treatment.