Paresis

Paresis is a condition in which muscle movement is weakened, but unlike paralysis, you still have some control over the affected muscles. It usually occurs due to nerve damage and can affect different parts of your body, from a single limb to all four limbs.

Table of contents

• What is Paresis?
• Difference Between Paresis and Paralysis
• Causes and Types of Paresis
• Symptoms of Paresis
• Diagnosis and Assessment
• Treatment and Management

What is Paresis?

Paresis refers to a condition in which muscle movement has become weakened or impaired. You may also sometimes see it referred to as “mild paralysis” or “partial paralysis.”^[1] The term comes from Ancient Greek, meaning “letting go” or “to let fall.”^[4]

Although paresis affects your muscles, it usually occurs due to nerve damage. A vast network of nerves controls the movement of the muscles in our bodies. If a part of this network is damaged, muscles in the affected area may not work properly.^[1] The neurological disorder manifests itself as decreased muscle strength.^[2]

A paresis refers to the incomplete paralysis of a skeletal muscle (muscles you control to move). It is caused by damage to the motor nerve that controls muscle movement.^[2]

Difference Between Paresis and Paralysis

Paresis is characterized by muscle weakness. A person with paresis can still move the affected muscle or muscles. However, these movements are weaker than normal.^[1]

Paresis is different from paralysis. An individual who has paralysis isn’t able to move a specific muscle or muscle group at all.^[1] When you’re paralyzed, or have paralysis, you can’t move certain parts of your body. Paralysis occurs when you’re unable to make voluntary muscle movements.^[3]

You may also see paresis used as a suffix to distinguish what part of the body is affected. For example, a person with monoparesis has muscle weakness affecting one limb. The corresponding suffix for paralysis is “-plegia.” Using the same example, a person with monoplegia has paralysis that affects one limb.^[1]

Causes and Types of Paresis

The paresis is caused by damage to the motor nerve which initiates muscle movement. The nerve can be damaged by pressure, accidents, infarctions or hemorrhages in the brain, or along its peripheral course. Pressure damage is often caused by tumors or herniated discs, which inhibit signal transmission via the spinal canal.^[2]

There are many different factors that can cause nerve damage that results in paresis. Several examples of causes include:^[1]

• Head injury
• Spinal cord injury
• Pressure on the spinal cord or nerves due to things like inflammation, bone spurs, or a tumor
• Stroke
• Seizures
• Multiple sclerosis (MS)
• Cerebral palsy
• Diabetes
• Certain infections, such as Epstein-Barr virus and syphilis
• Guillain-Barré syndrome
• Amyotrophic lateral sclerosis (ALS)

Pareses can be classified and described in different ways. On the one hand, they can be classified according to the number of damaged nerves or affected limbs and, on the other hand, according to the location of nerve damage in the body.^[2]

The location of the damage determines which of two forms exists:^[2]

Central paresis: Damage to the nerve between the brain and the anterior horn cell of the spinal cord (upper motor neuron). A central paresis involves damage to the brain or spinal cord.^[2]

Peripheral paresis: Damage to the nerve between the anterior horn cell of the spinal cord and the neuromuscular junction of the muscle (lower motor neuron). Peripheral paresis involves a nerve which is damaged along its course in the arms or legs.^[2]

Central pareses are classified according to the affected limb:^[2]

• Monoparesis: The incomplete paralysis affects only one limb, such as one arm or one leg^[1]
• Paraparesis: Both legs are paralyzed; arms are not affected^[2]
• Hemiparesis: The arm and leg of one side of the body are partially paralyzed^[2]
• Tetraparesis: It involves partial paralysis of all four limbs (arms and legs) as well as impaired control over the torso and head^[2]

In the case of central pareses, paralyzed muscles are always on the side opposite to the brain damage. This means that damage to the left brain hemisphere paralyzes the right side of the body and vice versa. In the case of peripheral paralyses, the paresis is always on the same side as the injury.^[2]

Symptoms of Paresis

Paresis is often categorized by the area of the body that’s impacted.^[1] You may experience the following symptoms:^[3]

• A steady loss of feeling and muscle control
• Muscle cramps
• Tingling or numbness in your limbs

Muscle weakness is the primary characteristic of paresis. The affected muscles can still be moved, but these movements are weaker than normal.^[1]

Diagnosis and Assessment

Paresis is diagnosed on the basis of a clinical examination, imaging technique, and specific additional tests which are optional. Paralyses are characterized by reduced muscle strength. For this reason, various scales are used to evaluate muscle strength in order to assess the degree of paralysis.^[2]

The most common assessment is the scale of the Medical Research Council (MRC). It awards points from 0 to 5 per muscle or per movement. 0 points stand for a complete paralysis (plegia); 5 points mean that the muscle contracts normally again.^[2]

The pattern of weakness can help localize the abnormality. The nervous system is distributed throughout the body and therefore weakness on its own cannot accurately define the location of the dysfunction. However, assessing the pattern of weakness and whether there are upper or lower motor neuron signs can help identify the underlying cause.^[6]

Treatment and Management

Treatment for paresis depends on the underlying cause and the severity of the condition. The goal is to help restore function and improve quality of life.

Treatment approaches may include:^[2]

• Physiotherapy: Physical therapy is crucial for the treatment of paresis. A physical therapist will develop a rehabilitation program that includes exercises to improve muscle strength, balance, coordination, and range of motion
• Occupational therapy: This focuses on improving functional skills and independent functioning, helping you regain everyday skills
• Speech therapy: If paresis affects speech and swallowing, speech therapy may be necessary

Medical interventions may also be considered depending on the specific situation. In some cases, medications may be used to manage accompanying symptoms such as pain, muscle spasms, or tremors.^[13]

For post-stroke paresis, advanced treatments like brain neuromodulation through Transcranial Magnetic Stimulation (TMS) may be used. This non-invasive technique uses magnetic pulses to modulate the activity of specific brain regions, supporting functional reorganization and helping restore motor abilities.^[13]

Living with paresis requires patience and adaptation. It’s important to accept and acknowledge the change, identify your physical limitations, and focus on what you can do rather than dwell on what you can’t control. Seeking support from family, friends, and support groups can provide emotional and practical assistance during the adjustment period.^[16]