Paralysis: Types, Causes and What to Do

What to do if someone suddenly cannot move

1. Call 911 or your local emergency number. Use BE FAST to check for stroke: Balance loss, Eyes (vision loss), Face drooping, Arm weakness, Speech difficulty, Time to call.
2. Note the time symptoms started or the person was last seen well. This decides which stroke treatments can be given.
3. After an injury, do not move the person unless they are in danger. Keep the head, neck and back aligned.
4. Do not give food, drink or medicines, as swallowing may be affected.
5. If they become unresponsive and are not breathing normally, start CPR.

Types of paralysis

Paralysis is also described as:

• Complete or partial: "-plegia" means complete loss; "-paresis" means weakness (for example hemiparesis).
• Flaccid or spastic: floppy, limp muscles from nerve or acute spinal damage, or stiff, tight muscles with brisk reflexes from brain or chronic spinal cord damage.
• Temporary or permanent: for example, Bell's palsy usually recovers, while a complete spinal cord injury usually does not.

Is hemiplegia complete paralysis on one side of the body?

Hemiplegia means paralysis of one side of the body. Strictly, it describes severe or complete loss of movement in the arm and leg (and often the face) on the same side. Partial weakness on one side is called hemiparesis, which is much more common. Doctors often use the terms loosely. Damage to the left side of the brain causes right-sided hemiplegia and vice versa. See hemiplegia.

Causes of paralysis

Brain

• Stroke: the leading cause. A blocked artery or bleed suddenly cuts off part of the brain, usually causing one-sided weakness, facial droop and speech problems.
• Transient ischemic attack (TIA): stroke-like symptoms that resolve, often within minutes. A major warning sign of stroke.
• Traumatic brain injury.
• Brain tumors and abscesses, with gradually increasing weakness.
• Cerebral palsy: brain injury around birth causing lifelong movement problems.
• Seizures: temporary weakness after a seizure (Todd's paralysis).
• Hemiplegic migraine: rare, with temporary one-sided weakness during migraine.

Spinal cord

• Spinal cord injury from falls, road accidents, diving and sports.
• Spinal cord compression from tumors, abscesses or a severe disc herniation.
• Transverse myelitis and multiple sclerosis: inflammation of the spinal cord.
• Spinal stroke, rare.

Nerves and muscles

• Guillain-Barré syndrome: weakness rising from the legs over days, often after an infection.
• Bell's palsy: sudden one-sided facial paralysis that usually recovers within weeks to months.
• ALS (motor neuron disease): progressive weakness with muscle twitching and wasting.
• Myasthenia gravis: fluctuating weakness that worsens with use.
• Botulism and tick paralysis: toxins that block nerve signals.
• Periodic paralysis: inherited episodes of weakness linked to potassium levels.
• Nerve injuries: for example foot drop from peroneal nerve compression.

Functional causes

Functional neurological disorder (once called conversion disorder) can cause real paralysis without structural damage. It is diagnosed by specific examination signs, not just by excluding other causes, and it can improve with targeted therapy.

How doctors find the cause

Emergency teams first check for stroke and spinal injury. Assessment includes:

• a neurological exam of strength, tone, reflexes, sensation and coordination
• CT scan of the brain immediately for suspected stroke, then MRI
• MRI of the spine for suspected spinal cord problems
• blood tests including blood sugar, electrolytes such as potassium, and infection markers
• lumbar puncture and nerve conduction studies for Guillain-Barré syndrome
• antibody tests for myasthenia gravis

Treatment

Treatment depends on the cause: clot-dissolving medicine or clot removal for ischemic stroke, surgery for spinal cord compression, immunotherapy (IV immunoglobulin or plasma exchange) for Guillain-Barré syndrome, steroids for Bell's palsy, and antitoxin for botulism. Rehabilitation starts early. For details on rehabilitation, equipment and long-term care, see living with paralysis.

Frequently asked questions

What is the most common cause of paralysis?

Stroke is the most common cause of paralysis, usually causing weakness on one side of the body. Spinal cord injury and multiple sclerosis are the next most common causes. Cerebral palsy is the most common cause in children.

Is hemiplegia complete paralysis on one side of the body?

Hemiplegia refers to paralysis of one side of the body, usually the arm, leg and sometimes the face. It can be complete or near complete. When the same side is weak but not fully paralyzed, the correct term is hemiparesis. Both are most often caused by stroke.

Can paralysis be temporary?

Yes. Paralysis can be temporary in Bell's palsy, Guillain-Barré syndrome (which usually improves over weeks to months), TIA, post-seizure weakness, periodic paralysis and sleep paralysis. Recovery after stroke or partial spinal cord injury is also possible with rehabilitation, especially in the first months.

What does paresis mean?

Paresis means partial weakness of a muscle or group of muscles, as opposed to plegia, which means complete paralysis. For example, hemiparesis is weakness on one side of the body, and paraparesis is weakness of both legs.