Difference Between Flaccid and Spastic Paralysis

The key difference between flaccid and spastic paralysis is that in flaccid paralysis, muscles cannot contract and stay weak and floppy while, in spastic paralysis, muscles stay in contraction, and it is too rigid.

Paralysis is a condition we associate with the loss of muscle function. Paralysis occurs mainly due to the failures in the nervous system. Nervous system failures may occur due to various reasons, such as trauma, polio, botulism, etc. Flaccid paralysis and spastic paralysis are two forms of paralysis. So, this article attempts to discuss the difference between flaccid and spastic paralysis.

CONTENTS

1. Overview and Key Difference
2. What is Flaccid Paralysis
3. What is Spastic Paralysis
4. Similarities Between Flaccid and Spastic Paralysis
5. Side by Side Comparison – Flaccid vs Spastic Paralysis in Tabular Form
6. Summary

What is Flaccid Paralysis?

Flaccid paralysis is paralysis or reduced muscle tone without other obvious cause. Diseases or trauma are the main reason for flaccid paralysis. This condition arises due to the affected nerves involved in muscle action. A particular muscle shows flaccid paralysis when its somatic nerves that are responsible for the skeletal muscle action got affected.

Due to flaccid paralysis, the muscles lose the ability to contract and become limp. Flaccid paralysis can be fatal depending on the type of affected muscle. A person may die as a result of affected respiratory muscles. Polio, botulism and curare can cause flaccid paralysis, but there can be other causes, as well. Acute flaccid paralysis often occurs due to polio. Furthermore, it can occur due to pathogens like enteroviruses. Clostridium botulinum is the causative agent of botulism, and it produces toxic substances during botulism. These toxins block the release of acetylcholine. Due to this, the muscles lose the ability to contract, leading to flaccid paralysis. Curare is a toxin a plant that grow in the rainforests of South America produce. This toxin binds to the acetylcholine molecule, which makes it unable to bind to the acetylcholine receptors on the muscle cells. Due to this, the muscles cannot be stimulated.

What is Spastic Paralysis?

A spastic paralysis is also a form of paralysis. Spastic paralysis causes unusual tightness of the muscles. It changes skeletal muscle performance in muscle tone involving hypertonia. It is a condition that arises upon the disability of the nerves coordinating the voluntary muscle actions. During this condition, the nerves controlling muscle movement become hyperirritable. As such, the skeletal muscles become unable to function in a coordinated manner. Therefore, spasmodic muscle contractions are caused by the impulses that arise from them.

Various kinds of brain damage or stroke can cause severe spastic paralysis. Spastic paralysis may also be caused by spinal cord injury. The injuries caused by inflammatory diseases of nerve tissue is an example of this. During this condition, the injured motor neuron fibres in the spine cause spastic paralysis. Intrauterine disease, birth injury or inherited nervous system defects may cause congenital spastic paralysis.

What are the Similarities Between Flaccid and Spastic Paralysis?

• Flaccid and spastic paralysis are two forms of paralysis.
• In both cases, muscles cannot move properly.
• They are neurological diseases.

What is the Difference Between Flaccid and Spastic Paralysis?

Flaccid Paralysis is a condition that gives rise to limp and floppy muscles that lack firmness. On the other hand, spastic paralysis is a condition that gives rise to muscle stiffness. So, this is the key difference between flaccid and spastic paralysis. Furthermore, in flaccid paralysis, the muscle stays weak and floppy. In spastic paralysis, muscle is too rigid. Moreover, flaccid paralysis is often associated with reduced muscle tone, while spastic paralysis is associated with increased muscle tone. Therefore, this is also a difference between flaccid and spastic paralysis.

Summary – Flaccid vs Spastic Paralysis

Flaccid and spastic paralysis are two types of paralysis that occur due to nervous system failures. In flaccid paralysis, muscles cannot contract. It stays weak and floppy. On the other hand, in spastic paralysis, muscles stay contracted and seem too rigid. So, this is the key difference between flaccid and spastic paralysis. Spastic paralysis is often associated with muscle stiffness, increased muscle tone and uncontrollable leg movements while flaccid paralysis is often associated with weak muscles and reduced muscle tone.

Reference:

1.“Flaccid Paralysis.” Wikipedia, Wikimedia Foundation, 22 June 2019, Available here.
2. “Hereditary spastic paraplegia.” NHS Choices, NHS, Available here.

Image Courtesy:

1. “This was a young Indian child who was reported to be suffering with acute flaccid paralysis (AFP), however, a follow up visit made by a heal” By: CDC/ Chris Zahniser, B.S.N., R.N., M.P.H., Courtesy: Public Health Image Library via Public Domain Files
2. “Spastic hand 2” By Genusfotografen (genusfotografen.se) & Wikimedia Sverige (wikimedia.se) (CC BY-SA 4.0) via Commons Wikimedia