Congenital Insensitivity to Pain - An Overview

Introduction

Humans and other living creatures experience physical pain from the time they are born. However, some individuals are born with the inability to experience pain. Congenital insensitivity to pain is a genetic disorder that impacts an individual’s capacity to sense physical pain. It is a condition that lasts throughout one’s life and is usually identified during the early stages of childhood. Individuals with the condition cannot experience pain, temperature alterations, or other similar physical sensations that often signify injury or disease. Although it might seem advantageous, this rare condition's inability to sense pain can cause severe health complications, as those affected are often unaware of wounds or illnesses.

What Are the Types of Congenital Insensitivity to Pain?

There are two main types of congenital insensitivity to pain:

• Congenital Insensitivity to Pain With Anhidrosis (CIPA) - CIPA is most often due to a mutation in the neurotrophic receptor tyrosine kinase 1 (NTRK1). It is a genetic disorder, which is rare and affects both the ability to sense pain and the body's ability to regulate temperature. Individuals with CIPA cannot sweat. This condition is also referred to as hereditary sensory and autonomic neuropathy type IV (HSAN IV).

• Congenital Insensitivity to Pain With Partial Anhidrosis (CIPPA) - CIPPA is often caused by a mutation in sodium voltage-gated channel alpha subunit 9 (SCN9A). This is a genetic disorder that affects the ability to sense pain and regulate temperature. Unlike CIPA, individuals with CIPPA can sweat, but only in certain parts of the body. Individuals may also experience repeated injuries due to their inability to feel pain.

What Is the Cause of Congenital Insensitivity to Pain?

The condition typically occurs when an individual inherits two mutated genes, one from each parent (autosomal recessive pattern of inheritance). Congenital insensitivity to pain is a result of genetic mutations that interfere with the normal functioning of certain genes responsible for transmitting pain and other sensory signals. These mutations can alter the development and function of nerve cells, leading to the inability to feel pain or respond appropriately to painful stimuli. Various gene mutations have been identified as causative for congenital insensitivity to pain, some of which are as follows:

• Sodium voltage-gated channel alpha subunit 9 (SCN9A).

• Neurotrophic receptor tyrosine kinase 1 (NTRK1).

• Clathrin heavy chain like 1 (CLTCL1).

• Nerve growth factor (NGF).

• PR domain zinc finger protein 12 (PRDM12).

• Zinc finger homeobox 2 (ZFHX2).

• Fatty acid amide hydrolase (FAAH).

Mutations to sodium voltage-gated channel alpha subunit 9 (SCN9A) and neurotrophic receptor tyrosine kinase 1 (NTRK1) are known to be the most common cause of congenital insensitivity to pain.

What Are the Symptoms of Congenital Insensitivity to Pain?

The primary symptom of congenital insensitivity to pain syndrome is the inability to feel physical pain. However, individuals may present with varying symptoms, some of which are as follows:

• The inability to feel extreme temperatures (hot or cold).

• The inability to sweat (anhidrosis) or experience sweating only in certain parts of the body.

• Frequent and repeated injuries due to a lack of pain sensation, such as cuts and broken bones.

• Joint deformities and damage caused by repeated injuries and delayed healing.

• Delayed healing of injuries and wounds due to the lack of appropriate protective behaviors and pain signals.

• Oral injuries due to biting of the tongue or inside of the cheeks.

• Corneal injuries are due to a lack of reflex reaction such as blinking of the eye on exposure to foreign particles such as dust, sand, or repeated rubbing of the eyes.

• Increased susceptibility to infections or inflammation due to the inability to feel pain or discomfort.

• Difficulty identifying injuries or illnesses, leading to delayed medical attention and potentially severe complications.

How to Diagnose Congenital Insensitivity to Pain?

Since congenital insensitivity to pain is a rare disorder, doctors may not immediately suspect it as a possible cause of the symptoms. However, if an individual shows symptoms such as the inability to feel pain, repeated injuries, and delayed wound healing, a doctor may perform a thorough evaluation to determine the underlying cause, which includes a physical examination, medical history, and subsequent genetic testing.

• Physical Examination - Involves assessing the individual's response to different types of stimuli, such as temperature and pain, and evaluating the ability to sweat. The doctor may assess and look for signs of previous injuries, joint deformities, or other physical abnormalities.

• Medical History - Medical history reveals that the parents of the individuals also suffer from the inability to experience physical pain.

• Genetic Testing - Genetic testing can confirm the diagnosis of congenital insensitivity to pain by identifying mutations in specific genes associated with the disorder. This may involve analyzing DNA samples from the affected individual and their parents.

How to Treat Congenital Insensitivity to Pain?

Since individuals with congenital insensitivity to pain lack the ability to perceive pain, it is important to take measures to prevent injuries and monitor any injuries or wounds closely to avoid complications. Some measures that may be helpful for the same include:

• Protecting the body from injury by wearing protective gear and avoiding activities that may lead to injury.

• Take extra care with oral hygiene practices and use mouth guards to prevent oral injuries. Smoothening of sharp incisal edges is also recommended as a preventive measure for oral injuries.

• Monitoring wounds and injuries closely to avoid complications such as infections and delayed healing.

• Taking medications to manage other symptoms, such as fever or inflammation, as needed.

• Timely follow-up with a healthcare provider to monitor for any potential complications and receive necessary care.

What Are the Complications of Congenital Insensitivity to Pain?

Congenital insensitivity to pain can lead to various complications for an individual. Some of the possible complications include:

• Injuries: Without the ability to feel pain, individuals may not realize when they have injured themselves, leading to cuts, bruises, or broken bones that go unnoticed and untreated. Subsequently, these can cause complications, such as delayed healing or infections.

• Oral Health Problems: Oral health problems are common in individuals, as one may not feel toothaches or mouth injuries that could lead to more severe dental problems if left untreated.

• Joint and Bone Problems: Individuals are at increased risk of developing joint and bone problems, such as osteoarthritis, as they may not feel the pain associated with overuse or injury to joints and bones.

• Infections: Without pain as an early warning sign, infections can go unnoticed and untreated. Infections could turn fatal for some individuals if timely and appropriate treatment is not given.

Conclusion

The ability to be insensitive to physical pain may sound exciting, but the complications could be a lifelong burden. Early diagnosis is crucial, as there is no known cure for this rare disorder. Based on the severity of the health condition, some individuals may require specialized care from a team of healthcare professionals, including neurologists, pain specialists, and orthopedic surgeons. Individuals with this condition require proper medical care and support to prevent complications and manage symptoms effectively.