Congenital insensitivity to pain

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at January 4, 2017
StartDiseasesCongenital insensitivity to pain

Congenital insensitivity to pain (CIP) is also known as congenital analgesia. It is a condition in which a person is born without the capacity to properly perceive pain. Since pain is the body’s warning system, CIP can be a very dangerous condition.

Contents

Definition & Facts

Congenital insensitivity to pain is a condition in which the patient cannot perceive pain. While they can recognize other sensations like hot or cold, dull or sharp, they cannot feel pain. They cannot, for example, tell if a hot drink is burning their tongue.

Congenital insensitivity to pain is considered a type of peripheral neuropathy for it affects the peripheral nervous system which connects the central nervous system to muscles and sensory cells that detect smell, touch and pain. CIP is extremely rare with only 20 documented cases in medical literature. As a result, there has been little research done on the condition.

Symptoms & Complaints

The chief symptom of CIP is an inability to feel pain. Patients with CIP also have anosmia or a complete lack of the sense of smell. They may also have dry eye and therefore be more vulnerable to abrasions of the cornea. They will also be more susceptible to infections in general.

Since the patient can’t feel pain, they often don’t realize they have hurt themselves. Small children with CIP bite their fingers, tongues or the insides of their mouths, for example. People with CIP can gradually accumulate a collection of burns, bruises, wounds, and even broken bones that sometimes go undetected and untreated.

The patient also can’t detect foreign objects in their eyes, so eye injuries can occur. Injuries around the mouth are particularly a problem because the patient can bite themselves without knowing it. 

Causes

Congenital insensitivity to pain is caused by genetic mutations in the SCN9A gene. It is an autosomal recessive condition, which means both parents must each have at least one copy of the mutated gene. Since CIP is recessive, it can skip generations.

The SCN9A gene is one of a group of genes that help make channels that transport sodium ions (sodium atoms with positive charges) into cells and thus help them transmit and generate electrical impulses. Researchers have found over a dozen mutations in the gene that prevent the production of working sodium channels and thus prevent pain signals from reaching the brain.

Specifically, the mutations disrupt the production of a part of the sodium channel and cause the creation of a defective subunit that can’t be used to properly form a functional sodium channel. In patients who also have anosmia, the lack of sodium channels prevents smell-related signals produced by the olfactory sensory neurons from reaching the brain.

Diagnosis & Tests

Diagnosing CIP can be difficult. The doctor can start by taking a medical history and family history and conducting a physical examination during which they will make note of any injuries that should be causing pain. In some cases, dentists will find small children who have bitten off part of their own tongue. Similarly, parents and doctors may find bite marks on a patient’s fingers. Doctors will take note if an infant or small child does not react to such painful stimuli as getting a shot or having their blood drawn.

The doctor will also order laboratory tests and genetic tests. The genetic analysis is a simple blood test during which the geneticist will look for the SCN9A genetic mutations. If this condition is suspected, the doctor should check for serious injuries like broken bones even if the patient claims to “feel fine.” The doctor should perform X-rays and similar tests if they suspect such injuries. They should probably perform a magnetic resonance imaging (MRI) skeletal exam every year to make sure the patient has no fractures or broken bones that have gone undetected.

Treatment & Therapy

There is so far no cure for CIP. Treatment for the condition will emphasize both finding and preventing injuries. Parents of young children with CIP will have to be particularly vigilant. They will need to check places like the eyes, mouth, hands, feet and joints every day for signs of injury. As the patient gets older, they will have to learn to perform such checks themselves. 

The patient may also need to use artificial tears or other lubricants for their eyes. They will also need to see an ophthalmologist at least once a year. The patient should avoid chemicals and irritants that might harm their eyes. 

Patients will also need to be vigilant against infections whether they are bacterial infections, viral infections, or fungal infection. They need to use the appropriate medications at the first sign of an infection in order to prevent that infection from becoming chronic. 

Camp Painless But Hopeful is a support group that was established in 2011 to help patients and their families. They provide information and arrange camps so that patients, accompanied by their families, can meet one another. 

Prevention & Prophylaxis

Congenital insensitivity to pain can't be prevented, but parents may wish to undergo genetic screening. Even if they don’t have the condition themselves, they still might be genetic carriers, especially if they have close relatives with CIP.

During the screening, the geneticist will draw a blood sample and look for abnormal genes. Since CIP is a recessive trait, both parents have to be carriers for them to have a child with CIP.