Introduction 

Central pain is a condition that is characterised by chronic pain caused by damage to the nervous system. Someone with central pain will experience heightened and intensified feelings of pain without a physical cause or actually being physically hurt. Both encephalitis and demyelinating disorders result in damage to the nervous system; if left untreated or progress severely they can lead to centralised pain disorders.¹

This article will follow specifically how these two conditions can result in central pain in children. We will look into the signs and symptoms to look out for in children and how to manage and treat the condition moving forward after diagnosis. 

What is central pain 

Central pain, also called central pain syndrome (CPS), is persistent or recurring feelings of pain which last for at least 3 months. It is caused by damage to the nervous system which causes it to malfunction and incorrectly process pain. Essentially the nervous system becomes overly sensitive and causes the individual to feel pain even when there is no visible damage or injury that would explain the painful sensations.¹

Symptoms of central pain

Common symptoms of central pain usually observed in adults, but can also be observed and described in children:

• Burning sensations 
• Tingling sensations 
• Numbness 
• Stabbing pains 
• Paresthesia (a numbness or pricking sensation of the skin)²

Two words you may come across often used to describe symptoms of CPS:¹

• Allodynia – the feeling of pain from a non-harmful stimulus
• Hyperalgesia – intensified and worsened feelings of pain

Pain is subjective and often difficult to diagnose, especially in children, who may struggle to explain the pain. They may give vague or harder to understand descriptions of what they are experiencing.

Here are some signs to look out for in your child which may indicate they have CPS:³

• Avoiding touching things 
• Limping 
• Withdrawing from activities 
• Feelings of frustration 
• Agitation 
• Mood changes
• Disrupted sleep
• Fatigue 

Encephalitis and demyelinating disorders 

Encephalitis 

Encephalitis is inflammation (swelling) of the brain, it is uncommon but a very serious condition and if not caught and treated early it can have long term effects. Children are especially at risk, due to them having weaker immune systems.⁴ 

Main causes of encephalitis:

• Infection by Herpes simplex (HSV) type 1 virus
• Autoimmune diseases 
• Bacterial or fungal infections 

The majority of cases are caused by viral infections. In these cases, the onset of encephalitis can happen quite rapidly, and the onset of serious symptoms can develop from as little as a few hours, but more generally over days or weeks. It is important to recognise the first signs and symptoms so your child can receive appropriate medical care quickly.⁵

Common symptoms of encephalitis:

• Flu-like symptoms 
• Fever, high temperature 
• Headache 
• Body aches

More serious symptoms of encephalitis: 

• Seizures
• Confusion
• Loss of consciousness
• Behavioral changes

Subtle symptoms, and the overlap of symptoms displayed in other less serious and non life threatening conditions, (e.g. the flu), may lead to delayed diagnosis or even misdiagnosis. This is a serious concern as delayed treatment of encephalitis leads to long-term health issues due to brain damage caused by infection and inflammation. 

The outcomes of delayed treatment of encephalitis vary from person to person, and can depend on which parts of the brain have acquired the most damage. Both the infection and the inflammation of the brain can cause nerve cell damage and loss.^5,6 

This can lead to complications such as:^4,6

• Cognitive disorders;problems with memory and attention span
• Emotional or behavioural changes
• Weakness and fatigue
• Difficulty controlling movements
• Sensory changes (pain may be caused by sensory changes relating to pressure or temperature change)
• Pain

Autoimmune encephalitis 

Another cause of encephalitis is when the immune system mistakenly attacks the brain tissue. There are different types of autoimmune encephalitis, the two we most commonly see in children are:^7,8

• Acute disseminated encephalomyelitis (ADEM), this form is specifically associated with demyelination and occurs after an infection or immunisation, as these trigger an immune response⁸
• Anti-N-methyl-D-aspartate (anti-NMDA) receptor encephalitis, this is when the immune system attacks a certain receptor (NMDA receptor) found in the nervous system which allows nerves to communicate with each other. This disruption can lead to problems with thinking, movement, and behaviour⁹

Like with viral encephalitis, autoimmune encephalitis causes damage to the brain and nervous system. Regions of the brain associated with the processing of pain can be damaged, leading to pain.if not treated properly and the damage persists, this can progress into central pain even after the encephalitis is treated.^6,10 

Encephalitis and pain 

Pain is often overlooked in encephalitis, due to the presence of other major symptoms and considering the fact that pain is difficult to describe and measure. In 2008, a study was conducted by the University of York and the Encephalitis Society. this paper highlights the after-effects some individuals experience after encephalitis due to long-term acquired brain injury (ABI). Chronic pain, including central pain was reported after encephalitis which is likely linked to long-lasting damage to pain processing pathways in the brain. Chronic headaches in particular were observed.¹¹

Any type of chronic pain has a big impact on an individual's life. it is important to understand the importance of chronic pain and its link to conditions such as encephalitis in order to educate and help people receive adequate support and care even after the primary illness is treated.

Demyelinating disorders

Myelin is the protective layer that surrounds your nerves and helps them to function correctly and efficiently. Demyelinating disorders cause damage to this protective layer and impair the functioning of your brain and nervous system.¹²

Often demyelination occurs due to inflammation; examples of diseases in which demyelination is caused by inflammation are:¹²

• Acute‐disseminated encephalomyelitis (ADEM), which usually affects children and is often triggered by a viral or bacterial infection or after an immunisation
• Multiple sclerosis, an autoimmune condition characterized by the immune system attacking the protective layer around nerves, this is less common in children 

Demyelinating disorders and pain

Demyelination and nerve cell damage disrupt the normal functioning of the nervous system. Both inflammation and nerve damage from demyelinating disorders can cause sensory changes in the nervous system and may increase feelings of pain.¹³  When the pain processing pathways are affected in this way overtime, as can happen after encephalitis, the pain can become centralised. Centralized pain persists independently from the original disease and is caused by nervous system malfunctioning rather than the disease.¹

How Encephalitis and Demyelinating Disorders Can Lead to Central Pain 

Whether the cause of damage to the brain and nervous system is from the inflammation or demyelination, they both affect the pain processing pathways in similar ways and lead to central pain in children. 

Living with and supporting children with central pain 

Research on central pain specifically in children is limited. While the main research suggests that pathologically there is not much difference in how it manifests; it is important to understand how a child may express and cope with chronic pain differently. 

It can be harder for children to explain or even understand feelings of chronic pain, which can make diagnosing this condition in children difficult. 

Parents, carers and healthcare providers need to pay close attention to behavioural, mood and physical signs that may indicate central pain disorder in children. Paying close attention to subtle cues which may indicate underlying central pain and listening to the child's expressions of what they are feeling and experiencing is important for reaching a quick and accurate diagnosis. 

FAQ

What are the main treatment approaches for children with central pain disorder?

Many factors can affect the way a child feels pain, for this reason treatment is approached at different angles. While pharmacological intervention can be a main line of treatment, other methods, such as physical therapy and sessions with a psychologist can help a child to better cope with their condition and make the pain more manageable.³ 

Summary

Central pain in children can be associated with various conditions, in this article we have discussed how central pain can develop and persist after encephalitis and demyelinating disorders. It is important to treat pain symptoms as serious as early recognition of such chronic pain can help lead to better management, treatment and overall a better quality of life for children dealing with central pain. 

If you suspect a child has central pain syndrome seek medical advice promptly so they can be properly assessed and receive appropriate support and treatment.