Symptoms

What does CHD2 look like?

CHD2 disorders normally begin to present between the ages of six months and four years. They are characterised by a number of different epileptic seizure types, with the seizures often unresponsive to anti-epileptic medication (this is what is known as “refractory” seizures).

Distinctive, commonly observed epileptic characteristics among people with CHD2 are eyelid myoclonia (i.e. eyelid flutters) and photosensitivity.

Other typical characteristics of CHD2 disorders include: learning disability; developmental delay; speech and language delays; autistic spectrum disorders or autistic behaviours; and challenging behaviours.

Epileptic seizures

Seizure types include:

• Tonic-clonic seizures. This is the most commonly recognised seizure type, when the whole body stiffens for a period of time before giving way to whole-body shaking. These seizures usually last a couple of minutes or longer. If a seizure of this type lasts more than five minutes it would be classed as a medical emergency requiring a 999 call for an ambulance (the exception to this being where parents/carers already have emergency medication prescribed that they themselves can administer). People often need several hours to recover after a tonic-clonic seizure as these seizures can be physically exhausting.
• Eyelid myoclonia (often referred to as “Jeavons syndrome”). This is one of the most commonly-occurring and typical symptoms of a CHD2 disorder. Eyelid myoclonia are most often recognised by the eyelids fluttering. The eyes may also roll back in the head or lose focus. These seizures may last only a few seconds, but they can ‘cluster’, so that a person may experience many of these seizures during the space of a few minutes or an hour, or throughout the day generally. Although these seizures seem small, they can cause people to lose track of what they were doing and become confused or distressed; for instance, they may forget that they have been asked a question and need it to be repeated.
• Absence seizures. This is where a person seems to ‘zone out’ or ‘go blank’ for a few seconds or longer. They will generally be unaware of what is happening or anything that is said while the absence is ongoing. As with eyelid myoclonia above, absence seizures can leave a person confused or distressed.
• Myoclonic jerks. These are sudden, short seizures that cause part of the body to jerk uncontrollably. Often both arms will jerk upwards into the air while the head jerks downwards. In some instances, the patient will lose control of their legs at the same time, causing them to fall to the floor (known as a “drop attack”). Myoclonic jerks may only last for a second or less but they can be very dangerous, depending upon what the individual is doing at the time. They can also leave people feeling confused and unwell.
• Focal seizures. Focal seizures can either be “aware” seizures or “impaired awareness” seizures (also known as “simple partial” or “complex partial” seizures). This means that the individual may either still be aware and conscious of the seizure sensation, or they may be completely unaware of it occurring. Focal seizures can present in very different ways and may include unusual feelings or sensations, or unusual movements (such as clapping, screaming, plucking at clothes). They may last a few seconds or a few minutes. Focal seizures can be very unpleasant, particularly when an individual is aware of what is happening, and so people can be quite distressed afterwards.
• Atonic seizures, also known as drop attacks. Usually a person’s muscles will go limp and they will drop to the floor, this can result in injuries to the head or face. Sometimes an individual might not completely fall, but their head may drop forward or they might sag at the knees. Atonic seizures are very short usually lasting less than a few seconds. Recovery is usually immediate although first aid may be required.
• Reflex seizures, including photosensitivity. Reflex seizures are ones that occur as a response to an external or internal stimuli. They can manifest in very different ways, including most of the seizure types mentioned above. The most typical reflex seizure is one induced by light (“photosensitivity”), such as sunlight through trees when in a moving car, or light flickering off water. Other triggers reported with CHD2-related disorders include alternating striped patterns, high pitched noises, eating and heightened emotional states such as over-excitement, anger and anxiety/distress.
• Subclinical seizure activity, is caused by abnormal electric activity within the brain. Often it does not manifest any outward clinical symptoms, not even to the patient. It is most frequently identified by EEG (electroencephalogram) and is more commonly present during sleep.

Because individuals with CHD2 have frequent seizures and the condition is often hard to control, there is an increased risk of SUDEP (Sudden Unexpected Death in Epilepsy) compared with other epileptic syndromes. SUDEP is when a person dies unexpectedly following a seizure, with no clear reason why. It is assumed that breathing stops or the heart stops after the seizure. Parents and carers of people with CHD2 will usually use seizure monitoring devices overnight so that they are alerted if a seizure occurs and can take appropriate action if necessary.

Other symptoms

Other common characteristics of a CHD2 disorder include:

• Learning disability. Many people with CHD2 are classed as learning disabled, though the severity of this can vary. They may struggle with understanding information and need things to be explained as simply as possible. They may have difficulties with everyday tasks such as dressing or washing; may have little understanding of money; may not be able to read or write; or may struggle to follow simple instructions. Learning disability is often closely bound up with:
• Developmental delay. Parents of a child with CHD2 may find that their child is developmentally behind others of the same age. In the early years, this may be seen as missed milestones (speech, crawling, walking etc.). Once at school, the gap between a CHD2 child and their peers will often widen and a child may eventually seem to plateau or make slow, limited progress. When seizures are severe and uncontrolled, there may even be regression or loss of skills, though equally these may well be regained if greater seizure control is achieved.
• Speech and language delays. One of the early symptoms seen amongst children with CHD2 is a lack of speech, or a loss of speech once seizures begin to manifest. Children may not begin to speak until several years after one would expect. They may continue to have communication difficulties even once speech develops, such as problems making certain sounds, or other speech problems. Very occasionally some people with CHD2 remain non-verbal into adulthood. Communication difficulties are often also closely bound up with:
• Autistic spectrum disorder (ASD) or autistic behaviours. People with CHD2 are frequently diagnosed with ASD or are said to have autistic traits. ASD is a broad spectrum of behaviours and characteristics, including: sensory difficulties or needs; repetitive and/or obsessional behaviour; difficulties in social interactions, such as conversation, or recognising facial expressions and non-verbal cues; difficulties recognising their own or others emotions. The severity of ASD is hugely variable.
• Challenging behaviours. Children and adults with CHD2 may exhibit behaviour that is difficult to manage, such as sudden aggression or anger, lashing out and throwing things. This type of behaviour can often be bound up with the occurrence of seizures and so has to be handled with sensitivity and understanding. Challenging behaviour can also be exacerbated by anti-epileptic medications, some of which (such as Levetiracetam – “Keppra”) are well-known to cause aggression and anger.

Individuals with CHD2 may also have some physical problems, though these are more variable. For instance, they may have low muscle tone, hypermobility, or develop scoliosis. A small number of people appear to develop regular posterior dislocation of the shoulder due to the damage caused by frequent tonic-clonic seizures, though the numbers involved are too small to make any real statistical inferences.

Some young adults (late teens / early 20s) with CHD2 have been known to develop psychosis (hallucinations, delusions) but again the numbers are too small to say with certainty there is any significance to this. Anti-epileptic medications and other drug interactions may also be one of the causes behind this rather than the CHD2 itself.