Dr Dan Lumsden | Consultant Paediatric Neurologist
How we move is fundamental to our identity as a species. Our upright bipedal gait pattern, and ability to fluidly manipulate objects with our hands is one of the things which truly sets us apart from other animal species (sorry cat lovers – but the opposable thumb rules!) If you’re not moved when watching a truly expert flamenco or ballet dancer, with the immaculate control they have over their movements, then you’re probably a little bit dead inside. That breath taking quality, a genuine mastery of body movement has contrasts sharply with the impact on a child and their family and carers when they have a problem with movement.
When you’re faced with a child whose parents are concerned may have funny movements, the following sequence of yes/no questions probably goes through your mind:
- Are these movements abnormal?
- Is this a seizure?
- If this is a seizure:
- Where’s the APLS protocol?
- If it’s not a seizure:
- What is it?
- Do I need to do something about it quickly?
- If this is a seizure:
On the face of it these are binary questions, but all too often the answer is “maybe” (apart from the question about the APLS protocol). That uncertainty can be unsettling to child, carer and clinician alike. In the middle of the night with a child presenting to ED, that can lead to reaching for a dose of benzodiazepine to stop the movement. The problem is, most movements stop if you give enough midazolam… unfortunately this includes respiratory movements, a very real risk when mistaking a movement disorder for a seizure. Deciding if a child’s movements are abnormal in the first place is not always clear cut. The types of movement a healthy normally developing child makes will change over time. The pattern of movements and postures that a 6 month old’s brain will produce would be profoundly abnormal in a 6 year old. The next time you examine a healthy 4 month old, take some time to consider the wriggling movements of their fingers and toes. You’d be perturbed if you saw a 14 year old making those type of movements.
The language of movement disorders can seem bewildering at first. To start with, what actually is a movement disorder, and how is that different to a motor disorder? When I describe a child as having a “movement disorder”, it means I think they are either moving too much, or not moving enough. Either way, they can’t control the amount of movement they making. Movement disorders are a subset of motor disorders, which I would more broadly describe as “problems making movements because of a problem with the brain or spine”.
If a child has too much movement, then they are “hyperkinetic”. Hyperkinesia takes many forms, which I’ll begin to discuss below. If a child can’t make enough movement, then they are “hypokinetic”. If they are slow to start and continue movements, then they are “bradykinetic”. The terms bradykinesia and hypokinesia are often (and incorrectly) used fairly interchangeably. As the two often occur together though, this is probably forgivable.
Before considering the different types of hyperkinetic movement, it’s worth thinking about how you can decide if an unwanted movement in is a seizure or a hyperkinetic movement disorder (HMD). This is not always simple. In both cases these movements are generated by abnormal neuronal activity in the brain – for seizures this activity is occurring over part or all of the cerebral cortex, for HMD it’s the deeper structures of the brain (that’s as complicated as the science is going to get in this blog). Unwanted movements during seizures are usually (but not always….) simpler, more regular (e.g. amplitude, frequency etc), more rhythmic and overall more repetitive. I’ve always found it a little easier to mimic the type of movements you typically see with many seizures types, but I wouldn’t consider that a strict diagnostic condition. Seizures originating in the frontal lobe of the brain are often very complex (so we already have one exception to that rule). Impaired awareness is very unlikely to be a feature of an HMD (but beware the child whose already been given some benzodiazepine). Autonomic features (e.g. a flushed or pale face) are probably less likely with a HMD, but, again, that’s not a hard and fast rule.
Once you’ve decided a child has abnormal movements, and you’ve decided those movements are a HMD, you have to decide what type. There’s no diagnostic test for this – no scan, blood test or sample of unspeakable body fluid which helps you decide. Instead, you have to be able to make a judgement based on your own assessment of the nature of the movements. One of the reasons so many neurologists have beards is so they have something to stroke when they’re thinking about this. Like much of medicine, this is pattern recognition. In this case though, the patterns are moving, but that doesn’t make it any more complex. Recognising what type of HMD a child has is the first step to diagnosing the underlying cause of their movement problem (ie. What’s gone wrong in their brain to generate these movements). It helps to guide investigations, and also treatment (if this is needed).
In this table I’ve listed the different types of HMD, given the text book definition, and also tried to give a plain language definition to capture the “essence” of the movement . I’ll consider each of these HMD in turn in future blog posts.
|Hyperkinetic Movement AKA “Excess” movements||Standardised Definition||What does that mean?|
|Dystonia||“A movement disorder in which involuntary sustained or intermittent muscle contractions cause twisting and repetitive movements, abnormal postures, or both”
“Dominated by abnormal postures that may give the impression of hypokinesia and muscle tone that is fluctuating (but with easily elicitable tone increase)”
“A movement disorder characterized by sustained or intermittent muscle contractions causing abnormal, often repetitive, movements, postures, or both”
Albanese et al 20131
|At some point the body part(s) stop moving and hold an involuntary posture. For some children this can be a sustained abnormal position (think about the children bent backwards like an inverted banana), but for others only a very brief fleeting pause. When the body part stops the abnormal contraction of muscle is still there (they’ll feel hard to the touch).|
|Athetosis||“Slow, continuous, involuntary writhing movement that prevents maintenance of a stable posture”
“Slower, constantly changing, writhing, or contorting movement”
|These are the movements that can be almost hypnotic to watch – no clear begin or end (or abrupt change of direction). Instead – one long continuous movement, with no posture held.
Often occurs together with chorea – that’s choreoathetosis.
|Chorea||“An ongoing random-appearing sequence of one or more discrete involuntary movements or movement fragment”
“Rapid, involuntary, jerky, often fragmented movement”
|Lots of chaotic movements that flow together, but when you watch them you can appreciate discrete fragments of movement that occur one after another (and another, and another…). No posture held. Often occurs together with chorea – that’s choreoathetosis.|
|Tremor||“A rhythmic back-and-forth or oscillating involuntary movement about a joint axis”
|“Shaky” movements. Body parts moving up and down, left and right, or forward and back etc. The movement is active in both directions – not a jerk moving the body part in one direction, and a relaxation moving the body part back.|
|Myoclonus||“A sequence of repeated, often nonrhythmic, brief shock-like jerks due to sudden involuntary contraction or relaxation of one or more muscles”
|Really quick jerk(s) of the body part(s) – with movement in one direction. The movements aren’t regular – but happen with fairly random appearing typing. No postures are held.|
|Tic||“Repeated, individually recognizable, intermittent movements or movement fragments that are almost always briefly suppressible and are usually associated with awareness of an urge to perform the movement”
|These are brief, usually quite simple movements that repeat themselves. There’s often a posture held (so it can look dystonic) – but the giveaway is children can stop themselves from doing it for a little while. That gets uncomfortable though, and the movements will break through (think – a can of fizzy pop you’ve shaken for a while).|
|Stereotypy||“Repetitive, simple movements that can be voluntarily suppressed”
|These are “excess” movements – but not involuntary. If you distract the child (try asking them to stop!) – the movements stop. Think about the toddler flapping their hands when they get excited.|
Table 1: Standardised and Plain language definitions of the different types of hyperkinetic movements.
Abbreviations – TCM – Taskforce on Childhood Movement Disorders, SCPE – Surveillance of Cerebral Palsy in Europe
1 Phenomenology and classification of dystonia: a consensus update.
Albanese A, Bhatia K, Bressman SB, Delong MR, Fahn S, Fung VS, Hallett M, Jankovic J, Jinnah HA, Klein C, Lang AE, Mink JW, Teller JK
Movements are (by definition!) a dynamic phenomenon, and are generally poorly captured by prose. If a picture paints a thousand word, then a video clip paints several million. For paroxysmal events which children are rarely obliging enough to perform during a clinic appointment, a recording of a typical episode can very often be enough to help decide if it’s a seizure or HMD. Asking for a description of the event can quickly become frustrating (What do you mean when you say “jerky”?). A consultation can rapidly descend into what to the outside observer looks like a bad interpretive dance session, with doctor and family waggling arms and legs at each other to try an imitate what they’ve seen. Often funny, and usually a good icebreaker, but of dubious diagnostic value.
Be careful when asking for videos to explain what you want the family to record. If not, you can end up with a poorly lit, poorly focused, shaky handheld recording accompanied by a cacophony of alarming sounds (think along the lines of an even lower budget remake of the Blair Witch project). Explain that you want to see the whole of the child (heads, shoulders, knees and toes) for at least part of the recording, zooming in on the face or hands etc if there’s a specific aspect of the movement you want to see. Also, consider how the recordings are going to get to you (email, post etc). Be mindful of local policies for consent (considering if you might want to use the recording for teaching or other purposes) and storage of these recordings as well.
Example video found on YouTube demonstrating choreoathetosis –
Whilst it’s key to consider what a child’s movements “look” like, never forget to ask the child what they “feel” like. One of the defining features of tics is the uncomfortable urge to perform the movement that children will experience. You won’t see this in a recording, no matter how well shot or high definition the video is.
One important lesson I’ve learnt about looking after children with HMD is to establish early on why the family are worried about the movement. Many families are concerned about abnormal movements being harmful/damaging to the brain, and so want them to be stopped as soon as they start. Whilst you might not be able to say exactly what a movement is, or what’s causing it in the first consultation, unless you’re concerned about generalised convulsive movements it usually possible to be reassuring that the movements are not damaging, and to avoid future unnecessary visits to the ED.
Dr Dan Lumsden, Consultant Paediatric Neurologist, Guy’s and St Thomas’ Hospital, London