My head shakes: is it dystonia?
Millions of people all over the world, uses her head and neck to carry heavy goods. The control of her head posture must be phenomenal and does not allow any slight involuntary movement of her head. Unfortunately, for some people the head starts shaking and even without relying on their head as a way of carrying, they found this condition very disabling.
Head tremor described a movement of oscillation of the head, making the head going side to side, called no-no tremor or up and down, called yes-yes tremor. The tremor can be regular like a pendulum or irregular, with the head going further away from time to time.
Head tremor can be due to a condition called essential tremor (essential head tremor: EHT) or due to dystonia and in that case the tremor is labeled dystonic tremor (dystonic head tremor: DHT).
The clinical diagnosis of the different types of head tremor can be a dilemma when the head tremor is isolated, as neurologists don’t agree between themselves on the definition of dystonic tremor. Nevertheless, the distinction needs to be done, as the treatment and the prognosis may differ.
Table1: Differential diagnosis between essential head tremor and dystonic head tremor. Dr Marie-Helene Marion, 2013, www.infodystonia.com
ESSENTIAL HEAD TREMOR
- Essential tremor (ET) is a clinical description of a familial regular tremor, which affects 50% of the siblings when one parent is affected.
- ET can affect hands, head, chin, tongue and voice.
- Women with ET have more chance to develop a head tremor.
- ET occurs on posture, so the essential head tremor (EHT) is present when sitting, walking and disappears when lying down.
- ET, mainly when the tremor is affecting the hands, has the particularity of being improved by drinking alcohol and responding to beta-blockers drugs such as Propanolol.
- EHT is not controlled by sensory trick such as touching the cheek or the chin with the hand.
- EHT is always associated with other tremor in the arms or tongue or voice. A collaborative study between Turkey and USA looking at head tremor due ET (583 ET cases) has not found one isolated case of head tremor; all were associated with at least a mild hand tremor.
DYSTONIC HEAD TREMOR, WITH FOCAL DYSTONIA.
- · Dystonic head tremor (DHT) is an irregular head tremor, which is easy to diagnose when it occurs in a patient with a obvious cervical dystonia (with abnormal head posture and muscle spasms), and considers as a tremulous cervical dystonia. DHT is one of the first symptoms of cervical dystonia in 30% of the cases and is reported in 30% to 60% of the established CD cases.
- · DHT can also be present in absence of neck dystonia, but associated with other focal dystonia, such as blepharospasm, oro-mandibular dystonia, voice dystonia or even a writer’s cramp. Therefore patients with head tremor need to be examine thoroughly when speaking, eating, writing…
ISOLATED DYSTONIC HEAD TREMOR
DHT can be present but without any associated dystonia on examination; the diagnosis in that case is more difficult.
· The family history of tremor or dystonia can be absent as the penetrance of the gene for focal dystonia is low (it means that the genetic abnormality can stay silent and is not always associated with dystonic symptoms and therefore can “skip a generation”).
· The diagnosis of dystonic head tremor will be made clinically on the association of others signs.
1. The head tremor is irregular on observation
2. The head tremor is relieved by a sensory trick (similar to what describes for cervical dystonia) with fingers on the cheek or the chin.
3. The head tremor persists when patient lying down.
4. The head tremor is worst in certain position of the head (position dependant).
5. The head tremor is associated with an irregular tremor of one hand, suggestive of a dystonic arm tremor as irregular and existing only in one hand. (at the difference of ET tremor which affects both hands).
6. The head tremor is isolated, with no tremor in the hands or in the face or voice. (at the difference of EHT which is always associated with tremor in other part of the body).
Despite the fact that the patients are not always aware of their head tremor, in particular in case of EHT, head tremor can be very disabling socially.
Head tremor can benefit from therapeutic options such as drug treatment and Botox injections, which have to be offered depending of the type of tremor.
Further research is needed to characterize more precisely this movement disorder. May be it will come from unexpected study such as the episodic head tremor observed in Doberman Pinsher dog …
Dr Marie-Helene Marion is a London neurologist, specialist in dystonia and its treatment with Botox.
Doberman Pinsher dog
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