Childhood Dystonia

ACNRSO13_Layout 1 26/08/2013 22:47 Page 18 PAEDIATRICNEUROLOGY Childhood Dystonia Aetiology Summary Primary dystonia occurs as an isolated presenta- • Dystonia means involuntary muscle tion and has a genetic (or presumed genetic) aeti- contractions causing repetitive ology (Table 1). Inheritance is often autosomal movements and twisted postures dominant; a careful family history may reveal previ- • The commonest clinical picture in ously undiagnosed relatives with milder pheno- children is dystonic cerebral palsy following hypoxic brain injury types. Dystonia occurring secondary to another • A trial of levodopa is warranted in cases disease process affecting the basal ganglia is the without a clear secondary cause more common finding in children (Table 2). • Management is often challenging, and Psychogenic pseudo-dystonia is an important must be holistic differential diagnosis. Clinical approach The aims of the clinical assessment will be to ystonia is a movement disorder in which confirm the presence of dystonia, and assess asso- involuntary muscle contractions cause Nadine McCrea ciated co-morbidities, functional impact, aetiology, Drepetitive movements and twisted postures. perpetuating factors and complications. is a Paediatric Neurology Trainee at Dystonia causes significant morbidity in sufferers, Addenbrooke’s Hospital, Cambridge. Having completed her and may even be fatal in severe cases. It may be a History undergraduate training at primary, genetic disorder, or secondary to a large A summary of key elements of the history is Manchester University, she has number of other disorders. In children, these are been continuing postgraduate provided in Table 3. mainly neurometabolic and degenerative. A thor- training in the East of England. As well as training in paediatric ough history, examination, and targeted use of inves- Examination neurology she has a strong interest tigations can provide the diagnosis in a subset of The key aims of the examination are to characterise in medical education, and leads a children, and help identify those in whom esoteric number of regional education the dystonia and the degree of functional impair- tests are warranted. Management is usually chal- initiatives. ment, document associated motor disorders, review lenging, with a lack of robust evidence for treatment growth parameters and home video footage. Correspondence to: strategies in children. This article summarises an Firstly, inspect from a distance: note the use of Nadine McCrea, approach to the child with dystonia, and provides a Paediatric Neurology, orthoses, plot the height, weight and head circum- framework for management. Addenbrooke’s Hospital, ference on a growth chart, looking specifically for Hills Road, Defining dystonia malnutrition or microcephaly. Next observe more Cambridge CB2 0QQ, UK. Dystonia is defined as “a movement disorder in closely: assess if the dystonia is isolated, or if there Email: [email protected] which involuntary sustained or intermittent muscle is additional chorea, athetosis, or spasticity. Ask the Conflict of interest statement: contractions cause twisting and repetitive move- child to walk if they can, preferably with shoes and The author declares that there are ments, abnormal postures, or both”.1 The postures clothes on at first, and then off. Video is very useful no financial or commercial produced by co-contraction of agonist and antago- as gait can be very difficult to evaluate as children conflicts of interest. nist muscle groups include hyperextension of the move swiftly around. Use functional techniques to back and neck, torticollis, foot inversion, upward bring out movement disorders: holding their extension of the great toe, and ‘spooning’ of the fingers “as near to the nose as possible without hands (Figure 1).2 Dystonia is often more promi- touching it” (tremor), heel- toe walking and turning nent when voluntary movement is attempted, or in (ataxia), walking on the heels looking for inserted certain postures. Muscle tone may be normal at movements of hands and feet (Fogg sign). If you rest, enabling the clinician to differentiate dystonia can see dystonia, note whether it is generalised, from hypertonia. Dystonia may be generalised (or focal or segmental, and postural or fixed. multi-focal), or localised to specific regions of the Next move them to the couch (even if wheel- body, such as in torticollis.1 In childhood, the chair bound): assess the character of the dystonia commonest clinical picture is one of cerebral and any additional movement disorders. Examine palsy with elements of spasticity and dystonia the cranial nerves with emphasis on fundi, eye together.3 However primary dystonia and dystonia movements, dysarthria, dysphagia (offer water if secondary to other causes also occur.1 they drink orally), and tongue thrusting. Examine the limbs for evidence of other movement problems, e.g. dysmetria, intention tremor, spasticity, or Figure 1 neuropathy. Assess function through handwriting, drawing spirals, and performing tasks such as pouring water into a cup. It is also useful to video this, looking for posture and movement during a simple activity. Home videos can provide excellent insights, and should be reviewed. Grading severity Severity of the current episode of dystonia should be determined. Features of increasing severity of dystonia include being unable to sleep, sit or lie 18 > ACNR > VOLUME 13 NUMBER 5 > SEPTEMBER/OCTOBER 2013 ACNRSO13_Layout 1 26/08/2013 22:47 Page 19 PAEDIATRICNEUROLOGY Table 1: Childhood-onset primary dystonia4 Gene Disease Inheritance Gene product & location DYT1 Idiopathic torsion dystonia AD Torsin A 9q34 DYT3 X-linked dystonia-parkinsonism XL TAF 1 Xq13-1 DYT4 Whispering dysphonia AD TUBB4a 19p13.12-13 DYT5a AD Segawa syndrome (Dopa responsive dystonia) AD GCH1 14q22.1-q22.2 DYT5b AR Segawa syndrome (TH deficiency) AR TH 11p15.5 DYT6 Adolescent/adult-onset Idiopathic torsion dystonia (mixed) AD THAP1 8p21-q22 DYT11 Myoclonus-dystonia syndrome AD SGCE 7q21.3 DYT12 Rapid onset dystonia-parkinsonism AD ATP1A3 19q12-q13.2 Table 2: Causes of secondary dystonia5 Table 3: History Cerebral Palsy following hypoxic brain injury (commonest cause) Birth history Metabolic Pregnancy complications, Gestation, Mode of delivery, Cord gas results, Biotinidase deficiency Mitochondrial diseases Neonatal resuscitation, Encephalopathic features Creatine deficiency Mucopolysaccharidoses Early life Galactosaemia Neuronal ceroid lipofuscinoses Feeding, Seizures, Hospital admissions, Medical diagnoses Glutaric acidura type 1 Neurotransmitter disorders Development GM1 and GM2 gangliosidosis Niemann-Pick C Milestones achieved, Delay, Regression, School Hartnup disease Proprionic acidaemia Family history Homocystinuria Sulphite oxidase deficiency Family tree, Consanguinity, Movement disorders, Neurological disorders, Stillbirths or early deaths Hypoparathyroidism Tyrosinosis Dystonia Krabbe disease Vitamin E deficiency Age of onset, Progression, Focality, Diurnal variation, Functional impact, Lesch-Nyhan Wilson disease activities of daily living Metachromatic leukodystrophy Dystonia exacerbating factors Methyl-malonic acidaemia Gastro-oesophageal reflux, Constipation, Dental caries, Orthopaedic Metabolic problems, including dislocated hips, fractures, Other causes of pain, Infection, Drug addition or withdrawal, Boredom, Emotional Ataxia telangiectasia Neuroaxonal dystrophy abuse/frustration/fear Ataxia with oculomotor apraxia type 1, 2 Panthothenate kinase 2-associated Dystonia complications Infantile bilateral striatal necrosis neurodegeneration (PKAN2) Swallowing problems, Failure to thrive, Anxiety, depression, Juvenile Huntington’s Pelizaeus-Merzbacher disease Aspiration pneumonia, Status dystonicus (potentially fatal exacerbation Neuroacanthocystosis Spinocerebellar ataxias with multisystem dysfunction) Drugs/Toxins Co-morbidity Phenothiazines Spasticity, Oculogyric crises. Chorea. Other neurological problems Haloperidol Metoclopramide Other Alternating hemiplegia of childhood Porencephaly Management strategies Basal ganglia infarction Sandifer syndrome There is a lack of robust evidence to inform pharmacotherapy for Basal ganglia neoplasm Striatal necrosis dystonia, therefore strict recommendations of first, second and third line medications are not practical.4 Therapeutic strategies tend to vary with HIV infection Vascular malformations individual clinician preference and experience. As well as dystonia- Kernicterus specific therapy, identifying and treating precipitating factors is para- mount (Table 3). Spasticity is a common co-morbidity, and it can be difficult to differentiate between spasticity and dystonia in some children. In these cases a pragmatic approach to symptom control should be taken.4 comfortably, and being systemically unwell. Children who show signs of Medications should be reviewed periodically, addressing whether the systemic illness require urgent assessment and treatment for status drug has had a positive effect on quality of life and the side effects. If dystonicus. Several formal grading scores are available.6 there is no improvement with second line medication, consider discus- sion with colleagues at a complex case review or referring to a quater- nary movement disorders clinic. As well as medication, supportive Investigation management in a multidisciplinary team including physiotherapy, occu- Investigation and treatment are interlinked, as a therapeutic trial of levo- pational therapy, speech therapy and psychosocial

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