Juvenile parkinsonism: a heterogeneous entity

Juvenile Parkinsonism with PARK2 Gene Mutation Misdiagnosed as Dopa-responsive Dystonia: a Case Report

Parkinson's disease is prevalent in elderly patients, usually aged over 50 years. If clinical symptoms of parkinsonism appear before 21 years of age, it is called juvenile parkinsonism (JP). JP may present atypical features such as dystonia, and is often misdiagnosed as other diseases, including dopa-responsive dystonia (DRD). Here, we report a case of JP with PARK2 mutation misdiagnosed as DRD. A 32-year old female, who presented dystonia of both legs, was initially diagnosed with hereditary spastic paraplegia and showed a dramatic response to low-dose L-dopa, which led to the diagnosis of DRD. However, Parkinson's disease caused by a mutation in the PARK2 gene was later diagnosed via next-generation sequencing. Accurate understanding of JP is necessary for early diagnosis and comprehensive management of movement disorders at a young age.

Movement disorder emergencies in childhood

The literature on paediatric acute-onset movement disorders is scattered. In a prospective cohort of 52 children (21 male; age range 2mo-15y), the commonest were chorea, dystonia, tremor, myoclonus, and Parkinsonism in descending order of frequency. In this series of mainly previously well children with cryptogenic acute movement disorders, three groups were recognised: (1) Psychogenic disorders (n = 12), typically >10 years of age, more likely to be female and to have tremor and myoclonus (2) Inflammatory or autoimmune disorders (n = 22), including N-methyl-d-aspartate receptor encephalitis, opsoclonus-myoclonus, Sydenham chorea, systemic lupus erythematosus, acute necrotizing encephalopathy (which may be autosomal dominant), and other encephalitides and (3) Non-inflammatory disorders (n = 18), including drug-induced movement disorder, post-pump chorea, metabolic, e.g. glutaric aciduria, and vascular disease, e.g. moyamoya. Other important non-inflammatory movement disorders, typically seen in symptomatic children with underlying aetiologies such as trauma, severe cerebral palsy, epileptic encephalopathy, Down syndrome and Rett syndrome, include dystonic posturing secondary to gastro-oesophageal reflux (Sandifer syndrome) and Paroxysmal Autonomic Instability with Dystonia (PAID) or autonomic 'storming'. Status dystonicus may present in children with known extrapyramidal disorders, such as cerebral palsy or during changes in management e.g. introduction or withdrawal of neuroleptic drugs or failure of intrathecal baclofen infusion; the main risk in terms of mortality is renal failure from rhabdomyolysis. Although the evidence base is weak, as many of the inflammatory/autoimmune conditions are treatable with steroids, immunoglobulin, plasmapheresis, or cyclophosphamide, it is important to make an early diagnosis where possible. Outcome in survivors is variable. Using illustrative case histories, this review draws attention to the practical difficulties in diagnosis and management of this important group of patients.

Juvenile parkinsonism: epidemiology, diagnosis and treatment

Juvenile parkinsonism, with onset prior to age 21 years, is a relatively rare syndrome. It is caused by a group of heterogeneous entities that can present with a clinical picture similar to idiopathic Parkinson's disease or manifest parkinsonism as part of a spectrum of other signs. Diagnostic testing is guided by the presenting symptoms and aimed at uncovering potentially reversible and/or treatable causes. If an underlying condition is found, treatment is tailored accordingly. Otherwise, treatment is symptomatic and relies on medications commonly employed to treat idiopathic Parkinson's disease. Juvenile parkinsonism patients tend to be plagued by treatment-induced complications, so caution must be employed.

Misdiagnoses in children with dopa-responsive dystonia

Dystonia is a state of continuous contraction of groups of agonist and antagonist muscles resulting in a sustained abnormal posture. Dopa-responsive dystonia was first described in 1976 by Segawa. Patients typically have diurnal variation of their symptoms with worsening at the end of the day and a dramatic response to low-dose L-dopa. This report presents five consecutive children with dopa-responsive dystonia who were misdiagnosed initially as spastic diplegic cerebral palsy, intractable epilepsy, hereditary spastic paraplegia, or a neurodegenerative disorder. There were two males and three females aged 3-13 years (mean 8.6 years). They were monitored for up to 2 years (mean 14.8 months). One had focal, one axial, one segmental, and two generalized dystonia. The dystonia was paroxysmal in two (tiptoe walking and opisthotonus), and all had a progressive course. All children responded dramatically to L-dopa (mean 200 mg/day), including three who were wheelchair-bound for several years. The difficulties in early diagnosis, variability of clinical presentation, and dramatic response to L-dopa will be illustrated. To conclude, dopa-responsive dystonia should be considered in any child who presents with paroxysmal or progressive hypertonia of unknown etiology, because it responds so dramatically to L-dopa.

Juvenile parkinsonism

Juvenile parkinsonism (JP) is a clinically and etiologically heterogeneous entity. Unlike in the adult form, secondary causes, hereditary and metabolic conditions, are the predominant causes of JP. Idiopathic Parkinson's disease is very rare in this age group. In most cases of JP, parkinsonism is accompanied by other neurologic features, such as dystonia, cognitive impairment, seizures, oculomotor and visual dysfunction, and ataxia. Systemic findings, such as liver dysfunction or hepatosplenomegaly, may be present depending on the cause. This review article describes the clinical characteristics, classification, genetic basis, pathophysiology, biochemistry, pathology, and treatment of JP.