Juvenile Paralysis Agitans of Hunt

At a glance

The association of progressive extrapyramidal neurologic disorder presenting in teenagers or even earlier and mild form of Parkinson disease. Characterized by tremor, bradykinesia, dysarthria, rigidity, and fixed facies. The disorder may be familial (genetically transmitted) or secondary to other heredodegenerative disorders, as it is observed in Huntington’s disease.

Synonyms

Corpus Striatum Syndrome; Dyssynergia Cerebellaris Myoclonica Syndrome; Hunt Paralysis Syndrome; Hunt Syndrome II; Juvenile Parkinson Disease of Hunt; Willige-Hunt Syndrome; Parkinson Disease of Childhood.

History

Degeneration of lenticular nuclei. First clinical report by Huchard in 1875.

Incidence

In Parkinson disease cases, 25% are genetically inherited, of which a small number of cases are represented by juvenile Parkinson disease.

Genetic inheritance

Familial forms may be transmitted as an autosomal dominant or autosomal recessive trait. The recessive form, called “Parkin type of juvenile Parkinson disease,” is caused by mutations within the Parkin gene PARK2, which is located on chromosome 6q25.2-q27. The dominant form is caused by mutations in the alpha-synuclein gene PARK1 (on chromosome 4q21); a fragment of the product of this gene is a known constituent of Alzheimer disease plaques. A few dominant forms of the disease involve other dominant loci, including ubiquitin cyclohydrolase L1 (UCHL1) on chromosome 2p12 (PARK3) and chromosome 4p (PARK4). These enzymes are part of the ubiquitin proteolytic system (UPS), which plays a central role in the regulation of many cellular processes, including removal of abnormal, misfolded, or damaged proteins.

Pathophysiology

Whatever the genetic transmission, the disease is associated with loss of dopaminergic neurons in the substantia nigra and dopamine deficiency in the striatum. There is a subsequent increase in the activity of the subthalamic nucleus and the globus pallidus, which is responsible for the extrapyramidal movements. Other nondopaminergic neurons are affected (serotonin, norepinephrine), the depletion of which causes psychological and behavioral disorders.

Diagnosis

Clinical diagnosis. An antiserum that is immunoreactive to the Parkin immunizing peptide by enzyme-linked immunoabsorbent assay (ELISA) is available.

Clinical aspects

Clinical features are very similar to the adult form of parkinsonism and begins between 5 and 15 years of age. Tremors appear first, then rigidity, dyskinesia, and unexpressive face. Disturbed gait and dysarthria. Ameliorated by L-dopa (levodopamine), monoamine oxidase (MAO) inhibitors, and anticholinergic agents.

Precautions before anesthesia

Check carefully the child’s medication (L-dopa and MAO inhibitors). Do not stop medication; give the morning dose of L-dopa. L-Dopa has a short half-life and stopping it for more than 6 to 12 hours can lead to severe muscular rigidity and worsening of the ventilation.

Anesthetic considerations