Due to the condition's rarity, it is frequently misdiagnosed, often as cerebral palsy. This results in patients often living their entire childhood with the condition untreated. The diagnosis of<unk>  can be made from a typical history, a trial of<unk>  medications, and genetic testing. Not all patients show mutations in the GCH1 gene (GTP cyclohydrolase I), which makes genetic testing imperfect. Sometimes a lumbar puncture is performed to measure concentrations of biopterin and neopterin, which can help determine the exact form of<unk><unk>  movement disorder: early onset parkinsonism (reduced biopterin and normal neopterin), GTP cyclohydrolase I deficiency (both decreased) and tyrosine hydroxylase deficiency (both normal). In approximately half of cases, a phenylalanine loading test can be used to show decreased conversion from the amino acid phenylalanine to tyrosine. This process uses BH4 as a cofactor. During a sleep study (polysomnography), decreased twitching may be noticed during REM sleep. An MRI scan of the brain can be used to look for conditions that can mimic<unk>  (for example, metal deposition in the basal ganglia can indicate Wilson's disease or pantothenate kinase-associated neurodegeneration). Nuclear imaging of the brain using positron emission tomography (PET scan) shows a normal radiolabelled<unk>  uptake in<unk> , contrary to the decreased uptake in Parkinson's disease. Other differential diagnoses include metabolic disorders (such as GM2 gangliosidosis, phenylketonuria, hypothyroidism, Leigh disease) primarily dystonic juvenile parkinsonism, autosomal recessive early onset parkinsonism with diurnal fluctuation, early onset idiopathic parkinsonism, focal dystonias, dystonia musculorum deformans and dyspeptic dystonia with hiatal hernia. ;Diagnosis - main * typically referral by GP to specialist Neurological Hospital e.g. National Hospital in London. * very hard to diagnose as condition is dynamic w.r.t. time-of-day AND dynamic w.r.t. age of patient. * correct diagnosis only made by a consultant neurologist with a complete 24-hour day-cycle observation (with video/film) at a hospital, i.e., morning (day1)->noon->afternoon->evening->late-night->sleep->morning (day2). * patient with suspected<unk>  required to walk in around hospital in front of Neuro'-consultant at selected daytime intervals to observe worsening walking pattern coincident with increased muscle tension in limbs. * throughout the day, reducing leg-gait, thus shoe heels catching one another. * diurnal affect of condition: morning (fresh/energetic), lunch (stiff limbs), afternoon (very stiff limbs), evening (limbs worsening), bedtime (limbs near frozen). * muscle tension in thighs/arms: morning (normal), lunch (abnormal), afternoon (very abnormal), evening (bad), bedtime (frozen solid). ;Diagnosis - additional * lack of self-esteem at school/college/university -> eating disorders in youth thus weight gains. * lack of energy during late-daytime (teens/adult) -> compensate by over-eating.
Dopamine-responsive dystonia
Paroxysmal exercise-induced dystonia
Levodopa-induced dyskinesia
Post-encephalitic parkinsonism
Myoclonic dystonia
Focal dystonia
Paroxysmal kinesigenic choreoathetosis
Cerebellar cognitive affective syndrome