B. Paroxysmal dyskinesia
Paroxysmal dyskinesia is a genetically and clinically heterogeneous group of syndromes characterized by recurrent attacks of abnormal, hyperkinetic movements in which consciousness is usually maintained. It is classified according to its precipitating factors:
- Paroxysmal kinesigenic dyskinesia (PKD)
- Paroxysmal non-kinesigenic dyskinesia (PNKD)
- Paroxysmal exercise-induced dystonia (PED)
The age of onset varies; typically between 4-15 years and commonly involves PRRT2, SLC2A1, or MR-1 mutations. It is often autosomal dominant, but can be due to a de novo mutation as well.
Pharmacologic and nonpharmacologic treatments include:
- Sodium channel blockers
- Ketogenic diet
Paroxysmal dyskinesia is often associated with infantile seizures, epilepsy, migraines, ataxia, tremors.
Why were the other choices incorrect?
- Conversion disorder is often linked to an acute stressor. This patient’s exam would be difficult to feign.
- Transient ischemic attacks would be brief. This patient had two days of persistent symptoms.
- Seizure activity would have been evident on video EEG during a captured episode.
- Heavy metal poisoning involves persistent symptoms, often including nausea, vomiting, diarrhea, and abdominal pain.
This young man’s symptoms improved markedly improved with lorazepam. Neurology eventually diagnosed him with paroxysmal non-kinesigenicdyskinesia (PNKD) and recommended outpatient genetic testing and clonazepam as needed. In the future they may consider adding daily carbamazepine.
Kim S, Lee J, Kim W, Kim H, Choi S, Lim B, Kim K, Chae J. Paroxysmal Dyskinesia in Children: from Genes to the Clinic. J Clin Neurol. 2018 Oct;14(4):492-497.
Latorre A and Bhatia K. Treatment of Paroxysmal Dyskinesia. Neurol Clin. 2020 May;38(2):433-447.
McGuire S, Chanchani S, Khurana D. Paroxysmal Dyskinesias. Semin Pediatr Neurol. 2018 Apr;25:75-81.