A rare yet treatable case of paroxysmal kinesigenic dyskinesia

Dear Sir, Paroxysmal dyskinesias are movement disorders that manifest with recurrent abnormal involuntary movements that are episodic. The movements can be chorea, athetosis, ballism, dystonia, or a combination of all.[1] Paroxysmal kinesigenic dyskinesia (PKD) is the most common type of movement disorder, and it can be primary or secondary to some illnesses and is precipitated by sudden voluntary actions.[2] The secondary causes implicated are trauma; stroke; neurosyphilis; encephalitis; multiple sclerosis; and metabolic abnormalities such as diabetes, hypoparathyroidism, hyperparathyroidism, and kernicterus.[3] Here, we describe a case of secondary PKD. A 32-year-old man with normal birth and developmental milestones presented with multiple episodes of dystonic posturing in the left upper and lower limbs precipitated by walking or activity for 10 years. The frequency of the episodes was 4–5 per day. There was no preceding aura, sensory disturbance, loss of consciousness, tongue bite, or urinary incontinence in any of the episodes. In addition, the patient denied any premonitory urge before the attacks, and they were not suppressible. Each episode lasted 25–40 seconds and used to occur soon after patient started walking and would subside spontaneously. There was no history of gait imbalance, cognitive impairment, or cranial nerve involvement. His family history was negative for similar complaints. He was treated with multiple antiseizure medications in the past with no relief in symptoms. On examination, the mini-mental state examination score was 30/30. His general physical examination was normal. His speech, cranial nerves, power, reflexes, and sensory and cerebellar examination were normal, and he was noted to have positive Trousseau sign. He underwent video electroencephalography recording with the possibility of seizures versus movement disorder. No epileptiform discharges were detected in both ictal and interictal electroencephalography. Routine investigations, including hemogram and renal and liver function tests, were within normal limits. The corrected serum calcium level was 5.1 mg/dL (8.6–10.2 mg/dL) and phosphorus level was 5.3 mg/dL (2.5–4.5 mg/dL). Serum ionized calcium measured during the dystonic attack was 0.8 mmol/L (1.16–1.3 mmol/L). Serum ceruloplasmin, peripheral blood film for acanthocytes, and thyroid function were within normal limits. Electrocardiogram revealed prolonged QTc interval. Non-contrast computed tomography (NCCT) head revealed calcifications in the bilateral caudate, putamen, thalami [Figure 1], and cerebellum. Subsequently, the intact parathyroid hormone level was 1.56 pg/mL (normal, 15–65 pg/mL) and vitamin D level was 40 ng/mL (11–42 ng/mL). He was managed with acetazolamide and high-dose calcium supplementation, following which the attacks remarkably diminished in duration and frequency at his 1-month follow up.Figure 1:: Non-contrast computed tomography head showing calcification of the bilateral basal ganglia structures and thalamiThis case is noteworthy as it remained a diagnostic dilemma for approximately 10 years. Simple investigations such as serum calcium and NCCT head clinched the diagnosis. A multitude of clinical features are reported in hypoparathyroidism such as seizures, tetany, depression, psychosis, and extrapyramidal manifestations.[4,5] However, case reports of hypoparathyroidism presenting as PKD are scarce.[6-9] The involuntary movements are due to low serum calcium levels; hypocalcemia renders the neuronal membrane hyperexcitable and leads to paroxysmal dyskinesia, but why the symptoms are paroxysmal is enigmatic. The symptoms usually respond to high-dose calcium supplementation. In addition, the dystonic movements can occur in the setting of normal serum calcium levels when there are extensive calcium deposits in the basal ganglia. Perfusion abnormalities have been noted in the basal ganglia of patients with PKD. The cause of hypoparathyroidism in this patient is highly likely to be idiopathic; we did not perform any genetic testing due to financial constraints. In conclusion, we report an uncommon but easily treatable secondary cause of PKD. Investigations such as serum calcium and NCCT head helped in the diagnosis, and the patient responded well to treatment. Acknowledgement The authors acknowledge their gratitude to the patient and his family. Author contribution 1) Research project: A. Conception, B. Organization, C. Execution; 2) Statistical Analysis: A. Design, B. Execution, C. Review and Critique; 3) Manuscript: A. Writing of the first draft, B. Review and Critique. SBG-1B,1C, 3A AS-3B AG-3B VVY-3B MBS-3B RB-3B PS-3B DMR-3B AS-3B RR-1A,1B,3B Ethical compliance statement The authors confirm that no ethical clearance was required for this study. Written informed consent has been obtained from the patient for publication. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.