Objective: To present a child with ADCY5 related movement disorder having clinical response to steroids.

Background: A 17 year old female, with delayed developmental milestones and subnormal intelligence, presented with abnormal movements starting at five months of age. She was the 1^st child of a non-consanguineous marriage with normal antenatal and perinatal history. Her parents noticed her having jerky movement of right upper limb and lower limb lasting for one-two seconds at five months of age. These episodes were not aggravated by loud noises or tactile stimuli. She also had intermittent posturing of right foot and turning of trunk to right side, starting at the age of 1 and ½ year. For these episodes of paroxysmal myoclonus and dystonia, she received ACTH injections for six months at four years of age, following which she had complete resolution of her symptoms. She again developed writing movements of upper limbs and lower limbs with occasional flinging movements for 4-6 minutes at age of 15 years. These limb movements were associated with perioral dyskinesias and used to occur during sleep (Video 1). With an initial frequency of 4-5/month, the frequency gradually increased to 80-100/month.

Method: With onset in infancy, developmental delay and combination of movement disorders, possibilities of mitochondrial disorders, inborn errors of metabolism (affecting glucose and protein) and disorders of brain iron accumulation were kept. Tandem mass spectrometry and gas chromatography mass spectrometry were negative. MRI brain with SWI sequences did not reveal any abnormality. A whole exome sequencing was done which showed c.1252C>T in exon 2 of ADCY5 gene.

Results: ADCY5 related disease has an early childhood onset with a fluctuating/paroxysmal course of dystonia, chorea and myoclonus (1). These are predominant during night time awakenings or morning awakenings. Patients with ADCY5 related movement disorder show good response to treatment with benzodiazepines. Methylphenidate, caffeine and deep brain stimulation (2) have also shown significant partial benefit in refractory cases. Our patient had good response to ACTH injection resulting in resolution of myoclonic jerks and paroxysmal dystonic episodes at age of five years. However during the present deterioration of night time dyskinesias, she responded well to clobazam.

Conclusion: ADCY5 related myoclonic jerks and dystonia can respond to steroids.

References: 1. Ferrini, A., Steel, D., Barwick, K., & Kurian, M. A. (2021). An Update on the Phenotype, Genotype and Neurobiology of ADCY5‐Related Disease. Movement Disorders, 36(5), 1104–1114.
2. Dy, M. E., Chang, F. C. F., Jesus, S. D., Anselm, I., Mahant, N., Zeilman, P., Waugh, J. L. (2016). Treatment of ADCY5-Associated Dystonia, Chorea, and Hyperkinetic Disorders With Deep Brain Stimulation. Journal of Child Neurology, 31(8), 1027–1035.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/a-child-with-infantile-onset-paroxysmal-episodes-of-jerks-and-stiff-limbs/