Objective: We present a case of MORC2-related neurodevelopmental disorder in a child with impairing tremor successfully managed with bilateral VIM/posterior subthalamic area deep brain stimulation (VIM/PSA-DBS) and provide accompanying video.

Background: Pathogenic variants in MORC2 have classically been reported in patients with an autosomal dominant form of Charcot-Marie-Tooth disease. Most recently, an expansion of the phenotype was described in 20 individuals which included developmental delay, growth failure, hypotonia, microcephaly, and craniofacial dysmorphism. Movement disorders reported within these patients include dystonia, tremor, and ataxia. As this is a newly described phenotype, treatment of tremor within these patients has not yet been described.

Method: A 3 year-old girl presented to our movement disorders clinic for evaluation of tremor.  She had a history of short stature, hypotonia, microcephaly, and global developmental delay, and developed action tremor at two years of age.  Tremor was impairing and interfered with feeding, toileting, and other manual tasks.  Examination revealed 2+ postural and kinetic proximal tremor with prominent intention component.  MRI brain was normal and whole exome sequencing revealed a variant in MORC2 now known to be pathogenic, inherited from mother who also has mild intellectual disability, sensorineural hearing loss, and neuropathy. Treatment of tremor included wrist weights, propranolol, primidone, and clonazepam with insufficient benefit.

Results: At 7 years of age, tremor remained impairing and as treatments yielded insufficient benefit, bilateral VIM/PSA-DBS was implanted, and the patient had significant improvements in impairing tremor noted following programming sessions, without adverse effects.

Conclusion: MORC2-related neurodevelopmental disorder is a newly described condition characterized by developmental delay, growth failure, hypotonia, microcephaly, and craniofacial dysmorphism. Movement disorders associated with this condition have included dystonia, ataxia, and tremor. The tremor can present in childhood and may be quite impairing. Our case suggests that treatment with bilateral VIM/PSA-DBS can be helpful in those not responsive to pharmacotherapy.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/management-of-tremor-secondary-to-morc2-related-neurodevelopmental-disorder-with-deep-brain-stimulation/