Objective: To describe a case of rapidly worsening dystonia in 18p deletion syndrome.

Background: 18p deletion syndrome resulting from deletion of the short arm of chromosome 18 is a rare disorder with clinical features including craniofacial dysmorphisms, intellectual disabilities, as well as various movement disorders, the most common being dystonia.

Method: Case report.

Results: A 24-year-old female with 18p deletion syndrome, psoriasis, and anxiety was referred to our clinic for rapidly worsening dystonia over 2 months. Starting 5 years ago, she developed slight intermittent head tremor with left head turn. About 2 months prior to presentation there was significant worsening of her dystonia with extreme pulling of the neck and upper trunk to the right and back, right arm adduction and elbow flexion, left arm extension and retroversion, left foot inversion and toe extension. The abnormal postures interfered with her activities of daily living, including eating and drinking, causing significant weight loss.

She was known to have a large ~15 Mb deletion of the short arm of chromosome 18. She had a history of cognitive, speech and motor delay – walking at 18 months, talking at 2 years, and required special education classes. She also had significant anxiety with behavioral issues including aggression. There was concern that the sudden change in dystonia could be due to her recent adjustments to her mood medications so her SSRI was stopped and she was started on topiramate. However, the dystonia worsened as topiramate dose was increased. There were no other recent changes in health or environment.

She was trialed on trihexyphenidyl, tetrabenazine, benztropine, and Sinemet, which were not helpful and/or caused side effects. After evaluation in our clinic she was started on clonazepam, baclofen and botulinum toxin injections, which have been helpful. She is undergoing evaluation for deep brain stimulation, although this has been delayed to treat her severe scalp psoriasis.

Conclusion: 18p deletion syndrome is most often associated with isolated dystonia, which is most likely due to deletion of GNAL gene (associated with DYT 25), located on the short arm of chromosome 18p11. However, the patient’s significant worsening from subtle cervical to severe generalized dystonia over a very short time frame (2 months) is unusual and of interest to the Movement Disorders community.

References: 1. Turleau C. Monosomy 18p. Orphanet J Rare Dis 2008;3:4.
2. Crosiers D, Blaumeiser B, Goethem GV. The spectrum of movement disorders in 18p deletion syndrome. Mov Disord Clin Pract 2019;6:70–73. 
3. Kumar N, Rizek P, Jog M. Movement disorders in 18p deletion syndrome: a case report and review of the literature. Can J Neurol Sci 2017;44(4):441-443.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/a-24-year-old-female-with-18p-deletion-syndrome-presenting-with-rapidly-worsening-dystonia/