Position-dependent arm dyskinesia due to severe craniocervical malformation.

Context: Spinal-generated movement disorders are a complex group of medical conditions, frequently misdiagnosed, originating in the spinal cord or from combined peripheral and central nervous system involvement. In this case report, we describe a novel form of position-dependent dyskinesia due to severe craniocervical malformation.

Findings: An 83-year-old woman with basilar invagination at the C2 vertebra above the line of Chamberlain, occipitocervical lordosis, platybasia with a short clivus, ankylosis of the C1-C2 complex and fusion of the C1 arch developed an unusual pattern of position-dependent left arm dyskinesia triggered by bending her neck forward with simultaneous contact of the flexed elbow with a flat surface. Symptoms did not improve with anticonvulsants and she progressed and died suddenly.

Conclusion/clinical relevance: A newly described form of position-dependent arm dyskinesia can be associated with severe craniocervical malformation.