Idiopathic hypoglossal nerve laceration detected by high-resolution three-dimensional constructive interference in steady state magnetic resonance imaging.

A 55-year-old man presented with acute onset dysarthria caused by left hypoglossal palsy. He had neither surgery nor injury prior to the onset of his symptoms. We detected no abnormalities with conventional magnetic resonance imaging (MRI) except for a slight gadolinium enhancement of the left hypoglossal nerve. Three-dimensional constructive interference in steady state MRI (CISS MRI) showed curling and thickening of the left hypoglossal nerve and fluid accumulation in the hypoglossal nerve canal. A systemic survey found no malignancies. After 8 months, sustained left hypoglossal palsy and no change in the MRI led to the diagnosis of idiopathic hypoglossal nerve laceration with evulsion. In such patients, the cause of the defect is not always apparent and 3-dimensional CISS MRI may resolve this issue.