To report a case of chronic isolated unilateral hypoglossal nerve palsy and discuss the challenge and approach to diagnosis 

A 70 year old male with a history of colonic schwanomma presented with sharp shooting pain on the right side of his neck that radiated to the temple. The pain lasted between a few seconds to a few minutes. On physical examination, he had atrophy of the tongue muscles on the right with no fasciculations. The tongue deviated to the right on protrusion. Rest of neurological examination was within normal limits. The findings were consistent with an isolated right hypoglossal nerve palsy. He had a brain MRI with and without contrast, which was reported normal. To evaluate further, we obtained a brain MRI with hypoglossal canal protocol, which revealed erosive changes at the C1-C2 articulation suggestive of an inflammatory spondyloarthropathy. There was a soft tissue density circumscribing the dens extending into the retro dental region compatible with pannus. His rheumatological and malignancy work up was negative.

Pannus formation and C1-C2 degenerative changes have not been previously reported as a cause of unilateral hypoglossal nerve paralysis. This finding, along with other causes including tumors, metastatic disease or other pathologies are likely to be missed on routine MRI brain. It is important to do an MRI brain with hypoglossal canal protocol in isolated cases for accurate diagnosis and prompt treatment.