Transient manic behavior after pallidotomy

We report two cases of transient hypomanic behavior following pallidotomy. Both of the reported patients had lesions involving non-motor portions of the globus pallidus. Patient 1 had a lesion in the left anteromedial portion of GPi, while patient 2 had one lesion involving the anteromedial portion of GPi on the right and a second lesion involving the postero-ventral most portion of the putamen on the left. These cases emphasize the importance of placing lesions within the sensori-motor portion of GPi without infringing on adjacent non-motor portions. Cases involving transient manic behavior after pallidotomy have not been previously reported. Centers performing pallidotomy or DBS should be aware that lesions or stimulation too anterior in the GPi might lead to manic behavior.