Secondary Hypomania Following Left Temporopolar and Bilateral Orbitofrontal Damage

We present the case of a 49-year-old man with secondary hypomania and subtle cognitive and emotional deficits subsequent to a traumatic brain injury. Hypomanic symptoms followed by a depressive episode were observed 3 weeks after the traumatic injury. Neuroradiological examinations revealed a circumscribed lesion in the left temporal pole and bilateral orbitofrontal cortices. The hypomanic episode was successfully treated with quetiapine. However, subtle cognitive and emotional deficits, including inappropriate laughing in the absence of humorous or pleasurable content, nonspontaneous speech, and irrelevant speech during verbal communication, have persisted. The present case study supports the idea that both the left temporopolar and bilateral orbitofrontal dysfunctions are candidates for the neurobiological basis of bipolar disorder and that subtle cognitive and emotional deficits leading to functional impairments may remain after resolving secondary hypomania.