Exacerbation of refractory chronic oral pain due to mild consciousness disorder associated with valproate-induced hyperammonemia: A case report

We describe a 48-year-old man with history of chronic pain radiating from the right oral cavity to the occipital region with comorbid depression. He received antidepressant drugs such as sodium valproate and maprotiline for comorbid depression, but these had little effect. His decreased concentration and motivation became protracted, leaving him unable to work. Electroencephalographic findings suggested a mild consciousness disorder. Blood tests indicated that his serum ammonia levels were abnormally elevated. After valproate administration was gradually tapered off, the symptoms of decreased motivation and cognitive inhibition rapidly improved and he became more active. Although his moderate pain persisted, he no longer complained of pain. Finally, he succeeded in returning to work. The central nervous system depression due to valproate and hyperammonemia may have decreased his activity levels and exacerbated his pain. The objective of chronic pain therapy should be to help improve the patient's quality of life, and attention must be paid to the possibility that the adverse drug effects may exacerbate pain due to a consciousness disorder and one's decreased activity levels. This case report is valuable because there are few reports regarding a relationship between chronic pain and disorders of consciousness.