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Approximately half of the cases of essential tremor are familial tremor, but the specific gene locus or exact pathophysiology is still unknown. However the tremor is already known for the uncommon side effect of acetylcholinesterase inhibitor, so it may be hypothesized that increased acetylcholine activity is associated with the essential tremor. In this report, we presented a case of the latent familial tremor induced by donepezil hydrochloride, the most commonly-used acetylcholinesterase inhibitor. A 68-year-old female with left hemispheric cerebral infarction was admitted to the hospital because of large cerebral infarction in the left frontal and parietal lobes. Previously she has been healthy without any neurological disorder. At admission, she had severe right hemiparesis and global aphasia, and donepezil 10mg was attempted to improve her aphasia. Several weeks after admission, she started having limb and head tremors which seriously impaired the motor function of her healthy left hand. Then we rechecked her family history, and found that her mother and elder sister suffered from the essential tremor. To treat her tremor, several medications had been tried, but nothing was effective. Then we also decided to discontinue medications which could induce the tremor, and she was taking donepezil, lexapro and methylphenideate. After discontinuation of donepezil hydrochloride, the tremor has been improved. In conclusion, although this could be another case of the sporadic drug induced tremor, her latent tremor might be evoked by donepezil hydrochloride. So it seemed that the pathophysiology of essential tremor, especially in the familial tremor, is partly associated with acetylcholine activity. |
