We appreciate the comments from Dr Lang and echo his suggestion that further study of the pharmacological treatment of dystonia is needed. In a follow-up of the observation that high doses of diphenhydramine hydrochloride are effective in the treatment of dystonia with jerky components in humans, we tested the effect in an animal model of dystonia. We demonstrated that a histamine dysfunction could contribute to the pathophysiological changes underlying dystonia, because unilateral microinjection of histamine into the red nucleus of the rat produced dose-dependent dystonic postures (torticollis). Concurrent administration of the histamine1 antagonists diphenhydramine or pyrilamine maleate or the histamine2 antagonist cimetidine significantly attenuated the histamine-induced torticollis. These effects are believed to be mediated through the red nucleus because significantly more torticollis was observed when histamine was injected into the red nucleus rather than other brain structures, including the substantia nigra and striatum.1
Truong DD, Sandroni P, Matsumoto RR. Antihistaminics in Idiopathic Dystonia-Reply. Arch Neurol. 1996;53(5):405. doi:10.1001/archneur.1996.00550050027013
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