(up to 20%), tremor (up to 11%), neuropathy (up to 9%), abnormal thinking (up to 9%), abnormal gait (up to 5%), confusion (up to 7%), speech disorder (up to 7%), amnesia (up to 6%), incoordination (up to 6%), twitching (up to 5%), vertigo (up to 4%), myoclonus (up to 4%), euphoria (up