Neuropsychological functioning in a patient with essential tremor with andwithout bilateral VIM stimulation

The effects of deep brain stimulation on motor functions, cognitive abiliti es, and mood were assessed in an 80-year-old, right-handed male with a chro nic history of essential tremor. Electrodes were implanted bilaterally in t he ventral intermediate nucleus of the thalamus during a single operation. Upon evaluation at 3 months postsurgery, bilateral stimulation was associat ed with a clinically significant reduction in tremor ratings and improvemen t in manual dexterity. At that time, a battery of neuropsychological measur es was administered with and without bilateral stimulation. The patient dem onstrated comparable performances on measures of visuospatial perception, a ttention, mental tracking, verbal learning, and verbal recognition memory i n both the "on" and "off" conditions. Without stimulation, the patient demo nstrated declines of greater than 1 SD on measures of verbal fluency and ve rbal recall compared to when the stimulators were active. Responses to mood rating scales also indicated greater subjective distress without stimulati on. Results are discussed in the context of previous studies of the effects of thalamic stimulation on neurocognitive functioning. (C) 2000 Academic P ress.