Assessment of ability/disability in patients treated with chronic thalamic stimulation for tremor.

Chronic thalamic stimulation (CTS) has a documented good effect on tremor in patients with Parkinson's disease (PD) and essential tremor (ET). This study evaluates whether the alleviation of impairment, i.e., tremor, translates into improvement of the patient's ability in performing instrumental activities of daily living (IADL). Thirteen patients were assessed with an occupational therapy tool called Assessment of Motor and Process Skills (AMPS). This observation-based scale rates the patient's motor and process skills needed to perform a given task. The evaluations were done at a mean of 13 months after surgery in the patient's home, and included assessments of IADL with the CTS activated and switched off, respectively. The results showed that most patients improved to variable degrees in their IADL ability when the thalamic stimulation was on. The improvement was more marked in patients operated on for tremor of their dominant hand. The improvement concerned mainly the skill items related to the patients' abilities of coordination, calibration, endurance, and accommodation during IADL task performance. The authors concluded that for some patients with tremor, CTS can improve independence in domestic activities of daily living.