Botulinum Toxin A to Treat Arm Tremor

Main Inclusion Criteria: * Diagnosis of 'definite essential tremor' in accordance with modified TRIG criteria, as follows: * Bilateral postural tremor with or without kinetic tremor, involving hands and forearms, that is visible and persistent. * It is to be noted that: * Tremor of other body parts may be present in addition to upper limb tremor. * Bilateral tremor may be asymmetric. * Tremor is reported by patient to be persistent, although the amplitude may fluctuate. * First onset of essential tremor at least 6 months before screening with stability of the tremor symptoms over 4 weeks and in the opinion of the investigator definite diagnosis of essential tremor. * Moderate-to-marked upper-limb postural and/or kinetic tremor at wrist level, corresponding to Fahn-Tolosa-Marin upper-limb tremor rating of at least 2 categories (scale part C, items 16-23) in the limb to be treated between of 2 or higher. * Visible tremor at wrist level in at least one of the four positions/tasks used in kinematic assessments * Tremor deemed by the investigator to require a treatment with 30 - 200 U NT 201 for a treatment of up to three joints of the selected upper limb (wrist treatment mandatory). * Stable concomitant anti-tremor medication and no clinically relevant findings in routine laboratory examinations. Main Exclusion Criteria: * Any neurological signs abnormal for the subject's age, other than the tremor itself and Froment's maneuver. * Exposure to the following tremorogenic drugs: Lithium, Valproic acid, Amiodarone, typical and atypical neuroleptics. Exposure to other than the listed tremorogenic or potentially tremorogenic drugs is allowed only if, in the opinion of the investigator, this will not interfere with the study drug evaluation. In these cases, a stable medication should be reached 4 weeks before screening and intended for the time during the study drug evaluation. * Trauma to the central nervous system or the nerves of the target limb within the three months preceding the onset of tremor. * Evidence of psychogenic origins of tremor. * Life habits (e.g. smoking, alcohol or substance abuse) prejudicial to study participation. * Prior surgery to treat tremor * Recent (16 weeks) treatment with any Botulinum toxin product for any reason. * Relevant recent or planned surgery or other specified relevant treatments and/or concomitant disorders.