Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system and the most common cause of non-traumatic disability in young adults (Kamm et al. 2014; Vanbellingen & Kamm, 2016). It is a heterogeneous disease, which is associated with long-term disability, leading to reduced quality of life (QoL). Disease-modifying pharmacological therapies (DMT) decrease activity and progression of the disease, and symptomatic pharmacological treatments reduce complaints to a certain extent, however MS patients often still suffer from various neurological deficits during the course of their disease (Kamm et al. 2014). Consequently, specific non-pharmacological therapies are needed in order to further reduce disability, eventually resulting in better QoL (Lamers et al. 2016; Vanbellingen & Kamm, 2016).

Impaired dexterity is a frequently observed impairment, affecting up to 76% of patients with MS (Johannson et al. 2007). The different neurological deficits caused by MS, such as ataxia, spasticity, sensory-motor deficits, and apraxia may be alone or in combination, impair manual dexterity (Kamm et al. 2012; Heldner, Vanbellingen et al. 2014). MS patients experience impairments in the performance of several activities of daily living (ADL), such as grooming, cooking, etc. Sometimes these problems are even associated with loss of work, and lack of social integration (Chruzander et al. 2013).

The effectiveness of the app based exercises still needs to be proven. With respect to dexterity, a first new app has been developed called "Finger Zirkus", by a team of experts including an occupational therapist, graphic designer, and IT expert. The app is already available to be downloaded from google play store or apple store (see for more details: www.fingers-in-motion.de).

Inclusion Criteria:

• The inclusion criteria for MS patients are as follows: males and females, age 18 to 75, diagnosis of MS (primary or secondary progressive, relapsing-remitting) following the McDonald criteria (Polman et al. 2011). In addition, patients must report difficulties in manual dexterity that impact ADL and/or have a pathological nine Hole Peg Test (9HPT) or Coin Rotation test (CRT) according to cut-off values (Mathiowetz et al. 1985; Heldner, Vanbellingen et al. 2014).

Exclusion Criteria:

• The exclusion criteria will be other conditions that may hand function or, impaired cognitive functioning (Mini Mental Status Examination score less than 24).