Validating a New Writer s Cramp Scale

Objective: Writer s cramp (WC) causes significant discomfort and disability to those afflicted by this condition. Studies on WC have been hampered by the lack of objective, validated rating scales. In this study, we will test and validate new instruments to rate WC; the WC impairment scale (WCIS) and a new disability scale (WCDS).We will also collect exploratory data about biomechanics of the hand.

Study population: The study population will consist of 20 subjects. Ten patients with WC and 10 age and handedness matched HVs will constitute the study population.

Design: 10 patients with WC and 10 age- and handedness-matched HV will be videotaped while writing. The WCIS scores will be given to each subject by four blinded raters (Drs. Mark Hallett, Barbara Karp, Katherine Alter, and Camilo Toro) based on the videos. The patients will complete the WCDS. In addition, each individual will be asked to repeat some basic elements of the scale while writing on the screen of a tablet PC, and on the surface of a detached digitizing tablet in order to generate high temporal and spatial resolution pen tip position samples for further numerical analyses and scoring. The biomechanics of the hand will be measured using a published scale.

Outcome measures: Using the WCIS, inter and intra-rater reliability, internal consistency (Cronbach s alpha) face validity, and reproducibility will be measured in addition to other secondary outcomes. The ease of use by the raters will be assessed for each subject. Reproducibility of writing on tablet, writing on paper placed on a writing tablet, and writing on a tablet PC will be assessed. Finally, biomechanics of the hands of patients with WC will be compared with those of the unaffected healthy volunteers.

• INCLUSION CRITERIA:
• Inclusion criteria for patients with WC and age and handedness-matched HVs:

• Subjects must be at least 18 years of age.
• Subjects must be willing to be videotaped while writing.
• Subjects must have regular hand function with the ability to write without an assistive device

Exclusion criteria

• Patients with WC:

• Botulinum toxin (BTX) administration within 3 months of participation.
• Unable to provide consent.
• Patients taking oral medications for WC including muscle relaxants or other centrally-active medications such as antidepressants which may enhance tremors.
• Medical conditions that affect hand function, such as stroke, nerve entrapment, tremor, parkinsonism, chorea, ataxia affecting the dominant hand.
• HVs:

• Unable to provide consent.
• Healthy volunteers taking oral medications that may affect motor function such as muscle relaxants or centrally-active medications including medications for psychiatric conditions like antidepressants and antipsychotics.
• Healthy volunteers with abnormal hand function including medical conditions that may influence hand function, e.g., strokes, nerve entrapments, tremor, parkinsonism, chorea, ataxia and psychiatric conditions (such as psychosis and depression) affecting the dominant hand.
• Have history of hand surgery and or hand trauma.
• Have abnormal findings on medical history and physical exam.