Differences in active range of motion measurements in the upper extremity of patients with writer's cramp compared with healthy controls.
Prachaya Srivanitchapoom, Ejaz A Shamim, Pierre Diomi and 7 others
PMID 27773588WHAT IT FOUND
Only 5 of 38 upper-extremity motion measurements differed between 8 people with writer's cramp and 8 controls.
Some finger movements were limited, others excessive, and index finger knuckle flexion decreased with longer disease and worse handwriting.
Key findings
01Only 5 of 38 active range of motion measurements were significantly different between the 8 patients with writer's cramp and the 8 healthy controls.
02Patients had limited active extension at the thumb MCP joint and limited active flexion at the index and little finger MCP joints, but greater active extension at the middle and little finger DIP joints.
03Active flexion at the index finger MCP joint was inversely correlated with disease duration and with the handwriting disability sub-score.
STILL TO COME
How it was doneWhat they foundWhat it means for OTs
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What it does not show
The study included only 8 patients with writer's cramp and 8 healthy controls, so it is a small exploratory comparison. The researchers measured many joint motions but did not correct for multiple comparisons, so the results are exploratory. Passive range of motion was not measured, so the study cannot distinguish joint restriction from active motor control problems. All patients were receiving onabotulinumtoxin-A, and injection muscles and doses had changed over time, so treatment effects cannot be separated from the disorder. Digit abduction and adduction were not measured, although earlier work reported abnormalities in these movements in focal hand dystonia. The study did not test an intervention, so it cannot show that changing range of motion will improve handwriting.
Declared interests
The authors declare no relevant conflicts of interest.
The easy way to misread this
Do not read the active range of motion differences as evidence of a treatment effect or a proven cause of writer's cramp. The study had only 8 patients, was exploratory, did not correct for multiple comparisons, and did not test an intervention.