Viser hvilken klinisk relevanse scratch collapse test har for å finne hvor nerver er i klem.

http://www.ncbi.nlm.nih.gov/pubmed/18984333

For the new test, the patient resisted bilateral shoulder external rotation with elbows flexed. The area of suspected nerve compression was lightly «scratched,» and then resisted shoulder external rotation was immediately repeated. Momentary loss of shoulder external rotation resistance on the affected side was considered a positive test.

For carpal tunnel syndrome, sensitivities were 64%, 32%, and 44% for the scratch collapse test, Tinel’s test, and wrist flexion/compression test, respectively. For cubital tunnel syndrome, sensitivities were 69%, 54%, and 46% for the scratch collapse test, Tinel test, and elbow flexion/compression test, respectively. The scratch collapse test had the highest negative predictive value (73%) for carpal tunnel syndrome. Tinel’s test had the highest negative predictive value (98%) for cubital tunnel syndrome.

The scratch collapse test had significantly higher sensitivity than Tinel’s test and the flexion/nerve compression test for carpal tunnel and cubital tunnel syndromes. Accuracy for this test was 82% for carpal tunnel syndrome and 89% for cubital tunnel syndrome.

Mer utfyllende studie om Scratch Collapse her: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2880669/

Though the exact mechanism of the scratch collapse test is unknown, we believe it may represent a gross physical manifestation of the “cutaneous silent period.” This EMG-demonstrated phenomenon is observed following noxious stimuli. A brief pause of voluntary muscle contraction is demonstrated following stimulation of a cutaneous nerve [24]. The scratch collapse yields a similar reflex response. We propose that as the nervi-nervorum at the site of neuritis are stimulated, an ipsilateral central inhibition is transiently activated. It is not surprising that this response would be most robust at the focus of the neuritis.

The scratch collapse examination shares several features with the cutaneous silent period. Both phenomena occur after a noxious stimulus, are very resistant to habituation, are able to override voluntary muscle contraction, and result in a deferment in resistance in a pattern that corresponds to the withdrawal of the extremity into a position of protection (e.g., in this case, internally rotating the arms in against the body) [9, 11, 13, 16, 17]. From an evolutionary standpoint, such a reflex would be important in survival.

The test offers an advantage over these other tests in that it appears to precisely localize the site of nerve compression.