The digital reflex described by Trömner1 in 1912 is generally acknowledged to be a fairly reliable sign of an organic lesion of the corresponding pyramidal pathway at some point above the sixth cervical segment of the spinal cord. The reflex is ordinarily elicited in suitable cases by suddenly flicking the terminal phalanx of the patient's middle or index finger toward his palm from a resting position of semiflexion of the wrist and fingers. The reflex response consists of a quick movement of flexion, principally at the terminal joint of the thumb and of the index finger, and less commonly at the more proximal joints also. Sometimes, in markedly spastic cases, the flexor response is seen in all the fingers of the affected side. The typical reflex is also elicited when the terminal segment of the patient's middle or index finger is pinched between the examiner's thumb and forefinger, the
COOPER MJ. MECHANICAL FACTORS GOVERNING THE TRÖMNER REFLEX. Arch NeurPsych. 1933;30(1):166–169. doi:10.1001/archneurpsyc.1933.02240130174011
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