Normative values of semitendinosus tendon reflex latencies

Area of Science:

• Neuroscience
• Clinical Neurophysiology

Background:

• The semitendinosus tendon reflex (STR), or medial hamstring reflex, is infrequently documented and thought to reflect L5 spinal nerve function.
• Clinical neurophysiological tests can measure STR latencies, but normative data are lacking.

Purpose of the Study:

• To establish normative values for STR latencies.
• To describe the technique for performing STR measurements in a clinical neurophysiological setting.

Main Methods:

• Measured the stimulus-response relation for STR using a reflex hammer and surface EMG electrodes on the semitendinosus muscle.
• The reflex hammer impact triggered EMG recording to determine latencies.

Main Results:

• Forty healthy subjects (18 women, 22 men; median age 30) participated.
• STR latencies correlated significantly with body height (r=0.70).
• The mean STR latency was 24.73 ms (SD 1.96), with an upper limit of normal for left-right differences of 2 ms.

Conclusions:

• This study provides the first reported normative values for STR latencies, elicitable in 100% of participants.
• Left-right STR latency differences appear most promising for clinical diagnosis.
• Findings offer practical utility for neurophysiologists and a basis for further research in L5 radiculopathy.