Deep Tendon Reflex: The Tools and Techniques. What Surgical Neurology Residents Should Know.

Ooi Lin-Wei,Vincent Tee Wei Shen,Jafri Malin Abdullah,Zamzuri Idris,Leonard Leong Sang Xian,Chee Yong Chuan,Abdul Rahman Izani Ghani,Sanihah Abdul Halim

doi:10.21315/mjms2021.28.2.5

Ooi Lin-Wei, Vincent Tee Wei Shen + Show 6 more

Open Access

https://doi.org/10.21315/mjms2021.28.2.5

Copy DOI

Abstract

The deep tendon reflex (DTR) is a key component of the neurological examination. However, interpretation of the results is a challenge since there is a lack of knowledge on the important features of reflex responses such as the amount of hammer force, the strength of contraction, duration of the contraction and relaxation. The tools used to elicit the reflexes also play a role in the quality of the reflex contraction. Furthermore, improper execution techniques during the DTR assessment may alter the findings and cloud the true assessment of the nervous system. Therefore, understanding the basic principles and the key features of DTR allows for better interpretation of the reflex responses. This paper discusses the brief history of reflexes, the development of the reflex hammer, and also the key features of a reflex response encompassing the amplitude of force needed to elicit a reflex response, the velocity of contraction, the strength of contraction, and the duration of contraction and relaxation phases. The final section encloses the techniques of eliciting DTR in the upper extremities, trunk, and lower extremities, and the interpretation of these reflexes.

Highlights

The muscle spindle is a receptor within the muscle that detects changes in the length of the muscle
The muscle spindle consists of a noncontractile centre portion and intrafusal muscle fibres which make up the contractile portion
The deep tendon reflex (DTR) remains an important aspect of the neurological exam despite the use of modern imaging

Summary

A Brief History

A reflex is an involuntary, unlearned, repeatable response to a specific stimulus that does not require any input from the brain [1]. Striking point: Biceps femoris tendon or head of the fibula Peripheral nerve: Tibial portion of the sciatic nerve Myotome: S1 Effector: Hamstring muscles Technique: i) In a patient who is sitting, recumbent, or lying on the opposite side, moderately flex the knee ii) Palpate the tendon at the posterolateral aspect of the knee and tap on the fingers iii) Observe for knee flexion. This reflex helps to determine if an absence of ankle jerk is due to peripheral neuropathy (preserved external hamstring reflex) or due to radiculopathy (absent lateral hamstring reflex). The effects last 1 sec–6 sec and is maximal for only 300 msec

Conclusion

Conflict of Interest