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Several types of reflexes can be tested as part of a physical examination and these all reveal something about the status of the elements of the nervous system that contribute to their functioning. They have been used for over a century as part of a routine neurological examination due to their safety, low cost, predictive value, and ability to be performed rapidly, even without specialized equipment. This article will focus on the “deep tendon reflexes” which are more appropriately named — and will be referred to herein — as muscle stretch reflexes (MSR). MSR grading is based on a clinician’s subjective evaluation of amplitude, with a wide range of what can be normal. They are particularly useful if there are asymmetric findings or if they occur in the context of other changes; isolated hyper or hypo reflexic MSR without other findings is generally not considered pathological. There are 6 MSR that are commonly tested and will be the focus of this article: biceps, triceps, brachioradialis, knee, ankle, and jaw jerk.

The MSRs are part of a physical exam typically performed by one clinician. They are routinely performed by clinicians and nurses in many medical specialties as well as in fields such as physical therapy. Neurologists, physiatrists, and orthopedists, among others, may use them as part of a consult note, which will then need to be interpreted by a primary care or hospitalist type clinician. A perinatal nurse may check reflexes frequently on an obstetric patient with eclampsia and enter their findings into a daily note. Therefore, a common language is important. As noted earlier, there are a variety of ways to denote the physical exam findings, so one should ensure that other clinicians, nurses, and other staff know how to interpret these findings and communicate clearly what was observed on physical examination. The subjective nature of grading MSRs adds to the importance of this. For instance, some scales indicate clonus would receive a “4,” whereas others would say it should be graded at whatever amplitude it was, and then “clonus” should be annotated. It is most clear and safest, therefore, for the clinician to write a very brief explanation of the finding as well as the scale they are using (“using NINDS MSR: 4, due to clonus”) to assist the next clinician or nurse who is accessing the chart. Similarly, as reinforcement can frequently elicit an otherwise absent reflex, it should be noted if reinforcement was attempted in an absent reflex.