Testing the reflexes
BMJ 2019; 366 doi: https://doi.org/10.1136/bmj.l4830 (Published 14 August 2019) Cite this as: BMJ 2019;366:l4830
- A J Lees, neurologist1,
- Brian Hurwitz, former general practitioner2
- 1The National Hospital, Queen Square, London WC1N 3BG, UK
- 2King’s College London, London WC2B 6LE, UK
- Correspondence to: A J Lees andrew.lees{at}ucl.ac.uk
What you need to know
Tendon reflex testing allows lower and upper motor neurone lesions to be distinguished reliably
Interpret reflexes alongside a clinical history and any abnormalities of power, tone, and sensation found on examination
Reflex testing is essential if you suspect spinal cord and cauda equina compression, acute cervical or lumbar disc compression, or acute inflammatory demyelinating polyradiculoneuropathy
Eliciting the deep tendon reflexes is a vital component of medical assessments in general practice (where 9% of medical problems are believed to be neurological in origin1) and in hospital (where 10-20% of admissions have a primary neurological problem2). Reflex testing contributes to accurate bedside diagnosis in many cases of neuromuscular disease, providing localising diagnostic information that cannot be obtained by any other method (including clinical neurophysiological and neuroradiological investigations). It can be helpful in deciding if neurological, neurosurgical, or orthopaedic referral is required.
This article briefly describes the clinical and pathological rationales for reflex testing and gives practical tips on when and how to elicit the deep tendon reflexes.
What are deep tendon reflexes?
When a tendon is tapped briskly its muscle contracts as a consequence of a synchronous volley of afferent impulses from the primary sensory endings of the muscle spindles in the stretched muscle. This involves a two neurone reflex in the spinal or brain stem segment that innervates the muscle (fig 1). At the same time, neurones modulated by descending corticospinal fibres are stimulated which activate opposing muscle groups around the joint dampening the resulting jerk.
The reflex arc
When to do it?
Patients presenting with motor or sensory symptoms in the limbs should have their reflexes tested to help distinguish between a lower motor neurone lesion (due to damage in the final common pathway that connects the anterior horn cells of the spinal cord with muscles via the nerve roots, plexuses, peripheral nerves, and neuromuscular junction) and …
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