Chaddock Reflex


Article Author:
Aninda Acharya


Article Editor:
James Fowler


Editors In Chief:
Kranthi Sitammagari
Mayank Singhal


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Phillip Hynes
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Sandeep Sekhon


Updated:
6/29/2019 12:26:27 PM

Introduction

Charles Gilbert Chaddock introduced the External Malleolar sign as an alternative to Babinski reflex in 1911[1]. This was later referred to as Chaddock reflex. Kisaku Yoshimura described a very similar sign in 1906 in the Japanese medical literature as a variation on the Babinski sign[2]. Both the Chaddock reflex and the Babinski reflex test the integrity of the corticospinal tract (CST). Both reflexes are easy to elicit and do not require significant cooperation from the patient, and therefore can be performed in patients who cannot fully cooperate with the neurological exam. The Babinski reflex is more commonly utilized as a part of the routine neurological exam. However, alternatives such as Chaddock sign can be employed when the patient exhibits a significant withdrawal response to plantar stimulation when performing the Babinski reflex.

Anatomy

The CST originates from the cerebral cortex in layer V cells (Betz cells). Sixty percent of fibers are from the primary motor area, premotor area, and supplementary motor area. Other fibers originate primary sensory area, parietal cortex, and parietal operculum. The CST descends through the internal capsule and brainstem (forming the pyramids in the medulla). At the medullary spinal junction, 75% to 90% of fibers decussate and forms the lateral CST (contralateral), and the remainder form the anterior/ventral CST (ipsilateral). The lateral CST synapses directly with IX neurons (anterior horn cells) or on interneurons in Layers V to VIII. The CST is the upper motor neuron (UMN), and the alpha motor neuron is the lower motor neuron (LMN). Together, the UMN and LMN control motor function.

When the lateral aspect of the foot is stroked with a dull instrument, this triggers afferents which mediate nociception stimulation of the S1 dermatome. The sensory input travels up the tibial and sciatic nerve to the S1 nerve root and triggers an efferent response at that spinal level causing downward contraction of the toes. The CST normally prevents the spread of this reflex to other nerve roots. When there is a pathological process that leads to dysfunction of the CST, there is spread of this sensory stimulation to adjacent nerve roots L5, L4, L3, L2, which leads progressively to increase in flexion (shortening) of LE.  One observes deviation (dorsiflexion) of the big toe upward and fanning of the other toes. This is a positive Chaddock reflex.

Indications

The Babinski reflex is part of the routine neurological examination to evaluate the integrality of the CST. However, in the setting where the patient has significant withdrawal to plantar stimulation, or if there is a lesion (such as an infection) on the lateral plantar aspect of the foot, then the Chaddock reflex offers a reasonable alternative. In the setting of stroke and spinal cord injury, the presence of this reflex may be an early indication of these emergent conditions[1].

Equipment

Generally, a dull instrument is used to perform the Chaddock reflex. A sharp instrument should be avoided to prevent pain or injury to the skin. Traditionally, the end of a reflex hammer, a tongue depressor, or edge of a key are utilized to elicit this reflex.

Preparation

The patient should be relaxed and comfortable when the examiner performs the Chaddock reflex. The patient should be advised that the sensation may be slightly uncomfortable. Patients may experience a tickling sensation, but this is less likely than with Babinski reflex which requires plantar stimulation. The examiner should ensure that the dorsolateral aspect of the foot is free of any lesions before proceeding.

Technique

Chaddock's reflex is elicited by stimulating the dorsolateral aspect of the foot from the posterior portion of the skin just beneath the external malleolus anteriorly and along the external edge of the foot. Both the Chaddock's and Babinski's reflex lead to flexion of the big toe and fanning of the other toes when there is dysfunction of the CST.

Clinical Significance

Both the Babinski and Chaddock reflex test the integrity of the CST. When a lesion occurs anywhere along this CST, the examiner may obtain a positive reflex[3]. The examiner watches for dorsiflexion (upward movement) of the big toe and fanning of the other toes. This is referred to as a "positive reflex," or one may state that the "reflex is present." When there is a downward deviation of the toes, this means the reflex is absent. The absence of the reflex suggests that the CST may be intact. If there is no response, this is considered a neutral response and has no clinical significance.

Infants have an incompletely myelinated CST, so a positive Babinski or Chaddock reflex in the absence of other neurological deficits is considered benign up to 2 years of age[4].

In comatose patients, one may see a triple flexion response. In this case, one observes dorsiflexion of the big toe, the fanning of the other toes, dorsiflexion of the foot, as well as knee and hip flexion. This represents profound dysfunction of the CST, with the spread of the reflex to the L3 and L2 myotomes. Care must be made to distinguish this from a withdrawal response. The triple flexion response is very stereotyped whereas the withdrawal response varies with each stimulation.

The advantage of Chaddock reflex over the Babinski reflex is that it may minimize withdrawal due to plantar stimulation. Because the CST has a long course, the presence or absence of these reflexes is useful in determining the health of the central nervous system. 

Alternative methods for eliciting this response have been developed. In each case, the examiner watches for upward deviation of the big toe and fanning of the other toes. Below are some of the alternative methods:

  • Gordon sign: The examiner squeezes the calf muscle.
  • Oppenheim sign: The examiner, applying pressure to the medial side of the tibia.
  • Stransky sign: The examiner vigorously abducting and suddenly releasing the little toe.
  • Schaeffer sign: The examiner squeezes the Achilles tendon.
  • Moniz sign: The examiner applies pressure to plantarflex the ankle.
  • Gonda sign: The examiner flexes and suddenly releases the fourth toe.
  • Throckmorton reflex: The examiner percusses over the metatarsophalangeal joint of the big toe.
  • Bing sign: The examiner applies multiple pinpricks on the dorsum of the foot.
  • Cornell sign: The examiner scratches along the inner side of the extensor hallucis longus tendon.

Enhancing Healthcare Team Outcomes

The emergency department physician, neurology nurses, neurologist, internist, and therapists often perform a neurological exam. To test for the integrity of the CST, the Babinski reflex is often performed. However, when the Babinski is not possible, the Chaddock reflex is an alternative. It is important to remember that the validity of the Chaddock reflex has never been tested in large clinical studies.[3][5][6][7] The reflex was introduced decades ago and it is sporadically used. A stroke or spinal cord injury should never be confirmed or refuted on the basis of the Chaddock reflex. An imaging test should always be done to confirm the CNS pathology.


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Chaddock Reflex - Questions

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The Chaddock reflex is elicited with stroking the:



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When stroking the lateral aspect of the foot of a patient below the lateral malleolus, the big toe goes up and the other toes flare out. Where is the lesion?



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A 35-year-old male is brought in to the emergency department after being in a motor vehicle accident. The examiner tries to elicit the Babinski reflex but encounters significant withdrawal. The examiner then strokes the lateral aspect of the foot below the lateral malleolus (Chaddock reflex). Which of the following findings would suggest possible damage to the central nervous system when testing for the Chaddock reflex?



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in which scenario would the Chaddock reflex be preferable to the Babinski reflex to test the integrity of the cortical spinal tract?



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A 75-year-old male with hypertension and diabetes mellitus is brought to the emergency department with left-sided weakness and numbness involving his face, arm, and leg. He has cellulitis affecting the lateral plantar aspect of his foot. Therefore, the examiner defers testing for the Babinski reflex. Instead, the examiner strokes the lateral aspect of the foot under the lateral malleolus to test for the Chaddock reflex. The left big toe shows an upward deviation in response. What is the best interpretation of this reflex in this clinical context?



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Chaddock Reflex - References

References

History of the extensor plantar response: Babinski and Chaddock signs., Goetz CG,, Seminars in neurology, 2002 Dec     [PubMed]
Kisaku Yoshimura and the Chaddock reflex., Tashiro K,, Archives of neurology, 1986 Nov     [PubMed]
Loo SF,Justin NK,Lee RA,Hew YC,Lim KS,Tan CT, Differentiating Extensor Plantar Response in Pathological and Normal Population. Annals of Indian Academy of Neurology. 2018 Apr-Jun     [PubMed]
Kumhar GD,Dua T,Gupta P, Plantar response in infancy. European journal of paediatric neurology : EJPN : official journal of the European Paediatric Neurology Society. 2002     [PubMed]
Matsuzono K,Yoshiki T,Wakutani Y,Manabe Y,Yamashita T,Deguchi K,Ikeda Y,Abe K, Synchronized Babinski and Chaddock signs preceded the MRI findings in a case of repetitive transient ischemic attack. Internal medicine (Tokyo, Japan). 2013;     [PubMed]
Singerman J,Lee L, Consistency of the Babinski reflex and its variants. European journal of neurology. 2008 Sep;     [PubMed]
Maranhão-Filho P,Dib E,Ribeiro RG, [Babinski and Chaddock signs without apparent pyramidal disfunction]. Arquivos de neuro-psiquiatria. 2005 Jun;     [PubMed]

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