Back To Search Results

Bekhterev-Jacobsohn Reflex

Editor: Hani Kushlaf Updated: 1/20/2025 12:31:23 AM

Introduction

The Bekhterev-Jacobsohn reflex, also known as the Jacobsohn finger flexion sign, was first described in the early 1900s by Dr Vladimir Bekhterev, a Russian neurologist, and Dr Louis Jacobsohn-Lask, a German neurologist.[1] The reflex is a simple clinical sign that can be elicited without requiring specialized equipment; it involves the abduction of the hand and flexion of the fingers when the distal radius is stroked. This reflex is particularly useful in clinical practice for determining the localization of neurological lesions, as it is indicative of a pyramidal tract lesion affecting the upper limb.[2]

The Bekhterev-Jacobsohn reflex is closely related to the Bekhterev-Mendel reflex (dorsiflexion of the toes when the dorsum of the foot is tapped) in the lower limb. Additionally, it shares similarities with the Hoffmann sign (flexion of the thumb and index finger when the nail of the middle finger is flicked downwards) and the Tromner reflex (flexion of the thumb and index finger elicited by tapping the palmar surface of the distal phalanx of the middle or index finger) in the upper limb, all of which are indicative of upper motor neuron (UMN) pathology.[3]

Anatomy and Physiology

Register For Free And Read The Full Article
Get the answers you need instantly with the StatPearls Clinical Decision Support tool. StatPearls spent the last decade developing the largest and most updated Point-of Care resource ever developed. Earn CME/CE by searching and reading articles.
  • Dropdown arrow Search engine and full access to all medical articles
  • Dropdown arrow 10 free questions in your specialty
  • Dropdown arrow Free CME/CE Activities
  • Dropdown arrow Free daily question in your email
  • Dropdown arrow Save favorite articles to your dashboard
  • Dropdown arrow Emails offering discounts

Learn more about a Subscription to StatPearls Point-of-Care

Anatomy and Physiology

The Bekhterev-Jacobsohn reflex is elicited by applying pressure distally on the radial edge of the forearm. This region includes the brachioradialis tendon, located near the radial styloid process. There is a hypothesis that hyperreflexia of the brachioradialis tendon may play a role in the observed response of the Bekhterev-Jacobsohn reflex. For this reason, the brachioradialis reflex warrants discussion.

The brachioradialis reflex is a deep tendon reflex mediated by the C5-C6 nerve roots and the radial nerve.[4] The reflex is initiated when a tap stretches the brachioradialis tendon, stimulating muscle spindle receptors.[5] These receptors generate a sensory impulse that follows a reflex arc, traveling via the afferent sensory nerve fibers to the spinal cord. After synapsing within the spinal cord, a response is sent back via the efferent motor nerve fibers, leading to contraction of the brachioradialis muscle and causing wrist supination—a normal response.[6][7]

In conditions associated with hyperreflexia, such as UMN lesions, the inhibitory pathways between the cerebral cortex and spinal cord are disrupted. This loss of cortical inhibition amplifies the reflex response, resulting in exaggerated or abnormal reflexes. For the brachioradialis reflex, hyperreflexia manifests as more pronounced wrist flexion or forearm supination. 

The Bekhterev-Jacobsohn reflex is characterized by finger flexion and hand abduction upon stimulation of the dorsum of the forearm in the area of the distal radius, with the arm in the supine position. This is a pathological reflex often associated with UMN lesions.[6][8] This phenomenon underscores the importance of recognizing reflex patterns and understanding their underlying neurophysiology in diagnosing and localizing neurological pathology.

Indications

The Bekhterev-Jacobsohn reflex is a valuable adjunct to the comprehensive neurological examination, particularly in assessing pyramidal tract lesions affecting the upper limb. While numerous clinical signs exist for detecting pyramidal tract lesions in the lower limb, fewer such indicators are available for the upper limb.[9][10] In addition to the Bekhterev-Jacobsohn reflex, other clinically useful signs include the Hoffmann sign and the Tromner reflex. These reflexes also indicate UMN pathology and are often associated with lesions affecting the cervical spinal cord.[11]

Contraindications

There are a few contraindications to performing the Bekhterev-Jacobsohn reflex. The primary contraindication is the presence of an open wound on the radial aspect of the forearm, which may hinder proper examination or pose a risk of further injury. Additionally, severe swelling in the region may limit the ability to elicit the reflex effectively. Interestingly, Dr Jacobsohn observed that the reflex remains useful in patients with hand contractures, which are not considered a contraindication for performing the test. This highlights the reflex’s utility even in cases of significant musculoskeletal abnormalities.

Equipment

The Bekhterev-Jacobsohn reflex can be performed without the need for specialized equipment. The clinician may use their hand or fingers to tap the patient’s wrist, although a reflex hammer can also be used if convenient. Various reflex hammers are suitable for this test, and the choice depends on the practitioner’s preference. To ensure accurate results, the patient should be seated or lying on a bed comfortably, with their arm fully relaxed during the procedure. This relaxation minimizes muscular interference and allows for proper elicitation of the reflex.

Personnel

Any healthcare professional properly trained in the technique can perform the Bekhterev-Jacobsohn reflex. This includes physicians, medical students, physician assistants, nurses, and other qualified medical staff. Inexperienced clinicians must first observe the reflex being performed correctly, either in person or through a reliable online tutorial, before attempting the test themselves. Practice and experience are critical to accurately eliciting and interpreting the response, ensuring its diagnostic utility.

Technique or Treatment

The Bekhterev-Jacobsohn reflex is best performed with the patient seated or lying supine, with both arms extended and fully relaxed. The patient's forearm should be supported to ensure complete relaxation, and there should be no tension in their arms, wrists, or fingers, which should remain extended. To ensure complete visibility of the forearm and hand, the patient should wear a hospital gown with the area uncovered.

The clinician should sanitize their hands before the examination. Standing on the patient's side being tested, the examiner supports the patient's forearm, with the thumb positioned laterally (palm facing upward). The clinician then taps on the dorsum of the forearm over the distal radius using a tendon hammer.

A positive (abnormal) reflex is observed as an abduction of the hand and distinct flexion of the fingers, particularly at the distal interphalangeal joints. A negative (normal) reflex is indicated when the fingers remain extended with no movement in the fingers or hand. The test may be repeated as needed to evaluate the reflex response accurately.

Complications

Complications associated with the Bekhterev-Jacobsohn reflex are rare. In some cases, tapping on the distal radius may cause mild bruising, pain, or soreness, though these occurrences are uncommon and typically resolve without intervention.

Clinical Significance

A positive (abnormal) response of the Bekhterev-Jacobsohn reflex indicates a pyramidal tract lesion and serves as a clinical UMN sign, aiding in narrowing the differential diagnosis. Various conditions can cause pyramidal tract lesions affecting the upper limb, including stroke, multiple sclerosis, spinal cord injuries, and brain tumors.[2] Dr Jacobsohn observed that the reflex was consistently present in mild and severe hemiplegia cases, noting its particular utility in diagnosing mild or early disease. This reflex is typically assessed alongside other UMN tests, such as the Hoffmann sign in the upper limb and the Babinski reflex in the lower extremities, to enhance diagnostic accuracy.[12]

Enhancing Healthcare Team Outcomes

Any properly trained healthcare professional can perform the Bekhterev-Jacobsohn reflex. Inexperienced clinicians should observe a skilled clinician perform the reflex or review instructional materials, such as an online tutorial, to learn the correct technique before attempting the test. Practice and experience are essential for accurately eliciting and interpreting the response. However, the validity of the Bekhterev-Jacobsohn reflex remains uncertain. The technique has not been rigorously evaluated in randomized clinical trials and should not be solely relied upon as a definitive indicator of UMN injury.

References


[1]

Demircubuk I, Candar E, Sengul G. Louis Jacobsohn-Lask (1863-1940). Journal of neurology. 2024 May:271(5):2919-2921. doi: 10.1007/s00415-024-12260-0. Epub 2024 Mar 6     [PubMed PMID: 38446144]


[2]

Miczak K, Padova J. Muscle Overactivity in the Upper Motor Neuron Syndrome: Assessment and Problem Solving for Complex Cases: the Role of Physical and Occupational Therapy. Physical medicine and rehabilitation clinics of North America. 2018 Aug:29(3):529-536. doi: 10.1016/j.pmr.2018.03.006. Epub 2018 May 8     [PubMed PMID: 30626513]

Level 3 (low-level) evidence

[3]

Hoffmann G, Kamper DG, Kahn JH, Rymer WZ, Schmit BD. Modulation of stretch reflexes of the finger flexors by sensory feedback from the proximal upper limb poststroke. Journal of neurophysiology. 2009 Sep:102(3):1420-9. doi: 10.1152/jn.90950.2008. Epub 2009 Jul 1     [PubMed PMID: 19571191]


[4]

Sahrmann SA, Norton BJ. Stretch reflex of the biceps and brachioradialis muscles in patients with upper motor neuron syndrome. Physical therapy. 1978 Oct:58(10):1191-4     [PubMed PMID: 693577]


[5]

Zimmerman B, Hubbard JB. Deep Tendon Reflexes. StatPearls. 2025 Jan:():     [PubMed PMID: 30285397]


[6]

McGibbon CA, Sexton A, Hughes G, Wilson A, Jones M, O'Connell C, Parker K, Adans-Dester C, O'Brien A, Bonato P. Evaluation of a toolkit for standardizing clinical measures of muscle tone. Physiological measurement. 2018 Aug 8:39(8):085001. doi: 10.1088/1361-6579/aad424. Epub 2018 Aug 8     [PubMed PMID: 30019689]


[7]

Bhattacharyya KB. The stretch reflex and the contributions of C David Marsden. Annals of Indian Academy of Neurology. 2017 Jan-Mar:20(1):1-4. doi: 10.4103/0972-2327.199906. Epub     [PubMed PMID: 28298835]


[8]

Musampa NK, Mathieu PA, Levin MF. Relationship between stretch reflex thresholds and voluntary arm muscle activation in patients with spasticity. Experimental brain research. 2007 Aug:181(4):579-93     [PubMed PMID: 17476486]


[9]

Bryden AM, Hoyen HA, Keith MW, Mejia M, Kilgore KL, Nemunaitis GA. Upper Extremity Assessment in Tetraplegia: The Importance of Differentiating Between Upper and Lower Motor Neuron Paralysis. Archives of physical medicine and rehabilitation. 2016 Jun:97(6 Suppl):S97-S104. doi: 10.1016/j.apmr.2015.11.021. Epub     [PubMed PMID: 27233597]


[10]

Maranhão-Filho P, Correa RB. Babinski's hand sign: many have tried…. Arquivos de neuro-psiquiatria. 2018 Oct:76(10):716-719. doi: 10.1590/0004-282X20180107. Epub     [PubMed PMID: 30427513]


[11]

Bryden A, Kilgore KL, Nemunaitis GA. Advanced Assessment of the Upper Limb in Tetraplegia: A Three-Tiered Approach to Characterizing Paralysis. Topics in spinal cord injury rehabilitation. 2018 Summer:24(3):206-216. doi: 10.1310/sci2403-206. Epub     [PubMed PMID: 29997424]


[12]

Moon DK, Johnson AMF. Lower Extremity Problem-Solving: Challenging Cases. Physical medicine and rehabilitation clinics of North America. 2018 Aug:29(3):619-631. doi: 10.1016/j.pmr.2018.04.009. Epub 2018 Jun 1     [PubMed PMID: 30626518]

Level 3 (low-level) evidence