A reflex hammer is a medical instrument used by practitioners to test deep

tendon A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...

reflex In biology, a reflex, or reflex action, is an involuntary, unplanned sequence or action and nearly instantaneous response to a stimulus. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs ...

es. Testing for reflexes is an important part of the neurological physical examination in order to detect abnormalities in the

central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known a ...

peripheral A peripheral or peripheral device is an auxiliary device used to put information into and get information out of a computer. The term ''peripheral device'' refers to all hardware components that are attached to a computer and are controlled by the ...

nervous system. Reflex hammers can also be used for chest

percussion A percussion instrument is a musical instrument that is sounded by being struck or scraped by a beater including attached or enclosed beaters or rattles struck, scraped or rubbed by hand or struck against another similar instrument. Exc ...

.Swartz MH. ''Textbook of Physical Diagnosis: History and Examination.'' Third edition. Philadelphia: WB Saunders; 1998

Models of reflex hammer

Prior to the development of specialized reflex hammers, hammers specific for percussion of the

chest The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the crea ...

were used to elicit reflexes.Lanska DJ. The history of reflex hammers. ''Neurology''. 1989 Nov;39(11):1542-9. However, this proved to be cumbersome, as the weight of the chest percussion hammer was insufficient to generate an adequate stimulus for a reflex. Starting in the late 19th century, several models of specific reflex hammers were created: *The Taylor or tomahawk reflex hammer was designed by John Madison Taylor in 1888 and is the most well known reflex hammer in the USA. It consists of a triangular

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, and ...

component which is attached to a flat metallic handle. The traditional Taylor hammer is significantly lighter in weight when compared to the heavier European hammers. *The Queen Square reflex hammer was designed for use at the ''National Hospital for Nervous Diseases'' (now the

National Hospital for Neurology and Neurosurgery The National Hospital for Neurology and Neurosurgery (informally the National Hospital or Queen Square) is a neurological hospital in Queen Square, London. It is part of the University College London Hospitals NHS Foundation Trust. It was the ...

) in

Queen Square, London Queen Square is a garden square in the Bloomsbury district of central London. Many of its buildings are associated with medicine, particularly neurology. Construction Queen Square was originally constructed between 1716 and 1725. It was formed ...

. It was originally made with a

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cane Cane or caning may refer to: *Walking stick or walking cane, a device used primarily to aid walking * Assistive cane, a walking stick used as a mobility aid for better balance *White cane, a mobility or safety device used by many people who are ...

handle of varying length, of average 10 to 16 inches (25 to 40 centimetres), attached to a 2-inch (5 centimetre) metal disk with a plastic bumper. The Queen Square hammer is also now made with plastic molds, and often has a sharp tapered end to allow for testing of plantar reflexes though this is no longer recommended due to tightened infection control. It is the reflex hammer of choice of the UK neurologist. *The Babinski reflex hammer was designed by

Joseph Babiński Joseph Jules François Félix Babinski ( pl, Józef Julian Franciszek Feliks Babiński; 17 November 1857 – 29 October 1932) was a French- Polish professor of neurology. He is best known for his 1896 description of the Babinski sign, a pathologic ...

in 1912 and is similar to the Queen Square hammer, except that it has a metallic handle that is often detachable. Babinski hammers can also be telescoping, allowing for compact storage. Babinski's hammer was popularized in clinical use in

America The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territori ...

by the neurologist Abraham Rabiner, who was given the instrument as a peace offering by Babinski after the two brawled at a

black tie Black tie is a semi-formal Western dress code for evening events, originating in British and American conventions for attire in the 19th century. In British English, the dress code is often referred to synecdochically by its principal element f ...

affair in

Vienna en, Viennese , iso_code = AT-9 , registration_plate = W , postal_code_type = Postal code , postal_code = , timezone = CET , utc_offset = +1 , timezone_DST ...

. *The Trömner reflex hammer was designed by Ernst Trömner. This model is shaped like a two-headed mallet. The larger mallet is used to elicit tendon stretch reflexes, and the smaller mallet is used to elicit percussion

myotonia Myotonia is a symptom of a small handful of certain neuromuscular disorders characterized by delayed relaxation (prolonged contraction) of the skeletal muscles after voluntary contraction or electrical stimulation. Myotonia is the defining symp ...

. *Other reflex hammer types include the Buck, Berliner and Stookey reflex hammers. There are numerous models available from various commercial sources.

Method of use

The strength of a reflex is used to gauge central and peripheral nervous system disorders, with the former resulting in hyperreflexia, or exaggerated reflexes, and the latter resulting in

hyporeflexia Hyporeflexia is the reduction or absence of normal bodily reflexes (areflexia). It can be detected through the use of a reflex hammer and is the opposite of hyperreflexia. Hyporeflexia is generally associated with a deficit in the lower motor n ...

or diminished reflexes. However, the strength of the stimulus used to extract the reflex also affects the magnitude of the reflex. Attempts have been made to determine the force required to elicit a reflex, but vary depending on the hammer used, and are difficult to quantify. The Taylor hammer is usually held at the end by the physician, and the entire device is swung in an arc-like motion onto the

in question. The Queen Square and Babinski hammers are usually held

perpendicular In elementary geometry, two geometric objects are perpendicular if they intersect at a right angle (90 degrees or π/2 radians). The condition of perpendicularity may be represented graphically using the '' perpendicular symbol'', ⟂. It c ...

to the tendon in question, and are passively swung with

gravity In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...

assistance onto the tendon. The

Jendrassik maneuver The Jendrassik maneuver is a medical maneuver wherein the patient clenches the teeth, flexes both sets of fingers into a hook-like form, and interlocks those sets of fingers together. The tendon below the patient's knee is then hit with a refl ...

, which entails interlocking of flexed

finger A finger is a limb of the body and a type of digit, an organ of manipulation and sensation found in the hands of most of the Tetrapods, so also with humans and other primates. Most land vertebrates have five fingers ( Pentadactyly). Chamber ...

s to distract a patient and prime the reflex response, can also be used to accentuate reflexes.Delwaide PJ, Toulouse P. The Jendrassik maneuver: quantitative analysis of reflex reinforcement by remote voluntary muscle contraction. ''Adv Neurol.'' 1983;39:661-9. In cases of hyperreflexia, the physician may place his finger on top of the tendon, and tap the finger with the hammer. Sometimes a reflex hammer may not be necessary to elicit hyperreflexia, with finger tapping over the tendon being sufficient as a stimulus.

References

{{Medical instruments and implants , state=expanded Neurology Hammers Medical equipment 1888 introductions

Models of reflex hammer

Method of use

See also

References