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Reflex hammer

life science Maturity 11-13 Next article →

A reflex hammer is a specialized medical instrument used by healthcare practitioners. Its primary purpose is to test deep tendon reflexes. These reflexes are automatic responses in the body. One of the most well-known examples is the patellar reflex, often called the knee-jerk reflex.

Neurological tools
Neurological tools

Testing these reflexes is a vital part of a neurological physical examination. This examination helps doctors detect abnormalities in the nervous system. Specifically, doctors look for issues in the central or peripheral nervous systems.

Reflex testing works by providing a stimulus to a tendon. The strength of the resulting reflex provides important medical information. If a reflex is exaggerated, it is called hyperreflexia. Hyperreflexia can indicate a disorder in the central nervous system. If a reflex is diminished or weak, it is called hyporeflexia. This condition may suggest a problem in the peripheral nervous system.

Queen square
Queen square

However, the magnitude of the reflex is also affected by the stimulus itself. It is difficult to quantify the exact force needed to elicit a reflex. This is because the force required varies depending on the hammer being used.

Doctors use different techniques to swing these tools. The Taylor hammer is typically held by the physician at the end. The doctor then swings the entire device in an arc-like motion onto the tendon. In contrast, the Queen Square and Babinski hammers are used differently. These are usually held perpendicular to the tendon. The practitioner then passively swings the hammer with the assistance of gravity.

Percussionshammer
Percussionshammer

Sometimes, a doctor may not even need a hammer to find hyperreflexia. They might simply tap their own finger on top of the tendon to provide a stimulus.

To help make a reflex response easier to see, doctors may use the Jendrassik maneuver. This involves asking the patient to interlock their flexed fingers. This action serves to distract the patient and prime the reflex response.

Reflexhammer nach Trömner
Reflexhammer nach Trömner

Before specialized reflex hammers were developed, doctors used hammers meant for chest percussion. These tools were used to tap on the chest to listen to sounds. However, these percussion hammers proved to be quite cumbersome. Their weight was often insufficient to generate the specific stimulus needed for a reflex.

Newer models began appearing in the late 19th century. John Madison Taylor designed the Taylor hammer in 1888. This tool is the most well-known reflex hammer in the United States. It features a triangular rubber component attached to a flat metallic handle. The Taylor hammer is significantly lighter than many heavier European models.

Queen square
Queen square

Another important design is the Queen Square reflex hammer. It was created for use at the National Hospital for Nervous Diseases in London. This hammer is the preferred choice for neurologists in the United Kingdom.

The Queen Square hammer originally used a handle made of bamboo or cane. These handles varied in length from 25 to 40 centimeters. The tool featured a 5-centimeter metal disk with a plastic bumper. Modern versions are often made with plastic molds. Some versions have a sharp, tapered end to test plantar reflexes. However, medical professionals no longer recommend this due to strict infection control rules.

Neurological tools
Neurological tools

Joseph Babinski designed his own hammer in 1912. The Babinski hammer is similar to the Queen Square model but has a metallic handle. This handle is often detachable, and some versions are even telescoping for compact storage.

There are several other specialized models used in medicine. The Trömner reflex hammer was designed by Ernst Trömner. This model is shaped like a mallet with two distinct heads. The larger mallet head is used to elicit tendon stretch reflexes. The smaller mallet head is used to elicit percussion myotonia.

Reflexhammer nach Trömner
Reflexhammer nach Trömner

Other known types of reflex hammers include the Buck, Berliner, and Stookey hammers. Because there are so many designs, numerous models are available from various commercial sources. These tools remain essential for understanding how signals travel through the human nervous system.

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File:Percussionshammer.jpg
Percussionshammer.jpg
File:Neurological tools.jpg
Neurological tools.jpg
File:Queen square.jpg
Queen square.jpg
File:Reflexhammer nach Trömner.jpg
Reflexhammer nach Trömner.jpg
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