The reflex hammer: A trusty tool that continues to stay in the doctor’s office

20170606130000, Zayani Bhatt
'Did You Know?' seeks to uncover a variety of stories from all facets of medicine and healthcare.
Today, a reflex hammer is one of the most used tools in a doctor’s office. This trusty tool – close to 130 years old – is a valuable medical innovation discovered by accident by the 18th century doctor, Leopold Auenbrugger.

Originally a hammer for wine bottles


Auenbrugger’s father ran a hotel in Vienna in which wine casks were kept. In order to ascertain how much wine was left, the casks were thumped with a hammer. A dull resultant sound informed employees that the cask was empty. Auenbrugger realised that this technique called percussion, could be used to determine how much fluid had collected around a heart. He wrote the paper New invention to detect diseases hidden deep within the chest, detailing his discovery.

Leopold Auenbrugger (with his wife, Marianne) is regarded as one of the founders of modern medicine, having applied the idea of detecting disease by sound. Photo credit: Wellcome Library, London/NPR
Leopold Auenbrugger (with his wife, Marianne) is regarded as one of the founders of modern medicine, having applied the idea of detecting disease by sound. Photo credit: Wellcome Library, London/NPR

This realisation was rudimentary, however, and the percussion hammer too light to generate an adequate stimulus for a reflex. So, in the decade following, there was a race among the medical community to produce the best hammer. The first scientist to develop a hammer was Scottish physician Sir David Barry in 1820.

The hammers were molded into different shapes such as axes and wands, and made of materials such as ebony, whalebone, rubber and brass. Scientists were also beginning to understand how reflexes work.

In 1875, physicians Heinrich Erb and Carl Friedrich Otto Westphal wrote a paper on how deep tendon reflexes could be used as a diagnostic tool. They developed the patellar reflex and its role in neurological exams. This discovery made researchers begin to create hammers specifically for reflexes.

The development of different models over the years


Since nearly 130 years ago, a number a reflex hammers have been created. Photo credit: Stanford Medicine
Since nearly 130 years ago, a number a reflex hammers have been created. Photo credit: Stanford Medicine

An American physician John Madison Taylor, developed the reflex hammer of today, in 1888. Taylor was working as an assistant at the Philadelphia Orthopedic hospital in America when he came up with the design. It had round edges to ease impact and a triangular rubber head.

Williams Christopher Krauss of Germany developed the next model with two rubber pieces, one for patellar reflexes and the other for bicep reflexes. As he described, “the handle being of hard rubber becomes warm on friction, while the head being of metal remains cold, thus offering the means of examining the senses of heat and cold.”

Dr Ernst Tromner’s hammer had a smooth handle that was used as a tongue blade and a sharp edge that was used for cutaneous and vascular reflexes. It had a two-headed mallet, the smaller of which was used to test myotonia and the larger, tendon stretch reflexes. Other hammers include the Babinski, Buck, Berliner and Stookey reflex hammers. Interestingly, the Stookey hammer had camel hair that could gauge touch sensation.

Anton Wintrich introduced this percussion hammer model in 1841. Photo credit: Wellcome Library, London/NPR
Anton Wintrich introduced this percussion hammer model in 1841. Photo credit: Wellcome Library, London/NPR
 

The most basic diagnostic tool for neurological diseases


In hammer is still invaluable today because it helps doctors determine whether a patient’s problem is in the brain or elsewhere in the body. For example, brain disorders present hyperactive reflexes whereas reduced or non-existent reflexes. 

As Dr Andrew Wilner, an assistant professor of neurology at Mayo Clinic explains, “the reflex hammer is arguably our most important tool in narrowing down the differential diagnosis.” 

"We could argue about the nuances of the hammer — the Queens Square, the Tomahawk, plastic handle, metal handle, weighted, flexible or rigid — but the hammer itself is always in the hand. Reflexes tell the story of neurologic diseases of all sorts," says multiple sclerosis expert Dr Stephen Krieger.

“Technology is glorious," admits Krieger, “and [it] will teach us things about patients that we could never have known or imagined.”

“But the simple, elegant, inexpensive almost plebeian swing of the reflex hammer has a cost/benefit ratio that I think no advanced technology will likely ever match.” MIMS

Read more:
8 medical procedures: Then and now
Who was the father of the lobotomy?
7 modern medical practices that were passed down from ancient times

Sources:
http://www.healio.com/endocrinology/news/print/endocrine-today/%7B354c7cea-ceca-4d98-ba1c-88c9fed65845%7D/how-percussion-hammers-evolved-into-reflex-hammers
http://www.npr.org/sections/health-shots/2017/05/28/529821714/in-the-age-of-digital-medicine-the-humble-reflex-hammer-hangs-on