“Observe, record, tabulate, communicate. Use your five senses. Learn to see, learn to hear, learn to feel, learn to smell, and know that by practice alone you can become expert.“

– William Osler

 

The senses are the gateway to experience. It is through them that we live and we learn. Patients too experience disease through their senses. Either from a decrease in a sense, such as the drawn curtain of blindness in amaurosis fugax, or a pathologic increase in a sense, such as the hyperalgesia of anterior thalamic pain syndrome.

 

Occasionally inaccurately described as a sixth sense¹, pain is a sensation which exists to be avoided. Entire specialties are devoted to researching, managing, and assuaging this experience for patients who suffer acutely or chronically. But, to the patient, pain, like other symptoms, requires no effort to understand. It does not need to be deciphered. It is biological and/or psychological: a reflex to harm.

 

It is only when the patient arrives at the physician are they tasked with classifying the sensation they want extinguished and are asked, “sharp, burning, aching, or radiating?” Thus begins the process of translating the patient’s experience to the physician’s: an impartation of things sensed.

 

These descriptions, to the medically minded known as “modifiers”, like tests and physical exam maneuvers, are essential to the doctor’s diagnosis. It is we who utilize the patient’s senses, often contained within the “subjective”, combined with the information from our own in the physical exam, somewhat hubristically declared the “objective”, to arrive at an assessment and diagnosis.

 

A physician treats pathologies with the aid of his or her senses, but not without the foreknowledge and expertise through practice, to decipher the meaning of the stimuli. The ultimate measure of a physician’s ability is the accurate translation of raw, subjective biological or psychological sensation into objective, additive data to diagnose and treat the patient accurately.

 

Before the utilization of a microscope to count blood cells in a known quantity of blood in 1852, before the first attempt of a nontraumatic, diagnostic laparotomy in 1888, before the unequivocally epochal incorporations of Quest Diagnostics and Labcorp in 1967 and 1969 respectively (I have no financial conflicts to disclose), physicians had to rely on his or her most basic, primitive faculties to diagnose: the senses. Aristotle defined five: sight, touch, hearing, taste, and smell.¹ Modern understanding may also consider proprioception and vestibular senses.² However, this article is not to debate taxonomy but to highlight certain aspects about the physician, the senses, and how they integrate to treat and diagnose, historically and currently.

 

Smell and taste

Going hand-in-hand, smell is often described as essential to taste. When one imagines the smells of healthcare, what first comes to mind? The sharp sterility of hand sanitizer? The often culinarily described burn of surgical electrocauterization? Consider the diagnoses that may have been diagnosed exclusively on what we now consider an antiquated olfactory assessment. When thinking pathologically, the most common clinical correlate that comes to mind may be the “fruity aroma” of diabetic ketoacidosis. Although how many physicians today can say they diagnosed an unspecific decompensated presentation solely on smelling a ketotic cornucopia?

 

First recorded in 600 BCE India, Sushruta, a Hindu physician, described “madhumeha,” a sort of “sweet urine disease” notable for attracting ants when poured on the ground. Similar descriptions were made in manuscripts from 250 BCE Greece by Apollonius of Memphis, and later in 200 AD, Aretaeus of Cappadocia is credited with attributing the term “diabetes” from the Greek “siphon” to a condition causing incessant thirst and urination. And finally, it was not until the Renaissance in 1675 that English physician Thomas Willis published the exact phrase “diabetes mellitus,” adding the Latin “mellitus” to attribute its sweet flavor. In fact, physicians and their assistants were colloquially referred to as “water tasters” for the frequency in which they would sample their patients’ urine.³

 

Additionally, liver failure was noted by Hippocratic-era physicians near 400 BCE for having a foul, fecal, and even sweetish breath called “foetor hepaticus.”⁴ Described in Latin, this “liver stench” is a result of portal-systemic shunting, resulting in the volatile metabolic byproduct of dimethyl sulfide to leak into the lungs and be expelled in the breath. In modernity, bedside examination of liver failure rarely requires us to approach as closely; however, the underlying pathophysiology remains and has instead been supplanted by serum measures of ammonia and aminotransferases.

 

However, not all smell and taste has been lost to history from the physician, as the sensation of volatile and non-volatile compounds may still take place in modern research. Most commonly extant is the urea breath test for H. pylori, which uses not a human nose but an electronic nose in the form of a gas chromatograph. Other medical applications of smell in non-humans are being continually studied to advance the fields of cancer diagnostics, metabolic disorders, and infectious diseases.⁵

 

Hearing

Whether over the lungs, heart, or even abdomen, through the ears are we able to see without seeing. Crackles, rhonchi, wheezing. Rubs, murmurs, abnormal beating. For any physician who endured medical school, the process of auscultation begins as an enigma. It has never been more evident, the experience required to translate subjective sensation into objective data, than being instructed to identify a murmur for the first time on a patient. After memorizing the waveforms and listening to recordings, truly, as Osler stated, only through “practice alone” on living people does one “become expert.”

 

Rene Laënnec invented the stethoscope in 1816, thereby unlocking the first tool to explore the inner workings of the body without a knife.⁶ Prior to this advent, listening as a diagnostic method was sparsely used due to involving direct placement of the clinician’s ear onto the patient’s body, limited at the time due to accuracy, application, and concerns of hygiene and modesty.

Hippocrates, famous for pioneering the division of medicine from the mystical near 400 BC, practiced this “immediate” auscultation. Many commonplace sounds were first documented during this period nearly 2,400 years ago, such as the “noise like that of boiling vinegar” describing the friction rub of pleurisy or the “succussion splash” of a bowel containing both air and water.⁷ Hearing is indispensable to a physician; however, occasionally all a patient requires is not a diagnosis, but simply to be heard.

 

Sight

In the perspective of some, sight may be envisioned as the most glaringly apparent choice when deciding which sense is paramount, while others may consider their peers myopic to overlook the value of hearing or not accommodate the faculty and touch. The optics of fixating on visualizing a “most important” sense may be seen as dim or lacking in acuity. But, if one thing is transparent, sight as a sense is clearly significant.

 

Evolutionarily, it allowed for the ability to assess threats or opportunities at a distance before they became immediate. In medicine, some diagnoses can be made through visualization alone, even without input from the patient. For example, in dermatology, many diseases are identified solely on their pathognomonically patterned presentation: the characteristic targetoid rash caused by Borrelia burgdorferi, the rough scaly patches of actinic keratosis, the bluish ovoid lumbosacral location of congenital dermal melanocytosis.

 

Numerous advances in medical technology serve for the explicit purpose of extending this critical sense further into the object of our treatment, such as the ophthalmoscope, otoscope, dermatoscope, and endoscope.

 

Perhaps more fascinating and inspiring are those who succeed in “becoming expert” per Sir William Osler without vision. Dr. Jacob Bolotin was born entirely blind in 1888. He mastered the medical knowledge of his time even without sight to graduate with honors from the Chicago Medical School. He then went on to focus his practice on treating cardiovascular and pulmonary disease. Although he passed away at the age of 36 years old, his pursuit of medicine despite his disability continues to inspire in the name of an award bestowed annually by the National Federation of the Blind.⁸

 

Touch

When conducting a physical exam, after taking a history by listening, then visual observation or inspection of the ailment, next may come touch.

 

Pain, a subjective sensation, is translated to “tenderness” only through the direct palpation of the physician. Often utilized in the abdominal examination, a physician may also reach out to identify pathologies in other systems such as the ballottement of a cyst, the persistent depression of pitting edema, or the end-point laxity of an anterior or posterior drawer test.

 

Physical contact is a powerful component of the physician’s repertoire. However, touch may also take part in healing, in lieu of the scalpel. Outside of being shown to strengthen the doctor-patient relationship through improvements in trust and communication, clinically, non-procedural contact has been correlated with higher medication adherence and thus improved patient outcomes. A 2010 study in the Journal of Behavioral Medicine by Guéguen et al. evaluated that slight touch of the forearm for one to two seconds when discussing the plan for bacterial pharyngitis resulted in greater adherence to antibiotic regimens.⁹

 

Touch is the primary way in which we can physically connect with patients, but a way we may also connect emotionally and even spiritually. Its utilization in medical diagnostics is indispensable, and its necessity in meeting our patients in their suffering is poorly actualized broadly. As there is a difference between “hearing” and “listening”, perhaps we can strive to understand the difference between simply “touching” and expressively “feeling” as clinicians.

 

To touch, see, and hear, to even smell and taste: these are the faculties of a physician, the most basal tools to decipher illness and employ healing. From commonplace to unconventional, we must be versed in every ability at our disposal to perform our duties for the betterment of the patient. Not that I am advocating that any of us become a “water taster.”

 

References:

1. Brandt T, Dieterich M, Huppert D. Human senses and sensors from Aristotle to the present. Front Neurol. 2024 Jul 3;15:1404720. doi: 10.3389/fneur.2024.1404720
2. Salvato G, Casile G, Squarza, SAC, Piano M, Sessa M, Bottini G. Proprioception as a sensory root for body and motor awareness. Brain Commun. 2025 Oct 1;7(5):fcaf379. doi: 10.1093/braincomms/fcaf379
3. Wilson C. Sweet Talk: A Layman’s History of Diabetes. Mensa.org. 2018 Nov 14.
4. Bass N. A Brief History of Hepatic Encephalopathy. Clin Liver Dis (Hoboken). 2021 Oct 29;18(Suppl 1):49–62. doi: 10.1002/cld.1119
5. Bijland L R, Bomers M K, Smulders Y M. Smelling the diagnosis: a review on the use of scent in diagnosing disease. Neth J Med. 2013 Jul-Aug;71(6):300-7.
6. Roguin A. Rene Theophile Hyacinthe Laënnec (1781–1826): The Man Behind the Stethoscope. Clin Med Res. 2006 Sep;4(3):230–235. doi: 10.3121/cmr.4.3.230
7. Hanna I, Silverman M. A history of cardiac auscultation and some of its contributors. The American Journal of Cardiology. Volume 90, Issue 3p259-267August 01, 2002
8. Bacon E. Dr. Jacob Bolotin Awards. National Federation of the Blind. https://nfb.org/bolotin
9. Guéguen N, Meineri S, Charles-Sire V. Improving medication adherence by using practitioner nonverbal techniques: a field experiment on the effect of touch. J Behav Med. 2010 Dec;33(6):466-73. doi: 10.1007/s10865-010-9277-5. Epub 2010 Jun 30.