On Taking A Pulse

Analog watches work, digitals don't.



A new discovery and proposition: Taking a pulse with a digital watch results in a fleeting situational form of Gerstmann-type dyscalculia. This phenomenon is virtually universal without exception! Its recognition may advance the study of developmental &/or pathological Gerstmann Syndrome…

Have you ever tried ‘taking a pulse’ using a digital watch (or clock)? You cannot! It can only be done with an analog watch (one with a smoothly sweeping second-hand). Why? The answer is not as simple as you might think. (Clue: think ‘Gerstmann.’) Before you read on, try doing it yourself—both ways—with an analog time piece and a digital time piece. You could also try a stop-watch if so inclined. If you don’t have both basic kinds of watches (analog and digital), you obviously cannot experiment, so just go ahead and theorize away happily in your head.

Now the primary object of taking a pulse is to ascertain its presence. The patient being alive, you go on to determine heart rate, i.e., how many times it beats in a minute. There are other reasons for examining a pulse, but we’ll stick to the one given. There are several places to feel pulses—neck, wrist and groin, to name but three—but we’ll confine our efforts to the wrist pulse. The principle I’m going to try and make, you’ll see, is exactly the same for all.


First, let’s get some technique: Because many doctors nowadays may never really take a pulse alone (in the old-fashioned, hands-on, way), without fancy computerized equipment that returns BP, HR, RR, skin temperature and number of BMs last week, all hooked up by nurses, and displayed on a flickering wall, I am going to begin with a labored outline of how to feel for a pulse as if you are quite naive or a complete layman person. But, never fear, it all gets mildly complicated near the end.

Detecting a wrist pulse: It is usually done while sitting facing the patient, who is also sitting facing you. Your right hand, perhaps with your left assisting, reaches across and cups or gently grasps the patient’s right hand and wrist and gently turns it palm down so that your right index finger (also sometimes with middle finger too) can conveniently be placed lightly over and parallel to the patient’s radial artery which runs near the surface along the bottom of a fleshy ‘groove’ between the tendons just above the wrist (on the patient’s thumb side). (I do remember what Gray’s Anatomy sounds like, if not its content.) It’s been said that this is also important: Be sure the tip of your index finger is closer up the arm to the patient than to you. Why? Try it and you’ll see that the patient’s wrist gets somehow higher up than her/his heart and hence the pulse might diminish to your touch. Anyway, you’ll almost immediately feel the pulse beat. If not, you might apply a little more pressure with your finger(s) in order to get a stronger feel of it. Once you are sure that you are able to keep the pulse right at your fingertips, consistently, you can go on to its measurement, i.e., counting it.

Counting the pulse: Watch your watch (at least intermittently) while, tongue in cheek, you feel the pulse. Definitely do not talk during the procedure. (Refer to a psychiatrist for that.) Count the pulse beats for a full minute for best accuracy. (If you’re feeling pressed for time, do it for ten seconds and multiply the result by six. If you’re feeling lazy and remember the 12-times table, count the pulse for five seconds and multiply by twelve.) Presto, you may have it—if you’re not wearing a digital watch.

The study: a true evidence-based medical office experiment [i]

Now, if you’re not just reading this and actually did the hands-on clinical experiment, you will have found out for yourself that digital watches just don’t work. They’re not up to the job. Otherwise you’ll just have to take my word for it. If you are a doctor that knows a bit of neurology (and computational science), it really doesn’t matter as you will be able to fully understand the explanation that’s soon to come. If you are a layperson, however, and do not know something about brain function, you could be lost from this point on. So, better get a hold of the two watches and try it for yourself. But make sure your doctor is in on it so that he can, as all good doctors do, set up a double blind study.

Results and theory

Any digital watch will totally confuse you. I repeat this repeatedly because I’ve watched a resident or two do it digitally and document it faithfully—and I know they lie. Anyway, you will lose track of the pulse count. It has to do with the nature of the two signals that are going to your brain. Digital data is dealt with on the left. Analog data is dealt with on the right. (This little clinical experiment, possibly involving thousands of doctors feeling pulses, may actually prove that sometimes contentious issue of brain sidedness.)

1) Your finger(s) feel the on-off pulse and your brain counts it, which is essentially a digital (computational) operation. If you’re right handed the parietal lobe on the left side of your brain, near the speech center, does the counting.[ii] (It may be exactly the reverse if you are left handed. But one’s handedness is not the issue at hand. For simplicity’s sake, however, consider all said to be for a right-handed left-brain dominant individual.)

2) Your eyes see (basically a spatial function) the watch:

a) If the watch is digital, the signals (after initial processing at the back of the brain by the occipital lobe), are sent to the left side—also, hopefully, for elaboration in the same area of your parietal lobe. Digital data is dealt with on the left.

b) If the watch is analog, the signals (after occipital processing) are ultimately sent to and elaborated by the right parietal lobe. Analog data is dealt with on the right.[iii]

You now have likely figured it out: The fingers send the (digital) pulse signal to the left side of the brain. Eyes and digital watches, watched, do the same. The two different (or even similar) digital signals arrive, briefly, at exactly the same time at the same place and interfere miserably with each other. As a result, we feel totally confused and quickly, almost immediately, lose count of the pulse. (It is much the same as the confusion felt when you are reading a number from the telephone book and someone kindly tries to help by reciting the same or another number aloud.) Now why do analog watches work? Ultimately, actually almost instantly, the smooth, spatial analog signal of the sweeping second hand, seen by the eyes, is sent to the right side of the brain. There it is ‘quietly’ monitored quite apart from the finger-count computation taking place on the other side. (The cerebral commissure nicely integrates both sides.) We only have to visually register the start and end points of counting. There is no interference during any chosen time period, five or ten seconds or a full minute. (Doctors: If this explanation is not entirely clear, I suggest that you make a diagram of the involved nerve tracts that do and don’t cross over. Laypersons: Tough luck; ask your doctor? Go to med school.)

On second thought I’ll rephrase and repeat the principle. A (digital) pulse signal, felt by your right hand, goes to the left side of your brain. A continuous analog watch signal, seen by your eyes, ultimately goes to the right side of your brain. That combination is mutually compatible, so you can count the pulse without ado. On the other hand, if you’re trying to use a digital watch, that particular signal goes to the left side of your brain and there interferes with your counting the pulse. Better?

Finally, tongue no longer in cheek and medically upright, I suggest that this phenomenon, the confusion that one  inevitably experiences trying to take a pulse using a digital watch, is a fleeting situational form of Gerstmann-type dyscalculia.[iv] [v] [vi]

Notes & References [vii]

[i] To do this experiment on yourself instead of a patient, hold your watch face up in the palm of your left hand. Reach over with your right hand and lay your index and middle fingers over your radial artery; they naturally rest in the best position for feeling a pulse.

[ii] Takayama Y., M. Sugishita, I. Akiguchi and J. Kimura Department of Rehabilitation, Tokyo Metropolitan Institute for Neuroscience, Japan. Isolated acalculia due to left parietal lesion. Archives of Neurology. Vol. 51 No. 3, March 1994. OBJECTIVE: To clarify the characteristics and the localization of isolated calculation disturbances due to left parietal lesions. DESIGN: Case series. SETTING: Tertiary care hospital. PATIENTS AND OTHER PARTICIPANTS: Three referred patients with isolated calculation disturbances due to stroke in the left parietal region. Sixteen volunteers for age and education constituted the control group. OUTCOME MEASURES: Neuropsychological tests, including a battery of tests for acalculia and the Wechsler Adult Intelligence Scale, and magnetic resonance imaging were performed. RESULTS: Three patients made calculation errors in the process where a number of steps were carried out simultaneously. The patients showed no aphasic components in number operations. They understood the basic processes of calculation. They showed little difficulty in the retrieval of table values. The patients had no impairment in aligning arithmetic problems or in assigning and maintaining place-holding values. They did not show any deficit of immediate memory for calculation problems. Overlapping lesions were located along the left intraparietal sulcus. CONCLUSION: The area lying along the left intraparietal sulcus is critical for isolated parietal acalculia. The profile of isolated acalculia suggests that it results from the disruption of the working memory for calculation.

[iii] Weintraub, S. and M. M. Mesulam. Right Cerebral dominance in spatial attention. Further evidence based on ipsilateral neglect. Archives of Neurology, Vol. 44 No. 6, June 1987. Tasks based on visuomotor scanning and tactile exploration were used to quantitate neglect behavior in patients with unilateral brain damage and in normal control subjects. The results confirm previous observations that contralateral neglect is markedly more severe following right-hemisphere injury and that it is independent of the modality of sensory input or motor output. In addition, patients with right-hemisphere injury also showed multimodal neglect for targets in the hemisphere ipsilateral to the brain lesion. The emergence of both contralateral and ipsilateral neglect in these patients strongly supports a model of right-hemispheric dominance for the distribution of attention within the extrapersonal space.

[iv] Ardila A and Rosselli M: Acalculia and dyscalculia. Neuropsychol Rev. 2002 Dec;12(4):179-231.Department of Communication Sciences and Disorders, Florida International University, Miami, Florida, USA. alfredoardila@cs.com Even though it is generally recognized that calculation ability represents a most important type of cognition, there is a significant paucity in the study of acalculia. In this paper the historical evolution of calculation abilities in humankind and the appearance of numerical concepts in child development are reviewed. Developmental calculation disturbances (developmental dyscalculia) are analyzed. It is proposed that calculation ability represents a multifactor skill, including verbal, spatial, memory, body knowledge, and executive function abilities. A general distinction between primary and secondary acalculias is presented, and different types of acquired calculation disturbances are analyzed. The association between acalculia and aphasia, apraxia and dementia is further considered, and special mention to the so-called Gerstmann syndrome is made. A model for the neuropsychological assessment of numerical abilities is proposed, and some general guidelines for the rehabilitation of calculation disturbances are presented. PMID: 12539968 [PubMed – indexed for MEDLINE][3]

[v] PeBenito R. Developmental Gerstmann syndrome: case report and review of the literature. J Dev Behav Pediatr. 1987 Aug;8(4):229-32. The tetrad of finger agnosia, dyscalculia, dysgraphia, and right-left confusion constitutes the Gerstmann syndrome (GS). A case of developmental Gerstmann syndrome (DGS) that occurred in a normal, highly intelligent child with exceptional reading skills is reported, together with a review of the literature. DGS occurs in both brain-damaged and seemingly normal children. Multiple neurological and behavioural manifestations coexisting with the Gerstmann elements suggest brain injury, whereas the occurrence of the Gerstmann tetrad (plus constructional apraxia) in an otherwise normal and intelligent child implies what is herein referred to as “constitutional.” The scarcity of reported cases indicates the rarity of the syndrome in children. Routine testing for the Gerstmann elements in learning-disabled children may uncover unrecognized cases. PMID: 3611364 [PubMed – indexed for MEDLINE]

[vi] Hogg, William F. Reversal of eye preference at reading distance, associated with specific reading disability (dyslexia). Can Psychiatr Assoc J. 1968 Feb;13(1):85-6. No abstract available. PMID: 5640476 [PubMed – indexed for MED LINE] The author includes this ancient reference to show that many years ago, long before digital watches, he was interested in handedness and eye preference problems. The paper shows that in vision the concept of eye preference is preferable to the term dominance. As the visual fields have bilateral point to point connections to the occipital lobe, there is no dominant eye. But in reading one or the other eye is preferred. In dyslexia eye preference switches at reading distance! A simple clinical method for the determination of eye preference, that also demonstrates this switchover, was developed and presented.

[vii] PS: I noticed (and figured out) this ‘digital-analog’ peculiarity years ago, when digital watches first became the rage. My $500 early Japanese model, with glowing, flashing, changing display was quite useless. It had buttons galore and back and forward egg-timers and elapsed time stop-levers. But it got me no pulse. So, I bought me a $1000 Omega Seamaster sweep-hand in the early-70s and have happily used it ever since. It is a very good medical investment; every MD should have one, not necessarily a gold standard Omega, but a good sweep-hand of any type. But, the Swiss Omega-maker has cleaned and polished mine every five years or so free of charge. All I pay is the postage. Now isn’t all of that interesting? Thank you for your time. End. /wfh