Early Neurological Tools

James Parkinson did not use special tools to study the condition that bears his name.  Other investigators of the 19th century, however developed a wide variety of diagnostic and therapeutic technologies to study Parkinson's disease.  They borrowed or adapted instruments from general medicine or other medical specialties than neurology to define and quantitate tremor, strength, and gait/balance deficits.  Some of these instruments were simple gadgets, but others were complex and highly cumbersome appliances.  These new diagnostic technologies helped to define the distinctive aspects of Parkinson's disease and to differentiate this diagnosis from others.  Further, these tools fostered the growth of neurology as distinct from internal medicine and psychiatry, fields to which neurology was previously linked.  The use of distinctive instruments permitted neurologists to define themselves as specialists and provided important nosographic data that delimited the various phenomenological categories of not only Parkinson's disease, but other movement disorders as well.

Dynamometers
Charcot was adamant that the term, “paralysis agitans” and “shaking palsy” were misleading, because patients were not particularly weak.  He based his conclusions on studies using the  dynamometer, an instrument widely utilized in general medicine to measure muscle strength.  Many dynamometers were adaptations of the prototypic model manufactured by the Paris instrument-maker Mathieu.  Dynameters were promoted in trade catalogs, neurological texts, and journal articles, although   results were often inconsistent and difficult to interpret,  because clear standards for instrument construction, calibration, and examination technique were not established.

The Mathieu dynamometer was especially promoted and popularized by the American neurologist, William A. Hammond.  Hammond optimistically envisioned that the dynamograph would prove useful in diagnosis and management of patients with numerous neurologic disorders, including tabes dorsalis, stroke, and meningeal irritation.  Because the dynamograph incorporated a difficult-to-manufacture clockwork mechanism from Europe, it was an expensive apparatus for which American neurologists paid a steep $75.00 (in current dollars approximately $1,350) for its purchase.


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Mathieu Dynamometer and Dynamograph
The dynamometer (A) produced by Paris instrument-maker Mathieu was used to measure muscle strength. The Mathieu dynamograph (B) was used to graphically record the output of a dynamometer.  These instruments were later used, studied, and promoted by New York neurologist William A. Hammond. 

{for A}
Drawing of dynamometer from Mills, C.K. (1898) The Nervous System and its Diseases: A Practical Treatise on Neurology for the Use of Physicians and Students, p. 167.  Philadelphia: J.B. Lippincott Co.

{for B}
Drawing of dynamograph from Hammond, W.A. (1871) A Treatise on Diseases of the Nervous System, p. XX.  New York: D. Appleton & Co.

Tremor Recorders
19th century tremor studies were based initially on simple observation and later on the use of graphical recording devices, like tambours and sphygmographs that were modified from instruments developed for other purposes.  A tambour used a drum-shaped pneumatic mechanism to transmit movements to a recording instrument, whereas the sphygomograph was a non-pneumatic mechanical device initially used to record the vascular pulse.

Charcot and Vulpian used tremor recordings to assist in their seminal differentiation between Parkinson’s disease and multiple sclerosis.  American neurologists Frederick Peterson, Charles Loomis Dana, and Augustus Eschner used increasingly sophisticated apparatus to record and study tremors, allowing them to make several important and novel observations.

Although 19th century measurements of tremor frequency were generally consistent with modern estimates, investigators found overlap among tremors in different diseases, precluding tremor recordings from being a definitive diagnostic tool.  Graphical recordings of tremors, however, allowed investigators to demonstrate that 1) tremor frequency varies in different body parts, due to different resonance frequencies as a function of weight and elastic properties; 2) tremor amplitude and frequency are inversely related; and 3) the tremor of Parkinson’s disease is a relatively low-frequency rest tremor, suppressed by action, and generally synchronous in symmetric body parts, but varying in amplitude and frequency in different body parts or over time. 


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B
Charcot and “myographic curves” 
A.  French neurologist Jean-Martin Charcot (1825-1893).
Portrait of Charcot: Private Collection, courtesy of MDS Member, Christopher G. Goetz, MD, Chicago, IL.

B.  Semi-diagrammatic “myographic curves” published by Charcot in 1887.  The top tracing represents an intention tremor in multiple sclerosis.  Segment AB indicates “at rest”, and BC indicates increasing oscillations during voluntary movement.  The lower tracing represents a Parkinsonian tremor.  Segment AB indicates a tremor at rest, which persists in segment BC during voluntary movement.  Charcot’s graphical recording method upon which these drawings were based is not described, but in other circumstances he relied on various pneumatic tambour-like mechanisms.
Tracing from Charcot JM. Tremors and Choreiform Movements.  Rhythmical Chorea.  In: Clinical Lectures on Diseases of the Nervous System: Delivered at the Infirmary of La Salpêtrière, Vol 3.  Translated by T. Savill.  London, New Sydenham Society, 1889, 183-197.


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B
Gowers and “myographic tracings” 
A.  British neurologist William Gowers (1845-1915).
Photograph of William R. Gowers: Courtesy of the National Library of Medicine.

B. Gower’s illustrations of “myographic tracings” of various forms of tremor c1888 from patients with: 
1.  Hemiplegia;
2-6. Parkinson’s disease;
7. Multiple sclerosis;
8. Neurosyphilis; and
9. Hysteria. 
Gowers did not indicate how his tracings were made, and his estimates of the tremor frequencies do not match his published recordings.
Tracing from Gowers WR.  A Manual of Diseases of the Nervous System.  Philadelphia:  P Blakiston Son and Co., 1888; 995-1014.

 


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B

C
Peterson and sphygmograph tracings of tremor
A. New York neurologist Fredrick Peterson (1859-1938).
Photograph of Frederick Peterson:  Courtesy of the National Library of Medicine.

B. The Edward sphygmograph utilized by Peterson c1888.  A wire stylus transfers perturbations onto smoked paper, which moves forward at a fixed speed by clockwork-driven rollers.
Sphygmograph from Peterson F. A Contribution to the Study of Muscular Tremor.  J Nerv Ment Dis 1889;16:99-112.

C.  Negatives of Peterson’s sphygmographic recordings of tremors (each is 10s duration).  Peterson’s estimates of tremor frequency are generally consistent with modern estimates.  These were the most sophisticated tremor recordings made to this point.
Tracings from Peterson F. A Clinical Study of Forty-Seven Cases of Paralysis Agitans.  NY Med J 1890;52:393-398.


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B


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Eshner and simultaneous tremor recording
A. Philadelphia physician Augustus Eshner (1862-1949).
Photograph of Augustus Eshner:  Courtesy of the National Library of Medicine.

B. Eshner’s tambour recording apparatus c1896 for simultaneous recording from both hands.  Eshner used this device to simultaneously record tremor from different body parts.
Photograph of apparatus from Eshner AA.  A Graphic Study of Tremor. J Exp Med 1897; 2:301-312.

C. Tracings from Eshner's apparatus. From Eshner AA. A Graphic Study of Tremor. J Exp Med 1897; 2:301-312.

Eschner’s work was performed at the Philadelphia Orthopedic Hospital and Infirmary for Nervous Diseases at the suggestion of Silas Weir Mitchell.  Escher showed that amplitude and frequency are inversely related, that the tremor of  Parkinson’s disease is generally synchronous in corresponding body parts, and that the tremor of Parkinson’s disease is suppressed with action.

Gait Analyses
One of the earliest techniques of gait analysis was to have patients walk on smoked paper so that their bare feet displaced the soot and left an imprint.  The stride length, base of stance, and planting of the foot on the surface were all detected with this methodology.  Among researchers in this field, Gilles de la Tourette wrote his thesis on gait analysis in health and disease, using cases of Parkinson’s disease and the marche à petits pas as cases of particular interest. William Osler also employed this technique.


A

B
Gilles de la Tourette and Footprint Diagrams
A. French neurologist George Gilles de la Tourette (1857-1904).
B. Footprint diagrams from the doctoral thesis of Gilles de la Tourette (1885) entitled Etudes Cliniques et Physiologiques sur la Marche.  This student work analyzed normal gait as well as the walking patterns of patients with Parkinson’s disease, locomotor ataxia, Friedreich’s ataxia and numerous neuropathies.
Portrait of Tourette and drawing of footprints:  Private Collection, courtesy of MDS Member, Christopher G. Goetz, MD, Chicago, IL.

Later techniques beginning in the late 19th century utilized sequential photography or motion pictures.  Philadelphia neurologist Francis Dercum (1856-1931) made a number of important observations on gait over the period from 1885 to 1888.  Some of his insights came from his clinical work, but much of his detailed observations derived from his collaboration in 1885 with pioneering American motion-picture photographer Eadweard Muybridge (1830-1904).  Muybridge had pioneered efforts at motion picture photography with the collodion and gelatin dry plate technology of the 1870s and 1880s, using sequential images taken with a series of uniformly spaced, mechanically or electronically triggered, single-image cameras, and projection with a rotating disk of transparencies.  The Dercum-Muybridge collaboration at the University of Pennsylvania in 1885 produced classic sequential images of abnormal movements in patients with neurological disease, the earliest examples of motion pictures of medical subjects.  Other early contributors to the cinematographic analysis of gait were G. Marinescu and A. van Gehuchten. 

In the late 1880s and 1890s further technological developments occurred, including the development of celluloid roll film, true motion-picture cameras (i.e., single cameras capable of creating multiple sequential images on roll film), and mechanical projectors that utilized mechanical innovations to create intermittent motion by synchronizing film and shutter motion.  Neurologists quickly capitalized on motion picture technology to record abnormal movements and to make representations available for study and education of trainees.

Indeed, by the turn of the century, several neurologists in the United States and Europe were experimenting with the new motion picture technology. 

From 1907-1912, with the assistance of photographer Sigmund Lubin, Philadelphia neurologist Theodore Weisenberg recorded approximately 10,000 feet of motion picture film of patients with nervous and mental diseases, including images of patients with Parkinson's disease.  In 1911, Weisenberg was the first to include strips of motion picture images of various neurologic conditions in medical textbooks.

Early motion picture sequences of a patient with Parkinson’s disease 
From 1907-1912, with the assistance of photographer Sigmund Lubin, Philadelphia neurologist Theodore Weisenberg recorded approximately 10,000 feet of motion picture film of patients with nervous and mental diseases, including images of patients with Parkinson's disease.  In 1911, Weisenberg was the first to include strips of motion picture images of various neurologic conditions in a medical textbook, A Text-book of Medical Diagnosis by James M Anders and L. Napoleon Boston.  The images shown were labeled “Moving picture of attitude and gait in Paralysis Agitans.”

Postural Sway Measures
Late 19th century neurologists developed several instruments to measure and record postural sway, and these were also applied to patients with Parkinson’s disease. The efforts of these pioneering neurologists anticipated later physiologic studies, and ultimately the introduction of computerized dynamic platform posturography.  Among these instruments were simple sway meters and “ataxiagraphs” for graphically recoding postural sway.  Philadelphia neurologist Silas Weir Mitchell and his pupil Guy Hinsdale were pioneers in the development of this technology.  In the early 20th century a number of investigators were using such technology in studies of normal physiology and pathology.


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B


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Mitchell’s Sway Meter
A. “Sway meter” developed by Philadelphia neurologist Silas Weir Mitchell (1829-1914).  It consisted of a pair of graduated rulers oriented perpendicular to each other and fixed upon a stand. 
Drawing of sway meter from Mitchell SW, Dercum FX.  Nervous Diseases and Their Treatments:  General Considerations.  In: Dercum FX, ed. A Text-Book on Nervous Diseases by American Authors.  Philadelphia: Lea Brothers & Co., 1895:2-50.

B. Mitchell examining a patient at the Philadelphia Orthopedic Hospital and Infirmary for Nervous Diseases c1890.  In the background (on the right) is Mitchell’s sway meter.  In his right hand, Mitchell is holding a reflex hammer invented c1888 by his assistant, John Madison Taylor (seated, recording Mitchell’s observations).
Photograph courtesy of the Library of the College of Physicians of Philadelphia.

C.  Another image of Mitchell at the Philadelphia Orthopedic Hospital and Infirmary for Nervous Diseases.  In the background (on Mitchell’s right) a man is leaning on Mitchell’s sway meter.  Mitchell is holding his Taylor reflex hammer.  Photograph courtesy of the Library of the College of Physicians of Philadelphia.


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B

Charles Dana and the Ataxiagraph
A.   New York neurologist Charles Dana (1852-1935).
Photograph courtesy of the National Library of Medicine.
B.   The “ataxiagraph” employed by Dana for graphically recording postural sway in the late 19th century.  The device was similar to the graphical recording device employed earlier by Hinsdale.  Dana also utilized sophisticated sphygmographic techniques to record tremors, and was one of the earliest to describe familial postural tremor.
From Dana CL, ed. Text-Book of Nervous Disease Being a Compendium for the Use of Students and Practitioners of Medicine.  5th Ed. New York: William Wood & Co., 1901: 39-59.


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B

Hinsdale and Early Posturography
A. Philadelphia neurologist Guy Hinsdale (1858-1948) at the Infirmary for Nervous Disease in Philadelphia (c1888-1889).  Hinsdale (seated, 2nd from left) was the chief clinical assistant to William Osler (seated in center of photo) and worked extensively with sway apparati.  On the table are texts and atlases, a skull, and fixed brain sections. 
Photograph courtesy of the Library of the College of Physicians of Philadelphia.

B. Postural sway of a healthy person (top) and a patient with tabes dorsalis (bottom), recorded by Hinsdale using a graphic recording apparatus (c1887).  To make the recordings, smoked paper was placed on a piece of cardboard and attached to the patient’s head.  The subject stood under an index, which was free to move up and down in a fixed vertical line. 
Sway recording from Mitchell SW, Dercum FX.  Nervous Diseases and Their Treatments: General Considerations.  In: Dercum FX, ed. A Text-Book on Nervous Diseases by American Authors.  Philadelphia: Lea Brothers & Co., 1895:2-50.


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