Essential tremor in ‘The tremulous hand of Worcester’: additional comments

Sir,

I read with great interest the paper by Thorpe and Alty on the kinetic tremor observed in the handwriting of the 13th century scribe who is known as ‘The tremulous hand of Worcester’ ( Thorpe and Alty, 2015 ). I agree with the authors that the most likely diagnosis is essential tremor. Essential tremor is extraordinarily prevalent; indeed, aside from enhanced physiological tremor, it is the most common cause of tremor in humans ( Louis and Ferreira, 2010 ), and based solely on population prevalence, the notion that this was essential tremor is a reasonable one. It is worth noting that one may find other documentary evidence of essential tremor in early handwritten texts. Indeed, three of the 56 signers of the American Declaration of Independence had essential tremor at the time or were developing it. These were Stephen Hopkins, Samuel Adams ( Louis, 2001 ) and John Adams ( Louis and Kavanagh, 2005 ); in the document, the tremor is most notable in Hopkins, who commented on it during the signing.

As pointed out by the authors, the quality of the handwriting of ‘The tremulous hand of Worcester’ is also consistent with essential tremor. With its remarkably regular oscillations, it looks strikingly similar to that of the abovementioned individuals and others with essential tremor. One argument against Parkinson’s disease is the absence of micrographia, which would have been detected as small letters or a reduction in the size of letters across a word or across a sentence (i.e. a decrement of amplitude). Such decrement does not seem to be apparent in the writing samples provided by Thorpe and Alty (2015) . Furthermore, it is of interest that the authors note the presence in some places of augmentation in the amplitude of the letters. We have previously reported the presence of macrographia as a feature of essential tremor ( Martinez-Hernandez and Louis, 2014 ). It is not clear whether this is the result of the cerebellar dysfunction in essential tremor or a compensatory mechanism attempting to clarify writing with larger letters.

I put forth the following additional considerations. In Fig. 2, the authors point out what is from one line to the next a clear reduction in tremor amplitude. They theorize that the scribe may have been experiencing fatigue, may have taken a break, and then may have returned to writing with a rested and steadier hand. Another possibility is that he may have changed the position of his hand so that he was in some way resting or steadying it more on the writing surface. The ability to steady the writing hand can result in marked reductions in handwriting tremor in patients with essential tremor ( Fig. 1 ).

Figure 1.

A patient with essential tremor attempts to draw Archimedes spirals with the right hand (A and B) and the left hand (C and D). In B , the writing hand is not steadied on the writing surface and the patient is not able to produce a legible spiral. After the patient steadies his hand on the writing surface, there is a marked reduction in tremor amplitude ( A ). Similarly, in C , there is a reduction in tremor amplitude (steadied hand) compared to D (not steadied).

My final comment is that the tremor is of moderate rather than marked severity and, for the samples provided, there seems to be no tremor in and out of the plane of the paper. That is, there seems to be a tremor in the x and y axes but not the z axis. Such multi-planar tremor can render writing very difficult. Given the presence of moderate bi-planar tremor rather than severe tri-planar tremor, the scribe did not seem to be completely disabled and was able, during the time period of these documents, to continue writing.

The report by these authors draws attention to and provides clear visual documentary evidence of the presence of a tremor diathesis from nearly a millennium ago, underscoring the fact that such disorders have been part of the human condition for a very long time.

Funding

Dr Louis has received research support from the National Institutes of Health: NINDS #R01 NS042859 (principal investigator), NINDS #R01 NS086736 (principal investigator), NINDS #R01 NS085136 (principal investigator) and NINDS #R01 NS088257 (principal investigator).