There is almost universal agreement that the best single guide to the diagnosis is the story told by the patient about the symptoms. The most characteristic feature of this is an account of awakening regularly in the middle of the night with unpleasant tingling and numbness in the hand but not every patient gets this and good clinicians take into account many subtle details of the overall story in reaching an opinion about how likely CTS is as a diagnosis. The symptom questionnaire found on this site is an attempt to standardise this way of reaching a diagnosis. It suffers from the fact that the history has to be elicited by leading questions rather than being volunteered spontaneously by the patient and answers have to be mathematically precise - there is no room for free expression in describing the symptoms to the computer, nor can it anticipate every special circumstance which could possibly apply in the individual patient. On the other hand the extent of the information collected is more extensive than would be managed by the average busy general practitioner and the analysis of the answers by mathematical methods may be more precise than the human brain in evaluating the probability of CTS.
The development of the symptom questionnaire and initial evaluation of how it performs on new data collected using the paper version is described in Bland (2011). It is now freely available here for anyone to use, whether or not you choose to register with the site but remember that it is only an aid to diagnosis - not 'gospel truth'. In particular you should be aware of the following:
1) The questionnaire is aimed at people who do not already have a diagnosis of CTS - if a doctor has already made the diagnosis and it has been confirmed by nerve conduction studies or ultrasound then it does not matter what your symptom score is - you have CTS!
2) CTS symptoms can change over time as the disorder becomes more severe. The questionnaire looks for the typical features of early to moderate CTS and will be less accurate in people with very advanced disease. We also know that it is slightly less accurate in people with diabetes, whose symptoms of CTS are often a bit odd. When answering the first part of the questionnaire (before 'severity assessment') you should be thinking of the symptoms as they were at their worst - if they have eased off recently.
More detail regarding the questionnaire can be found here.
Revision date - 14th March 2012