Symptoms and signs of carpal tunnel syndrome
The earliest symptoms of CTS are usually tingling / pins and needles, in some combination of the thumb, index, middle and ring fingers which most characteristically wake the patient during the night, usually at about 3:00 am but a variety of other things may be noticed by the patient or medical professional examining the hand.
Tingling/Pins and Needles (Paraesthesiae or Acroparaesthesiae)
This sensation is familiar to most people from the common experience of having a foot 'go to sleep' after sitting in an awkward posture for some time or after hitting the 'funny bone' at the elbow on a door frame. In ordinary life this sensation is mostly perceived as mildly unpleasant but distinct from 'pain'. In carpal tunnel syndrome the distinction between tingling and pain can sometimes become blurred, the tingling of CTS sometimes possessing a peculiarly unpleasant character. The anatomical distribution of the median nerve suggests that this abnormal sensation should be felt only in the thumb, index and middle fingers and the adjacent side of the ring finger but in some patients it appears to spread outside this area. Patients who get tingling ONLY outside this area probably do not have CTS.
Numbness / Loss of sensation
Whereas tingling/paraesthesiae can be thought of as an increase in sensation, this symptom refers to reduced sensation. It is rare for a digit to become completely numb in CTS such that no touch, pinprick, pain, burn etc can be felt at all but a perception of loss of sensitivity of the fingertips is common and when persistent suggests more severe nerve impairment. As with tingling, this symptom should theoretically occur only in the anatomical territory of the median nerve but some patients do seem to experience more widespread numbness. Occasionally loss of sensation can become so severe that the patient does begin to suffer injuries to the fingertips without noticing - burns being the most common.
This patient had no measurable function in the median nerve when tested and did not remember how these lesions of the fingertips developed.
Pain, as a distinct sensation recognisably different to tingling and numbness, undoubtedly occurs in carpal tunnel syndrome and can be an early or late feature. It is also the most variable symptom in distribution, sometimes affecting not only the hand and fingers but the arm all the way up to the shoulder. The mechanism by which CTS causes pain is poorly understood and patients attending the Canterbury clinic may notice that we ask a lot of questions about it while we try to understand the differences between patients in this respect.
We have assisted with a research study, based in Oxford and London, the - PiNS Study. This is now complete and demonstrated interesting changes in the small nerve fibres which carry pain sensation in carpal tunnel patients.
A surprising number of patients use this word to describe a sensation experienced in the hand for which there seems to be no entirely satisfactory technical medical term. It is a sudden, unpleasant, shock-like sensation in the palm and or fingers, or occasionally spreading into the forearm, usually precipitated by some movement of the hand. The analogy which patients seem to be making is that of plucking a tight string or suddenly releasing a rubber band. This symptom is described both by untreated and treated patients but seems to be especially noticeable after carpal tunnel surgery. It's relationship to carpal tunnel syndrome and exact cause are uncertain.
Many patients feel that the hand is swollen, or the fingers 'feel like sausages'. Objective examination of the hand and fingers usually fails to reveal any measurable enlargement of either hand or digits and in most cases this feeling of swelling is probably a misinterpretation of the sensations of numbness and clumsiness. There IS often a modest swelling just above the wrist, over the flexor tendons. This is referred to in the American literature as a 'volar hot-dog' and is of uncertain nature. Other swellings which are visible to an observer along with all forms of deformity of the hand joints are usually indicators of other disease processes (some of which may cause secondary CTS).
A common perception in CTS patients is that the fingers are stiff but when passively flexed by an examiner this is not usually the case. True rigidity of the fingers, like swelling, is usually an indicator of other diseases, either rheumatological (rheumatoid arthritis, systemic sclerosis), or neurological (dystonia, stiff person syndrome, spasticity of any cause). 'Locking' of the fingers in a flexed position is usually an indicator of 'trigger digits' - a separate condition which is frequently associated with carpal tunnel syndrome.
Coldness and Colour change
The hands may feel subjectively cold (or occasionally hot), but as with many of the symptoms described here measurement of the hand temperature usually does not reveal dramatic coldness. There have been studies of thermography (detailed imaging of the skin temperature) as an aid to diagnosis in CTS which suggest that there are slight changes in temperature but this has not taken off as a diagnostic method (Reilly 1989, Papez 2009). Marked coldness of the fingertips combined with colour change is sometimes a clue to the presence of Raynaud's disease, which is essentially a disorder of the small blood vessels. As with trigger finger, there may be an association between Raynaud's and carpal tunnel syndrome (Hartmann 2011).
Loss of power in the hand is a common complaint. It tends to be most marked for movements which involve use of the small muscles at the base of the thumb - pinch grip and manipulating small objects - and less marked for power grip, although power grip can be mildly impaired after surgery for CTS.
Even though there is usually not much demonstrable weakness of grip people with CTS do complain that they drop things a lot and CTS is responsible for a great deal of broken crockery. The mechanism for this is unclear and perhaps reflects a complex disturbance of motor control resulting from impaired proprioceptive input from the hand, modification of central control mechanisms in response to abnormal sensory inputs and subtle disturbance of function of the thenar muscles resulting from phenomena like frequency dependent conduction block.
Visible thinning of the muscles at the base of the thumb is a late feature of CTS indicating severe disease. Sometimes however, osteoarthritic degeneration of the underlying joints can lead to an appearance of wasting of these muscles when they are in fact normal in bulk and strength. An example can be seen on this page.
Tremor of the hand is NOT a symptom of CTS.
The next obvious question is 'Why do some people get CTS and not others?'
Revision date - 24th February 2012