The information - carpal tunnel syndrome
GPSI in minor surgery Dr Matthew Wordsworth continues our series of evidence-based lowdowns on common presentations using PUNs and DENs
The patient's unmet needs (PUNs)
A 50-year-old woman attends the surgery complaining of pain in her right hand that has been getting worse for about three months. She also suffers paraesthesiae in her thumb and index finger on the same side and complains that the symptoms wake her from sleep.
You diagnose carpal tunnel syndrome (CTS) and explain the treatment options. She is unwilling to consider an injection or surgery without confirmation of the diagnosis. She also points out that a friend with the same diagnosis was given ‘water tablets' and wants to know your views.
The doctor's educational needs (DENs)
How accurate is a clinical diagnosis of CTS?
How important is absolute confirmation of the diagnosis, and how is this best achieved?
CTS is primarily a clinical diagnosis. The sensitivity and specificity of the diagnosis will depend on elucidating the typical symptoms and signs and excluding other common differential diagnoses.
The most helpful presenting symptom is paraesthesiae. If a patient complains of paraesthesiae in the median nerve distribution, which is causing them to wake at night or is present first thing in the morning on waking, then CTS is likely. They may also complain of paraesthesiae while driving or holding the phone. Sometimes patients will describe their fingers feeling or actually being swollen in the morning – this is usually part of the paraesthesiae, but you should make sure patients are not describing true joint swelling.
The median nerve distribution is the thumb, index, middle fingers and radial half of the ring finger. Patients will often say all fingers are affected, but it is helpful to ask directly if the little finger is actually spared – if so, then that's a good description of the median nerve distribution being affected.
If symptoms are mostly medial then this may point to an ulnar nerve problem. This woman only has paraesthesiae in the thumb and index fingers – but as she is female, in the commonly affected age group and waking at night, CTS is still likely. The pain experienced by patients varies. Shooting pains from the wrist up the forearm or down into the fingers is a useful symptom in the diagnosis of CTS, as is a more diffuse pain in the forearm. Patients also often describe a general ache around the wrist.
If patients describe pain starting in the neck or shoulder area and travelling down the arm, this should alert you to the possibility of nerve-root impingement.
Initial examination should only take a couple of minutes and mainly includes looking for muscle wasting or weakness of thumb abduction, testing by light touch for diminished sensation at the tips of all fingers, Tinel's and Phalen's tests and a brief examination of the neck and shoulder for symptoms in these areas.
Older patients with CTS can rapidly develop permanent neurological deficit (thenar muscle wasting and permanent sensory loss).
In some cases, nerve conduction studies can be useful in confirming the diagnosis of CTS, but it would be unusual to do this in general practice prior to starting conservative treatments.
Common practice, and that advocated by the British Society for Surgery of the Hand, would be to use nerve conduction studies where there was diagnostic uncertainty, where you wanted to exclude an underlying peripheral neuropathy, where occupational issues are raised and for medico-legal reasons.1 Nerve conduction studies have a specificity and sensitivity of around 95% – but be cautious about using some of the hand-held devices.
How often is there an underlying cause, and should any tests routinely be performed to rule these out?
It is uncommon for an underlying cause to be found, but we should always remain vigilant. Consider a possible flare of osteoarthritis affecting the wrist, or inflammatory arthritis, and refer appropriately. There is no evidence to suggest all patients with possible CTS should be tested for for hypothyroidism, diabetes and B12/folate deficiency, but certainly consider testing if there are clinical pointers to an underlying issue.
The current literature does not support a causal relationship between specific work activities and the development of CTS, but symptoms may be associated with work activities in some patients.
Is there any evidence for the use of diuretics or any other specific medication?
Diuretics have been tried in the past, presumably on the basis that reduction of any oedema might relieve symptoms. But there is no evidence in favour of diuretics or any other medications.
How effective is splinting, and is this a long-term solution? Is local cortisone injection effective and, if so, should it be seen as diagnostic or potentially curative?
Untreated CTS will resolve or significantly improve in between 34% and 49% of cases.1 Night-time splinting is an effective means of symptom control while awaiting spontaneous improvement.
Local steroid injections are a useful conservative treatment, though conclusive evidence of their effectiveness for long-term relief is lacking.2 Most recent reviews by local public health consultants and commissioners would advocate a trial of steroid injection.
But you should consider that steroid injections are less likely to be of benefit in patients with severe symptoms, once symptoms have been present for a year, in patients with diabetes and in the elderly.
You should also always actively follow up any elderly patients treated with steroid injections, as these patients are at increased risk of permanent neurological deficit.
Which patients should be referred for decompression and how good are the results of surgery?
Patients with severe CTS should be referred immediately. Severe CTS as classified by the British Society for Surgery of the Hand includes those patients with symptoms and signs of neurological deficit and those with diminished sensation in the median nerve-supplied digits. Severe CTS would also include those patients with disabling pain.
You should also refer patients with mild or moderate CTS where symptoms persist despite the conservative measures of night-time splinting or steroid injection.
If there is diagnostic uncertainty then referral may be necessary, but it may be more effective to ask for the opinion of a practice colleague initially.
Carpal-tunnel release is an effective evidence-based treatment.3
It is common in the first couple of months following surgery for patients to complain of some discomfort in the palm, for the scar to be tender and discoloured – purple or a deep red colour – and for the hand to remain weak.
The amount of time off work varies and will depend on the nature of the patient's job, but is usually between one and four weeks. If a patient complains of ongoing pain and weakness following surgery, early referral to a hand therapist may help prevent the establishment of complex regional pain syndrome.
Recurrence happens in one in 200-300 cases and very rarely the motor branch of the median nerve can be damaged. Severe infection is also rare.
Dr Matthew Wordsworth is lead for hand surgery at the Association of Surgeons in Primary Care and director of the Independent Health Group
1 British Society for Surgery of the Hand. Guidelines for treatment of carpal tunnel syndrome. October 2010
2 Marshall S, Tardif G and Ashworth N. Local corticosteroid injection for carpal tunnel syndrome. Cochrane Database Sys Rev 2007;18:CD001554
3 American Academy of Orthopaedic Surgeons. Clinical practice guideline on the treatment of carpal tunnel syndrome. September 2008