Approach

Patients with a clinical diagnosis of carpal tunnel syndrome (CTS) without electromyogram (EMG) confirmation should be managed conservatively with wrist splints.[39][40]​​​ If further treatment is required, patients should be referred for an EMG to classify the severity of CTS and guide management. Based on EMG findings, patients are usually classified as having mild, moderate, or severe CTS. 

Untreated CTS can spontaneously improve in up to one third of individuals, particularly in younger women (this finding may reflect the natural course of pregnancy-induced CTS).[41][42]

Clinical diagnosis of CTS without EMG confirmation

Initially, all patients should wear a wrist splint at night.​​[40]​​​[43][44]​ Low certainty evidence suggests that night-time splinting may improve symptoms of CTS, compared with no treatment.[40]​ Most patients do well with resting wrist splints that have a rigid palmar splint built in. In reality there is no difference between splints with the wrist in neutral and those with approximately 20° of extension, except the latter are probably more comfortable to wear (the resting angle of the wrist is about 10° to 20° extension).[45][46]​ Likewise, wearing the splint all day confers no extra benefit and is often restricting for the patient in their day-to-day activities.[46][47]​ The splint should be worn for at least 1 month continuously, or longer if in the mild category. In addition, some degree of activity modification may be prudent, depending on the patient's circumstances.

Mild or moderate CTS based on EMG findings

Patients with mild CTS on EMG have sensory nerve abnormalities with no axonal loss, and patients with moderate CTS on EMG have sensory and motor nerve abnormalities but with no axonal loss. These groups are treated conservatively, although patients with mild disease should be encouraged to continue with conservative treatments for longer.

If the patient has not had good relief from splints (1- to 2-month trial in mild CTS; up to 1-month trial in moderate CTS), then corticosteroid injections are recommended in conjunction with the splint.​​[48] Corticosteroid injections are associated with an improvement in hand function at 6 months, and a reduction in the need for surgery at 12 months compared with placebo.[48] One Cochrane review concludes that the available evidence is too uncertain for reliable conclusions to be drawn about the benefits of corticosteroid injections compared with surgery for patients with carpal tunnel syndrome.[49] However, it should be noted that all of the studies included in the review compared single corticosteroid injections with surgery which does not reflect usual clinical practice.[49] A more appropriate comparison to evaluate the benefits of these treatments would be multiple corticosteroid injections versus surgery.

There is no consensus as to which is the best type or dose of corticosteroid to use. The volume should be kept as low as possible, as injection of fluid could exacerbate the already raised pressure in the carpal tunnel. A response should be seen within 4 weeks. A follow-up study of patients who were randomized to receive a high-dose methylprednisolone injection, a low-dose methylprednisolone injection, or placebo, found no difference between groups in symptom severity at 5 years. However, patients in the high-dose methylprednisolone group were significantly less likely to have undergone surgery than those in the placebo group.[50]

There are no long-term studies of the risks of corticosteroid injections for CTS. A concern is that the corticosteroid could mask continued median nerve damage; EMG monitoring could identify this deterioration. Other risks with corticosteroid injection are nerve damage from intrafascicular injection, tendon rupture, and hemorrhage. There is also a risk of skin hypopigmentation and soft tissue atrophy. In people with diabetes there may be a temporary increase in hyperglycemia lasting several days.

Moderate CTS refractory to conservative management

There is very little or no evidence for the efficacy of other conservative treatments.[51][52][53][54]​ 

Patients with moderate CTS (sensory and motor nerve abnormalities but with no axonal loss) should undergo surgical release if they have not responded to splints (1 month trial), or to splints plus corticosteroid injection (>2 injections in 12 months).[55]

One Cochrane review reported moderate quality evidence that surgery may result in a higher rate of clinical improvement, compared with splinting for >3 months.[56]

Severe CTS based on EMG findings

Patients in the severe category (any evidence of axonal loss in sensory or motor nerves) should be referred for surgical release regardless of response to conservative treatment. It is unclear whether any specific rehabilitation after surgery is helpful.[57]

Pregnancy

In pregnancy, symptoms can appear rapidly and worsen rapidly, which may require aggressive intervention and close monitoring (both clinically and electrophysiologically).

Typically, it is recommended to persevere with a wrist splint given that after delivery, symptoms usually quickly dissipate within several weeks.[58] 

Patients who are worse or no better immediately following surgical release

Lack of improvement may be due to:

  • The carpal tunnel itself being inadequately decompressed (this is the most common reason)

  • Postoperative swelling, hematoma, or infection that can temporarily worsen CTS symptoms

  • The median nerve itself (or more commonly the palmar branch) being traumatized intraoperatively

  • Wrong diagnosis or compression is more proximal than carpal tunnel.

With any of the above situations, EMG studies (particularly when compared with preoperative studies) are key investigations to determine the state of the median nerve and subsequent management. If the tunnel is inadequately decompressed, then repeat surgery is necessary. Further investigation with ultrasound can be helpful to identify hematomas and aneurysms within the tunnel.

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