Carpal tunnel syndrome grade and treatment results

The literature review shows that the choice of treatment method in patients with CTS should be based on the duration of symptoms and their intensity.

Nerve Conduction Study (NCS) is the only objective way to localize compression in the upper limb, quantify the degree of nerve dysfunction and the progression of changes, and is therefore considered the gold standard. It enables confirmation of the diagnosis and objective assessment of the degree of nerve damage [8, 9].

The electrophysiological classification, in agreement with the American Association of Electrodiagnostic Medicine (AAEM) guidelines, follows the neurophysiological progression of CTS severity and includes the following classes [10]:

In the case of mild and moderate severity of the syndrome, it is recommended to attempt conservative treatment (which includes immobilization of the wrist in an orthosis) before deciding on surgery. Most studies show good results of conservative treatment in patients with mild and moderate CTS [1].

Studies by Šošić et al. [6] show that the use of the immobilizing scales at night has beneficial effects not only in patients with mild, but also with severe CTS. Therefore, this method of therapy is recommended for all patients, regardless of the stage of the syndrome [6]. This may be important information, especially in the case of patients qualified for surgery and awaiting surgery.

Use of the orthosis during the day/night

As a rule, the orthosis is only used at night for several weeks [1, 6, 11–13]. In the period of exacerbation of symptoms, it is advisable to use it also during the day during everyday activity [1, 7]. Similarly, Weng et al. [5] believe that wrist immobilization is an effective method of treatment, especially when it is also used during the day. Farahmand et al. [14] suggest wearing the orthosis at night, and during the day only when the patients so wish. Halac et al. [15] report that the use of the immobilizing splint at night may be an effective treatment method, but in patients with symptoms that occur only at night.

In patients with persistent symptoms that also occur during the day, it is necessary to use an additional form of therapy in the conservative treatment of CTS. According to Walker et al. [16] the use of splints part-time (at night) had a more positive effect on functional activities than the use of splints full-time. The full-time use of splints is often not preferred by patients [14]. Cochrane confirmed that night immobilization is more effective than placebo, but the authors did not find a specific orthosis model that gave the best treatment results [3].

The angle of immobilization of the wrist

The therapeutic effect of using orthoses is associated with preventing the adoption of extreme positions in the wrist, which translates into lowering the pressure in the wrist canal. It has been shown that resting intra-canal pressure in patients with CTS is elevated, and wrist positions that are further away from the neutral position may increase it. Wearing wrist splints in a neutral position or a slight extension of 0–15 degrees (most often 0–5 degrees) can increase the carpal tunnel space, reduce pressure on the median nerve, and thus alleviate symptoms. Moreover, the neutral position improves hemodynamic parameters [1, 2, 4, 6, 12, 14, 15, 17, 18].

According to Farahmandl et al. [14] the angle of wrist immobilization differs between different orthosis designs. In their experience, some doctors prescribe splints without paying attention to the angle of the wrist; which can lead to disappointment in patients with the results of the treatment. This may be due to the fact that some of the orthoses in use keep the wrist near a functional angle (more than 20 extensions), which appears to increase the pressure in the wrist canal [14]. Wipperman and Goerl [3] report that patients who use wrist immobilization in the neutral position were twice as likely to report an improvement in symptoms compared to the straightened wrist position. Sprouce et al. [4] report that the optimal restraining position is still debatable with limited evidence for a neutral position.

Individually made orthoses/prefabricated (traditional) orthoses

Available publications suggest that there are no statistically significant differences in treatment results in both groups of orthoses. Malakar et al. [17] compared the effectiveness of traditional and custom-made orthoses. The obtained results showed no differences between people using prefabricated orthoses with the wrist placed in the wrist extension position at an angle of 20°, and those made individually to order with a neutral wrist position [17]. Figueiredo et al. [19] confirmed the presence of clinical improvement in both groups of orthoses. A greater degree of improvement was observed in the group treated with individually made scales; however, the observed differences were statistically insignificant.

Individually custom-made wrist braces are more expensive than ready-made ones, and so far have taken a long time to make. 3D printer technology can overcome these problems, making it possible to produce personalized medical products at low costs, with a shorter production time compared to the production methods used so far (thermoplastic orthoses are still used today) [2].

The use of prefabricated splints should always be combined with an accurate measurement of the forearm and/or hand for a better fit. Moreover, when putting on the wrist orthosis, it should be checked whether the fastening straps are fastened too tightly, leading to the intensification of paresthesia or impaired mobility of the fingers caused by blood flow disorders [7].

Palmar/dorsal splint

The vast majority of orthoses used in the treatment of CTS are palm splints. The only study comparing the effectiveness of the treatment of both types of splints was conducted by Farahmandl et al. [14] A splint with a dorsal block positioned the wrist in the neutral position (0–5°), the MCP joints were in the 0–10° position of flexion, and the proximal interphalangeal (PIP) had flexion of 20–30°. The DIP joints (1–5) and the MCP joint of the thumb remained free from immobilization. The palmar splint covered only the wrist in the neutral position (0–5°) and ended just before the MCP. Thus, the MCP and PIP were free from movement restrictions. Non-elastic Velcro fasteners are used in the splint to increase the efficiency of the splint and reduce the relative movement of the hand and wrist.

Farahmandl et al. [14] claim that the use of a dorsal orthosis as compared to the palmar splints may give better treatment results.

Immobilization of the wrist only/immobilization of the wrist and metacarpophalangeal joints

As a rule, most splints do not extend beyond the distal flexion line of the wrist. The advantage of such a splint is that the fingers can move freely, thus allowing the normal performance of everyday activities.

In some orthoses, the aim is to immobilize the metacarpophalangeal joints of fingers 2–5. According to the authors, this prevents retraction of the lumbrical muscles proximally thus theoretically reducing the pressure in the carpal tunnel [1].

Lewis et al. [11] suggest that the decision on the type of orthosis to be used may depend on the result of the Berger test, also found in the literature as the lumbrical provocation test. This test is performed to determine whether the displacement of the lumbrical muscles into the carpal tunnel affects the severity of the characteristic symptoms of CTS. It consists in actively performing the maximum flexion of the fingers (with the wrist set in the neutral position) and maintaining this position for a period of 30 seconds [4] or 60 seconds [20, 21]. The test result is positive if symptoms appear or worsen in the area innervated by the median nerve during this time [11, 20, 21].

If the Berger test is negative, the use of a neoprene orthosis with individually molded thermoplastic braces, which keep the wrist in a neutral position without immobilizing the MCP joints, is recommended.

People with a positive result of the Berger test receive an orthosis, which also keeps the wrist in a neutral position, but it is additionally extended, reaching distally to the level of the proximal phalanges (and thus limiting the possibility of bending the metacarpophalangeal joints 2–5) [11].

Rigid orthosis/soft orthosis

A comparison of the treatment efficacy using a rigid and soft orthosis made by Ostergaard et al. [22] showed no statistically significant differences between the two types of orthoses. This suggests that the choice of the type of orthosis may depend on the patient’s preferences and the experience of the therapist.

Other aspects of the use of wrist orthoses

Although the use of splints is a simple and safe procedure, it has some drawbacks. Some patients say that, after all, wearing even the best-fitting orthosis is uncomfortable and limits the ability to perform some professional and everyday activities.

The need to discontinue treatment due to skin irritation or orthosis intolerance is reported by less than 1% of patients [1, 6, 22–27]. Due to the above, the use of kinesiotaping may be an alternative method of CTS treatment, the effects of which are similar to immobilization in an orthosis. The advantage of this form of therapy is that it does not limit the functional capabilities of the hand [18]. Studies by Yeong-Dong et al. [28] showed that the use of taping improved the electrophysiological parameters of the median nerve by reducing the pressure in the carpal tunnel. Therefore, the technique used can be treated as an early prophylactic method in patients with mild CTS [28].

Some authors, for example Lewis et al. [11], suggest that immobilization in an orthosis should be combined with patient education and home exercises (flexor tendon sliding exercises) [11, 12]. Similarly, Weng et al. [5] recommended wearing an orthosis while sleeping, and additionally instructed patients to avoid bending their wrists during everyday activities such as washing clothes, cycling, working at the computer, and carrying heavy shopping bags.

Kaplan et al. [13] confirmed that the addition of kinesiotaping to the night use of the orthosis was more effective in achieving improvement than the orthosis alone or the additional use of paraffin in patients with mild and moderate CTS. Howell et al. [7] report that immobilization in an orthosis may be combined with physiotherapeutic procedures in order to obtain even better treatment results.