What is carpal tunnel syndrome?

    Carpal tunnel syndrome (also KTS, carpal tunnel syndrome or CTS) is a common disease that is based on damage to the metacarpal nerve (nervus medianus) on the wrist. The metacarpal nerve runs from the shoulder to the fingertips. It conveys the feeling of the thumb, forefinger, middle finger and half of the ring finger. The nerve traverses certain spatially limited places. The narrow point on the wrist is the so-called carpal tunnel and is also known as the carpal canal, through which the flexor tendons also run. The space is limited by a tight ligament of connective tissue (retinaculum flexorum) and the carpal bone. The metacarpal nerve runs through this tunnel along with nine tendons. Nerves are very sensitive to pressure, for example after crossing the legs for a long time. If, for various reasons, there is not enough space in the carpal tunnel, the metacarpal nerve (nervus medianus) will suffer from abnormal sensations. Colloquially one speaks of falling asleep of the fingers, in technical language of a Brachialgia paraesthetica nocturna.

    1 Connective tissue covers vessels and nerves 2 Deep flexor tendon 3 Finger nerve 4 Finger artery 5 Superficial flexor tendon 6 C1 Ring belt 7 A2 Ring belt 8 A1 Ring belt 9 Cutting of the ring band splitting 10 Thickened flexor tendon 11 Median nerve (median nerve) 12 muscles of the ball of the thumb 13 Incision of the carpal tunnel split 14 Connective tissue ligament (Retinaculum flexorum) 15 ulnar nerve (ulnar nerve) 16 Ulnar artery (Arteria ulnaris) 17 Palm branch of ulnar nerve 18 Median nerve belonging to the palm of the hand 19 Cutaneous nerve from the brachial plexus

    How common is carpal tunnel syndrome?

    The carpal tunnel syndrome is one of the bottleneck syndromes (peripheral nerve compression syndromes). The metacarpal nerve in the carpal tunnel is affected in 90 percent of all bottleneck syndromes. 3.1 percent of the general population will suffer from KTS at some point in their life. Pressure damage to the metacarpal nerve on the wrist occurs in 1.73 out of 1000 people per year. Women are affected about twice as often (Pourmemari M.-H., et al., 2018, Muscle Nerve). The 50-year-old age group is most commonly affected.

    What are the symptoms of carpal tunnel syndrome?

    The first signs of the syndrome are numbness or tingling in the fingers. This is caused by the pressure on the metacarpal nerve. Often the feeling is also described as an “electrifying”. The symptoms occur in the affected hand on the thumb, index finger, middle finger and half of the ring finger. In carpal tunnel syndrome, sensation at the base of the thumb and back of the fingers is normal. Initially, the typical symptoms usually occur at night while lying down and thus disturb the night’s rest. To relieve symptoms, some shake hands vigorously. Others hold their hand under cold running water. The longer the nerve is constricted, the more severe and lasting the nerve damage. Pain in the wrist that radiates to the arm or hand is not a typical symptom of KTS [1]. If the nerve impulses are no longer transmitted to the corresponding muscles, muscle atrophy occurs at the ball of the thumb. The ball of the thumb looks as if it has caved in due to muscle atrophy. Almost one third of patients with carpal tunnel syndrome also suffer from the so-called snapping finger [2].

    Typical findings of a KTS: A sunken ball of the thumb and a smooth fingertip relief.

    Carpal tunnel syndrome or herniated disc of the cervical spine

    The nerve fibers of the metacarpal nerve arise from the spinal cord as a plexus of nerves in the arm. Each nerve fiber supplies different muscles or sensory cells. In principle, a nerve can suffer pressure damage from its exit from the spinal cord to the sensory cells or muscles. Depending on the location of the damage, different failure symptoms occur. The fibers from several nerve exit holes in the cervical spine unite in the metacarpal nerve. Such a hole contains nerve fibers that unite in different bundles. A pressure damage at the level of the exit hole therefore causes different failure symptoms than damage at the level of the wrist. Typically, carpal tunnel syndrome (KTS) is accompanied by an uncomfortable feeling of numbness in the fingers, especially at night. A herniated disc leads to pain, which usually subsides when lying down. In contrast to a KTS, if the cervical spine has a herniated disc, the back of the fingers of the affected hand are numb. A herniated disc can lead to a loss of strength in the shoulder, elbow or wrist. In a CTS, only the muscle of the ball of the thumb is affected.

    Carpal tunnel syndrome diagnosis

    At the beginning of every diagnosis there is a medical interview and a targeted questioning about symptoms of carpal tunnel syndrome and other possible diseases. This typically includes tingling in the first three fingers of the hand. Initially, the symptoms usually appear at night. In the further course the numbness occurs more frequently and the tingling or “electrifying” feeling persists during the day. Later there is a loss of sensation and muscle weakness. This consequence of the complaints rarely occurs with diseases other than the KTS. The hand is then examined. In the advanced stage, the ball of the thumb has collapsed and the skin ridges typical of fingerprints have passed. The skin on the first three fingers of the hand may be a little dry. The changes are often evident when comparing both hands. Various tests can trigger the symptoms during the examination. During the nerve compression test, the doctor presses his thumb between the balls of his thumb and little finger. In carpal tunnel syndrome, the fingers fall asleep after a few seconds. In the Phalen test, the wrist is fully flexed. The test is positive if numbness is felt in the fingers after 20 to 30 seconds. A positive Hoffmann-Tinel sign describes electrifying abnormal sensations when tapping the nerve in the area of ​​the constriction.

    Device-based examination procedures can refine the diagnosis. The attending physician can use electrophysiological examination methods such as electroneurography for this purpose. For this, a neurologist (neurologist) measures the transmission of electrical impulses along the nerve fibers. The measurement of the nerve conduction velocity provides information about the impulses of the sense of touch and muscle control. For reasons that are not yet clear, the impulses of the sense of touch are impaired at the beginning (sensory nerve action potentials: SNAPs). A nerve conduction speed of less than 50 meters per second over the carpal tunnel or a significant side difference indicates a CTS (carpal tunnel syndrome). The time between a stimulus impulse and the muscle response (distal motor latency) is often longer than 4.2 milliseconds in a CTS. Other measurement methods are only important for very specific questions. This includes ultrasound control (to measure the cross-sectional area of ​​the median nerve) and magnetic resonance imaging (MRI) of the wrist (to detect an abnormal nerve signal).

    1 Connective tissue ligament (retinaculum flexorum) 2 Muscles of the ball of the thumb 3 Median nerve 4 Carpal bone (hook bone)

    What are the causes of carpal tunnel syndrome?

    The question of the causes of carpal tunnel syndrome has been researched intensively for a long time. Interestingly, depending on the reading audience, very different answers can be found on the Internet. Medical Internet sites with patient information list vitamin B deficiency or the functioning of the computer as common causes. Scientific sources of information for doctors, however, speak much more often of an inherited predisposition. The sometimes misleading presentation of information on health portals has been scientifically examined and proven (Scangas G., et al., 2008, J Hand Surg Am). Discussions about the development of KTS should differentiate the causes and risk factors. Even though not all questions have been answered yet, there is much evidence that the cause of carpal tunnel syndrome is in the genes. Hormonal changes can promote the development of a carpal tunnel. Risk factors for carpal tunnel include diabetes, underactive thyroid, menopause and pregnancy. If the metacarpal nerve is critically tense in the early stages of the syndrome, additional external pressure can cause discomfort. For example, excessive stress at a later stage can lead to other symptoms at work or at leisure, for example, when riding a bicycle. The connection between the use of computers (keyboard or mouse) and KTS is still controversial (Lozano-Calderón S., 2008, J Hand Surg Am). Many scientific studies indicate that the belief that this is caused by overload or by the professional environment hinders the healing process (Ynoe de Moraes V., 2013, Patient Saf Surg). If the wrist or forearm bones are injured, the metacarpal nerve can be severely crushed. In technical terms, there is talk of an acute post-traumatic carpal tunnel syndrome.

    Treatment of carpal tunnel syndrome without surgery

    The goals of treatment can be divided into two categories: eliminating the cause or alleviating the discomfort. Anti-fever measures, for example, relieve the symptoms of a cold without fighting the virus that caused it. Conservative treatments can alleviate the symptoms of carpal tunnel syndrome without affecting the spatial confinement of the carpal canal. Many conservative treatment methods are recommended on health portals:

    • Physical measures: massage, occupational therapy, exercises (Liebscher Bracht), osteopathy.
    • Naturopathy: St. John’s wort oil, Traumeel, Retterspitz.
    • Homeopathy: globules, Schuessler salts.
    • Traditional Chinese Medicine (TCM): acupuncture.
    • Home remedies: Quark compresses, ointments.
    • Food supplements: Vitamin B6, DMSO (DimethylSulfOxide).
    • Apparatus treatment: low-energy laser application (low-level laser therapy), TENS devices, magnetic field therapy.
    • Aids: bandages, splint for the night, ergonomic keyboards.

    There is no scientific evidence for the effect of naturopathy, homeopathy, TCM, dietary supplements or home remedies in treating carpal tunnel syndrome (Choi G.H., et al., 2018, Cochrane Database Syst Rev). In particular, there is no high quality evidence of the effectiveness of exercise and mobilization of carpal tunnel structures (Page M.J., et al., 2012, Cochrane Database Syst Rev). The effectiveness of ergonomic keyboards in treating carpal tunnel syndrome is unknown (O’Connor D., 2012, Cochrane Database Syst Rev). Cortisone injections, anti-inflammatory medication, and an overnight rail can relieve the symptoms. The relief is usually only temporary. In the long term, the relief harbors the risk that an effective treatment will be delayed due to the reduced symptoms. Waiting too long to receive treatment can cause permanent nerve damage. Surgery can give the nerve more space and is superior to other treatments, especially at an advanced stage. There is no high-quality scientific evidence that carpal tunnel syndrome can be prevented or that it can be cured without surgery.

    Which doctor treats carpal tunnel syndrome?

    The treatment of KTS requires in-depth knowledge of the detection and treatment of diseases of the forearm and hand. The following arguments should help you to find the right specialist:

    • The detection of a KTS requires a reliable differentiation from similar clinical pictures in the field of hand surgery. The three-year additional training course to become a hand surgeon provides in-depth knowledge of the detection and treatment of diseases of the hand and forearm.
    • For optimal advice, it is necessary to weigh up various alternative treatment methods. A hand surgeon is experienced in performing surgical and conservative treatment methods.
    • A doctor with the additional designation “Physical Therapy and Balneology” is comprehensively trained in the use of conservative measures. The additional training imparts knowledge, experience and skills in physiotherapy and occupational therapy.
    • In 16% to 43% of cases, a KTS also has a snap finger that requires treatment (tendovaginosis stenosans) (Kumar P., et al., 2009, J Hand Surg Eur Vol). The treatment of other accompanying diseases of the hand or wrist can be ensured by a hand surgeon.
    • A hand surgeon is also trained to identify and treat rare complications such as restricted mobility, inflammation, or damage to adjacent structures.
    • The KTS can also be caused by tumors or by individual anatomical features. The knowledge about this is imparted in a hand surgery training.
    • The European specialist designation (FESSH: European Society for Hand Surgery) is an additional award for a hand surgeon, which requires the passing of an additional written and oral examination.
    • Knowledge is constantly kept up-to-date through research and the training of medical students. The habilitation is the highest-ranking university examination in Germany and a recognition of technical expertise.
    • Lectures and contributions in standard textbooks distinguish the experience and specialist knowledge in a special way.

    When should carpal tunnel syndrome be operated on?

    Carpal tunnel syndrome is caused by an excessively narrow carpal canal. Pressure on the median nerve, if left untreated, leads to permanent numbness and muscle breakdown. The fingers falling asleep at night can be alleviated by a splint, a cortisone injection or an ergonomic keyboard. A relief of the discomfort is comparable to the lowering of fever with a flu. If the pressure on the nerve continues unnoticed, permanent nerve damage will result. Widening of the carpal tunnel through surgical therapy is the only known treatment that permanently improves the pressure on the nerve and thus the course of the disease. If there is only mild pressure on the nerve and temporary favoring circumstances, such as pregnancy, a conservative treatment attempt is warranted. The guideline of the AWMF (Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften e.V.) confirms that surgery is clearly superior to conservative measures. The procedure is also recommended for pregnant women if there are signs of failure.

    Carpal tunnel syndrome OP

    Surgical intervention to widen the carpal tunnel is the only known treatment that has a long-term positive effect on the course of the disease. The earlier the operation is performed, the better and faster the recovery of the constricted metacarpal nerve (Zyluk A., et al., 2020, Handchir Mikrochir Plast Chir). A distinction is made between the technique of open surgery (short longitudinal incision between the balls of the little finger and the balls of the thumb) and endoscopic surgery (keyhole method). The endoscopic technique requires a smaller incision and the remaining scar is about one to two centimeters shorter, but there is a greater risk of nerve injury (Sayegh ET, et al. 2015. Clin Orthop Relat Res). The procedure is carried out in a bloodless state and with the help of magnifying glasses in order to better differentiate the fine tissue structures. In the open surgical technique, on the other hand, an approximately three centimeter short skin incision is made between the ball of the thumb and little finger. The nerve is loosened from adhesions using microsurgical technology and the spanning ligament is expanded. The expansion of the ligament above the nerve (retinaculum flexorum) leads to an improvement in function and high patient satisfaction (Xu L, et al., 2011, J Pak Med Assoc). With appropriate follow-up care, a small, fine, inconspicuous scar remains. The nocturnal symptoms are usually significantly improved in the first night. The procedure takes about ten to twenty minutes. The risk of inflammation is increased in smokers and patients with comorbidities and averages 0.3 percent (Werner B.C., et al., 2018, J Hand Surg Am). Reluctant finger exercise after surgery can cause a complex regional pain syndrome. After the procedure, the patient should therefore move his fingers several times an hour according to the doctor’s instructions in specific exercises. Cooling and elevation prevent swelling of the hand.

    How long will you be unable to work after a carpal tunnel syndrome operation?

    The nocturnal tingling is usually completely eliminated immediately after a carpal tunnel operation. The longer the symptoms existed before the operation, the longer the nerve will take to recover afterwards. The wound pain is usually very slight. The skin sutures are removed ten to fourteen days after the operation. The fingers should be moved immediately after the procedure. Stress on the hand that goes beyond carrying a beverage bottle should be avoided for two to three weeks. A professional activity in the office can often be resumed after a week to ten days.

    How can you prepare for the procedure?

    • All your questions about possible complications and alternative treatments should be answered in advance.
    • Keep nicotine use to a minimum. The same goes for alcohol!
    • Surgery limits your ability to travel by air, so do not plan to travel by air in the 4 weeks following carpal tunnel syndrome surgery, either for business or pleasure!
    • Have ice cubes or cooling pads ready at home to cool the skin after the operation!

    What do you need to keep in mind after the procedure?

    • Elevating and cooling your hand for the first 72 hours is very important.
    • Complete fist closure and finger extension exercises should be performed several times every hour.
    • The skin sutures are removed after 10 to 14 days.
    • Postoperative clinical controls (physical examinations) are recommended on the 3rd postoperative day and after 1 and 2 weeks.
    • The independent scar massage from the 3rd postoperative week with moisturizing ointment (e.g. Bepanthen® wound and healing ointment, Linola® fat cream) helps to create inconspicuous soft scars..
    • Various light touch stimuli on the fingertips, such as learning to read Braille, encourage the nerves to recover.

    Carpal tunnel syndrome in pregnancy

    The appearance of discomfort around the due date leads to believe that carrying the baby creates a carpal tunnel. Hormones during pregnancy and breastfeeding can lead to water retention. If there is already a narrow carpal canal due to the condition, even small changes can lead to noticeable discomfort. The metacarpal nerve runs through the carpal canal at the wrist, along with nine tendons that are encased by tendon sheaths. Tendon sheaths are particularly sensitive to changes in the hormonal balance. Swelling of the tendon sheaths before or after birth can lead to pressure damage to the metacarpal nerve. If there is a slight tingling sensation in the fingers, an attempt at night treatment can be made with a positioning splint. If there are no improvements, German and international guidelines recommend relieving the metacarpal nerve as part of an outpatient surgical procedure under local or regional anesthesia.

    Experience reports on carpal tunnel syndrome operations

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    The author

    Dr. med. Stéphane Stahl

    “We provide you with extensive expert knowledge so that we can work with you to select the best possible treatment path.”

    Dr. med. Stéphane steel is the former director of the Clinic for Plastic, Reconstructive and Aesthetic Surgery / Hand Surgery at the Lüdenscheid Clinic. Dr. Stahl studied medicine at the Universities of Freiburg and Berlin. In 2011 he passed the European and 2012 the German specialist examination for plastic and aesthetic surgery. Further specialist qualifications and additional qualifications followed (including quality management, medical didactics, physical therapy, emergency medicine, laser protection officers, hand surgery) as well as prizes and awards. In 2015 he completed his habilitation in plastic and aesthetic surgery in Tübingen. He is an experienced microsurgeon, a sought-after expert and a regular speaker at specialist congresses. After a multi-stage selection process, Stéphane Stahl became a member of the American Society for Aesthetic Plastic Surgery (ASAPS), one of the world’s largest and most influential specialist societies for aesthetic surgery. His authorship includes numerous articles in respected peer review journals and standard surgical textbooks.


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