Carpal tunnel syndrome G56.0

Pierre Marie and Charles Folix were the first to describe carpal tunnel syndrome in 1913. The possibility of surgical decompression by splitting the flexor retinaculum was described by James Learmonth in 1933.

The name was given by Moersch in 1938.

The Phalen sign was developed by George Phalen in 1966 and named after him (Neurologienetz).

Carpal tunnel syndrome (CTS) is a symptom caused by compression of the median nerve (Herold 2021). The main symptom is hands that fall asleep during sleep (Guidelines 2022).

CTS is the most common nerve compression worldwide (Padua 2016).

According to a meta-analysis of 87 studies, the prevalence of CTS is 10.4% and the incidence is 3.45 cases per 100,000 inhabitants per year, with the highest incidence among 40 to 60-year-olds. Women are significantly more frequently affected than men (Guidelines 2022).

Idiopathic carpal tunnel syndrome occurs in > 40 % of those affected. The majority of these are female (Herold 2021).

Carpal tunnel syndrome can occur in the context of other diseases such as:

• Rheumatoid arthritis
• Chronic overloading of the wrists in the form of a strong flexion or extension posture
• After trauma near the wrist
• Hormonal causes, e.g.
  • Acromegaly (due to increased GH)
  • Diabetes mellitus
  • Hypothyroidism (due to increased TSH)
  • Gravidity
• Amyloidosis in dialysis patients
• Gout
• Idiopathic carpal tunnel syndrome (Herold 2021)

With the. Aβ2M amyloidosis, KTS is often the first symptom (Kasper 2015)

The cause of carpal tunnel syndrome is synovitis of the tendon sheaths under the transverse carpi ligament (Herold 2021).

Risk factors are:

• Obesity
• diabetes mellitus
• Excessive consumption of alcohol (Guidelines 2022)
• hypothyroidism
• pregnancy
• Amyloidosis (Harinesan 2024)

The carpal tunnel is a shallow, U-shaped, bony groove formed by the carpal bones and volarly by the carpal ligament. This carpal tunnel contains nine flexor tendons as well as the median nerve. Compression or ischemic damage leads to CTS (Wang 2018).

Symptoms of carpal tunnel syndrome are:

• Painful falling asleep of the hands during sleep
• Numbness of the fingers 1 - 4
• As a late syndrome: Thenar atrophy (Herold 2021)

The painful tingling paresthesias initially occur preferentially in the middle and ring fingers, later also in the thumb and index finger with radiation into the arm. The symptoms can be improved or eliminated by shaking out, pumping movements, changing position or cold water (Guidelines 2022).

As the clinical picture progresses, symptoms of loss occur with increasing hypaesthesia. Finally, in the late stage, there is atrophy of the abductor pollicis brevis and opponens pollicis muscles (Guidelines 2022).

The diagnosis is largely made clinically (Osiak 2022). However, there are also various tests that can be used to confirm a diagnosis, such as:

- Phalen's sign:

Maximum flexion or extension can trigger the symptoms (Herold 2021).

- Hoffmann- Tinel test:

Triggering the symptoms by tapping the carpal tunnel (Herold 2021).

- Neurography

Neurography shows a reduced nerve conduction velocity of the median nerve (Herold 2021).

- Sonography

High-resolution sonography shows moderate sensitivity and low specificity with regard to the diagnosis of CTS. Sonography therefore plays a subordinate role in the diagnosis (Guidelines 2022).

- MRI

MRI is also less suitable for the diagnosis of CTS. The sensitivity varies between 72 - 96 %, the specificity between 33 - 74 % (Guideline 2022).

- Electron neurographic diagnostics

This is the most reliable way of detecting CTS (Guideline 2022).

- Electromyography of the abductor pollicis brevis muscle

This examination is not usually performed routinely, but should be carried out if an axonal lesion is suspected, as well as in the case of pre-existing technical difficulties (Guideline 2022).

- Root injury C5 and C6 (Kasper 2015) or C6 and C7 (2022 guidelines)

- Polyneuropathy (2022 guidelines)

The paraesthesia can improve by shaking the hand (Herold 2021).

If there is an indication for conservative treatment, the patient should be prescribed a wrist splint for the night (Guidelines 2022).

If the above-mentioned conservative measures fail to improve the symptoms and the patient suffers from sensory and/or motor deficits, or if the abduction and opposition strength of the thumb is impaired by thenar atrophy, surgery should be performed (Guidelines 2022).

Two methods in particular have become established for surgical measures:

- 1. open retinaculum splitting

- 2. endoscopic retinaculum splitting

Both surgical techniques are generally performed in full-thickness block. The overall results are comparable.

Routine epineurotomy should not be performed for first-time procedures (Guidelines 2022).

Recurrences occur particularly in rheumatoid synovitis, dialysis patients and with severe scarring (Guidelines 2022).

1. German Society for Hand Surgery, German Society for Neurosurgery, German Society for Neurology, German Society for Orthopaedics and Trauma Surgery. (2022) Diagnosis and treatment of carpal tunnel syndrome. S3 guideline AWMF register no. 005 /003
2. Harinesan N, Silbsby M, Simon N G (2024) Chapter 4 - Carpal tunnel syndrome. Handbook of Clinical Neurology 201 Elsevier Urban and Fischer Verlag 61 - 88
3. Herold G et al (2021) Internal medicine. Herold Publishing House 661 - 662
4. Kasper D L, Fauci A S, Hauser S L, Longo D L, Jameson J L, Loscalzo J et al. (2015) Harrison's Principles of Internal Medicine. Mc Graw Hill Education 122, 724
5. Neurologienetz: The information portal for physicians. Doi: https://www.neurologienetz.de/fachliches/erkrankungen/periphere-neurologie/nervenlaesionen-an-schulter-und-arm/karpaltunnelsyndrom
6. Osiak K, Elnazir P, Walocha J A, Pasternak A (2022) Carpal tunnel syndrome: state- of- the- art review. Folia Morphol 81 (4) 851 - 862
7. Padua L, Corari D, Erra C, Pazzaglia C, Paolasso I, Loreti C, Caliandro P, Hobson- Webb L D (2016) Carpal tunnel syndrome: clinical festures, diagnosis and management. Lancet Neurol. 15 (12) 1273 - 1284
8. Wang L (2018) Guiding treatment for carpal tunnel syndrome. Phys Med Rehabil Clin N Am. 29 (4) 751 - 760