Carpal Tunnel Syndrome

La définition

The carpal tunnel is an anatomical passage located at the base of the hand. It is formed by bones at the back and a thick ligament at the front, called the flexor retinaculum (or transverse carpal ligament). It contains the flexor tendons of the fingers and thumb, as well as the median nerve.

At this level, the median nerve provides sensation to the first three fingers of the hand and supplies part of the muscles at the base of the thumb.

What causes it?

The median nerve may become compressed, leading to clinical symptoms known as “carpal tunnel syndrome.” In about 70% of cases, no cause is identified, and the condition is termed idiopathic.

When present, secondary causes of compression may include:

  • Conditions causing swelling within the tunnel: diabetes, hypothyroidism, inflammatory rheumatic diseases

  • Wrist positions in flexion or extension, or repetitive/intensive movements at work that reduce space around the median nerve (recognized as an occupational disease in certain cases)

  • Presence of anatomical structures within the tunnel, such as a cyst, muscular variation, hematoma, etc.

What are the symptoms?

The syndrome causes tingling in the thumb, index, and middle fingers, occurring at night and/or during the day. Pain may radiate to the forearm and arm. It may also be associated with weakness and dropping objects.

What tests may be required?

An electromyography (EMG) or nerve conduction study, performed by a specialized neurologist, is routinely prescribed. This test measures the speed of electrical conduction along the median nerve to confirm compression and assess its severity.

Depending on the clinical examination, additional tests such as ultrasound and/or X-rays may be requested.

Comment traite-t-on ce syndrome ?

Initial treatment is usually non-surgical, including splinting, rest, and sometimes corticosteroid injections. This can relieve symptoms in mild or temporary cases.

If medical treatment is ineffective or in severe cases, surgery may be recommended. The procedure involves opening the carpal tunnel—specifically cutting the ligament forming its “roof”—to relieve pressure on the median nerve and eliminate tingling.

In severe cases, particularly with muscle involvement, recovery of sensation and strength may be slow or incomplete.

Several techniques exist:

  • Open surgery: incision of about 5 cm

  • Mini-open surgery: incision of 1–1.5 cm

  • Endoscopic surgery: use of a camera with one or two small incisions (0.5–1 cm)

Short- and medium-term results (<6 months) may differ slightly between open and endoscopic techniques, but endoscopy has not shown superiority over mini-open surgery. Long-term outcomes (>6 months) are equivalent across techniques.

Postoperative course

  • No splint is required

  • Dressing is kept for 10 days

  • No routine physical therapy is needed; the hand can be used immediately

  • Strenuous movements should be avoided for 3–4 weeks

  • Temporary loss of strength is common and usually resolves within 3 months

  • Tenderness at the base of the hand (“pillar pain”) is common for a few weeks and relates to ligament healing

What are the risks?

They are rare:

  • General surgical risks (<1%):

    • Complex regional pain syndrome (chronic pain with swelling, redness, and heat)

    • Infection

    • Hematoma

  • Nerve injury (<0.5%) and arterial injury (<0.1%) are exceptional

  • Early recurrence (<6 months), often due to scar tissue around the nerve, more frequent in patients with diabetes or kidney disease.