Carpal tunnel syndrome

This is a condition where a nerve (the median nerve) passes through a very tight tunnel at the wrist. The tunnel consists of bone at its base and a tough fibrous sheath on the top.

Once under pressure, patients present with pins and needles and numbness particularly affecting the thumb, index and middle fingers. There may be associated pain and poor pinch control. The symptoms can be worse at night. In severe cases, this may lead to wasting of the muscles in the hand and weakness in grip. Examination includes tapping on the nerve (Tinnel’s) or putting constant pressure (Phalen’s) at the wrist to reproduce the symptoms.

The diagnosis is confirmed with nerve conduction studies. These are tests where the speed of nerve conduction across the wrist is measured and compared to the normal and to the other side.

Once confirmed, treatment consists of splinting to help with the night symptoms. Steroid injections can be tried but these often only have temporary effect. Surgery is carried out under local anaesthetic as a day case. It involves splitting the fibrous sheath to open up the tunnel and relief the pressure.