Recurrent carpal tunnel syndrome is the persistence or re-occurrence of carpal tunnel syndrome (CTS) symptoms after carpal tunnel release surgery.

Epidemiology

The re-operation rate for new or persistent CTS symptoms is 1-3% ^1-3.

Pathology

Persistence or re-occurrence of CTS symptoms may be due to ^1-3:

• incorrect pre-operative diagnosis, e.g. more proximal median nerve entrapment syndrome, brachial neuritis, thoracic outlet syndrome, nerve tumour, cervical radiculopathy, multiple sclerosis, peripheral neuropathies (from various causes)

• incomplete release of the flexor retinaculum

  • persistent or worsened symptoms post-surgery

  • most common cause found on revision carpal tunnel release

• nerve tethering/fibrosis

  • circumferentially around the nerve or adherence to the radial wall of the carpal tunnel

  • re-occurrent symptoms after initial improvement

  • second most common cause found on revision carpal tunnel release

• unrecognised carpal tunnel compressive lesions, e.g. flexor tenosynovitis, mass lesion, accessory muscle belly

• iatrogenic nerve injury: may be incomplete or complete laceration

• permanent nerve damage from chronic and severe compression

Radiographic features

Ultrasound

• detection of focal (more common) or longitudinal compression and site (i.e. proximal, mid, distal carpal tunnel) of compression ⁴

• persistence of the flexor retinaculum ⁴, although transducer compression can cause overlap of a transected flexor retinaculum ⁵

• absence of nerve gliding indicates perineural fibrosis, lateral gliding is easier to assess than longitudinal gliding ⁴

Treatment and prognosis

Response to a steroid injection around the median nerve can be considered a predictor for successful revision carpal tunnel release ^1,3.