A note on this column: This article is general medical information, not a description of a service offered at this practice. Dr. Ishiguro's surgical practice is focused on hip and knee conditions — he does not treat or perform surgery for carpal tunnel syndrome. This column is written to help readers understand a very common condition and know when and how to seek the right specialist, typically a hand surgeon or a neurologist for the diagnostic workup.
What carpal tunnel syndrome actually is
The carpal tunnel is a narrow passage on the palm side of the wrist, bounded by small wrist bones on three sides and a tough ligament (the transverse carpal ligament) on the fourth. Through this tight space run nine tendons that flex the fingers — and one nerve, the median nerve, which supplies sensation to the thumb, index, middle, and half of the ring finger, along with some of the small muscles at the base of the thumb.
When the tissue lining the tendons (the synovium) thickens or swells, or when the space itself is otherwise reduced, pressure builds on the median nerve. The result is the classic pattern of carpal tunnel syndrome (CTS): numbness, tingling, or a burning sensation in the thumb and first two-and-a-half fingers — notably sparing the little finger, which is supplied by a different nerve — often worse at night or when gripping a phone, steering wheel, or bicycle handlebar. In more advanced cases, weakness and wasting of the thumb muscles can develop, along with a tendency to drop small objects.
Who gets it — and why
CTS is the most common entrapment neuropathy, affecting roughly 3–6% of the general adult population, though estimates vary widely by region and diagnostic criteria used. It is two to three times more common in women than men, and typically presents between the ages of 40 and 60.
Established risk factors
- Sex and age — women, and adults in their 40s–60s, are disproportionately affected, likely reflecting a combination of anatomical and hormonal factors
- Diabetes — both diabetes itself and, more strongly, diabetic peripheral neuropathy raise the likelihood of developing CTS, with some series reporting the condition in around 30% of patients who already have diabetic neuropathy, compared with roughly 14% of the general adult population
- Obesity — a higher body mass index is independently associated with a substantially higher prevalence of CTS, even after accounting for diabetes
- Pregnancy — fluid retention and hormonal changes make CTS common in later pregnancy, though symptoms frequently resolve after delivery
- Hypothyroidism and rheumatoid arthritis — both are recognised, if comparatively weaker, associations
- Repetitive or forceful hand use — occupations or hobbies involving sustained wrist flexion, vibration exposure, or repetitive gripping are commonly cited, though the strength of this association is debated in the research literature compared with the factors above
What the evidence shows: A 2024 meta-analysis pooling prevalence data from 31 studies across 15 countries found substantial variation in reported CTS prevalence by region and population studied, reinforcing that this is a genuinely global condition rather than one specific to particular occupations or countries, and that population-level estimates should be interpreted with the underlying study population in mind (Gebrye et al., Musculoskeletal Care, 2024).
How the diagnosis is made
CTS is primarily a clinical diagnosis, built from the pattern of symptoms — numbness and tingling in the thumb, index, and middle fingers, often waking the patient at night — together with a physical examination. Provocative tests such as tapping over the nerve at the wrist (Tinel's sign) or holding the wrists flexed (Phalen's test) can support the diagnosis, though neither is reliable enough on its own to confirm or exclude it.
Electrodiagnostic testing — nerve conduction studies (NCS), sometimes combined with electromyography (EMG) — has traditionally been considered the confirmatory test, used to measure how well electrical signals travel through the median nerve at the wrist and to gauge severity. Ultrasound imaging of the nerve is increasingly used as well, particularly where electrodiagnostic testing is less accessible.
What the evidence shows: The American Academy of Orthopaedic Surgeons' 2024 clinical practice guideline on carpal tunnel syndrome states that strong evidence supports using a structured symptom-and-history tool (commonly referred to as CTS-6) to diagnose typical cases, without a routine requirement for ultrasound or nerve conduction/EMG testing in every patient. The same guideline notes moderate evidence against using MRI or upper-limb neurodynamic testing as diagnostic tools for CTS. In practice, electrodiagnostic testing and ultrasound remain valuable — particularly to confirm the diagnosis, gauge severity before surgery, or sort out atypical presentations — but the guideline's message is that a careful clinical assessment carries real diagnostic weight on its own (American Academy of Orthopaedic Surgeons, Management of Carpal Tunnel Syndrome Clinical Practice Guideline, 3rd ed., 2024).
What the evidence says about treatment
Treatment is generally staged according to severity and how much the symptoms are affecting daily function, ranging from simple measures to surgery.
| Approach | Typical role | What it involves |
|---|---|---|
| Activity modification | Mild, early symptoms | Reducing sustained wrist flexion/extension and repetitive gripping; addressing contributing factors like undiagnosed diabetes or hypothyroidism |
| Night wrist splinting | Mild to moderate | A neutral-position splint worn at night to prevent the wrist flexion that raises tunnel pressure and worsens symptoms during sleep |
| Corticosteroid injection | Mild to moderate | A single injection into the carpal tunnel to reduce inflammation around the nerve; effects are often rapid but can be temporary |
| Surgical release (open or endoscopic) | Moderate to severe, or after conservative treatment fails | Division of the transverse carpal ligament to permanently enlarge the tunnel and relieve pressure on the nerve |
A frequent question is how a single steroid injection compares with simple night splinting as a first-line option.
What the evidence shows: The INSTINCTS trial, a UK primary-care randomised controlled trial of 234 patients with mild-to-moderate CTS, compared a single 20mg methylprednisolone injection against six weeks of night splinting. At six weeks, the injection group showed significantly greater improvement on the Boston Carpal Tunnel Questionnaire than the splint group, leading the authors to conclude that a single corticosteroid injection is a reasonable first-choice treatment for mild-to-moderate CTS in primary care, with splinting remaining a reasonable option for patients who prefer to avoid injection (Chesterton, Blagojevic-Bucknall, Burton, et al., The Lancet, 2018). The AAOS 2024 guideline adds an important caveat: while corticosteroid injection often produces meaningful short-term relief, strong evidence indicates it does not reliably provide long-term improvement on its own, so patients whose symptoms are more than mild, or who relapse after injection, are often better served by moving toward definitive surgical treatment rather than repeating injections indefinitely.
For patients with persistent moderate-to-severe symptoms, particularly where there is measurable nerve dysfunction on electrodiagnostic testing or thumb muscle weakness, surgical release of the carpal ligament is a well-established and generally successful procedure. The two main techniques — open release through a small palm incision, and endoscopic release through one or two smaller portal incisions — are both widely used, and the choice between them is usually a matter of surgeon training and patient factors rather than one being clearly superior.
What the evidence shows: A 2024 systematic review comparing endoscopic and open carpal tunnel release, drawing on 11 studies (seven randomised trials and four meta-analyses) covering more than 8,000 procedures combined, found that endoscopic release was associated with comparable or better outcomes on measures including postoperative discomfort, functional recovery, grip strength, and time to return to work, along with lower rates of scar tenderness and wound-related complications. However, endoscopic release carried a higher reported rate of reversible nerve-related complications than open release, which the author attributes in part to the greater technical demands of the endoscopic approach. Both techniques were characterised as safe and effective overall, with the choice reasonably guided by surgeon expertise, patient preference, and cost considerations rather than a one-size-fits-all recommendation (Butt, Cureus, 2024).
When to see a specialist
Occasional nighttime tingling that resolves with shaking out the hand is common and not necessarily worrying. But persistent numbness, symptoms that interfere with sleep or work, weakness in the thumb, or any sense of the hand becoming clumsier are all reasons to seek a proper clinical evaluation rather than self-managing indefinitely — both because effective early treatment exists, and because prolonged, severe compression can lead to permanent nerve damage and muscle wasting that surgery cannot fully reverse. Anyone with diabetes, hypothyroidism, or a family history of CTS should have a lower threshold for getting new hand symptoms checked.
References (PubMed / Journal)
Chesterton LS, Blagojevic-Bucknall M, Burton C, Dziedzic KS, Davenport G, Jowett SM, Myers HL, Oppong R, Rathod-Mistry T, van der Windt DA, Hay EM, Roddy E. The clinical and cost-effectiveness of corticosteroid injection versus night splints for carpal tunnel syndrome (INSTINCTS trial): an open-label, parallel group, randomised controlled trial. Lancet. 2018;392(10156):1423–1433. DOI: 10.1016/S0140-6736(18)31572-1
Butt SR. Endoscopic Versus Open Carpal Tunnel Release: A Systematic Review of Outcomes and Complications. Cureus. 2024;16(7):e64991. DOI: 10.7759/cureus.64991
Gebrye T, Jeans E, Yeowell G, Mbada C, Fatoye F. Global and Regional Prevalence of Carpal Tunnel Syndrome: A Meta-Analysis Based on a Systematic Review. Musculoskelet Care. 2024;22(4):e70024. DOI: 10.1002/msc.70024
American Academy of Orthopaedic Surgeons. Management of Carpal Tunnel Syndrome Evidence-Based Clinical Practice Guideline, 3rd Edition. 2024. aaos.org — Carpal Tunnel Syndrome Clinical Practice Guideline
Genova A, Dix O, Saefan A, Thakur M, Hassan A. Carpal Tunnel Syndrome: A Review of Literature. Cureus. 2020;12(3):e7333. DOI: 10.7759/cureus.7333