Carpal tunnel syndrome: symptoms, causes and diagnosis
Author: Dr. Alexandru Grecu — Senior Orthopedic and Trauma Surgeon
Published: 7 iunie 2026 · Reviewed: June 7, 2026
Short answer: Carpal tunnel syndrome appears when the median nerve is compressed at the wrist. The typical sign: numbness and tingling in the thumb, index, middle and half of the ring finger, mostly at night. The cause is often a combination of factors — repetitive activity, pregnancy, hypothyroidism, diabetes — or remains idiopathic. The diagnosis starts from the clinical examination, with the Phalen test and Tinel's sign, and is confirmed with a nerve conduction study (EMG). In mild and moderate forms, treatment starts conservatively: a night splint, activity adjustment, sometimes an injection.
What the carpal tunnel is
At the wrist, the finger tendons and the median nerve pass through a narrow canal — the carpal tunnel — covered by a strong ligament. When pressure in this space rises, the median nerve is compressed. From there, in order: first numbness and tingling, then, if the pressure persists, weakness.
The median nerve carries sensation from the thumb, index, middle and half of the ring finger. The pattern of symptoms follows this distribution — the little finger stays outside it, because it belongs to another nerve. The detail orients the diagnosis.
The symptoms
- Numbness and tingling in the thumb, index, middle, half of the ring finger.
- Mostly nocturnal; they wake you from sleep. The reflex of shaking the hand until it passes is so constant that it has a name in clinical practice.
- Dropping objects, reduced grip strength.
- In advanced forms, the muscle at the base of the thumb wastes — a sign the nerve has been suffering for some time.
Why it appears
Rarely a single cause. Contributing factors include repetitive wrist activity, pregnancy and hormonal changes, hypothyroidism, diabetes, rheumatoid arthritis, an old fracture that narrowed the canal. In many patients it remains idiopathic — with no identifiable cause.
Who develops carpal tunnel syndrome
The condition does not appear at random. A clinical review published in Lancet Neurology gathers the factors that recur in patients with carpal tunnel syndrome, and the picture is useful because it tells you where you stand.
Women are affected more often than men. Middle age is when symptoms most commonly appear. Pregnancy brings a particular form, linked to fluid retention and hormonal change, which often eases after birth. Diabetes counts twice: the nerve is already vulnerable, and the compression adds to fragile ground. Hypothyroidism alters the tissues in the canal and raises the pressure. Obesity is consistently associated with the syndrome. Rheumatoid arthritis thickens the lining around the tendons, so it reduces the space available to the nerve.
Work contributes, but not in any form. The problem is not simply that you use your hands; it is the combination of repeated movement, force and position. What matters most is repetitive manual work, working with vibrating tools and sustained flexion or extension of the wrist, held for long minutes in the same position.
One important point: risk factors explain, they do not condemn. Many people with diabetes or with manual work never develop carpal tunnel syndrome, and many patients with typical symptoms have no identifiable factor. The value of the list is different — if you have a treatable factor, such as an unbalanced thyroid, correcting it is part of the treatment.
How it is diagnosed
The diagnosis starts from what you describe. The nocturnal pattern, the fingers involved, the habit of shaking the hand until the numbness passes — these orient before any device. The clinical examination follows, and the investigations confirm and grade.
The clinical tests
Three manoeuvres are in common use. The Phalen test: you hold the wrist flexed, and if the numbness is reproduced in the median fingers, the sign is positive. Tinel's sign: light tapping over the nerve at the wrist triggers tingling running into the fingers. The carpal compression test: direct, sustained pressure on the palmar side of the wrist reproduces the symptom.
These tests orient. They do not decide. A positive test in a patient without the typical picture is not a diagnosis, and a negative test in a patient who wakes at night with a numb hand does not exclude the condition. That is why the clinical examination complements the investigation rather than replacing it.
The nerve conduction study (EMG)
EMG measures how the median nerve conducts the signal through the tunnel. It does two things the clinical examination cannot: it objectively confirms the compression and establishes its degree — mild, moderate, severe. The degree matters in the decision, because severe compression tilts the discussion toward surgery even when the symptoms seem bearable. Its second role is just as useful: if the numbness does not come from the tunnel but from the neck or another segment of the nerve's path, EMG helps to separate them.
Ultrasound of the median nerve
Ultrasound entered practice for a simple reason: the compressed nerve swells just before it enters the tunnel, and its cross-sectional area can be measured. A meta-analysis on the performance of sonography in diagnosing carpal tunnel syndrome shows that the method has real diagnostic value and that measuring the nerve's cross-section at the entrance of the canal is the most used parameter.
I say exactly what the evidence says: ultrasound is a useful test, complementary to EMG, not a replacement for it. It has practical advantages — it is painless, quick, and it also shows local causes of compression, such as a mass in the canal or inflammation of the tendons. What it does not do is grade the nerve's functional suffering. Used together, the two complement each other.
Conservative treatment
In mild and moderate forms, treatment starts without surgery. I will tell you what is tried and, just as importantly, how certain the evidence behind each measure is.
The night splint
The splint holds the wrist in a neutral position during sleep. The purpose is mechanical: at night the hand flexes or extends without control, and the pressure in the canal rises exactly then — hence the numbness that wakes you. A correctly chosen splint blocks that position.
What the evidence says, exactly: a Cochrane review dedicated to splinting for carpal tunnel syndrome found possible short-term benefits, with low certainty of evidence. That wording is not stylistic hesitation. It means the splint is worth trying, because it is inexpensive, non-invasive and without risk, but I cannot promise you a result. On current data, a long-term benefit remains unproven.
The corticosteroid injection
An anti-inflammatory is injected near the tunnel, to reduce the volume of the tissues pressing on the nerve. A Cochrane review comparing local corticosteroid injection with placebo shows an improvement in symptoms in the short term.
The second part of the information matters just as much: the effect fades over time. The injection does not release the ligament pressing on the nerve, so it does not resolve the mechanical cause. Usually one injection, and repetition is limited and considered, not a maintenance treatment. It also carries information: a clear response, even a temporary one, supports that the source of the symptoms really is in the tunnel.
Activity modification and ergonomics
Here you do the work, not the doctor. The idea is not to give up your job, but to break the pattern that loads the nerve. In practice: short, frequent breaks in repetitive activity, the wrist kept as close to neutral as possible rather than bent over the edge of the desk, the keyboard and mouse placed so the forearm is supported, gripping objects with the whole hand rather than the fingertips, anti-vibration gloves where vibrating tools are used.
Many mild forms are controlled this way. When symptoms persist or weakness and wasting appear, conservative treatment is no longer enough and surgery is discussed — see carpal tunnel surgery.
The three situations that indicate surgery
- Symptoms that persist under conservative treatment. If, after a reasonable period of splinting and adjustment, the numbness keeps returning and disturbs your sleep or activity, the compression is not resolving on its own.
- EMG showing moderate or severe compression. Objective severity matters, not just the sensation. An EMG showing advanced involvement tilts the decision toward surgery, even if the symptoms seem tolerable.
- Weakness or wasting of the muscle at the base of the thumb. This is the sign that the nerve has been suffering for some time. Here delay costs the most.
Surgery: open or endoscopic
The essential step is the same in both techniques: the transverse carpal ligament, the one that forms the "roof" of the tunnel and presses on the nerve, is divided. Only the access differs — an incision at the base of the palm, under direct vision, or instruments introduced through smaller incisions, with a view on a monitor.
The comparison between them is not clear-cut. An umbrella review with meta-analysis found a somewhat faster return to activity for the endoscopic technique; for major complications, the differences remained unclear, because of statistical inconsistency and the risk of bias in the included studies. So I do not tell you that one technique is superior.
It is also worth knowing how the evidence on surgery itself looks, because it seems contradictory. A systematic review of surgical and post-surgical interventions concludes that surgical treatment appears more effective than splinting or anti-inflammatory drugs combined with hand therapy, in the short, medium and long term. The most recent Cochrane review concludes, in turn, that the effectiveness of surgery compared with conservative treatment remains unclear on current data.
The two do not cancel each other out. The reason is methodological: patients in the trials knew which treatment they received, which influences how they report symptoms, and many of them had not already failed conservative treatment — that is, they were not the group in which surgery is actually considered in practice. The practical conclusion stays the same: conservative measures are tried first, and surgery is discussed when symptoms persist or when the nerve shows signs of suffering. What follows the operation, step by step, is described in the article about recovery after carpal tunnel surgery.
Why it is not delayed too long
A nerve kept compressed gradually loses its capacity to recover. As long as it is only intermittent numbness, the margin is wide. When wasting appears — the muscle at the base of the thumb thins — part of the loss can become permanent, even after a successful operation. Surgery stops the compression; it cannot fully turn back time. That is why the timing of the operation makes the difference between a full and a partial recovery.
What happens if it is left untreated
I am not dramatising and I am not rushing you. Mild forms can stay mild for a long time, and some improve on their own — those in pregnancy, for instance, often settle after birth. The problem appears when the compression persists and increases.
Prolonged compression can lead to permanent numbness in the territory of the median nerve and to weakening of the muscles at the base of the thumb, with loss of pinch strength between thumb and index finger. Fine sensation goes first: buttons, a coin in the pocket, a key in the lock become operations you have to look at. That is exactly why the warning signs listed above matter. Not the urgency with which you come, but the moment at which you come changes the outcome.
What is not carpal tunnel syndrome
Not every numbness of the hand is carpal tunnel syndrome. If the little finger is also involved, the source may be the ulnar nerve, not the median. If the numbness comes from the neck and travels down the arm, it may be irritation of the nerve in the cervical spine. These are treated differently. That is why surgery is decided after a clinical examination and EMG, not from the symptom alone.
Frequently asked questions
Which fingers go numb in carpal tunnel syndrome?
The thumb, index, middle and half of the ring finger. Not the little finger — it belongs to another nerve, and its involvement points to a different cause.
Does carpal tunnel go away on its own?
Mild forms can improve with a splint and activity adjustment. Moderate and severe forms do not resolve on their own and need treatment.
What is the Phalen test?
You hold the wrist flexed for about a minute; if the numbness is reproduced, it points to carpal tunnel syndrome. It is a clinical sign, not a definitive diagnosis — that is confirmed with EMG.
Is EMG needed?
Usually yes: it confirms the diagnosis, measures the severity of the compression and guides the choice between conservative treatment and surgery.
How quickly must I be operated if I have wasting?
It is not an emergency of hours, but it is not delayed for months. The sooner after wasting appears, the better the chance of recovery.
My EMG is nearly normal but the symptoms are bothersome — is surgery done?
It depends on the clinical picture. Sometimes the EMG is repeated or conservative treatment is continued; the decision is made together, at the consultation.
What is the risk if I delay?
The shift from reversible numbness to sensory and motor deficits that can become permanent.
Does it heal on its own?
Mild forms can settle, especially if the trigger disappears — as often happens after childbirth, in the form that appears during pregnancy. Moderate and severe forms do not resolve on their own, because the space inside the canal does not widen by itself. If the numbness returns night after night, waiting does not work in the nerve's favour.
Can ultrasound replace EMG?
No. Ultrasound shows the nerve swollen at the entrance of the tunnel and can detect a local cause of compression, so it is a useful and easily repeated test. What it cannot do is measure how much the nerve's function is suffering. The degree of compression comes from the nerve conduction study, and that degree matters in the treatment decision. The two complement each other.
Does an injection solve it for good?
No. A corticosteroid injection improves symptoms in the short term, but the effect fades over time, because it does not release the ligament pressing on the nerve. Usually one injection; repetition is limited. A good response, even a temporary one, confirms that the source of the symptoms is in the tunnel.
Can I work at a computer with carpal tunnel syndrome?
Generally yes, with adjustments. Keep the wrist close to neutral, support the forearm, avoid bending it over the desk edge and take short, frequent breaks. If the numbness appears while you work or wakes you at night, that is the signal that the load exceeds what the nerve tolerates, and an assessment is worthwhile.
About the author
Dr. Alexandru Florian Grecu, senior specialist in orthopedics and traumatology and Senior Lecturer at UMF Craiova. He treats carpal tunnel syndrome, conservatively and surgically. Details on the About page.
For context, see the dedicated page on carpal tunnel surgery, and if you want to go deeper, read aboutrecovery after carpal tunnel surgery.
Have questions or need a consultation?
Scientific References
Padua L, Coraci D, Erra C et al. — Carpal tunnel syndrome: clinical features, diagnosis, and management. Lancet Neurol. 2016;15(12):1273-1284.
For the factors associated with the syndrome — female sex, middle age, pregnancy, diabetes, hypothyroidism, obesity, rheumatoid arthritis, repetitive manual work with vibration or sustained wrist flexion — and for the role of clinical tests and investigations in the diagnosis.
Phalen GS — The carpal-tunnel syndrome. Seventeen years' experience in diagnosis and treatment of six hundred fifty-four hands. J Bone Joint Surg Am. 1966;48(2):211-28.
The historical series on which the classic description of the syndrome is based.
Descatha A, Huard L, Aubert F et al. — Meta-analysis on the performance of sonography for the diagnosis of carpal tunnel syndrome. Semin Arthritis Rheum. 2012;41(6):914-22.
For the diagnostic value of ultrasound, with measurement of the median nerve cross-section at the entrance of the tunnel as the most used parameter: a useful test, complementary to the nerve conduction study.
Karjalainen TV, Lusa V, Page MJ et al. — Splinting for carpal tunnel syndrome. Cochrane Database Syst Rev. 2023;2(2):CD010003.
For the night splint: possible short-term benefits, with low certainty of evidence.
Ashworth NL, Bland JDP, Chapman KM et al. — Local corticosteroid injection versus placebo for carpal tunnel syndrome. Cochrane Database Syst Rev. 2023;2(2):CD015148.
For the corticosteroid injection: improvement in symptoms compared with placebo in the short term, with an effect that fades over time.
Huisstede BM et al. — Effectiveness of Surgical and Postsurgical Interventions for Carpal Tunnel Syndrome — A Systematic Review. Arch Phys Med Rehabil. 2018;99(8):1660-1680.
Surgical treatment appears more effective than splinting or anti-inflammatory drugs plus hand therapy, in the short, medium and long term; in the short term, local corticosteroid injection proved more effective than surgery; there is no unequivocal evidence that one surgical technique is more effective than another; after surgery, a bulky dressing kept for 2–3 days was preferable to one kept for 9–14 days.
El Masri J et al. — Endoscopic Versus Open Carpal Tunnel Release: An Umbrella Review and a Meta-analysis. Ann Plast Surg. 2024;92(6):677-687.
The endoscopic technique was associated with better pinch strength and a faster return to work; differences in major complications, such as nerve injury, remained unclear because of statistical inconsistency and risk of bias.
Miller LE et al. — Determinants of return to activity and work after carpal tunnel release: a systematic review. Expert Rev Med Devices. 2023;20(5):417-425.
The time to return to activities and to work after carpal tunnel release is highly variable and influenced by study-, patient- and physician-related factors.
Lusa V et al. — Surgical versus non-surgical treatment for carpal tunnel syndrome. Cochrane Database Syst Rev. 2024;1(1):CD001552.
For the comparison of surgical with non-surgical treatment.
American Academy of Orthopaedic Surgeons (AAOS) — Management of Carpal Tunnel Syndrome — Evidence-Based Clinical Practice Guideline. Adoptat 2016, actualizat 2024.
The guideline followed for the surgical indication.