Current Management of Carpal Tunnel Syndrome

Original Editor - Wanda van Niekerk based on the course by Loren Szmiga

Top Contributors - Wanda van Niekerk, Ewa Jaraczewska, Kim Jackson and Jess Bell  

Introduction

Carpal tunnel syndrome (CTS) is a common neurological disorder. The cases of CTS are on the rise as its incidence in the working population can reach 8%. Carpal tunnel syndrome is considered an occupational hazard, and production workers, material movers, and office administrative staff are at-risk occupations. Activities that involve excessive engagement of wrist flexion or prolonged wrist movements can lead to median nerve injury. Treatment options include conservative measures or surgery.

This article discusses the anatomy and pathophysiology of CTS along with treatment considerations.

What is Carpal Tunnel Syndrome

Carpal tunnel syndrome is an entrapment or compression of the median nerve at the wrist as it passes through the carpal tunnel. It is the most common compressive neuropathy and is more common in females. Symptoms occur in the thumb, index finger, middle finger and the radial half of the ring finger. Early symptoms include:

• Pain
• Numbness and tingling
• Paraesthesia
• Can also lead to burning symptoms

Clinically Relevant Anatomy

Anatomy of the Carpal Tunnel

Some clinically relevant anatomical structures include:

• The carpal tunnel is a U-shaped, osteofibrous canal
• The floor of the tunnel is formed by the carpal bones, and the roof by the flexor retinaculum
• The tunnel is located deep to the flexor retinaculum / transverse carpal ligament, between the tubercles of the scaphoid and trapezoid on the lateral side and the pisiform and hook of hamate on the medial side
• The four main structures passing through the tunnel are:
  • Four tendons of flexor digitorum superficialis
  • Four tendons of flexor digitorum profundus
  • One tendon of the flexor pollicis longus
  • 

    Path of the Median Nerve
    Median nerve
    • Path of the median nerve:
      • Begins in the axillary region with the root of median nerves situated in the anterior rami of C5-T1
      • The median nerve is formed by fascicles of the medial and lateral cords of the brachial plexus
      • Runs distally in the arm next to the brachial artery until the middle of the arm and descends into the cubital fossa (anterior elbow)
      • Principal nerve supply to the anterior compartment of the forearm
      • The muscular branch in the forearm supplies all the superficial and intermediate layers of the forearm flexors, except for flexor carpi ulnaris. These muscles are:
        • Pronator teres
        • Palmaris longus
        • Flexor digitorum superficialis
        • Flexor carpi radialis
      • The terminal branch of the median nerve enters the hand through the carpal tunnel, along with the tendons of flexor digitorum profundus, flexor digitorum superficialis and flexor pollicis longus
      • Distal to the carpal tunnel, the nerve supplies five intrinsic muscles in the thenar part
      • The median nerve supplies sensation to the skin on:
        • The entire palmar surface
        • The sides of the first three digits
        • The lateral half of the fourth digit and
        • The dorsal aspects of the distal halves of these digits
      • Innervation to the thenar eminence includes flexor pollicis brevis, opponens pollicis and abductor pollicis brevis

Aetiology

Increased pressure in the carpal tunnel and compression of the median nerve is the main cause of carpal tunnel syndrome. The aetiology of carpal tunnel syndrome can be related to:

• Work
• Lifestyle
• Injury
• Genetic predisposition
• History of repetitive wrist movement or exposure to vibrations or forceful angular motions such as typing, gaming, machine work
• Specific conditions may also be associated with an increased risk for the development of carpal tunnel syndrome (CTS). These can include:
  • Diabetes. The hyperglycemic conditions cause tendon inflammation and prevent tendons from gliding past one another
  • Pregnancy. Fluid retention during pregnancy may increase pressure in the carpal tunnel.
  • Obesity
  • Rheumatoid arthritis. Inflammatory conditions can lead to synovial hyperplasia, which reduces the space in the carpal tunnel.
  • Fall on an outstretched hand (FOOSH) – this can displace the lunate bone, which can cause pressure in the carpal tunnel

• CTS is more commonly seen in females, usually between 36 and 60. Females may be more susceptible than males to compression of the median nerve because of a smaller relative cross-sectional area of the carpal tunnel.

Pathophysiology

Increased interstitial pressure in the carpal tunnel due to various causes such as:

• Mechanical overuse
• Osteoarthritis
• Trauma
• Acromegaly

All of these place pressure on the median nerve.

It is hypothesised that the compression of the median nerve leads to the development of local ischaemia, and this may cause demyelination of the nerve, resulting in clinical symptoms. Normal pressure in the carpal tunnel varies between 2 – 10 mmHg. Repetitive wrist motion causes fluctuations in carpal tunnel pressure. Wrist extension can result in a 10-fold increase in pressure, and wrist flexion can result in an 8-fold increase in pressure. 

Clinical Presentation

• Symptoms can develop gradually over months, years or decades
• Symptoms may arise spontaneously, but not commonly
• Numbness
• Tingling or pins and needles sensation in the median nerve distribution of the hand (thumb, index finger, middle finger and radial half of the ring finger)
• Symptoms are worst at night or early morning (complaints of nocturnal burning pain) and are relieved by shaking of the hand
• As symptoms worsen, intermittent pain and numbness may be experienced during daytime activities such as driving, lifting, working on the computer
• Increased symptoms with static gripping of objects such as a phone or steering wheel
• As symptoms progress, increased tingling and numbness and burning pain in the hand may be reported
• If symptoms are left untreated, patients can complain of constant pain, hand swelling, difficulties with motor control and weakness and visible atrophy of the thenar eminence
• Sensory deprivation may also be present, resulting in clumsiness, weakness, loss of grip and pinch strength

Differential Diagnosis

The process of differential diagnosis should consider all conditions which could potentially cause dysfunction of the median nerve, the brachial plexus, C5 to C8 nerve root systems and the central nervous system. Conditions to consider can include:

• Pronator teres syndrome
• Anterior interosseous nerve syndrome
• Cervicobrachial syndromes
• Injury to the digital nerves at the palm of the hand
• Carpometacarpal arthritis of the thumb
• Cervical radiculopathy
• De Quervain’s tenosynovitis
• Peripheral neuropathy
• Raynaud's syndrome
• Ulnar compressive neuropathy

Diagnosis of Carpal Tunnel Syndrome

Electrophysical assessment (i.e., nerve conduction studies) can measure and examine median nerve dysfunction. This is useful when diagnosing carpal tunnel syndrome to assess nerve function and quantify damage to the nerve.

There is a debate in recent literature, with traditionalists arguing that nerve conduction studies are the gold standard for confirmation of a carpal tunnel syndrome diagnosis and contemporary thinkers arguing that a diagnosis is possible based on clinical symptoms. Furthermore, even amongst traditionalists in favour of nerve conduction tests, there seems to be no consensus on the single best technique to be used.

Neuromuscular ultrasound is a valuable tool to investigate carpal tunnel syndrome as it provides information on median nerve morphology and the surrounding structures. Recent research highlights that (based on expert consensus) combining electrodiagnosis and ultrasound is more effective than using either modality on its own. In cases where electrodiagnostic studies are normal or unable to localise suspected carpal tunnel syndrome, ultrasound can add value.

Magnetic Resonance Imaging (MRI) is becoming more popular as a diagnostic tool for carpal tunnel syndrome. It can define the deeper and lateral limits of the carpal tunnel in more detail than ultrasound. It has also been shown to provide objective and accurate information about the anatomy and pathologies of the carpal tunnel.

X-ray is recommended to exclude other causes of wrist pain or bony pathology 

Physical Examination

The location of symptoms is key for diagnosis.

• Carpal compression test
  • Apply firm pressure directly over the carpal tunnel for 30 seconds.
  • The test is positive when paraesthesia, pain or other symptoms are reproduced
  • Read more here: Carpal Compression Test

Carpal Compression Test video provided by Clinically Relevant

• Phalen’s test
  • Have the patient fully flex their wrists by placing the dorsal surfaces of both hands together for 30 – 60 seconds
  • A positive test is when symptoms (numbness, tingling, pain) are reproduced
  • Read more here: Phalen's Test

• Reverse Phalen’s test
  • Have the patient fully extend their wrists by placing the palms of both hands together for 30 – 60 seconds
  • A positive test is when symptoms are reproduced

• Tinel’s sign
  • Test is performed by lightly tapping over the median nerve for 30 seconds to reproduce symptoms
  • Read more here: Tinel's Sign

• Read more on other physical examination tests here: Physical Examination of Carpal Tunnel Syndrome

Management of Carpal Tunnel Syndrome

Conservative Management

• Wrist control orthosis – blocks wrist extension and flexion motion which decreases the compression of the carpal tunnel
  • Patients wear this orthosis mostly at night
• Activity modification – educate patients on how to modify daily activities and avoid positions that cause increased compression of the nerve
• Ergonomics education
• Desk and keyboard height
  • Elbow wrist and finger alignment
• Medication
  • Non-steroidal anti-inflammatory medication
  • Oral steroids

• Corticosteroid injections
  • At the treating physician’s discretion
• Neurodynamic techniques
  • Can improve short-term pain and functional status in individuals with carpal tunnel syndrome
  • Neurodynamic techniques are more effective than electrotherapy interventions in the improvement of function and more effective than surgery to improve pain
  • Read the systematic review here: Short-Term Effects of Neurodynamic Techniques for Treating Carpal Tunnel Syndrome: A Systematic Review With Meta-Analysis.
  • Read more on Median nerve neurodynamic techniques here: Neurodynamic Treatment
• Exercise therapy and mobilisation techniques
  • Researchers argue that gliding exercises may improve symptoms. The supporting theory is that gliding exercises may prevent or stretch adhesions around the tendons and median nerve and thus reduce oedema and increase venous return. This may result in reduced pressure in the carpal tunnel.
  • Examples of tendon gliding exercises are shown below in the section on Surgical Management
  • There is conflicting evidence on the effectiveness of tendon gliding exercises as conservative management. This may be due to the methodological quality of studies and the fact that the exercise therapy intervention is often applied and assessed in association with other management approaches. A Cochrane review (2012), reported limited evidence to justify the use of exercise and mobilisation techniques as a conservative intervention for Carpal Tunnel Syndrome, but the authors did suggest that decision-making and consideration for the use of exercise and mobilisation techniques as an intervention should be based on the clinician's experience as well as the patient's preference.
• Read more: Conservative therapeutic management of carpal tunnel syndrome

Surgical Management

Open or endoscopic surgery, where the transverse ligament is cut, creates space in the carpal tunnel and reduces pressure on the median nerve.

Open Carpal Tunnel Release

• Traditional incision or mini-incision can be used
• Risk of incomplete transverse ligament release with the choice of mini-incision technique
• Median nerve decompression and visualisation
• It is considered a safe procedure, with reports of only a few cases of wound infections

Endoscopic Carpal Tunnel Release

• Single-portal and two-portal techniques are used
• Two-portal techniques are considered the lower risk for complications as they allow better visualisation of the neurovascular structures
• Small post-surgical scars
• Quick recovery time and return to work

Post-Surgical Rehabilitation

• Exercises are aimed at reducing stiffness
• Therapy is short-term as recovery time is quick after surgery
• Finger abduction and adduction
  • Gets intrinsic muscles working
• Tendon glides
  • Promotes excursion of the flexor digitorum profundus and flexor digitorum superficialis
  • Hand straight
  • Hook fist
  • Full fist
  • Straight fist with fingers touching the palm of the hand
  • Tabletop position
  • Back to a straight hand

Finger Tendon Glide Exercises. [(A) straight; (B) hook; (C) fist; (D) straight fist; (E) table top.]

• Dosage of tendon glide exercises
  • Patient repeats tendon glides three to five times
  • Stiffness will determine how many times a day patients should perform tendon glides
    • Very stiff after surgery – perform tendon glides six to eight times a day
    • Minimal stiffness – perform tendon glides one to three times a day

• Digit blocking
  • If a patient experiences stiffness after surgery, digit blocking may help to increase motion
  • For example, if the patient has stiffness in the proximal interphalangeal (PIP) or distal interphalangeal (DIP) joints
    • Patient blocks the joint below with the other hand and performs movement
    • This forces motion to go through the stiff joint
    • Patient repeats this 5 times, holding it for 5 seconds
    • This exercise can be done with individual digits or all at once, depending on which joints are lacking in motion

• Thumb opposition
  • Allows for movement of flexor pollicis longus
  • Patient touching their thumb to fifth finger – thumb opposition

Final Thoughts

• Prolonged duration of symptoms without treatment leads to irreversible changes and thenar muscle atrophy

• Speedy and correct treatment is therefore crucial
• Have a look at this article: Carpal Tunnel Syndrome: A Summary of Clinical Practice Guideline Recommendations-Using the Evidence to Guide Physical Therapist Practice