Guyon’s Canal Syndrome

Guyon’s Canal Syndrome is a rare peripheral neuropathy caused by compression of the ulnar nerve as it passes through guyon’s canal, a fibro-osseous tunnel at the wrist. This condition results in sensory and motor dysfunction within the ulnar nerve distribution, leading to symptoms such as numbness, tingling and weakness in the ring and little fingers, as well as potential impairment of intrinsic hand muscles, leading to progressive functional impairment.

 

Classification of Lesions in Guyon’s Canal Syndrome

Lesions in Guyon’s canal are traditionally classified using the Shea and McClain subdivision, which divides the canal into three distinct zones based on the anatomy of the ulnar nerve and its bifurcation into sensory and motor branches. Each zone is associated with specific patterns of impairment depending on the location of the nerve injury.

Zone 1:

• Located in the distal section of the ulnar nerve before its bifurcation into sensory and motor branches.
• Injury to this zone causes combined motor and sensory deficits, affecting both intrinsic hand muscles and sensation in the ulnar nerve distribution (ring and little fingers).
• This zone is often affected in severe compression cases.

Zone 2:

• Situated distal to the bifurcation of the ulnar nerve and lies radial to Zone 3.
• This is the most commonly affected zone in Guyon’s Canal Syndrome.
• Injury here results in motor deficits only, as it involves the motor branch of the ulnar nerve supplying intrinsic hand muscles. Sensory function remains intact.

Zone 3:

• Located ulnar to Zone 2 and also distal to the bifurcation of the ulnar nerve.
• Injury to this zone leads to sensory deficits only, as it involves the sensory branch of the ulnar nerve. Motor function remains unaffected.

Symptom Similarity and Difference in Guyon’s Canal Syndrome:

The symptoms of Guyon’s Canal Syndrome resemble those seen in ulnar nerve groove (cubital tunnel) issues, such as numbness, tingling etc. However, a key difference is that Guyon’s Canal Syndrome does not affect the sensory innervation of the dorsum of the hand.

This distinction arises because the ramus dorsalis manus (dorsal cutaneous branch of the ulnar nerve) originates 5–8 cm proximal to Guyon’s canal. Since this branch exits the nerve before the ulnar nerve enters the canal, it is unaffected by compression within the canal. Consequently, the dorsum of the hand retains normal sensation in cases of Guyon’s Canal Syndrome.

 

Causes of Guyon’s Canal Syndrome

 

Clinical Presentation

1. Sensory Symptoms

• Numbness or tingling in the ulnar half of the ring finger and little finger.
• Pain or discomfort in the wrist or palm, often worsened by repetitive activities.
• Sensory deficits depend on the site of nerve compression:

         Zone 1 (Proximal Canal): Mixed sensory and motor deficits.

         Zone 3 (Sensory Branch): Sensory deficits only.

2. Motor Symptoms

• Weakness in intrinsic hand muscles innervated by the ulnar nerve (e.g., interossei, lumbricals of 4th & 5th digits).
• Difficulty with fine motor tasks such as pinching, gripping or manipulating small objects.
• Clawing of the ring and little fingers in severe cases due to imbalance between flexor and extensor muscles.
• Wartenberg’s sign - over-abduction of the little finger at rest.

3. Visible Signs

• Muscle wasting of the hypothenar eminence and intrinsic hand muscles in chronic cases.
• Froment’s sign - weakness in the adductor pollicis muscle (ulnar nerve), causing compensatory thumb flexion when holding a paper.  

Diagnosing Guyon’s Canal Syndrome

 

Differential Diagnosis of Guyon’s Canal Syndrome:

• Cubital Tunnel Syndrome
• Cervical Radiculopathy (C8/T1)
• Thoracic Outlet Syndrome
• Carpal Tunnel Syndrome
• De Quervain’s Tenosynovitis
• Ulnar Nerve Subluxation or Dislocation
• Fracture of the Hamate or Pisiform
• PeripheralNeuropathy (e.g., diabetic neuropathy)
• Complex Regional Pain Syndrome (CRPS)
• Flexor Tendinitis or Tenosynovitis

 

Physiotherapy Management of Guyon’s Canal Syndrome:

Management should be tailored based on the affected zone, as each presents with different impairments. The goal is to relieve compression, restore function, and prevent recurrence.

Education and Activity Modification

✅ Advice on avoiding exacerbating factors:

• Reduce repetitive wrist motions (e.g., typing, cycling, racket sports).
• Avoid prolonged wrist compression (e.g., resting wrist on hard surfaces like handlebars).
• Use ergonomic adjustments, such as padded gloves, wrist supports or ergonomic keyboards/mice.

✅ Modification of daily activities:

• Cyclists should use padded gloves and change hand position frequently on the handlebar.
• Office workers should use a wrist rest or an ergonomic mouse.
• Musicians must modify playing position to avoid prolonged wrist flexion or ulnar deviation.

Pain and Inflammation Management

✅ Cryotherapy/Thermotherapy:

• Ice therapy for acute inflammation.
• Heat therapy for chronic stiffness and muscle relaxation.

✅ Electrotherapy:

• TENS(Transcutaneous Electrical Nerve Stimulation) - for pain relief.
• Therapeutic Ultrasound - to reduce soft tissue tightness.

Soft Tissue Techniques

✅ Myofascial Release:

• Trigger point release for hypothenar muscles, flexor carpi ulnaris and forearm flexors.
• Gentle soft tissue mobilization to improve circulation and reduce tension.

Joint Mobilization

✅ Carpal bone mobilization:

Mobilization of pisiform, hamate and adjacent carpal bones to reduce compression.

Example:

Pisiform Glides - apply gentle anterior-posterior gliding movements on the pisiform bone.

Nerve Gliding Exercises

✅ Ulnar Nerve Glide:

• Position - extend the affected arm to the side with the elbow bent at 90°.
• Movement - slowly extend the wrist while tilting the head away from the arm.
• Progression - move the wrist into flexion while tilting the head toward the arm.

Goal is to reduce nerve adherence and improve mobility.

 

Strengthening Exercises

✅ Intrinsic Hand Muscle Strengthening:

• Finger abduction/adduction with resistance bands.
• Squeezing therapy putty or stress ball for grip strength.
• Thumb adduction exercises (to counteract Froment’s sign).

✅ Forearm Strengthening:

• Wrist curls (flexion & extension) with light weights.
• Resisted ulnar deviation exercises using a resistance band.

Stretching Exercises

✅ Stretching Wrist and Forearm Muscles:

• Flexor Carpi Ulnaris Stretch - extend the wrist while keeping the elbow straight.
• Flexor Digitorum Profundus Stretch - extend the fingers while maintaining wrist extension.

Proprioception and Functional Training

✅ Fine motor control exercises:

• Picking up small objects (e.g., beads, coins) using the affected fingers.
• Buttoning/unbuttoning exercises for dexterity.
• Grip and pinch strength training using therapy putty.

Splinting

✅ Use of a wrist splint in a neutral position:

• For nighttime use to prevent excessive wrist flexion.
• During repetitive activities to reduce stress on the nerve.

Example:

Cycling Wrist Brace - helps reduce compression from prolonged grip on handlebars.

Progress Monitoring

✅ Regular assessments of:

1. Grip strength (through dynamometer).
2. Hand dexterity tests (e.g., Purdue Pegboard Test).
3. Nerve function using Tinel’s sign and Two-Point Discrimination Test.
4. Functional improvements in daily activities (e.g., improved grip while holding objects).

Referral to a specialist is recommended if symptoms persist despite conservative management, indicating a need for further medical intervention. Additionally, severe motor weakness that affects hand function may require further interventions such as corticosteroid injections or, in more advanced cases, surgical decompression. 

Collaboration with an occupational therapist is also essential, particularly for patients requiring workplace modifications, adaptive devices or ergonomic adjustments to prevent recurrent nerve compression and optimize hand function in daily activities.