Carpal tunnel vs Cubital tunnel and Guyon canal syndromes
How to tell Carpal tunnel and Cubital tunnel and Guyon canal syndromes apart when a board question makes them look alike.
Carpal tunnel is median nerve at wrist; cubital tunnel is ulnar at elbow; Guyon canal is ulnar at wrist with dorsal ulnar sparing.
Side by side
Carpal tunnel syndrome compresses the median nerve at the wrist, causing nocturnal paresthesias in lateral three and a half digits and thenar weakness.
Cubital tunnel compresses ulnar nerve at the elbow; Guyon canal compresses ulnar nerve at the wrist, sparing dorsal ulnar hand sensation.
Median nerve compression beneath the transverse carpal ligament impairs sensory and thenar motor fibers.
Ulnar nerve compression at elbow or wrist affects intrinsic hand muscles and ulnar-sided digits with different dorsal sensory involvement.
Positive Phalen/Tinel at wrist, thenar atrophy, and lateral digit symptoms support carpal tunnel.
Elbow flexion symptoms support cubital tunnel; hypothenar/interossei weakness with dorsal sensory sparing supports Guyon canal.
The trap
Hand numbness overlaps, so nerve, compression site, and dorsal sensory sparing separate syndromes.
The repair move
For entrapment neuropathy, map sensory territory and lesion site before naming the tunnel.
Try a free question
CoreA 42-year-old hypothyroid woman who works at a computer has 3 months of progressive nocturnal hand numbness and tingling in the thumb, index, and middle fingers. She frequently shakes out her hand for relief. Exam shows positive Tinel sign at the wrist, positive Phalen maneuver, and thenar weakness. EMG/nerve conduction shows median nerve slowing at the wrist. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Carpal tunnel syndrome. Carpal tunnel syndrome is median nerve compression at the wrist with sensory symptoms in the thumb, index, middle, and radial half of ring finger, nocturnal worsening, thenar atrophy in advanced cases, and positive Tinel/Phalen tests; treatment includes wrist splinting, corticosteroid injection, or surgical release.
Why the other choices are tempting
- B. Cubital tunnel syndrome (ulnar nerve at elbow) affects the medial hand including small finger and ulnar half of ring finger.
- C. Guyon canal syndrome (ulnar at wrist) spares the dorsal ulnar hand (which is supplied by the dorsal cutaneous branch arising proximal to Guyon canal).
- D. C6 radiculopathy involves the radial forearm and thumb with neck pain and abnormal biceps reflex.
- E. Radial neuropathy causes wrist drop, not median territory numbness.
Flashcards
Tap a card to flip it.
What nerve is compressed in carpal tunnel?
The median nerve is compressed in carpal tunnel syndrome.
What clue separates Guyon canal from cubital tunnel?
Dorsal ulnar hand sensation is spared in Guyon canal syndrome.
Quick answers
What is the fastest way to tell Carpal tunnel from Cubital tunnel and Guyon canal syndromes?
Carpal tunnel is median nerve at wrist; cubital tunnel is ulnar at elbow; Guyon canal is ulnar at wrist with dorsal ulnar sparing.
What is the key clue for Carpal tunnel?
Carpal tunnel syndrome compresses the median nerve at the wrist, causing nocturnal paresthesias in lateral three and a half digits and thenar weakness.
What is the key clue for Cubital tunnel and Guyon canal syndromes?
Cubital tunnel compresses ulnar nerve at the elbow; Guyon canal compresses ulnar nerve at the wrist, sparing dorsal ulnar hand sensation.
What is the common trap with Carpal tunnel vs Cubital tunnel and Guyon canal syndromes?
Hand numbness overlaps, so nerve, compression site, and dorsal sensory sparing separate syndromes.