Hand Surgery Source

ULNAR ENTRAPMENT GUYON'S

Introduction

Guyon’s syndrome,1 commonly known as ulnar tunnel syndrome (UTS) or ulnar entrapment in Guyon's canal 2 is a symptomatic compression neuropathy represented by entrapment of the ulnar nerve at the level of the wrist and hypothenar eminence. The symptoms depend on the exact site of the ulnar nerve compression within the canal. As the ulnar nerve passes through Guyon’s canal, it bifurcates into a deep motor branch and a superficial sensory branch. Motor weakness in the interosseous muscles is observed when compression occurs in the deep branch.3 This manifests as difficulty in performing regular functions such as opening doorknobs or jars and other activities requiring power pinch, but without any sensory loss. Pain and paresthesias in the palmar side of the little finger and palmar-ulnar side of the ring finger appear when compression occurs in the superficial branch.4 A mix of motor weakness and sensory loss occur when ulnar nerve compression is proximal to the bifurcation.2,5,6

Pathophysiology2,6

  • Repetitive trauma or chronic pressure on the wrist such as cycling can cause entrapment symtoms
  • Benign cysts such as ganglion cysts and synovial cysts can occur in the Guyon's canal an cause nerve compression
  • Abnormalities such as muscle anomaly or anomalous course of ulnar nerve or carpal bone abnormalities can also compress the nerve
  • Fracture of the carpal bones, particularly the hook of the hamate, can cause related swelling or ulnar nerve damage

Related Anatomy2,6

  • The ulnar tunnel of the wrist, also known at the Guyon’s canal, is triangular with volar carpal ligament at anterior border, transverse carpal ligament at posterior border and pisiform bone and the flexor capri ulnaris (FCU) tendon at the median border
  • Ulnar artery is also in Guyon's canal and located radial and superficial to the ulnar nerve
  • Hook of hamate
  • Hypothenar muscles
  • Ulnar nerve bifurcates into a deep motor branch and a superficial sensory branch
    • Motor branch innervates the interosseous muscles
    • Superficial branch innervates the palmaris brevis and provides sensation to the hypothenar eminence, little finger, and ulnar side of the ring finger
  • Three anatomical zones of ulnar nerve compression in the wrist
    • Zone 1: part of the ulnar nerve proximal to or within Guyon’s canal before bifurcation of the ulnar nerve into superficial and deep branch
    • Zone 2: exit point of the deep branch of the ulnar nerve from Guyon’s canal
    • Zone 3: superficial branch of the ulnar nerve distal to the ulnar nerve bifurcation

Incidence and Related Conditions

  • Incidence of ulnar tunnel syndrome is not known, but is considered to be much less than carpal tunnel syndrome and cubital tunnel syndrome.2
  • Ulnar tunnel syndrome is often associated with carpal tunnel syndrome, hypothenar hammer syndrome and cyclist’s palsy2

Differential Diagnosis

  • Cubital tunnel syndrome
  • Carpal tunnel syndrome
  • Hypothenar hammer syndrome
  • C8-T1 radiculopathy
  • Thoracic outlet syndrome
  • Peripheral neuropathy
ICD-10 Codes

ULNAR ENTRAPMENT GUYON'S

Diagnostic Guide Name

ULNAR ENTRAPMENT GUYON'S

ICD 10 Diagnosis, Single Code, Left Code, Right Code and Bilateral Code

DIAGNOSIS SINGLE CODE ONLY LEFT RIGHT BILATERAL (If Available)
ULNAR ENTRAPMENT GUYON'S   G56.22 G56.21 G56.23

ICD-10 Reference

Reproduced from the International statistical classification of diseases and related health problems, 10th revision, Fifth edition, 2016. Geneva, World Health Organization, 2016 https://apps.who.int/iris/handle/10665/246208

Clinical Presentation Photos and Related Diagrams
Clinical Exam for Ulnar Entrapment at Guyon's Canal
  • Note ulnar intrinsic atrophy (arrow) caused by Guyon's Entrapment at Zone II.
    Note ulnar intrinsic atrophy (arrow) caused by Guyon's Entrapment at Zone II.
  • Note sensory testing in patient with ulnar entrapment in Guyon's Canal
    Note sensory testing in patient with ulnar entrapment in Guyon's Canal
Symptoms
Pain in the wrist and hand
Numbness or tingling sensation on the palmar surface of the little finger and ulnar side of the ring finger
Weakness of pinch and grip
Difficulty opening a jar or door knobs
Typical History

A typical patient is a long-distance cyclist or break dancer4 who overuses his/her palm, or a construction worker who frequently uses vibrating tools, causing repeated trauma on the palm. Initially, a patient may complain of inability to perform regular functions such as opening door knobs or jars. There might be tingling sensation in the hypothenar area. Muscle atrophy can develop over time in some cases. 

Positive Tests, Exams or Signs
Work-up Options
Images (X-Ray, MRI, etc.)
Imaging of Guyon's Canal
  • MRI showing hook of the hamate (HH) and a ganglion cyst compressing the ulnar nerve in Guyon's canal (GC). Carpal tunnel (CT) also visible.
    MRI showing hook of the hamate (HH) and a ganglion cyst compressing the ulnar nerve in Guyon's canal (GC). Carpal tunnel (CT) also visible.
Treatment Options
Treatment Goals
  • Relieve ulnar nerve related symptoms
  • Maintain normal pinch and grasp
  • Maintain normal ulnar sensation
Conservative
  • In patients with no motor deficits
    • Activity modification to avoid repetitive trauma
    • Protective braces
    • Non-steroidal anti-inflammatory medications (NSAIDs)
    • Sometimes aspiration in case of ganglionic cysts in Guyon's canal.  Ultrasound quidance maybe useful for this aspiratiion.
Operative
  • In patients with ganglion cysts or other tumors within Guyon's canal, the treatment is release of Guyon's canal and excision of the mass.
  • Surgical exploration with decompression of Guyon’s canal and piso-hammate hiatus is also indicated for patients with repetitive intermittent compression as seen in cyclists.
  • If multiple sites of compression are suspected, exploration of the ulnar nerve from the distal forearm to piso-hamate hiatus and cubital tunnel release
  • In patients with fracture nonunion of the hook of the hamate and Guyon's entrapment,  the treatment is release of the canal and excision of the hook of the hamate. 
  • In patients with thrombosis of the ulnar artery within Guyon's canal,  the treatment is remove of the thrombosis with or without vein grafting of the ulanr artery.
Treatment Photos and Diagrams
Surgical Release of Guyon's Canal
  • Ulnar artery retracted ulnarly (yellow vessel loop) and ulnar nerve at tip of the forceps.
    Ulnar artery retracted ulnarly (yellow vessel loop) and ulnar nerve at tip of the forceps.
  • Guyon's canal opened with superficial part of ganglion exposed (1); ulnar nerve (2); ulnar artery with vena comitans (3); cut edge of the transverse carpal ligament.
    Guyon's canal opened with superficial part of ganglion exposed (1); ulnar nerve (2); ulnar artery with vena comitans (3); cut edge of the transverse carpal ligament.
  • Guyon's canal dissected further with ulnar artery and vena comitans (1); motor branch of the ulnar nerve (2); sensory branch of the ulnar nerve (3); ganglion (4); and main ulnar nerve (5).
    Guyon's canal dissected further with ulnar artery and vena comitans (1); motor branch of the ulnar nerve (2); sensory branch of the ulnar nerve (3); ganglion (4); and main ulnar nerve (5).
  • Guyon's canal incision closed after releasing the carpal tunnel, Guyon's canal release, and excising a ganglion compressing the main ulnar nerve and the motor branch of the ulnar nerve.
    Guyon's canal incision closed after releasing the carpal tunnel, Guyon's canal release, and excising a ganglion compressing the main ulnar nerve and the motor branch of the ulnar nerve.
CPT Codes for Treatment Options

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Common Procedure Name
Ulnar nerve repair
CPT Description
Suture 1 nerve; hand or foot, ulnar motor
CPT Code Number
64836
CPT Code References

The American Medical Association (AMA) and Hand Surgery Resource, LLC have entered into a royalty free agreement which allows Hand Surgery Resource to provide our users with 75 commonly used hand surgery related CPT Codes for educational promises. For procedures associated with this Diagnostic Guide the CPT Codes are provided above. Reference materials for these codes is provided below. If the CPT Codes for the for the procedures associated with this Diagnostic Guide are not listed, then Hand Surgery Resource recommends using the references below to identify the proper CPT Codes.

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Complications
  • Persistent numbness
  • Persistent weakness
  • Infection post surgical release
  • Bleeding associated with surgical treatment
  • Muscle atrophy
  • Clawing
  • Vascular insufficiency in the ulnar hand and digits
Outcomes
  • Most patients recover and remain asymptomatic after treatment
YouTube Video
Lipoma of the Guyon's Canal
Key Educational Points
  • Guyon’s canal is approximately 4cm long. It starts at the proximal edge of the transverse carpal ligament and goes distally to the hypothenar muscle’s fibrous arch at the hook of the hamate. In the canal the ulnar nerve is ulnar and deep to the ulnar artery. The ulnar nerve bifurcates 6mm distal to the pisiform.
  • Many diagrams of Guyon’s canal suggest the bifurcation of ulnar nerve sends the sensory branch distally and the motor branch radially. In actual fact the motor branch first travels dorsal before turning radially to the adductor pollicis in the floor of the carpal tunnel. When releasing Guyon’s canal, the motor branch is not immediately visible because the motor branch is behind (dorsal) to the visible main ulnar nerve trunk and distal sensory ulnar branch.
  • The ulnar motor branch leaves Guyon’s canal via the pisohamate hiatus as it enters the deep palmar space (floor of carpal tunnel). 2
  • Hypothenar hammer syndrome is cause by thrombosis of the ulnar artery which is usually secondary to repetitive trauma. 2
  • Because the transverse carpal ligament forms part of Guyon’s canal structure, releasing the carpal tunnel (transverse carpal ligament) also increases the volume of Guyon’s canal and may decrease any co-existing tendency for ulnar entrapment in Guyon’s canal. 2,8
  • Phalen’s test and Tinel’s sign may both be positive with a Guyon’s entrapment of the ulnar nerve. 2
  • The space occupying lesions (ganglion) in Guyon’s canal are a common cause of ulnar tunnel syndrome. Therefore MRI imaging studies are an important part of the diagnostic work-up.2
  • The French surgeon, Jean Casmir Felix Guyon described the ulnar (Guyon’s) tunnel in 1861. 2,6
  • Ulnar tunnel syndrome (ulnar nerve entrapment in Guyon’s canal) was first described by DuPont in 1965. 2
References

Cited

  1. Guyon F. Note on the anatomical condition affecting the underside of the wrist not previously reported. 1861. J Hand Surg Br 2006 Apr;31(2):147–8. PMID:16442675
  2. Chen SH, Tsai TM. Ulnar tunnel syndrome. J Hand Surg 2014 Mar;39(3):571–9. PMID:24559635
  3. Grundberg AB. Ulnar tunnel syndrome. Iowa Orthop J 1981;1:73–4. PMID: 6707507
  4. Hu S-Y, Choi J-G, Son B-C. Type III Guyon Syndrome in “B Boy” Break-Dancer: A Case Report. Korean J Neurotrauma 2015 Oct;11(2):183–6. PMID: 27169091
  5. Ruas ES, Castilho RS, Maia PEC, Melo GLR. Guyon’s canal syndrome due to a synovial cyst. Rev Bras Ortop 2010 Dec;45(6):623–6. PMID: 27026975
  6. Maroukis BL, Ogawa T, Rehim SA, Chung KC. Guyon canal: the evolution of clinical anatomy. J Hand Surg 2015 Mar;40(3):560–5. PMID: 25446410
  7. Davidge KM, Gontre G, Tang D, et al. The “hierarchical” Scratch Collapse Test for identifying multilevel ulnar nerve compression. Hand (N Y) 2015 Sep;10(3):388–95. PMID: 26330768
  8. Richman JA, Gelberman RH, Rydevik BL et al. Carpal tunnel syndrome: morphologic changes after release of the transverse carpal ligament. J Hand Surg AM. 1989; 14(5): 852-857.

New Papers

  1. Davidge KM, Gontre G, Tang D, et al. The “hierarchical” Scratch Collapse Test for identifying multilevel ulnar nerve compression. Hand (N Y) 2015 Sep;10(3):388–95. PMID: 26330768
  2. Maroukis BL, Ogawa T, Rehim SA, Chung KC. Guyon canal: the evolution of clinical anatomy. J Hand Surg Am 2015 Mar;40(3):560–5. PMID: 25446410

Review

  1. Chen SH, Tsai TM. Ulnar tunnel syndrome. J Hand Surg 2014 Mar;39(3):571–9. PMID:24559635

Classics

  1. Guyon F. Note on the anatomical condition affecting the underside of the wrist not previously reported. 1861. J Hand Surg Br 2006 Apr;31(2):147–8. PMID:16442675
  2. Grundberg AB. Ulnar tunnel syndrome. Iowa Orthop J 1981;1:73–4. PMID: 6707507