Hypothenar Hammer Syndrome I74.2 444.21

Guyons Canal Image


Hyothenar Hammer Syndrome ICD-10

  • I74.2:    Embolism and thrombosis of arteries of the upper extremities

Hyothenar Hammer Syndrome ICD-9

  • 444.21 Arterial embolism and thrombosis; upper extremity

Hyothenar Hammer Syndrome Etiology / Epidemiology / Natural History

  • Thrombosis of the ulnar artery in Guyon's canal, resulting from blunt or repetitive trauma to the base of the hypothenar eminence.
  • Repetitive trauma may lead to formation of a pseudoaneursym or ulnar artery thrombosis.
  • Most common upper extremity arterial occlusion.
  • Males > females
  • Associated with smokingand fibromuscular dysplasia
  • May occur in baseball catchers or golfers.

Hyothenar Hammer Syndrome Anatomy

  • 22% of patients have an incomplete superficial palmar arch, 3% have imcomplete deep palmar arch.
  • mixed=proximal, motor only=hook of hamate, pure sensory=distal to hamate
  • roof=volar carpal ligament. Floor=transverse carpal ligament & pisohamate ligament. Ulnar wall=hook of hamate. Radial wall =pisiform &ADM muscle muscle.
  • sources=ganglia(85%)(MRI), hook of hamate nonunion(CT), ulnar artery thrombosis(U/S), anomalous muscle, palmaris brevis hypertrophy
  • Ulnar tunnel zone 1=proximal to bifurcation of nerve associated with mixed motor/sensory. Most common lesions = ganglions and hook of hamate fracture.
  • Ulnar tunnel zone 2=hook of hamate, deep motor branch only. Most common lesions = ganglions and hook of hamate fracture.
  • ulnar tunnel zone 3=superficial sensory branch only. Most common lesions = Ulnar artery thrombosis.

Hyothenar Hammer Syndrome Clinical Evaluation

  • Ulnar nerve symptoms: numbness, tingling, pain, weakness
  • Ischemic symptoms: cold intolerance, pain, occasionally ulceration of the small and/or ring finger or even gangrene.
  • Allen's test is positive.

Hyothenar Hammer Syndrome Xray / Diagnositc Tests

  • P/A and lateral views of the wrist typically normal.
  • Doppler ultrasonography confirms diagnosis.
  • EMG/NCVconsider for patients with ulnar nerve symptoms.
  • MRI: consider to evaluate for space occupying lesions
  • CTscan: best test to evaluate for hook of hamate fracture.

Hyothenar Hammer Syndrome Classification / Treatment

  • Acute: consider urokinase, streptokinase thrombolysis.
  • Conservative: smoking cessation, activity modification, calcium channel blockers, alpha blockers, beta blockers, steriods, intravenous prostaglandin, heparin.
  • Treatment = excision of the thrombosis segment with reconstruction using reversed vein graft. Reocclusion or aneurysm is not uncommon. Other options = endarterectomy, thrombus excision with ligation of artery.

Hyothenar Hammer Syndrome Associated Injuries / Differential Diagnosis

  • Ulnar artery thrombosis = Hypothenar hammer syndrome
  • Flexor tendonitis
  • TFCC tear
  • Hook of the Hamate fracture
  • Wartenberg's Syndrome
  • Cubital tunnel syndrome
  • Ulnar Tunnel Syndrome
  • Carpal tunnel syndrome(commonly coexist, release of transverse carpal ligament adequetely decompresses Guyons canal)
  • Autoimmune vasculitis
  • Thoracic outlet syndrome
  • Emboli

Hyothenar Hammer Syndrome Complications

  • Failure/ reocclusion
  • Persistent numbness
  • Palmar hypersensitivity
  • Distal Ulnar nerve palsy (motor branch)
  • Wound dehiscence
  • Infection
  • Gangrene

Hyothenar Hammer Syndrome Follow-up Care

  • Post-op: Volar splint, NWB
  • 7-10 Days: Remove sutures, consider night time splinting. Start gentle ROM exercises
  • 6 Weeks: Begin strengthening exercises
  • 3 Months:Return to full activities / sport

Hyothenar Hammer Syndrome Review References