Cubital Tunnel Syndrome and Ulnar neuropathy

Background/Epidemiology

• 2nd most common entrapment; men > women
• Anatomy
  • Ulnar nerve arises from the medial brachial plexus and innervates the muscles of the forearm and intrinsic muscles of the hand and provides sensory innvervation to the skin of the back of the forearm, palm and fourth and fifth fingers.

Pathophysiology

• Most common ulnar neuropathy is due to compression as the nerve passes through the cubital tunnel at the elbow
  • Other regions of compression include at the wrist (Guyon’s canal) and in the hand (against the pisiform and hamate bones)
• Space occupying lesions e.g. ganglions, bony spurs, hypertrophic callus etc can be the cause, but in most cases no such lesion is identified

Presentation

• Numbness/paraesthesia over the small/ring fingers, followed by weakness of the intrinsic muscles of the hand
  • In more severe disease, weakness of the flexor digitorum profundus or the small/ring fingers may also be seen and patient can present with a ‘claw’ postured hand
    • NB In more distal compression, FDP is often spared
  • Abduction of the little finger may also be seen due to unopposed action of the extensor muscle
  • Symptoms may be worse on elbow flexion
• On examination
  • There may be wasting of the small muscles of the hand
  • There is often loss of sensation in an ulnary distribution
  • It is important to look for any masses in the hand, wrist and over the cubital tunnel e.g. ganglia, which might be causing symptoms
  • Tinel’s test may be positive (tapping over the CUBITAL fossa for ulnar neuropathy)
  • Elbow flexion test:
    • Flex the elbow, supinate forearm and extend wrist- will exacerbate symptoms usually within a minute or so
  • There may also be a positive Froment’s sign (patient flexing the thumb to hold the sheet of paper due to weakness of intrinsic muscles)

Investigations

• Most diagnoses are clinical but nerve conduction tests may be useful in uncertain cases
• Occasionally, imaging can be done to view any lesions identified on examination

Management

• Conservative management is helpful in the majority of patients
  • NSAIDs, physio/activity modification (reducing elbow flexion and pressure on the elbow)
• Surgery can be considered in patients with troublesome and refractory symptoms
  • Usually decompressive surgery with or without (or and/or) nerve transposition