Ulnar Nerve Injection

Other Names

Borders of the cubital tunnel

• Ulnar Nerve Injection
• Cubital Tunnel Injection

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Background

Key Points

• Use a high frequency, linear transducer
• Small gauge and relatively short needle, e.g. 25 gauge, 1.5 inch
• Avoid injecting directly into the nerve or adjacent vascular structures

Anatomy of the Ulnar Nerve

• Originates from C8, T1 nerve roots
• Forms medial cord of bracial plexus
• After descending through the arm, it travels through the cubital tunnel
• Enters the flexor compartment of the forearrm between the two heads of flexor carpi ulnaris
• There it joints with the ulnar artery, travels deep to FCU
• 5 cm proximal to wrist, divides into dorsal and palmar branches
• Palmar branch enters the wrist through guyon's canal

Palpation Guidance vs Ultrasound Guidance

• This procedure can not be safely performed without ultrasound guidance

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Indications

• Ulnar Neuropathy
• Regional anesthesia of the Ulnar Nerve
  • Prior to procedures of the finger, hand and wrist

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Contraindications

• Absolute
  • Anaphylaxis to injectates
  • Overlying cellulitis, skin lesion or systemic infection
• Relative
  • Uncertainty in diagnosis
  • Can be treated with less invasive means
  • Hyperglycemia or poorly controlled diabetes
  • Lack of symptom improvement with previous injection

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Procedure

Ultrasound-guided injection into the cubital tunnel was conducted via an in-plane technique. (A) The patient was placed in a supine position with the shoulder abducted and the elbow flexed at 90°. (B) The ulnar nerve within the cubital tunnel was identified in transverse plane, and the injection was conducted after aseptic preparation. (C) The needle (arrowhead) passed between the medial epicondyle (ME) and ulnar nerve (dotted circle) at the level of the epicondyle. (D) After the injection, we confirmed that the ulnar nerve was separated from the epicondyle by the effect of hydrodissection. O, olecranon

Transducer and needle position for the below cubital tunnel approach.

Ultrasound image of below cubital tunnel approach with needle in plane on the ulnar nerve

Transducer and needle position for the above the cubital tunnel approach

Ultrasound image of above cubital tunnel approach with needle indicated by the arrow

Equipment

• Sterile including chloraprep, chlorhexadine, iodine
• Gloves
• Needle: typically 21-25 gauge, 1.5 inch
• Syringe: 5-10 mL
• Gauze
• Ethyl Chloride
• Bandage
• Injectate
  • Local anesthetic
  • Corticosteroid
• Sterile probe cover

Ultrasound Findings

• Starting position
  • Short axis at the bony landmarks of the elbow
  • Place the transducer to span the medial epicondyle, olecranon process
  • May appear more hypoechoic because of the hyperechoic fat surrounding the nerve here
• Distal
  • Follow the ulnar nerve into the cubital tunnel
  • Trace down between the two heads of the FCU
  • Arcuate ligament may be seen here
  • From here, can be traced down to hand
• Proximal
  • Can be scanned proximally from the starting position
  • Trace up to medial cord of the brachial plexus
• Dynamic Evaluation
  • Consider keeping the transducer in place, visualizing nerve with active flexion and extension
  • The nerve may dislocate medially over the medial epicondyle during flexion
  • Asymptomatic ulnar nerve dislocation occurs in up to 20% of the population
  • Snapping triceps syndrome can also be observed; the medial head of triceps dislocates medially over the medial epicondyle
  • Be careful not to apply too much pressure which can produce a false negative dislocation sign
• Ultrasound findings
  • Abnormal: cross-sectional area of the ulnar nerve above 7.5 mm2 at the level of the medial epicondyle
  • Look for causes of neuropathy such as vascular lesions, external compression, fractures, physeal injuries, etc

Below Cubital Tunnel Injection

• Patient Position
  • Supine
  • Arm abducted to approximately 15–30 degrees, forearm supined
• Transducer Position
  • Short axis over the ulnar nerve at the proximal third of the forearm
• Needle Orientation and Approach
  • In plane
  • Either medial-to-lateral or lateral-to-medial
• Target
  • Area surrounding the ulnar nerve
• Pearls and Pitfalls
  • Try to choose a point where the ulnar artery and nerve have not yet become immediately adjacent
  • Place needle close to nerve, do not touch nerve
  • If patient feels sharp pain, retract needle and redirect
  • To create a "halo" around nerve, you may need to inject above and below
  • If the ulnar side of the forearm needs to be anesthetized, perform proximal to medial epicondyle

Above Cubital Tunnel Injection

• Patient Position
  • Supine
  • Arm abducted to approximately 90 degrees, forearm supined
• Transducer Position
  • Short axis over the ulnar nerve above the cubital tunnel
• Needle Orientation and Approach
  • In plane
  • Either medial-to-lateral or lateral-to-medial
• Target
  • Area surrounding the ulnar nerve
• Pearls and Pitfalls
  • Avoid contact with ulnar artery, may lay superficial to nerve
  • Place needle close to nerve, do not touch nerve
  • If patient feels sharp pain, retract needle and redirect
  • To create a "halo" around nerve, you may need to inject above and below
  • If the ulnar side of the forearm needs to be anesthetized, perform proximal to medial epicondyle

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Aftercare

• Patient should be counseled on
  • Duration of anesthetic
  • Loss of motor function of extensor muscle groups

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Complications

• Intravascular injection
• Residual motor block
• Local trauma

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See Also

• Elbow Pain Main
• Procedures Main

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