Monday, March 19, 2007

Ring Blocks

A digital ring block (aka digital block) is the technique of blocking the nerves of the digits to achieve anesthesia of the finger(s). It is a useful procedure to facilitate minor surgery of the finger.

The nerves to be blocked are the palmar and dorsal digital nerves.

The two palmar nerves supply the anterior aspect of the fingers and are the terminal branches of the median nerve (lateral 3 1/2 fingers) and ulnar nerve (little finger and 1/2 ring finger).

The two dorsal nerves supply the posterior aspect of the fingers and arise from the radial nerve (lateral 2 1/2 to 3 1/2 fingers) and ulna nerve (medial 1 1/2 to 2 1/2 fingers).

If seen in cross section the nerves are at two, five, seven and ten o'clock positions

The procedure:
  • The patient's hand and fingers are extended and fingers abducted from each other.
  • The head of the metacarpal bone and base of the proximal phalanx is felt.
  • The skin is cleaned.
  • The needle is introduced between the fingers at the point of the interdigital fold and a skin wheal is raised. This is at the level of the head of the metacarpal bone.
  • The needle is advanced along the axis of the fingers until the palmar aponeurosis is
    reached which is felt as a resistance.
  • Before injection of local anaesthetic the needle must be aspirated to prevent intra-
    vascular injection.
  • 1 to 2 mls of local anaesthetic is introduced as the needle is withdrawn.
  • Subcutaneous injection around the base of the finger is then done through the same skin
    wheal to block the palmar and dorsal digital nerves.
  • The procedure is repeated on the opposite side of the finger.
  • Massaging the finger after infiltration facilitates spread and increases absorption of the
    local anaesthetic.

  • "Digital Ring Block", Dr. Mary Daniels, Department of Anaesthesia, The Chinese University of Hong Kong,
  • "Digital Nerve Block", Dr A Hazdic, New York School of Regional Anaesthesia,


Calliope said...

Good words.

Anonymous said...

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Anonymous said...

I'm trying to find out how long this will last. I had one done, it is now 18 hours later and my finger is 80% numb, the tip is frozen. How long is this supposed to last? It was done to remove a splinter from under the nail bed.

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