hand of benediction

**Definition:** On attempted fist formation, the index and middle fingers cannot flex and stay extended. The ring and little fingers flex normally. The posture resembles a priest's blessing.

**Pathophysiology:** The cause is a proximal median nerve lesion. The median nerve (via the anterior interosseous branch and the main trunk) supplies the flexor digitorum superficialis (FDS) to all four digits. It also supplies the flexor digitorum profundus (FDP) to digits 2 and 3 (lateral half), and the flexor pollicis longus (FPL). The ulnar nerve supplies the FDP to digits 4 and 5 (medial half). With a proximal median lesion, flexion at the PIP joints of all fingers and at the DIP joints of digits 2 and 3 is lost. The ulnar-innervated FDP still flexes digits 4 and 5, so they curl normally. Digits 2 and 3 stay extended.

**Causes (proximal median nerve injury):** - Supracondylar humerus fracture (classic in children) - Pronator teres syndrome (compression between the two heads of pronator teres) - Elbow dislocation or other trauma, or a ligament of Struthers - Anterior interosseous nerve syndrome (isolated loss of FDP2/3 and FPL, giving the "OK sign" weakness with no sensory loss)

**Associated findings in a proximal median nerve lesion:** - Weak wrist flexion with ulnar deviation (the FCR is lost, but the FCU is ulnar-innervated) - Weak forearm pronation - Weak thumb opposition and abduction (APB, opponens pollicis), with thenar atrophy ("ape hand") - Loss of the lateral two lumbricals - Sensory loss over the palmar lateral 3½ digits and the thenar eminence

**Don't confuse with:** - **Ulnar claw (hand of benediction's "opposite"):** Distal ulnar nerve lesion (e.g., at the wrist or Guyon canal) causes hyperextension at the MCP joints and flexion at the PIP and DIP joints of digits 4 and 5. It is seen at rest. It is worse with distal lesions because the FDP is spared, so unopposed FDP flexion increases the claw ("ulnar paradox"). A proximal ulnar lesion (e.g., at the elbow) gives less claw because the FDP to digits 4 and 5 is also lost. - **Hand of benediction in ulnar lesions:** Some texts describe a "benediction sign" with ulnar nerve injury. The classic Step 1 usage is for the median nerve, on attempted fist formation. Some sources describe the ulnar claw at rest as a "benediction" posture, which is a point of confusion. For boards, **the median nerve lesion with failure of digits 2 and 3 to flex on making a fist is the standard answer**, and a distal ulnar lesion gives the claw hand. - **Radial nerve injury:** Wrist drop.

**Clinical pearls:** - Test by asking the patient to make a fist. A positive sign is when digits 2 and 3 do not flex. - Carpal tunnel syndrome (a distal median lesion) does **not** cause hand of benediction. It causes thenar atrophy, weak opposition, and sensory loss, and spares the palmar cutaneous branch. - Supracondylar fracture can also injure the brachial artery, causing Volkmann ischemic contracture. Always check the pulses and compartments.