Definition/Introduction

The Benediction sign is a pathological hand posture consisting of the extension of the second and third fingers, abduction of the first finger, and flexion of the fourth and fifth fingers. If triggered when attempting to make a fist, functional failure of the intrinsic muscles involved in flexion of the first, second, and third fingers should be suspected. If the sign is observed when attempting extension of the palm and fingers, then the affected muscles are those involved in extending the fourth and fifth fingers. Muscular impairment is most frequently the result of peripheral nerve pathologies, although rare cases of central nervous system lesions have been associated with these findings.[1][2][3] 

This sign has also been referred to by other names, such as the Preacher’s hand and “main-en-griffe”. The papal benediction sign was first recognized in the historical artwork representing Saint Peter, who presumably suffered from ulnar neuropathy. After him, other popes imitated his hand gesture in preaching.[4][5]

Issues of Concern

While the Benediction sign has been extensively documented in medical literature, including historical images dating back to the second and third centuries, the precise nerve lesion responsible for this pathological hand posture has remained a subject of ongoing debate. Some clinicians and anatomists have associated this clinical sign with median nerve neuropathy, whereas others have advocated for ulnar nerve neuropathy as the underlying etiology. Nevertheless, the hand posture is similar in both scenarios, as discussed below.[4]

The median nerve provides mixed motor and sensory functions. It originates from the brachial plexus, where the C5 to C7 roots merge to form the lateral cord, and the C8 and T1 roots form the medial cord. Both cords converge at the level of the pectoralis minor in a Y-shaped configuration (the "median nerve fork") and give rise to the median nerve. It runs alongside the brachial artery, from lateral to medial, and enters the antecubital fossa beneath the lacertus fibrosus. It continues through the forearm between the heads of the pronator teres (PT) and the flexor digitorum superficialis (FDS). It ultimately enters the carpal tunnel between the flexor digitorum profundus (FDP) and the FDS.[2][6] It innervates the FDP, flexor pollicis longus (FPL), pronator quadratus (PQ), and lumbrical muscles to the second and third fingers, and the intrinsic thenar muscles: abductor pollicis brevis, opponens pollicis, and flexor pollicis brevis.[7]

A low median nerve lesion can manifest as a positive Benediction sign when attempting to make a fist, given its role in innervating the muscles responsible for flexing the first to third fingers. Notably, the FDP and FPB muscles may exhibit dual innervation, mitigating the appearance of a complete benediction sign in the presence of a low median nerve lesion.[8] In contrast, recent studies have consistently indicated that patients with high median nerve lesions do not present this clinical sign.[9][10] 

The ulnar nerve is derived from the medial cord of the brachial plexus, incorporating nerve roots C8 to T1. When it reaches the forearm, it gives rise to motor branches that innervate the flexor carpi ulnaris and the medial half of FDP. In the hand, the ulnar nerve innervates medial 2 lumbricals supplying the fourth and fifth fingers, interossei, and hypothenar muscles.[11][12][13] When relating the injury to the ulnar nerve, the Benediction sign would present if the affected individual tries to open their hand and extend the fingers. Due to the loss of function of the medial 2 lumbricals, the metacarpophalangeal joints of the fourth and fifth fingers will be in extension, while the interphalangeal joints will be in flexion. A figure illustrating the different hand positions described in this section is shown (see Image Hand Positions).

Clinical Significance

Due to the anatomical considerations discussed above, the Benediction sign indicates lesions affecting the medial or ulnar nerves. It is important to note that while it may manifest, this sign is not pathognomonic for either of these pathologies. Accurate diagnosis hinges upon a comprehensive assessment, including clinical history, thorough examination, nerve conduction, electromyography, and imaging studies. During physical examination, attention should be directed toward specific findings associated with median and ulnar pathologies.

For median nerve lesions, sensory impairment is characterized by hypoesthesia and paresthesia on the palmar side of the first to third fingers. Additionally, the lesion level along the median nerve pathway often dictates distinct clinical manifestations.[6][14] Recent literature showed that high median nerve lesions do not correlate with the Benediction sign, making its occurrence highly unlikely. Median nerve lesions most commonly occur at the level of the carpal tunnel, in which scenario the following signs can be present:[15]

• Thenar atrophy
• Nocturnal symptoms
• Positive Phalen, Tinel, and Durkan tests: The Phalen test consists of the flexion of both wrists, positioning the dorsal sides of the hands facing each other. The Tinel test is performed by gently tapping the wrist along the nerve pathway, while the Durkan test entails compression rather than percussion. A positive response is determined when these tests elicit the onset of tingling and numbness within the nerve territory. 

In ulnar nerve lesions, sensory impairment manifests as hypoesthesia and paresthesia on the fifth finger, the median side of the fourth finger, and the palmar and dorsal sides of the hypothenar region. Unlike median nerve lesions, the pathological hand position found in affected patients does not appear to vary based on the lesion level. Most commonly, lesions will be localized near the elbow.[16] Specific clinical signs indicative of ulnar nerve pathology are:

• Froment sign occurs due to the weakness of the adductor pollicis muscle, which adducts the thumb. Therefore, when the clinician asks a patient to pinch a piece of paper between thethumb and index fingers, the distal phalanx of the thumb flexes due to involuntarily activation of the FPL, a median nerve–innervated muscle.
• Wartenberg sign occurs due to the weakness of the third palmar interosseous muscle. It results in the inability to adduct the little finger. Therefore, the little finger remains abducted and gets caught when the patient tries to put the hand in a pocket.[1]
• Atrophy of the intrinsic muscles, particularly the hypothenar muscles, may develop in more advanced cases. Therefore, prevention and prompt diagnosis and treatment are essential for a favorable prognosis.[17][18]

Confirmation through nerve conduction and electromyography is mandatory upon suspicion of a median or ulnar nerve lesion. These studies provide valuable insights into the nerve's functionality and often pinpoint the location and extent of the lesion. Furthermore, incorporating imaging studies such as ultrasound and magnetic resonance imaging into the diagnostic process might contribute to our understanding of the structural aspects of the affected nerve.[19][20]

Nursing, Allied Health, and Interprofessional Team Interventions

A primary care physician or a neurologist often diagnoses the condition and makes a timely referral or evaluates for neuropathy. An interprofessional team that includes a primary care physician, neurologist, neurosurgeon, physical therapist, hand surgeon, nurse practitioner, and specially trained nursing staff should be involved in further managing this condition. The specific management depends upon the underlying cause, if present. Physical therapy, occupational therapy, and extensive rehabilitation with strength training are necessary for all individuals to ensure good clinical outcomes. Interprofessional information sharing and collaborative effort in diagnosis and treatment will bring optimal patient outcomes.