The Electric Shock Sign-An Indication of a Partial Digital Nerve Laceration: A Report of Three Cases

Electric shock sign after digital nerve injury; report of a case and review of literature

INTRODUCTION AND IMPORTANCE

Digital nerve lacerations are rationally common, especially following penetrating injuries. The majority of patients suffer from numbness as the main complaint. However, electric shock pain is a rare manifestation of partial nerve injury.

CASE PRESENTATION

A 65-year-old woman with partial digital nerve injury and an electric shock sign due to a 1 cm laceration on the volar side of the proximal phalanx three weeks earlier. The surgical exploration revealed a neuroma-like mass in the digital nerve; however, the continuity of the nerve was grossly intact.

CLINICAL DISCUSSION

Due to the superficiality of digital nerves, penetrating nerve injuries are rationally common in this area. Laceration of the digital nerve could lead to loss of sensation, clumsiness, and even loss of function. Gradually, neuroma formation would add a local pain and electric shock sign to the mentioned symptoms.

CONCLUSION

Electric shock sign is characteristic for partial digital nerve injury with unknown mechanism. It seems the symptoms would be progressive and more complicated with neuroma formation.

LEVEL OF EVIDENCE

V.

Ultrasound features of traumatic digital nerve injuries of the hand with surgical confirmation

OBJECTIVE

Characterize the appearance of digital nerve injuries in different ultrasound planes and correlate the presence and size of neuromas with time from injury.

MATERIALS AND METHODS

Surgically confirmed nerve injuries were retrospectively evaluated. Appearances of the nerve injury in the available imaging planes were reviewed by two readers. Associations between presence and size of neuroma with time from injury were analyzed.

RESULTS

Injuries of 29 digital nerves (3 incomplete lacerations, 17 complete lacerations, 6 with 7 stump neuromas, 3 neuromas-in-continuity) noted on ultrasound were surgically confirmed. Among the 20 lacerations, long-axis images were obtained in 15, of which 10 depicted the injury and 4 did not. Among the 10 depicting the injury in long axis, 2 showed a discrete gap, and 7 showed the nerve obscured by laceration tissue without a gap. In short axis, the nerve injury was visible in all 20, and nerve laceration was seen as a discrete gap in 2, and obscuration by laceration tissue in 14. Neuromas were hypoechoic and well-defined. There was a positive association between time and presence of neuroma (OR = 1.3, p = 0.002). Correlations between time and cross-sectional area (r_s = 0.45) and volume (r_s = 0.57) of neuromas were moderately positive.

CONCLUSION

Ultrasound long axis may be less useful, and those short axis may be more reliable for assessing digital nerve injuries than previously reported. Neuromas are hypoechoic and well-defined, and their size can vary based on time from injury.