Ioannis Karakis1, Wendy Liew2, Heather Szelag Fournier3, H Royden Jones4, Basil T Darras3, Peter B Kang5. 1. Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA; Department of Neurology, Lahey Clinic, Burlington, MA, USA; Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA. 2. Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA; Department of Neurology, KK Women's & Children's Hospital, Singapore. 3. Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA. 4. Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA; Department of Neurology, Lahey Clinic, Burlington, MA, USA. 5. Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA; Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, USA; Department of Neurology, University of Florida College of Medicine, Gainesville, FL, USA. Electronic address: pbkang@ufl.edu.
Abstract
OBJECTIVE: To analyze patterns of nerve injury in pediatric ulnar neuropathy (PUN). METHODS: Retrospective analysis of 49 children with PUN. RESULTS: Sensory loss in digit V was the prevailing complaint (89%). Predominant localization was at the elbow (55%). Diminished ulnar SNAP was the most common abnormality (71%) with median axon loss estimate (MAXE) of 62%. Dorsal ulnar cutaneous (DUC) sensory nerve action potential (SNAP) was reduced in 55% with MAXE of 43%. Abductor digiti minimi (ADM) and first dorsal interosseous (FDI) compound muscle action potential (CMAP) were reduced half of the time, with MAXE of 30% and 28% respectively. There was high correlation between ulnar sensory MAXE and ADM MAXE (r=0.76, p<0.0001), FDI MAXE (r=0.81, p<0.0001) and DUC MAXE (r=0.60, p=0.0048). Neurogenic changes were seen in the ADM, FDI, flexor carpi ulnaris (FCU) and flexor digitorum profundus IV (FDP IV) in 79%, 77%, 25% and 35% respectively. Pathophysiology was demyelinating in 27%, axonal in 59% and mixed in 14%. CONCLUSIONS: In proximal axonal lesions, sensory fibers to digit V and motor fibers to distal muscles are predominantly affected, whereas in demyelinating lesions, slowing occurs twice as frequently as conduction block. SIGNIFICANCE: There is frequent axonal and fascicular injury in PUN.
OBJECTIVE: To analyze patterns of nerve injury in pediatric ulnar neuropathy (PUN). METHODS: Retrospective analysis of 49 children with PUN. RESULTS: Sensory loss in digit V was the prevailing complaint (89%). Predominant localization was at the elbow (55%). Diminished ulnar SNAP was the most common abnormality (71%) with median axon loss estimate (MAXE) of 62%. Dorsal ulnar cutaneous (DUC) sensory nerve action potential (SNAP) was reduced in 55% with MAXE of 43%. Abductor digiti minimi (ADM) and first dorsal interosseous (FDI) compound muscle action potential (CMAP) were reduced half of the time, with MAXE of 30% and 28% respectively. There was high correlation between ulnar sensory MAXE and ADM MAXE (r=0.76, p<0.0001), FDI MAXE (r=0.81, p<0.0001) and DUC MAXE (r=0.60, p=0.0048). Neurogenic changes were seen in the ADM, FDI, flexor carpi ulnaris (FCU) and flexor digitorum profundus IV (FDP IV) in 79%, 77%, 25% and 35% respectively. Pathophysiology was demyelinating in 27%, axonal in 59% and mixed in 14%. CONCLUSIONS: In proximal axonal lesions, sensory fibers to digit V and motor fibers to distal muscles are predominantly affected, whereas in demyelinating lesions, slowing occurs twice as frequently as conduction block. SIGNIFICANCE: There is frequent axonal and fascicular injury in PUN.