Electrophysiologic features of ulnar neuropathy in childhood and adolescence.
To analyze patterns of nerve injury in pediatric ulnar neuropathy (PUN).



Retrospective analysis of 49 children with PUN.



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%.



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.



There is frequent axonal and fascicular injury in PUN.
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.
Ioannis
I
Karakis
Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA; Department of Neurology, KK Women's & Children's Hospital, Singapore.
Wendy
W
Liew
Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA.
Heather Szelag
HS
Fournier
Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA; Department of Neurology, Lahey Clinic, Burlington, MA, USA.
H Royden
HR
Jones
Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA.
Basil T
BT
Darras
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.
Peter B
PB
Kang
D000200:Action Potentials; D000293:Adolescent; D001369:Axons / Q000473:pathology / Q000502:physiology; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D009046:Motor Neurons / Q000473:pathology / Q000502:physiology; D018482:Muscle, Skeletal / Q000254:growth & development / Q000294:innervation; D009186:Myelin Sheath / Q000473:pathology; D011930:Reaction Time; D014459:Ulnar Nerve / Q000503:physiopathology; D020424:Ulnar Neuropathies / Q000473:pathology / Q000503:physiopathology*; D055815:Young Adult
Clinical neurophysiology; Electrodiagnosis; Electromyography (EMG); Pediatric EMG; Ulnar nerve; Ulnar neuropathy