title: The role of the brachioradialis H reflex in the management and prognosis of obstetrical brachial plexus palsy.
abstract: The H reflex was investigated to determine if it can be useful in the prognosis of obstetrical brachial plexus palsies. The H reflex is an electrically stimulated monosynaptic or oligosynaptic response which can be recorded in peripheral nerves in all muscles of infants up to approximately two years of age. It is essentially the electrophysiologic counterpart of the deep tendon reflex, and its presence indicates intact afferent and efferent axons at the particular spinal segment. Our objectives were to document the Brachioradialis H (Br H) reflex latency and amplitude in normal upper extremities of infants, to evaluate the presence or absence of the Br H reflex in obstetrical palsy neonates and infants between one and seven months of age and to determine if this test was a valid predictor of final clinical outcome. A prospective study of 109 patients was performed to measure the Br H reflex in the affected and the contralateral normal limb. The results from the abnormal limb were compared to the final clinical decision made by nine months for or against surgical intervention. In the normal limbs, a Br H latency of 10.7 +/- 0.8 msec was determined with an amplitude of 1.2 +/- 1.2 mV. The chi 2 analysis in infants from one month to seven months old revealed a strong relationship between an absent Br H reflex and little or no clinical improvement (p < 0.0001), with a sensitivity for predicting poor outcome of 85.7%. The odds ratio (with a 95% confidence interval) of a child with an absent Br H reflex not significantly improving by nine months was 8.4 times higher than if the Br H reflex was present. The false positive rate was 42% however, indicating that a significant number of patients improved clinically, despite having a nonrecordable Br H reflex at age seven months or less. The low false negative rate of 14.3% suggested that in the presence of a Br H reflex, the majority of patients recover. Therefore, the presence of the Br H reflex is a helpful test in the prognostication of good recovery in obstetrical upper plexus palsy patients.
authors.affiliation: Division of Plastic Surgery, Hospital for Sick Children, University Health Network and Department of Surgery, University of Toronto, Toronto, Ontario, Canada.
authors.forename: J T S
authors.initials: JT
authors.lastname: Kao
authors.forename: S
authors.initials: S
authors.lastname: Sharma
authors.forename: C G
authors.initials: CG
authors.lastname: Curtis
authors.forename: H M
authors.initials: HM
authors.lastname: Clarke
mesh_terms: D001720:Birth Injuries / Q000503:physiopathology / Q000601:surgery*; D001917:Brachial Plexus / Q000293:injuries* / Q000503:physiopathology / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006181:H-Reflex / Q000502:physiology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010291:Paresis / Q000503:physiopathology / Q000601:surgery*; D011183:Postoperative Complications / Q000175:diagnosis / Q000503:physiopathology; D011247:Pregnancy; D011446:Prospective Studies; D011826:Radial Nerve / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*; D016896:Treatment Outcome