ABSTRACT
BACKGROUND AND PURPOSE: The F wave, a late response of low amplitude, is widely used in the study of peripheral nerve lesions, and its persistence and latencies are the main parameters that are usually considered. The analysis of repeater F-waves, which are commonly observed in association with focal or generalized motor neuropathy, is not always performed as a standard electrodiagnostic protocol. METHODS: We recorded and quantified the F waves from 13 healthy subjects and 22 patients with unilateral lumbosacral radiculopathy (ULSR) affecting the L5 or S1 roots. RESULTS: We found differences between the injured and normal sides of patients with ULSR in several F-wave parameters. Taking into consideration the normalized and pooled values of tibial and peroneal nerves in the injured side of patients with ULSR, the minimum and mean latencies were higher (1.05 and 1.04 with respect to 1.00; P < 0.01), the relative amplitude of the F waves was higher (1.95 with respect to 1.00; P < 0.001), and the percentage of repeater F-waves was also higher (4.19 with respect to 1.00; P < 0.001). This latter parameter was the most sensitive to detect lateral differences as indicated by the percentage of change and its high z score. CONCLUSIONS: Our results show that the use of F-waves may improve the electrodiagnosis of the ULSR if the number of repeater waves is evaluated given the clear and consistent increase of this variable in patients with lumbosacral root injury.
Subject(s)
Electrodiagnosis/methods , Lumbar Vertebrae/pathology , Neural Conduction/physiology , Radiculopathy/diagnosis , Sacrum/pathology , Action Potentials/physiology , Adolescent , Adult , Aged , Electric Stimulation , Electromyography , Female , Humans , Male , Middle Aged , Radiculopathy/physiopathology , Signal Processing, Computer-AssistedABSTRACT
OBJECTIVES: The objective of this study was to analyze the usefulness of electrophysiological studies [electroencephalogram (EEG) and auditory-evoked potential (AEP)] during the follow-up of children with perinatal asphyxia antecedents. PATIENTS AND METHODS: A prospective epidemiological study of perinatal asphyxia in term neonates born at the University Hospital San Juan (Alicante, Spain) between November 1991 and February 1995 was performed. Perinatal asphyxia was graded as non-severe (1 minute Apgar score < or = 6 and/or umbilical artery pH < 7.20, with abnormal fetal heart patterns and/or meconium-stained amniotic fluid and the need for immediate neonatal resuscitation) and severe (1 minute Apgar score < or = 3 and umbilical artery pH < 7.10). The incidence of hypoxic-ischemic encephalopathy (classification of Levene and Sarnat & Sarnat) during the neonatal period and neurological sequelae (classification of Finer and Amiel-Tison) during the follow-up period were studied. Electrophysiological studies (EEG and AEP) were made mainly between 12 and 18 months of life. RESULTS: During the study period there were 156 cases of perinatal asphyxia in full-term live births (31 severe and 125 non-severe). Hypoxic-ischemic encephalopathy was present in 25.6% of asphyxiated newborn infants, being mild in 30 cases, moderate in 5 and severe in 5. The incidence of neurological sequelae in 115 asphyxiated newborns followed for 24 month was 16.5%. This included mainly motor disabilities. We did not find any case of epilepsy, but there were 4 children with febrile seizures and one case of benign myoclonic seizures. EEG was performed in 88 cases during follow-up, and only was abnormal in two infants without seizures. AEP was performed in 82 cases during follow-up and hearing loss was detected in 4 children with neurosensorial hypoacusia (3 unilateral and 1 bilateral). CONCLUSIONS: Rutinary EEG is not useful during follow-up of children with antecedents of perinatal asphyxia. However, AEP is a hearing screening procedure for infants at risk of deafness, such as in perinatal asphyxia, and the cases of neurosensorial hearing loss detected by AEP in our population were clinically unapparent.
