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Special Considerations in Pediatric Electromyography
ELECTROMYOGRAPHY
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SPECIAL CONSIDERATIONS IN PEDIATRIC ELECTROMYOGRAPHY Lynne M. Stempien, MD
Electrodiagnostic examination of children provides unique circumstances, diagnoses, and considerations for the clinician. There is a broad spectrum of conditions, many inherited or rare, that may prompt pediatric electrodiagnostic investigation. Continuing maturation of the central and peripheral nervous system impacts the expected baseline values early in life. A child's smaller size, with limited surface area and distance, can provide technical challenges. Also, the child's age has much bearing on the cognitive abilities and emotional maturity available to elicit cooperation. Neurophysiologic maturation of the peripheral nerves, muscle, and neuromuscular junction impacts the data expected when performing nerve conduction studies and electromyography in children. The contrast with adult values is heightened in the infant and gradually diminishes as the child matures. Familiarity with the evolution of these norms is critical in order to accurately interpret results. Myelination of peripheral nerves begins during gestation at approximately the 15th week. This continues throughout the first years of life, with completion estimated to be between 3 and 5 years of ageY As myelination progresses and the axon enlarges in diameter, conduction velocity increases and distal latency decreases. Nodes of Ranvier also are remodeled.26 As the efficiency of nerve conduction increases, the amplitude of the compound muscle action potential (CMAP) increases. This process of improving conduction efficiency is related strongly to the age of conception. This allows nerve conduction studies to assist in estimating development, such as distinguishing between infants who are small for gestational age versus those of low birth weight. Motor nerve conduction studies have been completed in children as young as 23 weeks' gestation. iO Normal motor conduction velocities (MCV) begin at 19
From the Children's Hospital Rehabilitation Center; and Department of Rehabilitation Medicine, University of Colorado, Denver, Colorado
PHYSICAL MEDICINE AND REHABILITATION CLINICS OF NORTH AMERICA VOLUME 9 • NUMBER 4 • NOVEMBER 1998
897
1047-9651/98 $8.00
+
.00
SPECIAL CONSIDERATIONS IN PEDIATRIC ELECTROMYOGRAPHY Lynne M. Stempien, MD
Electrodiagnostic examination of children provides unique circumstances, diagnoses, and considerations for the clinician. There is a broad spectrum of conditions, many inherited or rare, that may prompt pediatric electrodiagnostic investigation. Continuing maturation of the central and peripheral nervous system impacts the expected baseline values early in life. A child's smaller size, with limited surface area and distance, can provide technical challenges. Also, the child's age has much bearing on the cognitive abilities and emotional maturity available to elicit cooperation. Neurophysiologic maturation of the peripheral nerves, muscle, and neuromuscular junction impacts the data expected when performing nerve conduction studies and electromyography in children. The contrast with adult values is heightened in the infant and gradually diminishes as the child matures. Familiarity with the evolution of these norms is critical in order to accurately interpret results. Myelination of peripheral nerves begins during gestation at approximately the 15th week. This continues throughout the first years of life, with completion estimated to be between 3 and 5 years of ageY As myelination progresses and the axon enlarges in diameter, conduction velocity increases and distal latency decreases. Nodes of Ranvier also are remodeled.26 As the efficiency of nerve conduction increases, the amplitude of the compound muscle action potential (CMAP) increases. This process of improving conduction efficiency is related strongly to the age of conception. This allows nerve conduction studies to assist in estimating development, such as distinguishing between infants who are small for gestational age versus those of low birth weight. Motor nerve conduction studies have been completed in children as young as 23 weeks' gestation. iO Normal motor conduction velocities (MCV) begin at 19
From the Children's Hospital Rehabilitation Center; and Department of Rehabilitation Medicine, University of Colorado, Denver, Colorado
PHYSICAL MEDICINE AND REHABILITATION CLINICS OF NORTH AMERICA VOLUME 9 • NUMBER 4 • NOVEMBER 1998
897