Electromyography and biopsy correlation with suggested protocol for evaluation of the floppy infant

Abstract

Eighty infants with nonarthrogrypotic floppy infant syndrome (FIS) were evaluated between 1979 and 1990. Electromyographic data were correlated with results of muscle and nerve biopsies in 41 of 80 who had concomitant biopsies (38) or other diagnostic analyses (3). A diagnosis was made of Werdnig-Hoffmann disease (WHD) in 15, a congenital infantile polyneuropathy (IPN) in 3, neuromuscular transmission defect (NMTD) in 2, myopathy in 12, and presumed "central" hypotonia in 9. A very positive correlation rate between nerve conduction studies with electromyography and biopsy results was found in 93% (14 of 15) with WHD and 100% in IPN (3 of 3). However, only 4 of 10 infants (40%) with biopsy-proven myopathy had an abnormal EMG. Only once did the results of electromyography and biopsy conflict.

Diagnostic approach to neonatal hypotonia: retrospective study on 144 neonates

“…Only few clinical studies have published accurate data on large series of patients, and they partly refer to years before most DNA-based diagnostic tests became routinely available [1,10,14,17]. Several studies are biased by a specific recruitment, for example limited to intensive care units [15], or focus on particular subgroups such as neuromuscular diseases [5,6,9,18,23], genetic and metabolic disorders [16] or benign congenital hypotonia [3,19,21]. The retrospective design of these studies and ours is a significant limitation, but several conclusions can still be drawn from the study of our large cohort which reflects the diagnostic profile of neonatal hypotonia in a tertiary care hospital in the era of modern molecular genetics.…”

Muscle ultrasound in neuromuscular disorders

“…43 The sensitivity of EMG in detecting neurogenic disorders was very high in every age group (88%-100%). 12,19,43 EMG has more problems in detecting myopathies, especially in children. In floppy FIGURE 12.…”

“…EMG is the investigation of choice in detecting peripheral neuropathies, with high diagnostic accuracy even in young children (88%-100%), 19,43 and ultrasound of nerves can detect common nerve entrapments. 6,7,29,53,91,92 Muscle ultrasound, however, can also detect the consequences of FIGURE 10.…”

“…12,19,43,81 As EMG is a measurement of function, and ultrasound is concerned with structure, the use of both techniques is complementary for the most part. Application of dynamic muscle ultrasound can provide a bridge between the study of muscle structure and function.…”

Neonatal Hypotonia

“…NCV and EMG studies can be helpful in localizing the defect, but can be technically difficult and sometimes demanding to interpret in the newborn and young infant. EMG is very accurate in the diagnosis of spinal muscular atrophy, 13 and NCV is helpful in investigating hereditary motor sensory neuropathies by distinguishing between axonal and demyelinating conditions. 14 These studies can also be helpful in distinguishing between a neuronal and a myopathic process 15 and in the diagnosis of a neuromuscular transmission defect (congenital myasthenia gravis).…”