Transcranial magnetic stimulation as an additional diagnostic tool in children with acute inflammatory demyelinating polyneuropathy

Abstract

Context:The diagnosis of polyneuropathy may be challenging at the early stages of the disease. Despite electromyography (EMG) efficacy in the establishment of polyneuropathy diagnosis, in some cases, results are dubious and neurophysiologists may implement additional techniques to ensure that conduction is affected.Aims:The aim of the study was to evaluate motor-evoked potential (MEP) characteristics in children with acute inflammatory demyelinating polyneuropathy (AIDP).Settings and Design:The study was conducted at a pediatric research and clinical center for infectious diseases.Subjects and Methods:Twenty healthy children (7–14 years old) without signs of neurological disorders were enrolled as controls. Thirty-seven patients (8–13 years old) with AIDP were enrolled as the main group. EMG and transcranial magnetic stimulation (TMS) were performed on the 3rd–7th days from the onset of the first symptoms.Statistical Analysis Used:Descriptive statistics and Student's t-test were used. Bonferroni method was applied to implement appropriate corrections for multiple comparisons.Results:Significant differences between children with AIDP and controls on latencies of both cortical and lumbar MEPs were registered. Cortical MEP shapes were disperse in 100% of the cases and lumbar MEPs were disperse in 57% of the cases.Conclusions:Diagnostic TMS on the early stage of the AIDP in children may be implemented as the additional tool. The main finding in this population is lengthening of the latency of cortical and lumbar MEPs. Disperse shape of the lumbar MEPs may be used as the early sign of the acute demyelization.

Review of Acute Inflammatory Demyelinating Polyradiculoneuropathy

“…The presence of a nerve conduction block and distance motor latency prolongation are the 2 findings in AIDP 13 . In comparison to the AMAN and AMSAN forms of GBS, the demyelinating findings of AIDP on EMG have longer peripheral conduction times, larger interside differences, and lower amplitudes 11 .…”

“…With this in mind, serial EMGs should be performed throughout the course of the disease to ensure the diagnosis is consistent with the findings. Common EMG findings indicative of AIDP include prolonged or absent F-wave latencies, H-reflex abnormality, slowing of conduction velocities, and lower amplitudes 11,12 . In approximately 98% of patients, the first abnormal finding on the EMG study is an abnormal H-reflex.…”

“…Nerve conduction studies (NCSs) (Fig. 2) and electromyography (EMG) are performed to initially evaluate peripheral nerve function 11 . Patients' EMG studies may be normal at first, but by one week, most EMG studies will then reveal classic AIDP findings 12 .…”

“…Common EMG findings indicative of AIDP include prolonged or absent F-wave latencies, H-reflex abnormality, slowing of conduction velocities, and lower amplitudes 11,12 . In approximately 98% of patients, the first abnormal finding on the EMG study is an abnormal H-reflex.…”