Brachial plexus magnetic resonance imaging differentiates between inflammatory neuropathies and does not predict disease course

Abstract

ObjectiveThe main objective of this study was to evaluate the correlation between the distribution of brachial plexus magnetic resonance imaging (MRI) abnormalities and clinical weakness, and to evaluate the value of brachial plexus MRI in predicting disease course and response to treatment in multifocal motor neuropathy (MMN), Lewis‐Sumner syndrome (LSS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP).MethodsSixty‐seven patients with an inflammatory neuropathy diagnosed at our tertiary referral center for neuromuscular diseases had undergone bilateral T2‐weighted short tau inversion recovery (STIR) MRI of the brachial plexus. We obtained clinical follow‐up data and scored all MRIs for abnormalities and the symmetry of their distribution.ResultsBrachial plexus MRI abnormalities were detected in 45% of the patients. An abnormal MRI did not predict disease course in terms of patterns of weakness, sensory disturbances or response to treatment. Within the spectrum of radiological abnormalities, asymmetrical clinical syndromes, MMN and LSS were significantly associated with asymmetrical radiological abnormalities, whereas symmetrical abnormalities predominated in CIDP (p < .001, phi 0.791).ConclusionT2 STIR brachial plexus MRI abnormalities correspond with the distribution of neurological deficits in inflammatory neuropathies, but do not correlate with specific clinical characteristics, response to treatment or disease course.

Comparison of MRI and motor evoked potential with triple stimulation technique for the detection of brachial plexus abnormalities in multifocal motor neuropathy

“…Brachial plexus MRIs were abnormal in 35–63% of MMN patients in previous studies, and in 69% of patients in our study. This difference may be explained by an improvement in MRI technique, by the fact that the MRI examinations were read by an experienced and unblinded radiologist, and because nearly half of our patients fulfilled the diagnostic criteria for definite MMN.…”

“…However, it was not observed in our MMN patient cohort or in any from previous studies . MRI abnormalities are usually more symmetrical in CIDP and asymmetrical in MMN . A benefit of plexus MRI is that it can be informative, even in cases of severe muscle atrophy, while the MEP‐TST test is not possible when distal CMAPs amplitudes are too low.…”

“…However, these data should be considered with caution, as there was no difference in disease duration between the two groups. Furthermore, previous studies have not found a correlation between plexus MRI and disease progression …”

“…When abnormal, brachial plexus MRI showed T2‐hyperintensity in 86–100% of MMN patients, as well as nerve enlargement in 64–86% of such patients. In CIDP, plexus MRI detected nerve enlargement in 40–55% of patients, as well as T2‐hyperintensity in 44–70% of such patients . Gadolinium enhancement has been reported in up to 36% of CIDP patients .…”

“…Brachial plexus MRI scans may show nerve enlargement or an increased signal intensity on T2‐weighted imaging. Few studies have focused on the importance of brachial plexus MRI in the diagnosis of MMN, and brachial plexus MRI scans have not been compared with MEP‐TST results in the context of MMN diagnosis.…”