Peripheral Nerve Imaging Aids in the Diagnosis of Immune-Mediated Neuropathies—A Case Series

Abstract

Background: Diagnosis of immune-mediated neuropathies and their differentiation from amyotrophic lateral sclerosis (ALS) can be challenging, especially at early disease stages. Accurate diagnosis is, however, important due to the different prognosis and available treatment options. We present one patient with a left-sided dorsal flexor paresis and initial suspicion of ALS and another with multifocal sensory deficits. In both, peripheral nerve imaging was the key for diagnosis. Methods: We performed high-resolution nerve ultrasound (HRUS) and 7T or 3T magnetic resonance neurography (MRN). Results: In both patients, HRUS revealed mild to severe, segmental or inhomogeneous, nerve enlargement at multiple sites, as well as an area increase of isolated fascicles. MRN depicted T2 hyperintense nerves with additional contrast-enhancement. Discussion: Peripheral nerve imaging was compatible with the respective diagnosis of an immune-mediated neuropathy, i.e., multifocal motor neuropathy (MMN) in patient 1 and multifocal acquired demyelinating sensory and motor neuropathy (MADSAM) in patient 2. Peripheral nerve imaging, especially HRUS, should play an important role in the diagnostic work-up for immune-mediated neuropathies and their differentiation from ALS.

Nerve Ultrasound as Helpful Tool in Polyneuropathies

“…Only few reports concerning patients with Lewis-Sumner Syndrome (LSS) or multifocal acquired demyelinating sensory and motor neuropathy (MADSAM) are available [ 80 , 81 , 82 , 83 , 84 , 85 , 86 ]. Most authors mixed them with other CIDP types, which might hamper the right description of this immune-mediated subtype.…”

Imaging in peripheral neuropathy: Ultrasound and MRI

“…[14] In MMN and MADSAM, both US and MRI show asymmetric fascicular enlargement with increase in the nerve CSA of the nerve, hyperintense signal on T2W images with postcontrast enhancement and increased vascularity. [30] Parsonage-Turner syndrome, also known as acute idiopathic brachial plexus neuritis refers to a condition in which there is weakness of the shoulder muscles preceded by neck or shoulder pain. MRI of the brachial plexus reveals unilatera, or bilateral asymmetrically enlarged nerves with hyperintense signal in fluid-sensitive sequences and denervation changes in the muscles [Figure 15].…”

Bilateral widespread segmental swelling on nerve sonography in multifocal acquired demyelinating sensory and motor neuropathy

“…point of the LRN; Rt. facial nerve under the parotid gland 6/51/M [3] Intermittent fine motor dysfunction in the Lt. hand (digits I-III)…”

“…[2] Although numerous nerve ultrasound studies in classical CIDP have been published, MADSAM Medicine ® OPEN ultrasound studies are still scarce. [3][4][5][6][7][8] CIDP and MADSAM have been observed to share similar heterogeneous echointensity patterns (hypoechogenicity or mixed echogenicity) in enlarged nerves, but the nerve swelling pattern differs between these 2 diseases: diffuse enlargement with a varying predominance in CIDP versus regional nerve enlargements corresponding to conduction blocks in MADSAM. [2] As bilateral sampling is performed routinely in nerve conduction studies (NCSs), whether bilateral sampling is recommended in sonography remains undetermined.…”

“…Ultrasound has been used widely as an imaging tool to evaluate different neuropathies [2] . Although numerous nerve ultrasound studies in classical CIDP have been published, MADSAM ultrasound studies are still scarce [3–8] . CIDP and MADSAM have been observed to share similar heterogeneous echointensity patterns (hypoechogenicity or mixed echogenicity) in enlarged nerves, but the nerve swelling pattern differs between these 2 diseases: diffuse enlargement with a varying predominance in CIDP versus regional nerve enlargements corresponding to conduction blocks in MADSAM [2] .…”