Ultrasound follow-up study in two cases of inflammatory demyelinating sensory-motor neuropathy

Background: Ultrasound imaging is an emerging method for visualizing peripheral nerve pathology, since it is painless, non invasive and inexpensive (Martinoli et al, 2004; Padua et al, 2007). First focused on nerve entrapment pathology (Beekman and Vissler, 2003), its applications have widened to chronic inflammatory demyelinating neuropathies (CIDP), Charcot-Marie-Tooth and multifocal neuropathies, demonstrating focal enlargements. To our knowledge, only a few ultrasound studies focused on immune mediated neuropathies with repeated measures (Zaidman et al., 2009). Here, we report two cases of demyelinating sensory-motor neuropathy and their follow up at 6 months with electroneurographic and ultrasound studies. Methods and results: The first patient (female, age 77) (see Figure 1 and 2) presented to the outpatients EMG clinic due to lower limbs tingling and marked hypostenia that prevented her from autonomous walking, that spread also to the upper arms, and began 10 days before the neurophysiological examination. ENG showed clear-cut conduction blocks (Hadden et al., 1998) at multiple sites, with distal latencies (DLs) lengthening, and proximal nerve (F waves) and nerve conduction velocities (NCVs) involvement. Marked amplitude reductions were also observed. No sensory potential was detected either at upper and lower limbs. Ultrasound at the site of a block showed only a minor nerve enlargement (peroneal nerve) in comparison to normative values as measured by nerve cross-sectional area (NCSA) (see Table 1). She was treated with a course of IvIG and tapered on steroid. At follow up, 6 months later, she was able to stand and walk alone; amplitude and NVCs reductions persisted although with slight improvements towards the lower limit values. Late responses and SAPs reappeared. Ultrasound reveled persistence of nerve hypoechoic enlargements at the site of previous blocks, with a tendency toward NCSA reduction. The second patient (female, age 77) (see Figure 3 and 4) was admitted for progressive distal lower limbs hypostenia and tingling. ENG showed clear-cut conduction blocks at the lower segments and right median nerve, with amplitude reductions, VdCs slowing and distal latency increase in the other sites. SAPs were unobtainable. Ultrasound visualized increased NCSAs at the site of the block and at the site were temporal dispersion was identified by ENG. She was treated with IvIG. At follow up, she had clinically improved. At ENG, potentials amplitudes increased, although they remained under the lower normal value, with only a slight recovery of DLs and VdCs (see Figure 3), and SAP reappeared. Ultrasound study visualized multiple areas of enlargement at the site of previous block and temporal dispersions; comparison with previous examination available values pointed to a trend toward further enlargement (tibial) and only minor reductions of NCSA otherwise (p= 0.82) (Table 2). Conclusion: We demonstrated the presence at ultrasound imaging in the early phases of demyelinating sensory-motor neuropathy of focal nerve enlargements at the site of block. At follow up, although the number of sites compared was limited, we were not able to determine a clear NCSAs reduction at such site in one patient despite the slight clinical improvement, posing further questions on the pathophysiology of this neuropathy and the correlation of ultrasounds parameters with ENG ones