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We aimed to establish the cross-sectional area (CSA) reference values for peripheral nerves of lower extremities in a healthy Chinese population, and to determine their diagnostic values for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and Charcot-Marie-Tooth disease type1A (CMT1A). One hundred eleven healthy subjects, 15-70 years of age, as well as 104 CIDP patients and 26 CMT1A patients were recruited. CSA at predetermined sites of the tibial, fibular, sciatic and sural nerves was measured. The CSA of the tibial nerve ranged from 10.2 ± 1.9 to 20.7 ± 3.6 mm 2 , and for fibular nerve from 8.4 ± 1.8 to 9.5 ± 1.9 mm 2 . 86% CIDP patients had upper limb nerve enlargement, while only 67% had lower limb nerve enlargement. In CIDP patients with normal upper limb ultrasound, 56% (5/9) would have lower limb nerve enlargement. All CMT1A patients had both upper and lower limb nerve enlargement. Addition of lower limb nerve ultrasound showed no added value in diagnosis of CMT1A, but could be supplementary for CIDP when upper limb ultrasound is normal., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Diseases related to peripheral myelin protein 22 (PMP22) have been implicated to involve the central nervous system (CNS). This study aimed to detect central nerve impairment using somatosensory evoked potentials (SSEPs) in patients with Charcot-Marie-Tooth disease (CMT) 1A. A total of 30 CMT1A patients and 26 healthy volunteers were included. Baseline characteristics, brain MRI and segmental SSEPs were collected from the participants. The peak latencies of N9, N13 and N20 were recorded, and central conduction velocity (CCT) was calculated and compared between groups. Significant differences were found in the peak latencies and amplitudes of N9, N13 and N20 between the two groups. CCT was significantly prolonged in the CMT group (7.05 ± 2.09 ms) compared to the control group (5.40 ± 1.79 ms) (p = 0.003). Six of 30 CMT patients had abnormal MRI signals, but no correlation with CCT was found. The central somatosensory pathway that carries SSEPs was impaired in CMT1A patients, which implies an important underlying role of PMP22 in the CNS., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Background: Charcot-Marie-Tooth Disease (CMT) is a rare disorder with less than 200,000 cases reported in the US every year, making diagnosis challenging. MR and CT imaging has become more common in the evaluation of CMT to identify areas of disease involvement., Case Report: A 27-year-old female from Guatemala with a past history of polio initially presented to the emergency room for necrotizing pneumonia. MRI images demonstrated smoothly enlarged, mildly enhancing trigeminal nerves. CT showed bony widening of the skull base foramina. The patient was noted to have atrophy and weakness of her extremities with decreased sensation, distal more than proximal, and pes cavus. An electromyogram demonstrated absent response in the right median, ulnar, peroneal, and tibial motor studies and bilateral radial and right sural sensory studies. MRI of the spine demonstrated smooth, symmetric enlargement and mild enhancement of the distal spinal nerve roots and cauda equine., Discussion: CMT is a group of disorders with a wide range of clinical presentations and abnormalities. Cranial nerve involvement is infrequently described in CMT 1A. In our case and prior studies, there does not appear to be a correlation between cranial nerve involvement and symptoms. Trigeminal neuralgia has been described in patients in CMT, but is not common and was not seen in our patient despite abnormal trigeminal nerve findings on imaging. Our patient also demonstrated involvement of the facial nerve without facial muscle weakness. Clinical features are key in distinguishing CMT 1A from other forms of HMSN., (Copyright © 2016 Elsevier Ltd. All rights reserved.)