Study of total duration of distal compound muscle action potential in demyelinating and axonal Guillain-Barre' syndrome.

OBJECTIVES: Electrophysiology plays a crucial role in Guillain-Barré syndrome (GBS) diagnosis and subtype classification. The aim of our study was to assess the potential role of distal compound muscle action potential (dCMAP) for early differentiation between acute inflammatory demyelinating polyneuropathy (AIDP) and axonal GBS. METHODS: We retrospectively reviewed the medical records of 24 subjects with AIDP and 18 subjects with axonal GBS. We built up receiver operating characteristic curves for total dCMAP duration and negative phase of dCMAP duration, in order to derive cut-off values able to differentiate between AIDP and axonal GBS. RESULTS: The total duration of dCMAP was significantly prolonged in AIDP compared to axonal GBS. AUCs, odds ratio and positive predictive values were higher for total duration than for negative peak duration. Nerve conduction parameters in the lower limbs were more sensitive than those in the upper limbs in distinguishing AIDP from axonal GBS. DISCUSSION: Total duration of dCMAP dispersion may capture an adjunctive component of distal demyelination, not measured by the more traditional parameters and may thus represent a useful tool for early differentiation between AIDP and axonal GBS.

Clinical Features and Outcome of the Guillain-Barre Syndrome: A Single-Center 11-Year Experience.

Background: Clinical presentation, electrophysiological subtype, and outcome of the Guillain-Barre' Syndrome (GBS) may differ between patients from different geographical regions. This study aims to assess clinical-neurophysiological features of an adult, Italian GBS cohort over 11 years. Methods: Retrospective (from 1 January 2011 to 31 December 2021) analysis was carried out on patients admitted to the Siena University Hospital who fulfilled the GBS diagnostic criteria. Demographic data, clinical characteristics, treatment, need of mechanical ventilation (MV), laboratory and electrophysiological tests, preceding infections/vaccination/other conditions, and comorbidities were collected for each patient. Results: A total of 84 patients (51 men, median age of 61 years), were identified. GBS subtype was classified as acute inflammatory demyelinating polyneuropathy (AIDP) in the 66.6% of patients, acute motor/sensory axonal neuropathy (AMAN/AMSAN) in 20.2%, and the Miller Fisher syndrome in 5 (5.9%). Flu syndrome and gastrointestinal infection were the most common preceding conditions. In total, five (5.9%) subjects had concomitant cytomegalovirus (CMV) infection. Cranial nerve involvement occurred in 34.5% of subjects. Differences between the axonal and AIDP forms of GBS concerned the presence of anti-ganglioside antibodies. In total, seven (8.33%) patients required MV. Discussion: The epidemiological and clinical characteristics of GBS in different countries are constantly evolving, especially in relation to environmental changes. This study provides updated clinical-epidemiological information in an Italian cohort.

Sporadic hereditary motor and sensory neuropathies: Advances in the diagnosis using next generation sequencing technology.

Hereditary motor and sensory neuropathies (HMSN) are genetically heterogeneous disorders affecting peripheral motor and sensory functions. Many different pathogenic variants in several genes involved in the demyelinating, the axonal and the intermediate HMSN forms have been identified, for which all inheritance patterns have been described. The mutation screening currently available is based on Sanger sequencing and is time-consuming and relatively expensive due to the high number of genes involved and to the absence of mutational hot spots. To overcome these limitations, we have designed a custom panel for simultaneous sequencing of 28 HMSN-related genes. We have applied this panel to three representative patients with variable HMSN phenotype and uncertain diagnostic classifications. Using our NGS platform we rapidly identified three already described pathogenic heterozygous variants in MFN2, MPZ and DNM2 genes. Here we show that our pre-custom platform allows a fast, specific and low-cost diagnosis in sporadic HMSN cases. This prompt diagnosis is useful for providing a well-timed treatment, establishing a recurrence risk and preventing further investigations poorly tolerated by patients and expensive for the health system. Importantly, our study illustrates the utility and successful application of NGS to mutation screening of a Mendelian disorder with extreme locus heterogeneity.