Studying Nerve Function and Structure in Charcot-Marie-Tooth Disease, Anti-MAG Neuropathy and CIDP

Official title

Axonal Excitability and Ultrasound Patterns in Charcot-Marie-Tooth Disease and Other Demyelinating Disorders

Overview

The project aims to perform both conventional nerve-conduction studies and axonal-excitability assessments using the TRONDF protocol in patients with selected forms of Charcot-Marie-Tooth disease, with comparison to individuals affected by dysimmune, acquired neuropathies, specifically chronic inflammatory demyelinating polyneuropathy (CIDP) and anti-MAG-neuropathy. The study further includes the analysis of nerve fibers obtained from skin biopsy in patients with CMT, as well as ultrasound evaluation of nerves (from the wrist to the axilla) and of intrinsic hand muscles. Axonal-excitability techniques involve the delivery of two electrical stimuli to the nerve under investigation; both stimuli vary in intensity, whereas only the first, known as the conditioning stimulus, varies in duration. Changes in response amplitude are then measured as these stimulation parameters are systematically adjusted. Some preliminary studies have already suggested the effectiveness of this method in distinguishing CMT1A from certain forms of acquired demyelinating disease, including acute inflammatory demyelinating polyradiculoneuropathy (AIDP) and CIDP. Despite the promising results, only a limited number of studies have so far been conducted in humans and mice, and no comprehensive and systematic study has yet been carried out describing the changes in axonal excitability in the various CMT subtypes, either in humans or in mouse models.

Detailed description

Charcot-Marie-Tooth neuropathy (CMT) is the most prevalent hereditary neuromuscular disorder, estimated to affect 11.8 to 82.3 individuals per 100,000 in Europe. While genetic assessment is increasingly gaining significance, neurophysiology continues to play a crucial role in classifying CMT into axonal, intermediate or demyelinating forms. Despite its diagnostic importance, standard neurophysiology techniques may prove inadequate to reliably capture disease progression, advocating for the adoption of newer methodologies in the near future. Among these, axonal excitability testing, providing information about the properties of axonal membranes insight into the behaviour of voltage-gated ion channels, pump and exchangers involved in impulse conduction, could have potential additional diagnostic and prognostic value in neuromuscular disorder.

Axonal excitability techniques provide insights into ion channel function, serving as an in vivo surrogate markers of axonal membrane potential in human axons. Recent advancements in this field have standardized procedures, increased execution speed, and minimized patients' discomfort enabling routine clinical application. These advancements include the development of standardized semi-automated recording setups and the publication of international guidelines. It is plausible that progressive ion-channel dysfunction and spontaneous baseline depolarization of nerves maybe associated with disease severity and response to therapy (in patients with acquired polyneuropathies).

Investigators plan to study a series of patients with different types of CMT with this technique and compare results with diseased controls affected by dysimmune neuropathies and corresponding mouse models, by conventional nerve conduction studies, by electrical nerve stimulation to study neuronal excitability as below depicted, and by examining myelinated skin nerves by performing skin biopsy in a subset of patients.

Moreover, literature data demonstrate that nerve ultrasound supports the diagnosis and follow-up of neuromuscular disorders. In the context of neuropathies, nerve ultrasound enables an anatomical and structural evaluation that provides useful data for the differential diagnosis between hereditary and acquired forms. In particular, in Charcot-Marie-Tooth disease, nerve ultrasound allows the identification of pathognomonic patterns that can significantly guide genetic testing (e.g CMT1A).

In severe acquired forms, where the pathological process is so extensive that clear electrophysiological findings are not always present, nerve ultrasound can detect specific alterations that may help guiding the diagnosis. Moreover, nerve ultrasound can identify certain features that may suggest (and correlate with) the severity of the disease.

Muscle ultrasound in neuromuscular disorders is instead a more recent application. The detection of specific patterns of muscle involvement can suggest a possible regional distribution, described in some nosological entities. Furthermore, literature data show that the structural and ultrasound characteristics of the muscle correlate with the degree of strength deficit. Despite the increasing amount of literature in the field, no nerve or muscle ultrasound studies have yet been published on some acquired forms and rare forms of Charcot-Marie-Tooth disease. The collection and analysis of ultrasound data in these cases would allow for a broader understanding of the related pathological processes, potentially identifying patterns that support diagnosis and follow-up.

Collaborators for this project are the following: Inherited Neuropathy Consortium (INC); Prof. Christian Krarup (Dept of Clin. Neurophys., Rigshospitalet, Copenhagen, DK; Dept of Neuroscience, Univ. of Copenhagen, Copenhagen, DK); Prof. Mihai Moldovan (Dept of Neurol., North Zealand Hospital, Hillerød, DK; Dept of Clin. Neurophys., Rigshospitalet, Copenhagen, DK; Dept of Neuroscience, Univ. of Copenhagen, Copenhagen, DK); Prof. Hatice Tankisi (Aarhus University Hospital, Department of Clinical Neurophysiology, Aarhus, Denmark; Aarhus University, Department of Clinical Medicine, Aarhus, Denmark)

Primary outcome measures

• Strength-Duration Time Constant [Time frame: 2 years]
• Recovery Cycle of Nerve Excitability Parameters [Time frame: 2 years]
• Threshold Electrotonus [Time frame: 2 years]
• Current-Threshold (I/V) Relationship [Time frame: 2 years]

Secondary outcome measures (4)

• Peripheral nerve cross-sectional area by ultrasound [Time frame: 2 years]
• Muscle thickness by ultrasound [Time frame: 2 years]
• Muscle echogenicity by ultrasound (Heckmatt scale) [Time frame: 2 years]
• Correlation of ultrasound parameters with clinical and electrophysiological measures [Time frame: 2 years]

Eligibility criteria

Inclusion criteria

• The subject is ≥ 18 years old.

AND:

• A genetically confirmed diagnosis of one of the several CMT subtypes (i.e., CMT1A, CMT1B, CMTX1, CMT2I/J, CMT4B, CMT4D and CMT4J) OR
• A clinical diagnosis of either Chronic Inflammatory Demyelinating Polyneuropathy or anti-MAG polyneuropathy

Exclusion criteria

• Known neuropathy from another cause (e.g., diabetes, chronic renal insufficiency, medications, alcohol), including previous carpal tunnel syndrome surgery.
• History of exposure to chemotherapeutic agents (e.g., bortezomib, vincristine, cisplatin, taxol, vedotin/auromycin-conjugated antibodies), or other medications (e.g., disulfuram, thalidomide, voriconizole, chronic colchicine use) that can cause neuropathy, active alcohol abuse.
• History of cancer, other than skin cancer, within 5 years prior to enrollment.
• Pregnancy or nursing.
• Known systemic disease that predisposes to neuropathy.
• Other central nervous system diseases.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Observational model

Other

Study locations

Italy · 1 center

• Fondazione IRCCS Istituto Neurologico Carlo Besta — Milan

Publications

• Shahrizaila N, Noto Y, Simon NG, Huynh W, Shibuya K, Matamala JM, Dharmadasa T, Devenney E, Kennerson ML, Nicholson GA, Kiernan MC. Quantitative muscle ultrasound as a biomarker in Charcot-Marie-Tooth neuropathy. Clin Neurophysiol. 2017 Jan;128(1):227-232. doi: 10.1016/j.clinph.2016.11.010. Epub 2016 Nov 21. PMID 27940147
• Padua L, Granata G, Sabatelli M, Inghilleri M, Lucchetta M, Luigetti M, Coraci D, Martinoli C, Briani C. Heterogeneity of root and nerve ultrasound pattern in CIDP patients. Clin Neurophysiol. 2014 Jan;125(1):160-5. doi: 10.1016/j.clinph.2013.07.023. Epub 2013 Oct 5. PMID 24099922
• Noto Y, Shiga K, Tsuji Y, Mizuta I, Higuchi Y, Hashiguchi A, Takashima H, Nakagawa M, Mizuno T. Nerve ultrasound depicts peripheral nerve enlargement in patients with genetically distinct Charcot-Marie-Tooth disease. J Neurol Neurosurg Psychiatry. 2015 Apr;86(4):378-84. doi: 10.1136/jnnp-2014-308211. Epub 2014 Aug 4. PMID 25091364
• Schreiber S, Oldag A, Kornblum C, Kollewe K, Kropf S, Schoenfeld A, Feistner H, Jakubiczka S, Kunz WS, Scherlach C, Tempelmann C, Mawrin C, Dengler R, Schreiber F, Goertler M, Vielhaber S. Sonography of the median nerve in CMT1A, CMT2A, CMTX, and HNPP. Muscle Nerve. 2013 Mar;47(3):385-95. doi: 10.1002/mus.23681. Epub 2013 Feb 4. PMID 23381770
• Manganelli F, Nolano M, Pisciotta C, Provitera V, Fabrizi GM, Cavallaro T, Stancanelli A, Caporaso G, Shy ME, Santoro L. Charcot-Marie-Tooth disease: New insights from skin biopsy. Neurology. 2015 Oct 6;85(14):1202-8. doi: 10.1212/WNL.0000000000001993. Epub 2015 Sep 11. PMID 26362287
• Nobbio L, Visigalli D, Radice D, Fiorina E, Solari A, Lauria G, Reilly MM, Santoro L, Schenone A, Pareyson D; CMT-TRIAAL Group. PMP22 messenger RNA levels in skin biopsies: testing the effectiveness of a Charcot-Marie-Tooth 1A biomarker. Brain. 2014 Jun;137(Pt 6):1614-20. doi: 10.1093/brain/awu071. Epub 2014 May 8. PMID 24812204
• Burke D, Kiernan MC, Bostock H. Excitability of human axons. Clin Neurophysiol. 2001 Sep;112(9):1575-85. doi: 10.1016/s1388-2457(01)00595-8. PMID 11514239
• Kiernan MC, Burke D, Andersen KV, Bostock H. Multiple measures of axonal excitability: a new approach in clinical testing. Muscle Nerve. 2000 Mar;23(3):399-409. doi: 10.1002/(sici)1097-4598(200003)23:33.0.co;2-g. PMID 10679717

Identifiers

NCT: NCT07461896 · CMT-NFS

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗