An Unusual Clinical Evolution in Anticontactin- 1 Positive CIDP

ABSTRACT

Specific clinical, electrophysiological and serological features are used to recognise a phenotype fitting the atypical chronic inflammatory demyelinating (CIDP) variant spectrum. We report a 28-year-old male patient, without any significant history apart from a recent asymptomatic COVID-19 infection, presenting at first with bilateral facial nerve palsy, subsequently -three months later- developing an subacute onset symmetric sensory ataxia and arefl exia, and thirdly experiencing diffuse rapidly progressive motor deficits. Additional investigations suggested an autoimmune polyneuropathy Liquor analysis showed cytoalbuminologic dissociation. Cerebrospinal fluid protein elevation was remarkable 631 mg/dL. Nerve conduction studies showed prominent distal latencies prolongation and dispersion of the potentials, meeting the electrodiagnostic criteria of the European Federation of Neurological Societies/Peripheral Nerve Society for CIDP (2021). Full spine magnetic resonance imaging depicted pathological thickening and enhancement of the roots of the cauda equina as seen in radiculitis. There was no or poor response to conventional treatment, i.e. immunoglobulins (IVIG), corticosteroids and even plasmapheresis. Muscle weakness deteriorated. Presence of serum IgG4 anti- contactin-1 (CNTN1) antibodies was found by ELISA identifi- cation and titration, and the patient improved substantially after rituximab treatment. While contributing to the expanding confidence in nodal and paranodal antibodies as valuable biomarkers in clinical practice, our case entails several peculiarities 1/ SARS-CoV2 positivity as a possible trigger of this auto-immune polyneuropathy 2/ A considerably younger age of onset than in the patients already described (range 33-76 years). 3/ The clinical course progressed in an atypical manner even for atypical CIDP Initial presentation with bilateral asymmetric facial palsy, followed by sensory ataxia, which prompted the initial diagnosis of Miller-Fisher syndrome, and later development of severe motor impairment. 4/ Proteinorachy was so pronounced that we considered neuroborreliosis as a potential associated disorder. Borrelia seroconversion occurred after the first IVIG-treatment, and could be false positive. However, the patient was treated with intravenous ceftriaxone, which had no effect on the clinic. 5/ Antibodies against CNTN1 were undetectable after 2 months of rituximab. Emphasising the both diagnostic and therapeutic importance of recognising a phenotype compatible with atypical CIDP, an underrecognized and consequently undertreated disease where early diagnosis and prevention of axonal damage is crucial in.