We present a case of linear, non-nodular enhancement of the distal conus medullaris, cauda equina nerve roots, adjacent leptomeninges, and cervical-thoracic nerve roots in a patient with NF155 and CNTN1 seropositive autoimmune nodopathy, and otherwise normal neuroaxis configuration.

Autoimmune nodopathies (AN), initially regarded as a subset of CIDP-like syndromes, are associated with antibodies to nodal/paranodal proteins, such as NF155 and CNTN1. These patients often present with chonic, progressive asymmetric or symmetric sensorimotor polyneuropathy, areflexia, sensory ataxia, and cranial nerve involvement.

A previously healthy 39-year-old woman presented with a 6-month history of progressive, symmetric, distal-predominant sensorimotor polyneuropathy and sensory ataxia. Physical exam demonstrated areflexia and decreased temperature, vibratory in upper extremities, absent in lower extremities and absent proprioception throughout. Dysarthria, facial weakness, impaired bilateral oculomotor abduction, and perioral/lingual paresthesias were also noted on initial evaluation.

Patient underwent labratory work up demonstrating Hgb A1C 5.7, ESR 28, elevated B12 (1480), negative lyme antibody screen (with isolated 41 KD IgM band), and positive HSV-1 IgG (47.7). 

EMG/NCV obtained showed demyelinating features meeting criteria for CIDP: prolonged latencies, reduced amplitudes, conduction block, and temporal dispersion in multiple nerves.

MRI brain was unremarkable except for a subtle T2/FLAIR hyperintensity. Spinal MRI revealed enhancement of ventral/dorsal roots at the cervico-thoracic junction and linear, non-nodular enhancement of the conus, cauda equina roots, and adjacent leptomeninges extending to T9.

CSF showed albuminocytologic dissociation, positive myelin basic protein, and seropositivity for both NF155 and CNTN1 antibodies.

This case meets electrodiagnostic criteria for CIDP, but the presence of both NF155 and CNTN1 antibodies, and patient's clinical presentation strongly supports autoimmune nodopathy. While root enhancement is documented in CIDP, this specific pattern of combined root, conus, cauda equina and adjacent leptomeningeal linear non-nodular enhancement is, to our knowledge unreported in CIDP or AN, suggesting a broader imaging spectrum for nodopathies.