To report a novel case of pure sensory ganglionopathy/neuronopathy associated with plexin-D1 antibody.

Sensory neuronopathies are rare polyneuropathies characterized by degeneration of the dorsal root and trigeminal ganglia. Reported etiologies include autoimmune diseases, paraneoplastic syndromes, viral infections, vitamin B6 toxicity, and neurotoxic drug exposures. Plexin-D1 antibody has been associated with small fiber neuropathy and trigeminal neuropathy; however, its pathophysiological association with sensory neuronopathy remains incompletely understood.   

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A 40-year-old woman presented with 4-week history of progressive numbness and paresthesia with subjective weakness involving all extremities. Clinical exam was notable for profound sensory deficits to pain, temperature, vibration, and proprioception in all limbs, with pseudoathetosis in the upper extremities, diffusely absent reflexes, malar rash, and Jaccoud’s arthropathy.

EMG/NCS results were consistent with a pure sensory neuronopathy with preserved motor responses. Sensory neuropathy/neuronopathy and small fiber panel was positive for plexin-D1 antibody. Anti-SSA and anti-TPO antibodies were positive. Vitamin B6, ANA, RF, anti-dsDNA, anti-Sm, and anti-SSB were normal. Vitamin B12 and B1 levels were initially low, and appropriate supplementation was given. Serology was negative for HIV, HTLV I/II, lyme, syphilis, and ganglioside panel. Paraneoplastic panel was non-contributory. CT chest, abdomen, pelvis, and PET scan showed no evidence of malignancy. MRI brain, cervical, thoracic, lumbar spine, and CSF studies were all unremarkable.

She was empirically treated with IVIG 2 g/kg. Due to concurrent suspicion for systemic lupus erythematosus (SLE), she was subsequently treated with azathioprine 100 mg oral daily and IV methylprednisolone with a prednisone taper. She reported subjective improvement in perceived weakness and sensory deficits.

Sensory neuronopathy is a rare presentation with limited etiologies, and clinical hallmarks of ataxia and non-length dependent sensory dysfunction. We report a novel case of sensory neuronopathy associated with plexin-D1 antibody affecting the limbs and trunk. This case highlights a unique clinical phenotype associated with plexin-D1 antibody.