Peripheral neuropathy due to neuroborreliosis: Insensitivity for CXCL13 as early diagnostic marker

The case of a 69-year-old woman with peripheral neuropathy caused by Lyme neuroborreliosis (LNB) in an endemic region in Eastern Austria is reported. The patient had noticed transient numbness of her left leg. On initial examination, she had patchy sensory disturbances of the left lower leg, but ancillary examinations of nerve conduction and cerebrospinal fluid (CSF), including the B-cell chemokine CXCL13, were normal. A re-tap performed 54 days later, following clinical progression with foot drop, widespread lower leg paresthesia, and pain, revealed an increased cell count, autochthonous IgM production, synthesis of Borrelia-specific IgM, and elevated CXCL13. Neurophysiological examinations disclosed an incomplete conduction block, mixed axonal and demyelinating sensorimotor neuropathy, and subacute neurogenic damage of muscles innervated by the peroneal nerve. This case study presents rare evidence of very early diagnostic findings in peripheral neuropathy caused by LNB. These are characterized by insensitivity of CXCL13 in CSF to aid earlier diagnosis and the development of an intrathecal immune response against Borrelia at a later stage. These findings reinforce the need for a re-tap to confirm the diagnosis and facilitate appropriate treatment in this rare manifestation of LNB.