Findings on Magnetic Resonance Imaging in Neuroborreliosis-A Nationwide Cohort Study

To explore pathological findings on magnetic resonance imaging (MRI) and their diagnostic implications in early-stage neuroborreliosis (NB).

Adult patients from the Danish neuroinfections cohort (DASGIB, 2015-2019) with confirmed NB, symptom duration < 6 months, and MRI performed within 14 days of diagnosis were included. MRIs were retrospectively reinterpreted by an unblinded neuroradiologist.

In 116 patients, 123 MRIs were performed (99 brain, 44 spine, 46 with contrast). White matter lesions (WML) were common, but non-specific and associated with increasing age (p < 0.001). Six patients showed WML not typical for small vessel disease. Acute infarctions occurred in four patients. Encephalitis was clinically diagnosed in five patients; one showed brainstem FLAIR hyperintensities. In 45 contrast-enhanced brain scans, leptomeningeal enhancement was identified in 6 (13%) and cranial nerve enhancement in 29 (64%). There was poor correlation between facial palsy and enhancement. Spinal cord lesions (1.6-14 cm) were identified in 10 of 44 scans (23%) without symptoms of transverse myelitis. Among 13 contrast-enhanced spine scans, 8 showed leptomeningeal enhancement (61%), and 8 showed nerve root enhancement (61%). Most enhancements did not match symptoms.

Pathological findings were found in 35 of 46 patients with contrast-enhanced MRIs. Key findings included cranial nerve, spinal nerve root, and leptomeningeal enhancement-often without clinical correlation. Spinal cord lesions were relatively frequent; cerebral infarction was rare. While key findings can support the diagnosis, their absence does not exclude NB.