Unexpected Cause of Progressive Decrease in Sensorimotor Function of the Left Leg

Background/Purpose: In childhood, progressive unilateral decrease in sensorimotor function of the lower extremity is rare. Therefore, thorough exploration is required.

Methods/Case Report: A 13-year-old girl, pain and progressive numbness of left calf and lower leg since 1 month. Frequent falls due to impossibility of left leg elevation. No fever, no further symptoms, no recollection of trauma, tick bite/erythema migrans. Family history: grandfather with multiple sclerosis.

Results: Physical examination: left PTR, ATR absent, muscular strength: left hip, plantar flexion left foot ⅖, elevation of left foot impossible when standing, gait unstable. CSF: cell count 24/3, lymphocytes 24/3, granulocytes 0/3, erythrocytes 3,296/3, protein 1,935 mg/L (elevated) lactate 1.51 mmol/L, glucose 55 mg/dL. Oligoclonal bands: positive immunology: Aquaporin-4 AB: negative, Anti-MOG AB: negative, Ganglioside AB: negative infectiology: Borrelia-specific antibodies (serum): IgG 189 AU/mL (< 10), IgM 36 AU/mL (< 18). (CSF): IgG ASI 3.48 (<1.5), IgM ASI 2.46 (<1.5), Borrelia-Immunoblot: positive electroneurography (SEP left tibial nerve): conduction block, decrease of nerve conduction velocity (32.9 m/s) cMRI/MRI spine: no pathology.

Conclusions: In this case, symptoms were most likely due to neuroborreliosis. This is a rare cause for plexus neuritis in childhood and adolescence, but can be treated very efficiently. Since oligoclonal bands can here be also positive, it is essential to rule out multiple sclerosis. Our patient was asymptomatic with normal gait after administration of antibiotics (cefotaxime/doxycycline) and immunoglobulins.