Canalicular magnetic stimulation lacks specificity to differentiate idiopathic facial palsy from borreliosis in children

ObjectiveTo investigate the role of transcranial magnetic stimulation (TMS) to differentiate between idiopathic facial nerve palsy (iFNP) and facial nerve palsy due to borreliosis (bFNP).Patients and methodsTranscranial and intracanalicular magnetic and peripheral electrical stimulation of the facial nerve together with clinical grading according to the House and Brackmann scale were performed in 14 children and adolescents with facial palsy (median age 11.5 yr, range 4.6–16.5 yr). Serum and cerebrospinal fluid (CSF) were evaluated for antibodies against Borrelia burgdorferi and CSF cell count, glucose and protein content were screened with methods of routine laboratory testing. Data of patients were compared with normal values established in 10 healthy subjects (median age 10.2 yr, range 5.1–15.3 yr).ResultsPatients with iFNP showed a significant decrease in MEP amplitude to canalicular magnetic stimulation compared with healthy controls (p=0.03). However, MEP amplitude did not discriminate sufficiently between the two groups, because the ranges of dispersion of MEP amplitudes overlapped. Patients with bFNP had normal MEP amplitudes to canalicular magnetic stimulation compared with normal subjects.ConclusionDiagnostic assessment by TMS failed to provide a reliable diagnostic criterion for distinguishing between iFNP and bFNP in children and adolescents.