Utility of temporally-extended signal space separation algorithm for magnetic noise from vagal nerve stimulators

Yosuke Kakisaka, John C. Mosher, Zhong I. Wang, Kazutaka Jin, Anne Sophie Dubarry, Andreas V. Alexopoulos, Richard C. Burgess

Research output: Contribution to journalArticlepeer-review

21 Citations (Scopus)


Objective: To evaluate the utility of a temporally-extended signal space separation algorithm (tSSS) for patients with vagal nerve stimulator (VNS). Methods: We evaluated median nerve somatosensory evoked responses (SER) of magnetoencephalography (MEG) in 27 VNS patients (48 sides) with/without tSSS processing. We classified SER dipoles as 'acceptable' if: (A) the location of the dipole was in the expected location in the central sulcus, and (B) the goodness of fit value (GOF) was greater than 80%. We evaluated (1) the number of sides which produced acceptable dipoles in each dataset (i.e. with/without tSSS processing), and in cases where the both data produced reliable dipoles, (2) compared their GOFs and the 95% confidence volumes (CV) (mm3). Statistical differences in the GOF and CV between with/without tSSS conditions were determined by paired t test. Results: Only 11 (23%) responses had reliable dipoles without tSSS processing, while all 48 (100%) had acceptable dipoles under tSSS processing. Additionally, the latter group had significantly higher GOF (increased by 7% on average) and lower CV (mean decrease of 200mm3) than the former (p<0.01). Conclusions: Processing with tSSS quantitatively improves dipole fitting of known sources in VNS patients. Significance: This algorithm permits satisfactory MEG testing in the relatively commonly encountered epilepsy patient with VNS.

Original languageEnglish
Pages (from-to)1277-1282
Number of pages6
JournalClinical Neurophysiology
Issue number7
Publication statusPublished - 2013 Jul


  • A temporally-extended signal space separation algorithm
  • Magnetoencephalography
  • Vagal nerve stimulator

ASJC Scopus subject areas

  • Sensory Systems
  • Neurology
  • Clinical Neurology
  • Physiology (medical)


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