J of Neurophysiological Monitoring

Approach to challenges in a case of cervical spine neuromonitoring - One case many learnings: Case report and review of literature

Poornima A Shah — 2025-08-05

Introduction: Intraoperative monitoring (IONM) during spine surgery can be fraught with challenges at various stages. Mal-occluded teeth can impede transcranial motor evoked potential (TcMEP) monitoring. Prone positioning may further compromise existing myelopathy. Tibial somatosensory evoked potentials (SSEP) may be absent at baseline due to the myelopathy. Certain total intravenous anesthesia (TIVA) can enhance the SSEPs. Here, a case is reported with such challenges that required customizing the IONM along with systematic interpretation of IONM signals, leading to a good outcome.

Case presentation: A 73-year-old male with severe cervical myelopathy underwent C3-7 decompression with fixation under IONM. He had a deep bite, which was covered with 3 soft bite blocks made of gauze placed between the molars and incisors. Preposition baseline bilateral Median SSEPs were well elicited, but bilateral baseline Tibial SSEPs were absent. Hence, Ulnar SSEPs were recorded to increase the yield of SSEP monitoring. Postposition TcMEPs were absent from the foot muscles and attenuated significantly in the other muscles. Reducing the neck extension restored the signals. The patient was given bolus etomidate prior to closure. A significant augmentation of SSEP amplitudes was noted. Etomidate can augment the amplitude of cortical SSEP recordings. The surgery was completed uneventfully, and the patient did not have any postoperative neurologic deficits.

Conclusion: This case highlights the importance of tailoring IONM methodology, like creating the soft bite block, so that TcMEP could be monitored, employing Ulnar SSEPs when Tibial SSEPs were unrecordable because it was below the level of the lesion, prompt recognition and correction of position-related signal alerts, and awareness of specific effects of anesthetic agents to avoid misinterpretation

Focused Ultrasound for Movement Disorders: Evidence from a Systematic Review of Efficacy and Safety

Cherrender Brown — 2025-08-23

This systematic review evaluates the clinical efficacy and safety of focused ultrasound (FU) as a non-invasive neurosurgical modality for treating movement disorders, including Parkinson’s disease (PD), essential tremor (ET), and dystonia. FU enables precise targeting of deep brain structures without incisions or implanted devices, using advanced imaging guidance to ablate or modulate dysfunctional neural circuits. Magnetic resonance-guided focused ultrasound (MRgFUS), the most widely adopted technique, is examined in detail to assess therapeutic outcomes and procedural characteristics.

Recent clinical studies consistently demonstrate that MRgFUS offers significant symptom relief, particularly in tremor reduction, with a favorable safety profile. Compared to conventional lesioning surgeries, MRgFUS produces smaller, more controlled lesions, minimizing adverse effects while preserving surrounding tissue integrity. In PD patients, improvements in tremors and bradykinesia have been observed following unilateral MRgFUS, which is currently considered the standard approach. However, bilateral applications remain under active investigation due to concerns regarding cumulative risk and long-term neurocognitive outcomes.

Overall, MRgFUS represents a promising and precise intervention for select movement disorders, with growing evidence supporting its integration into neurosurgical practice. Further longitudinal studies are warranted to refine patient selection criteria, optimize targeting strategies, and evaluate the durability of clinical benefits.

Evaluating Neurological Outcomes in Neonates Through SSEP: A Review of Current Evidence

Emma R Siddiqui — 2025-08-21

Somatosensory evoked potentials (SSEPs) are increasingly recognized as valuable tools for assessing neurological function, maturation, and prognostic outcomes in neonatal populations. This systematic review evaluates the efficacy and practicality of SSEPs in preterm infants (less than 32 weeks of gestation) and full-term infants up to 6 months of age.

Findings indicate that SSEPs provide reliable biomarkers for neural development and predictive indicators for conditions such as cerebral palsy (CP). Posterior tibial SSEP recordings demonstrated a positive predictive value of 83% for CP, outperforming cerebral ultrasound and visual evoked potentials (VEPs). SSEPs also show clinical relevance in intraoperative neurophysiological monitoring (IONM), particularly during procedures involving extracorporeal membrane oxygenation (ECMO).

Despite promising results, limitations persist, including small sample sizes, lack of longitudinal follow-up, and variability in recording protocols. Factors such as anesthesia response, physiological state, and gestational age contribute to inconsistencies. Future research should prioritize protocol standardization and multimodal integration with brainstem auditory evoked potentials (BAEPs), motor evoked potentials (MEPs), and electroencephalography (EEG). Longitudinal studies are essential to assess the enduring impact of early SSEP findings on neurodevelopmental trajectories. Establishing SSEPs as a routine diagnostic tool may enhance early intervention strategies and improve outcomes for at-risk neonatal populations.