General

OBJECTIVE To describe the technical parameters and findings of blink reflex (BR) and laryngeal adductor reflex (LAR) in children during the intraoperative neuromonitoring (IONM) of brainstem and posterior fossa surgery. METHODS Retrospective review of 17 patients (1-16 years old) who underwent posterior fossa surgery with multimodal IONM, including BR and/or LAR (tube-based methodology with adhesive electrodes), CoMEPs, and free-running EMG. We analyzed the elicitability of each modality, number of intraoperative events and the first modality to raise an alarm.

OBJECTIVE: Cervical Microsurgical DREZotomy (MDT) aims to relieve neuropathic pain in patients with brachial plexus injury by destroying the nociceptive neural structures and the hyperactive neurons in the dorsal horn. Useful information can be harvested by intraoperative mapping and testing of cervical C4–Th1 roots. METHODS: 18 patients with intractable pain due to brachial plexus injury underwent cervical MDT. 216 roots were tested (6 ventral and 6 dorsal roots for each patient).

Objective: Even for an experienced neurophysiologist, it is challenging to look at a single graph of an unlabeled motor evoked potential (MEP) and identify the corresponding muscle. We demonstrate that supervised machine learning (ML) can successfully perform this task and surpass trained neurophysiologists. Methods: Intraoperative MEP data from surgery on 36 patients was included for the classification task with 4 muscles: Extensor digitorum (EXT), abductor pollicis brevis (APB), tibialis anterior (TA) and abductor hallucis (AH).

Objective Pedicle screw stimulation (PSS) is used during scoliosis surgery to warn about screw malposition and impact on spinal neural structures. In thoracic segments, PSS may stimulate nerve roots, spinal cord or both. Single electrical pulse is sufficient to stimulate nerve roots, and train of pulses is needed for spinal cord.

OBJECTIVE: The influence of anesthetic depth on Tc-mMEP (transcranial electrical stimulation muscle motor-evoked-potential) characteristics is not known. Anesthetic depth is commonly quantified with the bispectral-index (BIS). The association of stepwise changes in BIS on Tc-mMEP characteristics in an adolescent patient is described. METHODS: A female with idiopathic scoliosis was included in an ongoing prospective observational study examining the effects of depth of anesthesia on Tc-mMEPs. Preoperative neurological examination showed no abnormalities.

Objective: Neurological deficits, such as cerebral palsy (CP) can hinder the feasibility of motor evoked potentials (MEPs) and somatosensory evoked potentials (SSEPs). This study investigated patient characteristics predicting feasibility of monitoring in neuromuscular scoliosis patients. Methods: We retrospectively included 82 neuromuscular scoliosis patients (age 14.3 years± 3.35). For MEP stimulation, we used voltage stimulation, 75µs pulsewidth, and double train stimulation whenever necessary (n=38). Tibial nerve SSEPs were recorded at both cervical and cortical sites.

Objective: We demonstrate the case series in which the intra-operative central motor conduction time (CMCT) was measured during untethering surgery to provide additional information about spinal cord function, distinct from peripheral nervous system.

Objective: Microvascular decompression (MVD) of hemifacial spasm (HFS) may be guided by IONM. Described techniques include lateral spread response (LSR), blink reflex (BR), corticobulbar motor evoked potentials (CoMEPs), facial nerve F-wave and AEP. Although the BR is widely used, the intraoperative disappearance of blink synkinesis in lower facial nerve branches is scarcely described₁-₂. We present a case of MVD of HFS adding blink synkinesis assessment to the standard modalities to test hyper-excitability.

Background: Epidermoid cysts of the cavernous sinus are rare benign tumours. Their closeness to neurovascular structures carries a certain morbidity when it comes to plan their radical removal, which has been reduced by the development of minimally invasive approaches, such as modern endoscopic techniques. Still, for cases where wider exposure of the workspace is required, the use of intraoperative neurophysiologic monitoring (IONM) gains value. Methods: We present the case of a 19 years old woman with acute photopsia and headache.

Objective: The aim of this project is to modulate the pulse-width (PWM) during stimulation of pedicle screws, and record the response thresholds associated with each PWM setting. The relationship between pulse-width and threshold will then be analyzed Methods: Upon completion of the pedicle screw placements, each screw will be stimulated utilizing three different pulse-width settings, 0.4 milliseconds, 0.2 milliseconds, and 0.05 milliseconds. The stimulation intensity required to elicit a compound muscle action potential (CMAP) will be recorded for each pulse-width parameter.