The Neurodiagnostic Journal最新文献

Medically refractory seizures affect one-third of patients with epilepsy (PwE), for whom epilepsy surgery is considered. Video electroencephalography (vEEG) monitoring is a fundamental tool for pre-operative seizure localization. Facial and cranial myogenic artifacts can obscure vEEG findings, thus interfering with seizure localization. Studies have shown the beneficial effects of botulinum toxin type A (BTX-A) injection into cranial muscles for reducing myogenic artifacts. This longitudinal study aimed to assess the effects of BTX-A injection on these artifacts. Twenty-two patients with medically refractory hypermotor seizures with daily seizure frequency and undetermined epilepsy localization were included in this study and underwent Dysport® injection (200 units) into the frontotemporal region. vEEG recordings were performed at baseline (one week before the injection), and at three days and six days post-injection. Before and after the injection, the amplitudes of myogenic artifacts were compared during various states (ictal, blinking, chewing, bruxism, head lateralization, scowling, talking, and yawning). BTX-A injection significantly reduced the amplitudes of EEG myogenic artifacts, except during blinking (day three) and talking (days three and six). On day six, significant reduction in EEG myogenic artifacts were noted during blinking, chewing, and bruxism for the greatest number of patients (95.5%, 90.9%, 81.8%), while significant reductions in EEG myogenic artifacts during talking, head lateralization, and ictal phase were associated with the least number of patients (22.7%, 36.3%, and 40.9%). Therefore, BTX-A injection could be a convenient method for filtering myogenic contamination, improving EEG interpretation, and facilitating seizure localization in patients with medically refractory seizures.

The use of cervical facet spacers has shown favorable clinical results in the treatment of cervical spondylotic disease; however, there are limited data regarding neurological complications associated with the procedure. This case report demonstrates the specificity of multi-myotomal motor evoked potentials (MEPs) in detecting acute postoperative C5 palsy following placement of facet spacers. A posterior cervical fusion with decompression and instrumentation involving DTRAX (Providence Medical Technology; Lafayette, CA) was used to treat a patient with cervical stenosis and myelopathy. Intraoperative neurophysiological monitoring (IONM) consisting of MEPs, somatosensory evoked potentials (SSEPs), and free-run electromyography (EMG), was used throughout the procedure. Immediately following the placement of the DTRAX spacers at C4-5, a decrease in amplitudes from the right deltoid and biceps MEP recordings (>65%) was detected. All other IONM modalities remained stable; it is noteworthy that there was an absence of mechanically elicited EMG. A novel post-alert regression analysis trending algorithm of MEP amplitudes confirmed the visual alert. This warning along with an intraoperative computed tomography (CT) scan of the cervical spine subsequently resulted in the decision to remove one of the facet spacers. Surgical intervention did not result in recovery of the aforementioned MEP recordings, which remained attenuated at the time of wound closure. Postoperatively, the patient exhibited an immediate right C5 palsy (2/5). A post-surgery application of the trending algorithm demonstrated that it correlated to the visual alert until the end of monitoring.

Anastomoses between the median and ulnar nerves are commonly found on electrodiagnostic studies. These anastomoses are usually asymptomatic and are not discovered until nerve injuries occur that lead to unusual motor or sensory deficits. Their presence can cause difficulties in the interpretation of electrophysiological findings for the diagnosis of neuropathies and suppose a risk of iatrogenic damage during surgical procedures. We describe a rare case of bilateral Martin Gruber and Marinacci anastomosis, associated with median and ulnar nerve injuries in the carpal tunnel and Guyon's canal, respectively. The detailed anatomical knowledge of these anastomosis allows the electromyographist to identify them correctly, facilitating the interpretation of the findings and, incidentally, preventing iatrogenic injuries.

Current intraoperative somatosensory evoked potential (SSEP) guidelines recommend bipolar stimulation with the anode at or near the crease of the wrist and the cathode 2-4 cm proximal to the anode for median nerve SSEPs. The rationale for this cathode proximal bipolar configuration appears to be the avoidance of anodal blocking; however, there is a paucity of experimental support for the existence of anodal blocking. Evidence that bipolar stimulation preferentially drives stimulation from the cathode better than monopolar cathodal or monopolar anodal in peripheral nerves in human neurophysiology is also lacking. This study compared anode proximal to anode distal bipolar stimulation of median nerve SSEPs and the efficacy of monopolar cathode to monopolar anode stimulation in generating median, ulnar, and tibial nerve SSEPs. No difference in median nerve cortical SSEP amplitude was observed between anode proximal and anode distal bipolar stimulation at supramaximal stimulation suggesting cathode proximal bipolar is equal to anode proximal bipolar stimulation at supramaximal intensity. This data suggests that anodal blocking does not occur in intraoperative SSEPs. Furthermore, no differences were observed in ulnar, median, and tibial nerve SSEP cortical or subcortical amplitudes and latencies between monopolar cathodal or monopolar anodal stimulation suggesting monopolar cathode and anode stimulation are equally effective at evincing intraoperative SSEPs at supramaximal intensity.