Kim Ds

The incidence of and risk factors for ischemic complications after microsurgical clipping of unruptured middle cerebral artery aneurysms and the efficacy of intraoperative monitoring of somatosensory evoked potentials: A retrospective study

OBJECTIVES Ischemic complications (ICs) account for 6.7% after microsurgical clipping of unruptured intracranial aneurysms. This study aimed to evaluate the efficacy of somatosensory evoked potential (SSEP) monitoring during microsurgical clipping of unruptured middle cerebral artery (MCA) aneurysms and evaluate the incidence of and risk factors for ischemic complications after clipping of unruptured MCA aneurysms. PATIENTS AND METHODS Herein, 1208 patients with cerebral aneurysms and treated with microsurgical clipping between May 2003 and February 2015 were enrolled. Those with multiple aneurysms, history of head trauma, subarachnoid hemorrhage, bypass and/or endovascular treatment, and intraoperative rupture were excluded. Subsequently, 411 patients with single unruptured MCA aneurysms treated with simple microsurgical clipping were enrolled. Patients were divided into two groups based on the application of SSEP monitoring during surgery. RESULTS The IC rate was 0.9% and 5.6% in the SSEP and non-SSEP groups, respectively. Univariate analysis revealed that age≥62.5years, aneurysm size≥4.15mm, temporary clipping, history of hyperlipidemia and stroke, and no-SSEP monitoring were risk factors for ICs. Multivariate logistic regression analysis showed that age≥62.5years (odds ratio [OR]=7.7; 95% confidence interval [95% CI]=1.5-37.7; P=0.011), previous stroke (OR=26.8, 95% CI=2.4-289.2, P=0.007), and inversely SSEP monitoring (OR=0.14, 95% CI 0.02-0.72, P=0.019) were independent risk factors for ICs. CONCLUSION Clinicians should consider the possibility of IC during microsurgical clipping of unruptured MCA aneurysms in patient≥62.5years and/or a history of stroke. Intraoperative SSEP monitoring is an effective and feasible tool for preventing IC.

Split-hand phenomenon in amyotrophic lateral sclerosis: A motor unit number index study

Introduction: The split‐hand phenomenon refers to preferential wasting of the thenar muscles with relative sparing of the hypothenar muscles in amyotrophic lateral sclerosis (ALS). Methods: We compared the split‐hand index (SI) calculated from the compound muscle action potential (CMAP; SICMAP) with that calculated from the motor unit number index (MUNIX; SIMUNIX). We performed MUNIX on the abductor policis brevis (APB), first dorsal interosseous (FDI), and abductor digiti minimi (ADM) muscles of 39 ALS patients and 40 age‐matched, healthy controls. SI is derived by multiplying the CMAP (or MUNIX) recorded over the APB and FDI and dividing by the CMAP (or MUNIX) recorded over the ADM. Results: Receiver‐operating characteristic curve analysis revealed good diagnostic accuracy for both indices, but better performance of SIMUNIX than SICMAP. Conclusion: SIMUNIX and SICMAP were useful in differentiating ALS patients from healthy controls. SIMUNIX appears to be a better electrophysiological marker than SICMAP for the split‐hand sign of ALS. Muscle Nerve 53: 885–888, 2016

Differences in Multimodality Intraoperative Neurophysiological Monitoring Changes Between Spinal Intramedullary Ependymoma and Hemangioblastoma.

Introduction: Intraoperative neurophysiological monitoring using transcranial muscle motor evoked potentials (MEPs) and somatosensory evoked potentials is an established method for intramedullary spinal cord tumor surgery. Ependymomas and hemangioblastomas arise in different anatomic locations and require different surgical techniques. The aim of our study was to assess differences in intraoperative neurophysiological monitoring findings between ependymoma and hemangioblastoma. Methods: Fifty-six limbs from 16 patients diagnosed with ependymoma and 18 limbs from six patients with hemangioblastoma were included. The alarm criterion for MEPs was a 50% decrease in amplitude, whereas for somatosensory evoked potentials, it was a 50% decrease in amplitude and/or a 10% delay in latency. Results: We found that 14 of the 56 ependymoma limbs (25.9%) and 8 of the 18 hemangioblastoma limbs (44.4%) showed MEP decrement during surgery. Eight limbs of patients with ependymoma (57.1%) and one limb of a patient with hemangioblastoma (12.5%) did not show recovery of MEPs at the end of surgery. Among those who showed recovery of MEPs, six ependymoma (10.7%) and six hemangioblastoma (33.3%) limbs did not show postoperative motor deficits (P = 0.04). Finally, 11 limbs of patients with ependymoma and one limb of a patient with hemangioblastoma showed postoperative weakness. Conclusions: In our study, the incidence of transient changes in MEPs was higher in hemangioblastoma than in ependymoma. Our data suggest that it may be necessary to consider tumor features and the type of surgical technique used, particularly when interpreting intraoperative neurophysiologic monitoring profiles of intramedullary spinal cord tumors such as ependymomas and hemangioblastomas.

Intraoperative Motor-Evoked Potential Disappearance versus Amplitude-Decrement Alarm Criteria During Cervical Spinal Surgery: A Long-Term Prognosis

Background and Purpose We studied the clinical significance of amplitude-reduction and disappearance alarm criteria for transcranial electric muscle motor-evoked potentials (MEPs) during cervical spinal surgery according to different lesion locations [intramedullary (IM) vs. nonintramedullary (NIM)] by evaluating the long-term postoperative motor status. Methods In total, 723 patients were retrospectively dichotomized into the IM and NIM groups. Each limb was analyzed respectively. One hundred and sixteen limbs from 30 patients with IM tumors and 2,761 limbs from 693 patients without IM tumors were enrolled. Postoperative motor deficits were assessed up to 6 months after surgery. Results At the end of surgery, 61 limbs (2.2%) in the NIM group and 14 limbs (12.1%) in the IM group showed MEP amplitudes that had decreased to below 50% of baseline, with 13 of the NIM limbs (21.3%) and 2 of the IM limbs (14.3%) showing MEP disappearance. Thirteen NIM limbs (0.5%) and 5 IM limbs (4.3%) showed postoperative motor deficits. The criterion for disappearance showed a lower sensitivity for the immediate motor deficit than did the criterion for amplitude decrement in both the IM and NIM groups. However, the disappearance criterion showed the same sensitivity as the 70%-decrement criterion in IM (100%) and NIM (83%) surgeries for the motor deficit at 6 months after surgery. Moreover, it has the highest specificity for the motor deficits among diverse alarm criteria, from 24 hours to 6 months after surgery, in both the IM and NIM groups. Conclusions The MEP disappearance alarm criterion had a high specificity in predicting the long-term prognosis after cervical spinal surgery. However, because it can have a low sensitivity in predicting an immediate postoperative deficit, combining different MEP alarm criteria according to the aim of specific instances of cervical spinal surgery is likely to be useful in practical intraoperative monitoring.

Multi-channel motor evoked potential monitoring during anterior cervical discectomy and fusion

Highlights • We analyzed 200 patients undergoing ACDF with multi-channel MEP monitoring.• Multi-channel MEP monitoring showed a higher diagnostic accuracy for long tract and segmental injury.• Multi-channel MEP monitoring could be useful for single- and multi-level ACDF.

Is thyrotoxic periodic paralysis a disease caused by muscle membrane dysfunction

Introduction: Thyrotoxic periodic paralysis (TPP) is characterized by recurrent episodes of reversible paralysis with hyperthyroidism. It is clinically similar to hypokalemic periodic paralysis (HOPP), which features significant ion‐channel dysfunction and reduced muscle fiber conduction velocity (MFCV). However, the muscle membrane function in TPP is not known. Methods: For 13 patients with TPP and 15 age‐matched controls, clinical assessment and serial neurophysiological testing, including nerve conduction, prolonged exercise (PE) testing, and MFCV. were performed. Results: MFCV values were elevated up to 1 year from the paralytic attack in TPP patients. In the group with a positive PE test, MFCV values were higher. There was no significant relationship between MFCV values and either hypokalemia or hyperthyroidism. Conclusions: Although clinical manifestations in TPP are similar to those observed in HOPP, TPP appears to feature an alternate pathogenic mechanism. Specifically, MFCV values increased rather than decreased. Further studies are needed to support these findings. Muscle Nerve, 2016 Muscle Nerve 56: 780–786, 2017

Corticobulbar motor evoked potentials from tongue muscles used as a control in cervical spinal surgery

Highlights • The corticobulbar MEPs from tongue muscles were successfully elicited from 96% of the tested patients.• Corticobulbar MEPs from tongue muscles were monitorable from the baseline in 92% of the tested hypoglossal nerves.• Corticobulbar MEPs from the tongue muscle might be useful as controls in cervical spine surgery.

SU-E-J-34: Clinical Evaluation of Targeting Accuracy and Tractogrphy Delineation of Radiosurgery.

PURPOSE Focal radiosurgery is a common treatment modality for trigeminal neuralgia (TN), a neuropathic facial pain condition. Assessment of treatment effectiveness is primarily clinical, given the paucity of investigational tools to assess trigeminal nerve changes. The efficiency of radiosurgery is related to its highly precise targeting. We assessed clinically the targeting accuracy of radiosurgery with Gamma knife. We hypothesized that trigeminal tractography provides more information than 2D-MR imaging, allowing detection of unique, focal changes in the target area after radiosurgery. METHODS Sixteen TN patients (2 females, 4 male, average age 65.3 years) treated with Gamma Knife radiosurgery, 40 Gy/50% isodose line underwent 1.5Tesla MR trigeminal nerve . Target accuracy was assessed from deviation of the coordinates of the target compared with the center of enhancement on post MRI. Radiation dose delivered at the borders of contrast enhancement was evaluated RESULTS: The median deviation of the coordinates between the intended target and the center of contrast enhancement was within 1mm. The radiation doses fitting within the borders of the contrast enhancement the target ranged from 37.5 to 40 Gy. Trigeminal tractography accurately detected the radiosurgical target. Radiosurgery resulted in 47% drop in FA values at the target with no significant change in FA outside the target, suggesting that radiosurgery primarily affects myelin. Tractography was more sensitive, since FA changes were detected regardless of trigeminal nerve enhancement CONCLUSION: The median deviation found in clinical assessment of gamma knife treatment for TN Is low and compatible with its high rate of efficiency. DTI parameters accurately detect the effects of focal radiosurgery on the trigeminal nerve, serving as an in vivo imaging tool to study TN. This study is a proof of principle for further assessment of DTI parameters to understand the pathophysiology of TN and treatment effects.