Cauda Equina Syndrome Due To Dural Sac Shift with Engorgement of the Epidural Venous Plexus: Rare Complication After Lumbar Microdiscectomy.

BACKGROUND: Several postoperative complications related to lumbar microdiscectomy have been reported, including cauda equina syndrome. However, to the best of our knowledge, postoperative cauda equina syndrome resulting from dural sac shift with engorgement of the epidural venous plexus is yet to be reported. CASE DESCRIPTION: A 71-year-old male patient was referred to our hospital with a chief complaint of pain and sensory disturbance due to the lumbar disc herniation of L5-S1. Microdiscectomy was performed to treat the lumbar disc herniation, and his sensory disturbance improved. However, from postoperative day 2, he started to complain of motor weakness, sensory disturbance of S2, and difficulty in urination. Magnetic resonance imaging showed the dural sac shifted to the bone window of L5-S1 with engorgement of the ventral epidural venous plexus. The dural sac shift was thought to be the cause of postoperative cauda equina syndrome, and laminoplasty was chosen to return the dural sac shift into the spinal canal. Cauda equina syndrome completely resolved after laminoplasty. Postoperative magnetic resonance imaging showed the reduction of the dural sac into the spinal canal. The patient was discharged from the hospital without any residual clinical symptoms. CONCLUSION: We report a rare case of postoperative cauda equina syndrome due to dural sac shift and discuss the nascent mechanism of the dural sac shift focusing on anatomic features of the dural sac. We also propose laminoplasty as an option to treat dural sac shift with engorgement of the epidural venous plexus.

An Isolated Posterior Spinal Aneurysm Resection in Which Intraoperative Electrophysiological Monitoring Was Successfully Used to Locate the Lesion and to Detect the Possibility of Ischemic Complications.

STUDY DESIGN: A case report. OBJECTIVE: To report the successful use of electrophysiological monitoring in the surgical resection of a ruptured spinal artery (SA) aneurysm to locate the lesion, and to predict ischemic complications. SUMMARY OF BACKGROUND DATA: Isolated aneurysm of the posterior SA is an extremely rare event without established treatment and diagnosis procedures. Reports describing the surgical intervention of aneurysm of the posterior SA using electrophysiological monitoring are scant. METHODS: We performed the surgical resection of a dissected posterior SA aneurysm in an older patient who presented with spinal subarachnoid hemorrhage using intraoperative electrophysiological monitoring. RESULTS: Intraoperatively, motor evoked potentials decreased over 50% when a distal site of the lesion was clipped, indicating that site was the posterior SA. This lead to further investigation of the vascular anatomy around the lesion, which revealed the descending part of the posterior SA buried deeply in a thick thrombus. Clipping and resection were successful, and ischemia of the posterior SA was avoided. The postoperative clinical course was good, and there was no recurrence or long-term squeal. CONCLUSION: Electrophysiological monitoring might be useful when intraoperative anatomical findings of the hemodynamic structure are inadequate. Moreover, in our case, intraoperative changes in motor evoked potentials indicated the risk to occlude one of posterior SAs, although it is said that posterior circulation of spinal cord has ischemic tolerance.

Asymmetric bilateral effect of the supplementary motor area proper in the human motor system.

OBJECTIVE: This study aimed to clarify the function of human supplementary motor area proper (SMA) by the single-pulse electric stimulation method and its clinical usefulness for SMA mapping. METHODS: We studied five patients with epilepsy or brain tumour who underwent invasive functional mapping with subdural electrodes. Single-pulse electric stimulation of primary motor area (MI) and SMA was carried out through pairs of subdural electrodes, and motor-evoked potentials (MEPs) were recorded from surface electromyogram on both sides and also cortico-cortical-evoked potentials (CCEPs) from electrocorticogram. RESULTS: SMA stimulation elicited: (1) MEPs and following silent periods (SPs) in the contralateral upper and lower extremities, (2) SPs with or without minimal MEPs in the ipsilateral upper extremity and (3) CCEPs in the somatotopically corresponding region of the ipsilateral MI. Compared with MI stimulation, SMA stimulation required higher stimulus intensities (mean 14.2 mA (SMA) vs. 8.5 mA (MI)) to elicit MEPs and showed significantly longer onset latencies in upper extremity (range: 4-10 ms). CONCLUSIONS: The results demonstrated an asymmetric bilateral effect of human SMA upon the corticospinal pathway. SIGNIFICANCE: Single-pulse electric cortical stimulation would be clinically useful for distinguishing SMA from MI. The asymmetric bilateral effect of SMA might be conveyed through the direct descending pathway.

Evaluation of tongue sensory disturbance by somatosensory evoked magnetic fields following tongue stimulation.

Quantitative measurement is required in clinical situation for sensory disturbance of the tongue due to lingual nerve injury. To assess disabled sensory function of the tongue, somatosensory evoked magnetic fields (SEFs) were measured following electric tongue stimulation in 13 patients with sensory disturbance by unilateral lingual nerve injury and in 10 age-matched healthy volunteers. Affected- and healthy-sides of the tongue were stimulated separately with the same intensity. Although the healthy-side stimulation induced clear responses over the contralateral hemisphere of all participants, the affected-side stimulation evoked hardly traceable responses in 6 patients and no activity in the remaining 7 patients. We evaluated the cortical activity via activated root-mean-square (aRMS), which is the time-averaged activity between 10 and 150 ms from the 18-channel RMS over the contralateral hemisphere. The laterality index of aRMS, expressed as [(left-right)/(left+right)], was out of the pre-defined normal range (-0.287 to 0.337) in 12 patients, and within the range in all healthy volunteers. The test sensitivity and specificity of the procedure were 92.3% and 100%, respectively. Tongue SEFs are reproducible and objective method to evaluate sensory disturbance of the tongue.

Left anterior temporal cortex actively engages in speech perception: A direct cortical stimulation study.

Recent neuroimaging studies proposed the importance of the anterior auditory pathway for speech comprehension. Its clinical significance is implicated by semantic dementia or pure word deafness. Neurodegenerative or cerebrovascular nature, however, precluded precise localization of the cortex responsible for speech perception. Electrical cortical stimulation could delineate such localization by producing transient, functional impairment. We investigated engagement of the left anterior temporal cortex in speech perception by means of direct electrical cortical stimulation. Subjects were two partial epilepsy patients, who underwent direct cortical stimulation as a part of invasive presurgical evaluations. Stimulus sites were coregistered to presurgical 3D-MRI, and then to MNI standard space for anatomical localization. Separate from the posterior temporal language area, electrical cortical stimulation revealed a well-restricted language area in the anterior part of the superior temporal sulcus and gyrus (aSTS/STG) in both patients. Auditory sentence comprehension was impaired upon electrical stimulation of aSTS/STG. In one patient, additional investigation revealed that the functional impairment was restricted to auditory sentence comprehension with preserved visual sentence comprehension and perception of music and environmental sounds. Both patients reported that they could hear the voice but not understand the sentence well (e.g., heard as a series of meaningless utterance). The standard coordinates of this restricted area at left aSTS/STG well corresponded with the coordinates of speech perception reported in neuroimaging activation studies in healthy subjects. The present combined anatomo-functional case study, for the first time, demonstrated that aSTS/STG in the language dominant hemisphere actively engages in speech perception.