Epileptogenic but MRI-normal perituberal tissue in Tuberous Sclerosis Complex contains tuber-specific abnormalities

Introduction: Recent evidence has implicated perituberal, MRI-normal brain tissue as a possible source of seizures in tuberous sclerosis complex (TSC). Data on aberrant structural features in this area that may predispose to the initiation or progression of seizures are very limited. We used immunohistochemistry and confocal microscopy to compare epileptogenic, perituberal, MRI-normal tissue with cortical tubers. Results: In every sample of epileptogenic, perituberal tissue, we found many abnormal cell types, including giant cells and cytomegalic neurons. The majority of giant cells were surrounded by morphologically abnormal astrocytes with long processes typical of interlaminar astrocytes. Perituberal giant cells and astrocytes together formed characteristic “microtubers”. A parallel analysis of tubers showed that many contained astrocytes with features of both protoplasmic and gliotic cells. Conclusions: Microtubers represent a novel pathognomonic finding in TSC and may represent an elementary unit of cortical tubers. Microtubers and cytomegalic neurons in perituberal parenchyma may serve as the source of seizures in TSC and provide potential targets for therapeutic and surgical interventions in TSC

Epilepsy and Neuromodulation—Randomized Controlled Trials

Neuromodulation is a treatment strategy that is increasingly being utilized in those suffering from drug-resistant epilepsy who are not appropriate for resective surgery. The number of double-blinded RCTs demonstrating the efficacy of neurostimulation in persons with epilepsy is increasing. Although reductions in seizure frequency is common in these trials, obtaining seizure freedom is rare. Invasive neuromodulation procedures (DBS, VNS, and RNS) have been approved as therapeutic measures. However, further investigations are necessary to delineate effective targeting, minimize side effects that are related to chronic implantation and to improve the cost effectiveness of these devices. The RCTs of non-invasive modes of neuromodulation whilst showing much promise (tDCS, eTNS, rTMS), require larger powered studies as well as studies that focus at better targeting techniques. We provide a review of double-blinded randomized clinical trials that have been conducted for neuromodulation in epilepsy

Value of neurophysiologic monitoring in confirming indirect decompression of severe pediatric non-traumatic C1–C2 subluxation. A case report

Spinal cord compression from severe C1–C2 subluxation is a complex and challenging neurosurgical problem. A combination of surgical approaches may be required to decompress the spinal cord, including anterior transoral odontoidectomy, posterior cervical laminectomy, or indirect decompression by subluxation reduction. After decompression, an instrumented posterior fusion is then required to stabilize the spine. We report a case of a 13-year-old-girl who presented with spastic quadriparesis secondary to severe atlantoaxial subluxation, where intraoperative neurophysiologic monitoring (IOM) guided surgical decision making. The patient had congenital osseous abnormalities, including incomplete segmentation of C2 on C3, predisposing her to atlantoaxial dislocation. She underwent open surgical reduction of the C1–C2 subluxation with multi-modal intraoperative neurophysiologic guidance. Translaminar C2 screws and C1 lateral mass screws were placed bilaterally. Using a previously described distraction technique, we performed ventral translation of C2 relative to C1, thereby reducing the subluxation. Intraoperative radiographic images and neurophysiologic monitoring revealed significant improvements, confirming that adequate indirect decompression had been achieved. After subluxation reduction with intraoperative monitoring (IOM) improvements, we decided to proceed with a C1–C2 posterior fusion and avoid a cervical laminectomy and more extensive occipital cervical fusion procedure. After one year, the girl made a complete neurologic recovery and remains symptom-free 3 years post-surgery. Fusion to the occiput would have potentially caused greater morbidity in this patient. The neurophysiologic monitoring confirmed indirect decompression and served as a critical tool for the prediction of favorable neurologic outcome. Keywords: Atlanto-axial, Cervical traction, Intraoperative monitorin

Neurophysiological monitoring of the laryngeal adductor reflex during cerebellar-pontine angle and brainstem surgery.

OBJECTIVE To correlate intraoperative changes of the laryngeal adductor reflex (LAR), alone or in combination with corticobulbar motor evoked potential of vocal muscles (vocal-CoMEPs), with postoperative laryngeal function after posterior fossa and brainstem surgery. METHODS We monitored 53 patients during cerebellar-pontine angle and brainstem surgeries. Vocal-CoMEPs and LAR were recorded from an endotracheal tube with imbedded electrodes or hook-wires electrodes. A LAR significant change (LAR-SC) defined as ≥ 50% amplitude decrement or loss, was classified as either transient or permanent injury to the vagus or medullary pathways by the end of the surgery. RESULTS All patients with permanent LAR loss (n = 5) or LAR-SC (n = 3), developed postoperative laryngeal dysfunction such as aspiration/pneumonia and permanent swallowing deficits (5.6%). Vocal-CoMEP findings refined postoperative vocal motor dysfunction. All seven patients with transient LAR-SC or loss, reverted by changing the surgical approach, did not present permanent deficits. CONCLUSIONS Permanent LAR-SCs or loss correlated with postoperative laryngeal dysfunction and predicted motor and sensory dysfunction of the vagus nerve and reflexive medullary pathways. In contrast, a LAR-SC or loss, averted by a timely surgical adjustment, prevented irreversible damage. SIGNIFICANCE Monitoring of the LAR, with vocal-CoMEPs, may enhance safety to resect complex posterior fossa and brainstem lesions

Intracarotid amobarbital disrupts synchronous and nested oscillatory activity ipsilateral to injection

The mechanism of amobarbital action during the intracarotid amobarbital procedure is poorly understood. We report a patient case who underwent IAP while implanted with bilateral stereo-EEG. We analyzed the spectral power, phase amplitude coupling, and cluster-phase group synchrony during the procedure. Delta and gamma power increased bilaterally. By contrast, phase amplitude coupling increased only ipsilateral to the injection. Similarly, 4–30 Hz cluster-phase group synchrony declines and gamma cluster-phase group synchrony increases only ipsilateral to the injection. These results suggest that a possible additional mechanism for amobarbital action in the IAP is by altering the precise timing of oscillatory activity. Keywords: Intracarotid amobarbital procedure, Wada, Stereo-EEG, Synchrony, Phase amplitude coupling, Epilepsy surger